WorldWideScience

Sample records for repeated visual search

  1. Visual Scan Adaptation During Repeated Visual Search

    Science.gov (United States)

    2010-01-01

    locating the target, such as fixation durations and the number of fixations to find the target (Hidalgo- Sotelo , Oliva, & Torralba, 2005). Adaptations...6, doi:10.1167/ 3.1.6. [PubMed] [Article] Hidalgo- Sotelo , B., Oliva, A., & Torralba, A. (2005). Human learning of contextual priors for object search

  2. RepeatsDB 2.0: improved annotation, classification, search and visualization of repeat protein structures

    Science.gov (United States)

    Paladin, Lisanna; Hirsh, Layla; Piovesan, Damiano; Andrade-Navarro, Miguel A.; Kajava, Andrey V.; Tosatto, Silvio C.E.

    2017-01-01

    RepeatsDB 2.0 (URL: http://repeatsdb.bio.unipd.it/) is an update of the database of annotated tandem repeat protein structures. Repeat proteins are a widespread class of non-globular proteins carrying heterogeneous functions involved in several diseases. Here we provide a new version of RepeatsDB with an improved classification schema including high quality annotations for ∼5400 protein structures. RepeatsDB 2.0 features information on start and end positions for the repeat regions and units for all entries. The extensive growth of repeat unit characterization was possible by applying the novel ReUPred annotation method over the entire Protein Data Bank, with data quality is guaranteed by an extensive manual validation for >60% of the entries. The updated web interface includes a new search engine for complex queries and a fully re-designed entry page for a better overview of structural data. It is now possible to compare unit positions, together with secondary structure, fold information and Pfam domains. Moreover, a new classification level has been introduced on top of the existing scheme as an independent layer for sequence similarity relationships at 40%, 60% and 90% identity. PMID:27899671

  3. Visual search

    NARCIS (Netherlands)

    Toet, A.; Bijl, P.

    2003-01-01

    Visual search, with or without the aid of optical or electro-optical instruments, plays a significant role in various types of military and civilian operations (e.g., reconnaissance, surveillance, and search and rescue). Advance knowledge of human visual search and target acquisition performance is

  4. Putamen Activation Represents an Intrinsic Positive Prediction Error Signal for Visual Search in Repeated Configurations.

    Science.gov (United States)

    Sommer, Susanne; Pollmann, Stefan

    2016-01-01

    We investigated fMRI responses to visual search targets appearing at locations that were predicted by the search context. Based on previous work in visual category learning we expected an intrinsic reward prediction error signal in the putamen whenever the target appeared at a location that was predicted with some degree of uncertainty. Comparing target appearance at locations predicted with 50% probability to either locations predicted with 100% probability or unpredicted locations, increased activation was observed in left posterior putamen and adjacent left posterior insula. Thus, our hypothesis of an intrinsic prediction error-like signal was confirmed. This extends the observation of intrinsic prediction error-like signals, driven by intrinsic rather than extrinsic reward, to memory-driven visual search.

  5. Putamen Activation Represents an Intrinsic Positive Prediction Error Signal for Visual Search in Repeated Configurations

    Science.gov (United States)

    Sommer, Susanne; Pollmann, Stefan

    2016-01-01

    We investigated fMRI responses to visual search targets appearing at locations that were predicted by the search context. Based on previous work in visual category learning we expected an intrinsic reward prediction error signal in the putamen whenever the target appeared at a location that was predicted with some degree of uncertainty. Comparing target appearance at locations predicted with 50% probability to either locations predicted with 100% probability or unpredicted locations, increased activation was observed in left posterior putamen and adjacent left posterior insula. Thus, our hypothesis of an intrinsic prediction error-like signal was confirmed. This extends the observation of intrinsic prediction error-like signals, driven by intrinsic rather than extrinsic reward, to memory-driven visual search. PMID:27867436

  6. Collaboration during visual search.

    Science.gov (United States)

    Malcolmson, Kelly A; Reynolds, Michael G; Smilek, Daniel

    2007-08-01

    Two experiments examine how collaboration influences visual search performance. Working with a partner or on their own, participants reported whether a target was present or absent in briefly presented search displays. We compared the search performance of individuals working together (collaborative pairs) with the pooled responses of the individuals working alone (nominal pairs). Collaborative pairs were less likely than nominal pairs to correctly detect a target and they were less likely to make false alarms. Signal detection analyses revealed that collaborative pairs were more sensitive to the presence of the target and had a more conservative response bias than the nominal pairs. This pattern was observed even when the presence of another individual was matched across pairs. The results are discussed in the context of task-sharing, social loafing and current theories of visual search.

  7. Visually guided haptic search

    NARCIS (Netherlands)

    Plaisier, M.A.; Kappers, A.M.L.; Bergmann Tiest, W.M.; Ernst, M.O.

    2010-01-01

    In this study, we investigate the influence of visual feedback on haptic exploration. A haptic search task was designed in which subjects had to haptically explore a virtual display using a force-feedback device and to determine whether a target was present among distractor items. Although the targe

  8. Perceptual training for visual search.

    Science.gov (United States)

    Schuster, David; Rivera, Javier; Sellers, Brittany C; Fiore, Stephen M; Jentsch, Florian

    2013-01-01

    People are better at visual search than the best fully automated methods. Despite this, visual search remains a difficult perceptual task. The goal of this investigation was to experimentally test the ways in which visual search performance could be improved through two categories of training interventions: perceptual training and conceptual training. To determine the effects of each training on a later performance task, the two types of trainings were manipulated using a between-subjects design (conceptual vs. perceptual × training present vs. training absent). Perceptual training led to speed and accuracy improvements in visual search. Issues with the design and administration of the conceptual training limited conclusions on its effectiveness but provided useful lessons for conceptual training design. The results suggest that when the visual search task involves detecting heterogeneous or otherwise unpredictable stimuli, perceptual training can improve visual search performance. Similarly, careful consideration of the performance task and training design is required to evaluate the effectiveness of conceptual training. Visual search is a difficult, yet critical, task in industries such as baggage screening and radiology. This study investigated the effectiveness of perceptual training for visual search. The results suggest that when visual search involves detecting heterogeneous or otherwise unpredictable stimuli, perceptual training may improve the speed and accuracy of visual search.

  9. Cascade category-aware visual search.

    Science.gov (United States)

    Zhang, Shiliang; Tian, Qi; Huang, Qingming; Gao, Wen; Rui, Yong

    2014-06-01

    Incorporating image classification into image retrieval system brings many attractive advantages. For instance, the search space can be narrowed down by rejecting images in irrelevant categories of the query. The retrieved images can be more consistent in semantics by indexing and returning images in the relevant categories together. However, due to their different goals on recognition accuracy and retrieval scalability, it is hard to efficiently incorporate most image classification works into large-scale image search. To study this problem, we propose cascade category-aware visual search, which utilizes weak category clue to achieve better retrieval accuracy, efficiency, and memory consumption. To capture the category and visual clues of an image, we first learn category-visual words, which are discriminative and repeatable local features labeled with categories. By identifying category-visual words in database images, we are able to discard noisy local features and extract image visual and category clues, which are hence recorded in a hierarchical index structure. Our retrieval system narrows down the search space by: 1) filtering the noisy local features in query; 2) rejecting irrelevant categories in database; and 3) preforming discriminative visual search in relevant categories. The proposed algorithm is tested on object search, landmark search, and large-scale similar image search on the large-scale LSVRC10 data set. Although the category clue introduced is weak, our algorithm still shows substantial advantages in retrieval accuracy, efficiency, and memory consumption than the state-of-the-art.

  10. Supporting Web Search with Visualization

    Science.gov (United States)

    Hoeber, Orland; Yang, Xue Dong

    One of the fundamental goals of Web-based support systems is to promote and support human activities on the Web. The focus of this Chapter is on the specific activities associated with Web search, with special emphasis given to the use of visualization to enhance the cognitive abilities of Web searchers. An overview of information retrieval basics, along with a focus on Web search and the behaviour of Web searchers is provided. Information visualization is introduced as a means for supporting users as they perform their primary Web search tasks. Given the challenge of visualizing the primarily textual information present in Web search, a taxonomy of the information that is available to support these tasks is given. The specific challenges of representing search information are discussed, and a survey of the current state-of-the-art in visual Web search is introduced. This Chapter concludes with our vision for the future of Web search.

  11. Haptic Influence on Visual Search

    Directory of Open Access Journals (Sweden)

    Marcia Grabowecky

    2011-10-01

    Full Text Available Information from different sensory modalities influences perception and attention in tasks such as visual search. We have previously reported identity-based crossmodal influences of audition on visual search (Iordanescu, Guzman-Martinez, Grabowecky, & Suzuki, 2008; Iordanescu, Grabowecky, Franconeri, Theeuwes, and Suzuki, 2010; Iordanescu, Grabowecky and Suzuki, 2011. Here, we extend those results and demonstrate a novel crossmodal interaction between haptic shape information and visual attention. Manually-explored, but unseen, shapes facilitated visual search for similarly-shaped objects. This effect manifests as a reduction in both overall search times and initial saccade latencies when the haptic shape (eg, a sphere is consistent with a visual target (eg, an orange compared to when it is inconsistent with a visual target (eg, a hockey puck]. This haptic-visual interaction occurred even though the manually held shapes were not predictive of the visual target's shape or location, suggesting that the interaction occurs automatically. Furthermore, when the haptic shape was consistent with a distracter in the visual search array (instead of with the target, initial saccades toward the target were disrupted. Together, these results demonstrate a robust shape-specific haptic influence on visual search.

  12. Visual Representation Determines Search Difficulty: Explaining Visual Search Asymmetries

    Directory of Open Access Journals (Sweden)

    Neil eBruce

    2011-07-01

    Full Text Available In visual search experiments there exist a variety of experimental paradigms in which a symmetric set of experimental conditions yields asymmetric corresponding task performance. There are a variety of examples of this that currently lack a satisfactory explanation. In this paper, we demonstrate that distinct classes of asymmetries may be explained by virtue of a few simple conditions that are consistent with current thinking surrounding computational modeling of visual search and coding in the primate brain. This includes a detailed look at the role that stimulus familiarity plays in the determination of search performance. Overall, we demonstrate that all of these asymmetries have a common origin, namely, they are a consequence of the encoding that appears in the visual cortex. The analysis associated with these cases yields insight into the problem of visual search in general and predictions of novel search asymmetries.

  13. Visualizing search results: evaluating an iconic visualization

    Science.gov (United States)

    Erfani Joorabchi, M.; Dalvandi, A.; Seifi, H.; Bartram, L.; Shaw, C. D.

    2010-01-01

    Commercial websites offer many items to potential site users. However, most current websites display results of a search in text lists, or as lists sorted on one or two single criteria. Finding the best item in a text list based on multi-priority criteria is an exhausting task, especially for long lists. Visualizing search results and enabling users to perceive the tradeoffs among the results based on multiple priorities may ease this process. To investigate this, two different techniques for displaying and sorting search results are studied in this paper; Text, and XY Iconic Visualization. The goal is to determine which technique for representing search results would be the most efficient one for a website user. We conducted a user study to compare the usability of the two techniques. Collected data is in the form of participants' task responses, a satisfaction questionnaire, qualitative observations, and participants' comments. According to the results, iconic visualization is better for overview (it gives a good overview in a short amount of time) and search with more than two criteria, while text-based performs better for displaying details.

  14. Oral messages improve visual search

    CERN Document Server

    Kieffer, Suzanne

    2007-01-01

    Input multimodality combining speech and hand gestures has motivated numerous usability studies. Contrastingly, issues relating to the design and ergonomic evaluation of multimodal output messages combining speech with visual modalities have not yet been addressed extensively. The experimental study presented here addresses one of these issues. Its aim is to assess the actual efficiency and usability of oral system messages including brief spatial information for helping users to locate objects on crowded displays rapidly. Target presentation mode, scene spatial structure and task difficulty were chosen as independent variables. Two conditions were defined: the visual target presentation mode (VP condition) and the multimodal target presentation mode (MP condition). Each participant carried out two blocks of visual search tasks (120 tasks per block, and one block per condition). Scene target presentation mode, scene structure and task difficulty were found to be significant factors. Multimodal target presenta...

  15. The development of organized visual search

    Science.gov (United States)

    Woods, Adam J.; Goksun, Tilbe; Chatterjee, Anjan; Zelonis, Sarah; Mehta, Anika; Smith, Sabrina E.

    2013-01-01

    Visual search plays an important role in guiding behavior. Children have more difficulty performing conjunction search tasks than adults. The present research evaluates whether developmental differences in children's ability to organize serial visual search (i.e., search organization skills) contribute to performance limitations in a typical conjunction search task. We evaluated 134 children between the ages of 2 and 17 on separate tasks measuring search for targets defined by a conjunction of features or by distinct features. Our results demonstrated that children organize their visual search better as they get older. As children's skills at organizing visual search improve they become more accurate at locating targets with conjunction of features amongst distractors, but not for targets with distinct features. Developmental limitations in children's abilities to organize their visual search of the environment are an important component of poor conjunction search in young children. In addition, our findings provide preliminary evidence that, like other visuospatial tasks, exposure to reading may influence children's spatial orientation to the visual environment when performing a visual search. PMID:23584560

  16. Visual instance search from one example

    OpenAIRE

    Tao, R.

    2017-01-01

    A visual instance is a visually unique entity (e.g., Brooklyn bridge), or a set of entities with identical visual appearance and hence not visually distinguishable (e.g., a Miffy doll with many identical copies). The same instance may vary tremendously in appearance in different images due to self-deformation, occlusion, illumination variations, viewpoint change and other recording factors. This thesis is dedicated to visual instance search from one example. Given one image of an instance, th...

  17. Visual Search Across the Life Span

    Science.gov (United States)

    Hommel, Bernhard; Li, Karen Z. H.; Li, Shu-Chen

    2004-01-01

    Gains and losses in visual search were studied across the life span in a representative sample of 298 individuals from 6 to 89 years of age. Participants searched for single-feature and conjunction targets of high or low eccentricity. Search was substantially slowed early and late in life, age gradients were more pronounced in conjunction than in…

  18. Aurally and visually guided visual search in a virtual environment.

    Science.gov (United States)

    Flanagan, P; McAnally, K I; Martin, R L; Meehan, J W; Oldfield, S R

    1998-09-01

    We investigated the time participants took to perform a visual search task for targets outside the visual field of view using a helmet-mounted display. We also measured the effectiveness of visual and auditory cues to target location. The auditory stimuli used to cue location were noise bursts previously recorded from the ear canals of the participants and were either presented briefly at the beginning of a trial or continually updated to compensate for head movements. The visual cue was a dynamic arrow that indicated the direction and angular distance from the instantaneous head position to the target. Both visual and auditory spatial cues reduced search time dramatically, compared with unaided search. The updating audio cue was more effective than the transient audio cue and was as effective as the visual cue in reducing search time. These data show that both spatial auditory and visual cues can markedly improve visual search performance. Potential applications for this research include highly visual environments, such as aviation, where there is risk of overloading the visual modality with information.

  19. Features in visual search combine linearly.

    Science.gov (United States)

    Pramod, R T; Arun, S P

    2014-04-08

    Single features such as line orientation and length are known to guide visual search, but relatively little is known about how multiple features combine in search. To address this question, we investigated how search for targets differing in multiple features (intensity, length, orientation) from the distracters is related to searches for targets differing in each of the individual features. We tested race models (based on reaction times) and co-activation models (based on reciprocal of reaction times) for their ability to predict multiple feature searches. Multiple feature searches were best accounted for by a co-activation model in which feature information combined linearly (r = 0.95). This result agrees with the classic finding that these features are separable i.e., subjective dissimilarity ratings sum linearly. We then replicated the classical finding that the length and width of a rectangle are integral features-in other words, they combine nonlinearly in visual search. However, to our surprise, upon including aspect ratio as an additional feature, length and width combined linearly and this model outperformed all other models. Thus, length and width of a rectangle became separable when considered together with aspect ratio. This finding predicts that searches involving shapes with identical aspect ratio should be more difficult than searches where shapes differ in aspect ratio. We confirmed this prediction on a variety of shapes. We conclude that features in visual search co-activate linearly and demonstrate for the first time that aspect ratio is a novel feature that guides visual search.

  20. Enhancing learners’ visual search in video cases

    NARCIS (Netherlands)

    Balslev, Thomas; Jarodzka, Halszka; Holmqvist, Kenneth; Nyström, Marcus; Scheiter, Katharina; Gerjets, Peter; Eika, Berit

    2012-01-01

    Balslev, T., Jarodzka, H., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2012, May). Enhancing learners’ visual search in video cases. Poster presented at the International Child Neurology Association (ICNA) congress, Brisbane, Australia.

  1. History effects in visual search for monsters: search times, choice biases, and liking.

    Science.gov (United States)

    Chetverikov, Andrey; Kristjansson, Árni

    2015-02-01

    Repeating targets and distractors on consecutive visual search trials facilitates search performance, whereas switching targets and distractors harms search. In addition, search repetition leads to biases in free choice tasks, in that previously attended targets are more likely to be chosen than distractors. Another line of research has shown that attended items receive high liking ratings, whereas ignored distractors are rated negatively. Potential relations between the three effects are unclear, however. Here we simultaneously measured repetition benefits and switching costs for search times, choice biases, and liking ratings in color singleton visual search for "monster" shapes. We showed that if expectations from search repetition are violated, targets are liked to be less attended than otherwise. Choice biases were, on the other hand, affected by distractor repetition, but not by target/distractor switches. Target repetition speeded search times but had little influence on choice or liking. Our findings suggest that choice biases reflect distractor inhibition, and liking reflects the conflict associated with attending to previously inhibited stimuli, while speeded search follows both target and distractor repetition. Our results support the newly proposed affective-feedback-of-hypothesis-testing account of cognition, and additionally, shed new light on the priming of visual search.

  2. Visual Testing: Searching for Guidelines.

    Science.gov (United States)

    Van Gendt, Kitty; Verhagen, Plon

    An experiment was conducted to investigate the influence of the variables "realism" and "context" on the performance of biology students on a visual test about the anatomy of a rat. The instruction was primarily visual with additional verbal information like Latin names and practical information about the learning task: dissecting a rat to gain…

  3. Fractal fluctuations in gaze speed visual search.

    Science.gov (United States)

    Stephen, Damian G; Anastas, Jason

    2011-04-01

    Visual search involves a subtle coordination of visual memory and lower-order perceptual mechanisms. Specifically, the fluctuations in gaze may provide support for visual search above and beyond what may be attributed to memory. Prior research indicates that gaze during search exhibits fractal fluctuations, which allow for a wide sampling of the field of view. Fractal fluctuations constitute a case of fast diffusion that may provide an advantage in exploration. We present reanalyses of eye-tracking data collected by Stephen and Mirman (Cognition, 115, 154-165, 2010) for single-feature and conjunction search tasks. Fluctuations in gaze during these search tasks were indeed fractal. Furthermore, the degree of fractality predicted decreases in reaction time on a trial-by-trial basis. We propose that fractality may play a key role in explaining the efficacy of perceptual exploration.

  4. Visual search elicits the electrophysiological marker of visual working memory.

    Science.gov (United States)

    Emrich, Stephen M; Al-Aidroos, Naseem; Pratt, Jay; Ferber, Susanne

    2009-11-26

    Although limited in capacity, visual working memory (VWM) plays an important role in many aspects of visually-guided behavior. Recent experiments have demonstrated an electrophysiological marker of VWM encoding and maintenance, the contralateral delay activity (CDA), which has been shown in multiple tasks that have both explicit and implicit memory demands. Here, we investigate whether the CDA is evident during visual search, a thoroughly-researched task that is a hallmark of visual attention but has no explicit memory requirements. The results demonstrate that the CDA is present during a lateralized search task, and that it is similar in amplitude to the CDA observed in a change-detection task, but peaks slightly later. The changes in CDA amplitude during search were strongly correlated with VWM capacity, as well as with search efficiency. These results were paralleled by behavioral findings showing a strong correlation between VWM capacity and search efficiency. We conclude that the activity observed during visual search was generated by the same neural resources that subserve VWM, and that this activity reflects the maintenance of previously searched distractors.

  5. Automatization and training in visual search.

    Science.gov (United States)

    Czerwinski, M; Lightfoot, N; Shiffrin, R M

    1992-01-01

    In several search tasks, the amount of practice on particular combinations of targets and distractors was equated in varied-mapping (VM) and consistent-mapping (CM) conditions. The results indicate the importance of distinguishing between memory and visual search tasks, and implicate a number of factors that play important roles in visual search and its learning. Visual search was studied in Experiment 1. VM and CM performance were almost equal, and slope reductions occurred during practice for both, suggesting the learning of efficient attentive search based on features, and no important role for automatic attention attraction. However, positive transfer effects occurred when previous CM targets were re-paired with previous CM distractors, even though these targets and distractors had not been trained together. Also, the introduction of a demanding simultaneous task produced advantages of CM over VM. These latter two results demonstrated the operation of automatic attention attraction. Visual search was further studied in Experiment 2, using novel characters for which feature overlap and similarity were controlled. The design and many of the findings paralleled Experiment 1. In addition, enormous search improvement was seen over 35 sessions of training, suggesting the operation of perceptual unitization for the novel characters. Experiment 3 showed a large, persistent advantage for CM over VM performance in memory search, even when practice on particular combinations of targets and distractors was equated in the two training conditions. A multifactor theory of automatization and attention is put forth to account for these findings and others in the literature.

  6. Visual search engine for product images

    Science.gov (United States)

    Lin, Xiaofan; Gokturk, Burak; Sumengen, Baris; Vu, Diem

    2008-01-01

    Nowadays there are many product comparison web sites. But most of them only use text information. This paper introduces a novel visual search engine for product images, which provides a brand-new way of visually locating products through Content-based Image Retrieval (CBIR) technology. We discusses the unique technical challenges, solutions, and experimental results in the design and implementation of this system.

  7. Do oral messages help visual search?

    CERN Document Server

    Carbonell, Noëlle

    2005-01-01

    A preliminary experimental study is presented, that aims at eliciting the contribution of oral messages to facilitating visual search tasks on crowded visual displays. Results of quantitative and qualitative analyses suggest that appropriate verbal messages can improve both target selection time and accuracy. In particular, multimodal messages including a visual presentation of the isolated target together with absolute spatial oral information on its location in the displayed scene seem most effective. These messages also got top-ranking ratings from most subjects.

  8. Conditional probability modulates visual search efficiency.

    Science.gov (United States)

    Cort, Bryan; Anderson, Britt

    2013-01-01

    We investigated the effects of probability on visual search. Previous work has shown that people can utilize spatial and sequential probability information to improve target detection. We hypothesized that performance improvements from probability information would extend to the efficiency of visual search. Our task was a simple visual search in which the target was always present among a field of distractors, and could take one of two colors. The absolute probability of the target being either color was 0.5; however, the conditional probability-the likelihood of a particular color given a particular combination of two cues-varied from 0.1 to 0.9. We found that participants searched more efficiently for high conditional probability targets and less efficiently for low conditional probability targets, but only when they were explicitly informed of the probability relationship between cues and target color.

  9. Conditional Probability Modulates Visual Search Efficiency

    Directory of Open Access Journals (Sweden)

    Bryan eCort

    2013-10-01

    Full Text Available We investigated the effects of probability on visual search. Previous work has shown that people can utilize spatial and sequential probability information to improve target detection. We hypothesized that performance improvements from probability information would extend to the efficiency of visual search. Our task was a simple visual search in which the target was always present among a field of distractors, and could take one of two colors. The absolute probability of the target being either color was 0.5; however, the conditional probability – the likelihood of a particular color given a particular combination of two cues – varied from 0.1 to 0.9. We found that participants searched more efficiently for high conditional probability targets and less efficiently for low conditional probability targets, but only when they were explicitly informed of the probability relationship between cues and target color.

  10. The influence of literacy on visual search

    OpenAIRE

    Olivers, C.; Huettig, F; Singh, J; Mishra, R

    2014-01-01

    Currently one in five adults is still unable to read despite a rapidly developing world. Here we show that (il)literacy has important consequences for the cognitive ability of selecting relevant information from a visual display of non-linguistic material. In two experiments we compared low to high literacy observers on both an easy and a more difficult visual search task involving different types of chicken. Low literates were consistently slower (as indicated by overall RTs) in both experim...

  11. Attention during visual search: The benefit of bilingualism

    Science.gov (United States)

    Friesen, Deanna C; Latman, Vered; Calvo, Alejandra; Bialystok, Ellen

    2015-01-01

    Aims and Objectives/Purpose/Research Questions Following reports showing bilingual advantages in executive control (EC) performance, the current study investigated the role of selective attention as a foundational skill that might underlie these advantages. Design/Methodology/Approach Bilingual and monolingual young adults performed a visual search task by determining whether a target shape was present amid distractor shapes. Task difficulty was manipulated by search type (feature or conjunction) and by the number and discriminability of the distractors. In feature searches, the target (e.g., green triangle) differed on a single dimension (e.g., color) from the distractors (e.g., yellow triangles); in conjunction searches, two types of distractors (e.g., pink circles and turquoise squares) each differed from the target (e.g., turquoise circle) on a single but different dimension (e.g., color or shape). Data and Analysis Reaction time and accuracy data from 109 young adults (53 monolinguals and 56 bilinguals) were analyzed using a repeated-measures analysis of variance. Group membership, search type, number and discriminability of distractors were the independent variables. Findings/Conclusions Participants identified the target more quickly in the feature searches, when the target was highly discriminable from the distractors and when there were fewer distractors. Importantly, although monolinguals and bilinguals performed equivalently on the feature searches, bilinguals were significantly faster than monolinguals in identifying the target in the more difficult conjunction search, providing evidence for better control of visual attention in bilinguals Originality Unlike previous studies on bilingual visual attention, the current study found a bilingual attention advantage in a paradigm that did not include a Stroop-like manipulation to set up false expectations. Significance/Implications Thus, our findings indicate that the need to resolve explicit conflict or

  12. Persistence in eye movement during visual search

    Science.gov (United States)

    Amor, Tatiana A.; Reis, Saulo D. S.; Campos, Daniel; Herrmann, Hans J.; Andrade, José S.

    2016-02-01

    As any cognitive task, visual search involves a number of underlying processes that cannot be directly observed and measured. In this way, the movement of the eyes certainly represents the most explicit and closest connection we can get to the inner mechanisms governing this cognitive activity. Here we show that the process of eye movement during visual search, consisting of sequences of fixations intercalated by saccades, exhibits distinctive persistent behaviors. Initially, by focusing on saccadic directions and intersaccadic angles, we disclose that the probability distributions of these measures show a clear preference of participants towards a reading-like mechanism (geometrical persistence), whose features and potential advantages for searching/foraging are discussed. We then perform a Multifractal Detrended Fluctuation Analysis (MF-DFA) over the time series of jump magnitudes in the eye trajectory and find that it exhibits a typical multifractal behavior arising from the sequential combination of saccades and fixations. By inspecting the time series composed of only fixational movements, our results reveal instead a monofractal behavior with a Hurst exponent , which indicates the presence of long-range power-law positive correlations (statistical persistence). We expect that our methodological approach can be adopted as a way to understand persistence and strategy-planning during visual search.

  13. Personalized online information search and visualization

    Directory of Open Access Journals (Sweden)

    Orthner Helmuth F

    2005-03-01

    Full Text Available Abstract Background The rapid growth of online publications such as the Medline and other sources raises the questions how to get the relevant information efficiently. It is important, for a bench scientist, e.g., to monitor related publications constantly. It is also important, for a clinician, e.g., to access the patient records anywhere and anytime. Although time-consuming, this kind of searching procedure is usually similar and simple. Likely, it involves a search engine and a visualization interface. Different words or combination reflects different research topics. The objective of this study is to automate this tedious procedure by recording those words/terms in a database and online sources, and use the information for an automated search and retrieval. The retrieved information will be available anytime and anywhere through a secure web server. Results We developed such a database that stored searching terms, journals and et al., and implement a piece of software for searching the medical subject heading-indexed sources such as the Medline and other online sources automatically. The returned information were stored locally, as is, on a server and visible through a Web-based interface. The search was performed daily or otherwise scheduled and the users logon to the website anytime without typing any words. The system has potentials to retrieve similarly from non-medical subject heading-indexed literature or a privileged information source such as a clinical information system. The issues such as security, presentation and visualization of the retrieved information were thus addressed. One of the presentation issues such as wireless access was also experimented. A user survey showed that the personalized online searches saved time and increased and relevancy. Handheld devices could also be used to access the stored information but less satisfactory. Conclusion The Web-searching software or similar system has potential to be an efficient

  14. Eye Movements and Visual Search: A Bibliography,

    Science.gov (United States)

    1983-01-01

    0D, rOK 221 Feinstein, R.; Williams , W.J. An al.orithmic nodel for aspects of visual information processing and eye movements. Proceedings of the 23rd...RR-4-SER-B, 7-3, June 1981. INS, RED 320 Hochberg, J. Components of literacy: speculations and exploratory research. In H. Levin & J.P. Williams (Eds...selection accuracy and exgosure in visual search. Perception, 1975, 4, 411-41. VIS, TAC, REC 652 Spady , Jr.; A.A. Airline pilots’ scan behaviour

  15. Episodic retrieval and feature facilitation in intertrial priming of visual search

    DEFF Research Database (Denmark)

    Asgeirsson, Arni Gunnar; Kristjánsson, Árni

    2011-01-01

    Abstract Huang, Holcombe, and Pashler (Memory & Cognition, 32, 12–20, 2004) found that priming from repetition of different features of a target in a visual search task resulted in significant response time (RT) reductions when both target brightness and size were repeated. But when only one...... feature was repeated and the other changed, RTs were longer than when neither feature was repeated. From this, they argued that priming in visual search reflected episodic retrieval of memory traces, rather than facilitation of repeated features. We tested different varia- tions of the search task...... introduced by Huang et al., with the aim of uncovering when priming is episodic and when feature based. We found that varying the signal strength of target against distractors had a strong effect on the priming pattern. In difficult search with low signal-to-noise ratios of target against distractors...

  16. Long-Term Priming of Visual Search Prevails against the Passage of Time and Counteracting Instructions

    Science.gov (United States)

    Kruijne, Wouter; Meeter, Martijn

    2016-01-01

    Studies on "intertrial priming" have shown that in visual search experiments, the preceding trial automatically affects search performance: facilitating it when the target features repeat and giving rise to switch costs when they change--so-called (short-term) intertrial priming. These effects also occur at longer time scales: When 1 of…

  17. Top-down visual search in Wimmelbild

    Science.gov (United States)

    Bergbauer, Julia; Tari, Sibel

    2013-03-01

    Wimmelbild which means "teeming figure picture" is a popular genre of visual puzzles. Abundant masses of small figures are brought together in complex arrangements to make one scene in a Wimmelbild. It is picture hunt game. We discuss what type of computations/processes could possibly underlie the solution of the discovery of figures that are hidden due to a distractive influence of the context. One thing for sure is that the processes are unlikely to be purely bottom-up. One possibility is to re-arrange parts and see what happens. As this idea is linked to creativity, there are abundant examples of unconventional part re-organization in modern art. A second possibility is to define what to look for. That is to formulate the search as a top-down process. We address top-down visual search in Wimmelbild with the help of diffuse distance and curvature coding fields.

  18. Temporal Stability of Visual Search-Driven Biometrics

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Hong-Jun [ORNL; Carmichael, Tandy [Tennessee Technological University; Tourassi, Georgia [ORNL

    2015-01-01

    Previously, we have shown the potential of using an individual s visual search pattern as a possible biometric. That study focused on viewing images displaying dot-patterns with different spatial relationships to determine which pattern can be more effective in establishing the identity of an individual. In this follow-up study we investigated the temporal stability of this biometric. We performed an experiment with 16 individuals asked to search for a predetermined feature of a random-dot pattern as we tracked their eye movements. Each participant completed four testing sessions consisting of two dot patterns repeated twice. One dot pattern displayed concentric circles shifted to the left or right side of the screen overlaid with visual noise, and participants were asked which side the circles were centered on. The second dot-pattern displayed a number of circles (between 0 and 4) scattered on the screen overlaid with visual noise, and participants were asked how many circles they could identify. Each session contained 5 untracked tutorial questions and 50 tracked test questions (200 total tracked questions per participant). To create each participant s "fingerprint", we constructed a Hidden Markov Model (HMM) from the gaze data representing the underlying visual search and cognitive process. The accuracy of the derived HMM models was evaluated using cross-validation for various time-dependent train-test conditions. Subject identification accuracy ranged from 17.6% to 41.8% for all conditions, which is significantly higher than random guessing (1/16 = 6.25%). The results suggest that visual search pattern is a promising, fairly stable personalized fingerprint of perceptual organization.

  19. Temporal stability of visual search-driven biometrics

    Science.gov (United States)

    Yoon, Hong-Jun; Carmichael, Tandy R.; Tourassi, Georgia

    2015-03-01

    Previously, we have shown the potential of using an individual's visual search pattern as a possible biometric. That study focused on viewing images displaying dot-patterns with different spatial relationships to determine which pattern can be more effective in establishing the identity of an individual. In this follow-up study we investigated the temporal stability of this biometric. We performed an experiment with 16 individuals asked to search for a predetermined feature of a random-dot pattern as we tracked their eye movements. Each participant completed four testing sessions consisting of two dot patterns repeated twice. One dot pattern displayed concentric circles shifted to the left or right side of the screen overlaid with visual noise, and participants were asked which side the circles were centered on. The second dot-pattern displayed a number of circles (between 0 and 4) scattered on the screen overlaid with visual noise, and participants were asked how many circles they could identify. Each session contained 5 untracked tutorial questions and 50 tracked test questions (200 total tracked questions per participant). To create each participant's "fingerprint", we constructed a Hidden Markov Model (HMM) from the gaze data representing the underlying visual search and cognitive process. The accuracy of the derived HMM models was evaluated using cross-validation for various time-dependent train-test conditions. Subject identification accuracy ranged from 17.6% to 41.8% for all conditions, which is significantly higher than random guessing (1/16 = 6.25%). The results suggest that visual search pattern is a promising, temporally stable personalized fingerprint of perceptual organization.

  20. Guided Text Search Using Adaptive Visual Analytics

    Energy Technology Data Exchange (ETDEWEB)

    Steed, Chad A [ORNL; Symons, Christopher T [ORNL; Senter, James K [ORNL; DeNap, Frank A [ORNL

    2012-10-01

    This research demonstrates the promise of augmenting interactive visualizations with semi- supervised machine learning techniques to improve the discovery of significant associations and insights in the search and analysis of textual information. More specifically, we have developed a system called Gryffin that hosts a unique collection of techniques that facilitate individualized investigative search pertaining to an ever-changing set of analytical questions over an indexed collection of open-source documents related to critical national infrastructure. The Gryffin client hosts dynamic displays of the search results via focus+context record listings, temporal timelines, term-frequency views, and multiple coordinate views. Furthermore, as the analyst interacts with the display, the interactions are recorded and used to label the search records. These labeled records are then used to drive semi-supervised machine learning algorithms that re-rank the unlabeled search records such that potentially relevant records are moved to the top of the record listing. Gryffin is described in the context of the daily tasks encountered at the US Department of Homeland Security s Fusion Center, with whom we are collaborating in its development. The resulting system is capable of addressing the analysts information overload that can be directly attributed to the deluge of information that must be addressed in the search and investigative analysis of textual information.

  1. Do Multielement Visual Tracking and Visual Search Draw Continuously on the Same Visual Attention Resources?

    Science.gov (United States)

    Alvarez, George A.; Horowitz, Todd S.; Arsenio, Helga C.; DiMase, Jennifer S.; Wolfe, Jeremy M.

    2005-01-01

    Multielement visual tracking and visual search are 2 tasks that are held to require visual-spatial attention. The authors used the attentional operating characteristic (AOC) method to determine whether both tasks draw continuously on the same attentional resource (i.e., whether the 2 tasks are mutually exclusive). The authors found that observers…

  2. Search for Gravitational-Wave Bursts from Soft Gamma Repeaters

    Science.gov (United States)

    Abbott, B.; Abbott, R.; Adhikari, R.; Ajith, P.; Allen, B.; Allen, G.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M. A.; Araya, M.; Armandula, H.; Armor, P.; Aso, Y.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Ballmer, S.; Bantilan, H.; Barish, B. C.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barton, M. A.; Bartos, I.; Bastarrika, M.; Bayer, K.; Betzwieser, J.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, D.; Bland, B.; Bodiya, T. P.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brinkmann, M.; Brooks, A.; Brown, D. A.; Brunet, G.; Bullington, A.; Buonanno, A.; Burmeister, O.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cao, J.; Cardenas, L.; Casebolt, T.; Castaldi, G.; Cepeda, C.; Chalkley, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Christensen, N.; Clark, D.; Clark, J.; Cokelaer, T.; Conte, R.; Cook, D.; Corbitt, T.; Coyne, D.; Creighton, J. D. E.; Cumming, A.; Cunningham, L.; Cutler, R. M.; Dalrymple, J.; Danzmann, K.; Davies, G.; Debra, D.; Degallaix, J.; Degree, M.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doomes, E. E.; Drever, R. W. P.; Duke, I.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; Echols, C.; Effler, A.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, T.; Fairhurst, S.; Fan, Y.; Fazi, D.; Fehrmann, H.; Fejer, M. M.; Finn, L. S.; Flasch, K.; Fotopoulos, N.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L.; González, G.; Gossler, S.; Gouaty, R.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grimaldi, F.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hallam, J. M.; Hammer, D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G.; Harstad, E.; Hayama, K.; Hayler, T.; Heefner, J.; Heng, I. S.; Hennessy, M.; Heptonstall, A.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hosken, D.; Hough, J.; Huttner, S. H.; Ingram, D.; Ito, M.; Ivanov, A.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kamat, S.; Kanner, J.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalili, F. Ya.; Khan, R.; Khazanov, E.; Kim, C.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R. K.; Kozak, D.; Kozhevatov, I.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lang, M. M.; Lantz, B.; Lazzarini, A.; Lei, M.; Leindecker, N.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lin, H.; Lindquist, P.; Lockerbie, N. A.; Lodhia, D.; Lormand, M.; Lu, P.; Lubiński, M.; Lucianetti, A.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Mandic, V.; Márka, S.; Márka, Z.; Markosyan, A.; Markowitz, J.; Maros, E.; Martin, I.; Martin, R. M.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McIntyre, G.; McIvor, G.; McKechan, D.; McKenzie, K.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C. J.; Meyers, D.; Miller, J.; Minelli, J.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Mohanty, S.; Moreno, G.; Mossavi, K.; Mowlowry, C.; Mueller, G.; Mukherjee, S.; Mukhopadhyay, H.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nash, T.; Nelson, J.; Newton, G.; Nishizawa, A.; Numata, K.; O'Dell, J.; Ogin, G.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pan, Y.; Pankow, C.; Papa, M. A.; Parameshwaraiah, V.; Patel, P.; Pedraza, M.; Penn, S.; Perreca, A.; Petrie, T.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Postiglione, F.; Principe, M.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D. S.; Radkins, H.; Rainer, N.; Rakhmanov, M.; Ramsunder, M.; Rehbein, H.; Reid, S.; Reitze, D. H.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; de La Jordana, L. Sancho; Sandberg, V.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Savov, P.; Schediwy, S. W.; Schilling, R.; Schnabel, R.; Schofield, R.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Searle, A. C.; Sears, B.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Siemens, X.; Sigg, D.; Sinha, S.; Sintes, A. M.

    2008-11-01

    We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3×1045 and 9×1052 erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models.

  3. A Visual Search Tool for Early Elementary Science Students.

    Science.gov (United States)

    Revelle, Glenda; Druin, Allison; Platner, Michele; Bederson, Ben; Hourcade, Juan Pablo; Sherman, Lisa

    2002-01-01

    Reports on the development of a visual search interface called "SearchKids" to support children ages 5-10 years in their efforts to find animals in a hierarchical information structure. Investigates whether children can construct search queries to conduct complex searches if sufficiently supported both visually and conceptually. (Contains 27…

  4. Adding a visualization feature to web search engines: it's time.

    Science.gov (United States)

    Wong, Pak Chung

    2008-01-01

    It's widely recognized that all Web search engines today are almost identical in presentation layout and behavior. In fact, the same presentation approach has been applied to depicting search engine results pages (SERPs) since the first Web search engine launched in 1993. In this Visualization Viewpoints article, I propose to add a visualization feature to Web search engines and suggest that the new addition can improve search engines' performance and capabilities, which in turn lead to better Web search technology.

  5. Repeatability and reliability of human eye in visual shade selection.

    Science.gov (United States)

    Özat, P B; Tuncel, İ; Eroğlu, E

    2013-12-01

    Deficiencies in the human visual percep-tion system have challenged the efficiency of the visual shade-matching protocol. The aim of this study was to evaluate the repeatability and reliability of human eye in visual shade selection. Fifty-four volunteering dentists were asked to match the shade of an upper right central incisor tooth of a single subject. The Vita 3D-Master shade guide was used for the protocol. Before each shade-matching procedure, the definitive codes of the shade tabs were hidden by an opaque strip and the shade tabs were placed into the guide randomly. The procedure was repeated 1 month later to ensure that visual memory did not affect the results. The L*, a* and b* values of the shade tabs were measured with a dental spectrophotometer (Vita Easyshade) to produce quantitative values to evaluate the protocol. The paired samples t-test and Pearson correlation test were used to compare the 1st and 2nd selections. The Yates-corrected chi-square test was use to compare qualitative values. Statistical significance was accepted at P shade matching, but they are able to select clinically acceptable shades.

  6. Usability Testing of a Large, Multidisciplinary Library Database: Basic Search and Visual Search

    Directory of Open Access Journals (Sweden)

    Jody Condit Fagan

    2006-09-01

    Full Text Available Visual search interfaces have been shown by researchers to assist users with information search and retrieval. Recently, several major library vendors have added visual search interfaces or functions to their products. For public service librarians, perhaps the most critical area of interest is the extent to which visual search interfaces and text-based search interfaces support research. This study presents the results of eight full-scale usability tests of both the EBSCOhost Basic Search and Visual Search in the context of a large liberal arts university.

  7. Activation of phonological competitors in visual search.

    Science.gov (United States)

    Görges, Frauke; Oppermann, Frank; Jescheniak, Jörg D; Schriefers, Herbert

    2013-06-01

    Recently, Meyer, Belke, Telling and Humphreys (2007) reported that competitor objects with homophonous names (e.g., boy) interfere with identifying a target object (e.g., buoy) in a visual search task, suggesting that an object name's phonology becomes automatically activated even in situations in which participants do not have the intention to speak. The present study explored the generality of this finding by testing a different phonological relation (rhyming object names, e.g., cat-hat) and by varying details of the experimental procedure. Experiment 1 followed the procedure by Meyer et al. Participants were familiarized with target and competitor objects and their names at the beginning of the experiment and the picture of the target object was presented prior to the search display on each trial. In Experiment 2, the picture of the target object presented prior to the search display was replaced by its name. In Experiment 3, participants were not familiarized with target and competitor objects and their names at the beginning of the experiment. A small interference effect from phonologically related competitors was obtained in Experiments 1 and 2 but not in Experiment 3, suggesting that the way the relevant objects are introduced to participants affects the chances of observing an effect from phonologically related competitors. Implications for the information flow in the conceptual-lexical system are discussed.

  8. Search for gravitational-wave bursts from soft gamma repeaters.

    Science.gov (United States)

    Abbott, B; Abbott, R; Adhikari, R; Ajith, P; Allen, B; Allen, G; Amin, R; Anderson, S B; Anderson, W G; Arain, M A; Araya, M; Armandula, H; Armor, P; Aso, Y; Aston, S; Aufmuth, P; Aulbert, C; Babak, S; Ballmer, S; Bantilan, H; Barish, B C; Barker, C; Barker, D; Barr, B; Barriga, P; Barton, M A; Bartos, I; Bastarrika, M; Bayer, K; Betzwieser, J; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Biswas, R; Black, E; Blackburn, K; Blackburn, L; Blair, D; Bland, B; Bodiya, T P; Bogue, L; Bork, R; Boschi, V; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brinkmann, M; Brooks, A; Brown, D A; Brunet, G; Bullington, A; Buonanno, A; Burmeister, O; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cannizzo, J; Cannon, K; Cao, J; Cardenas, L; Casebolt, T; Castaldi, G; Cepeda, C; Chalkley, E; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Christensen, N; Clark, D; Clark, J; Cokelaer, T; Conte, R; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Cumming, A; Cunningham, L; Cutler, R M; Dalrymple, J; Danzmann, K; Davies, G; Debra, D; Degallaix, J; Degree, M; Dergachev, V; Desai, S; Desalvo, R; Dhurandhar, S; Díaz, M; Dickson, J; Dietz, A; Donovan, F; Dooley, K L; Doomes, E E; Drever, R W P; Duke, I; Dumas, J-C; Dupuis, R J; Dwyer, J G; Echols, C; Effler, A; Ehrens, P; Espinoza, E; Etzel, T; Evans, T; Fairhurst, S; Fan, Y; Fazi, D; Fehrmann, H; Fejer, M M; Finn, L S; Flasch, K; Fotopoulos, N; Freise, A; Frey, R; Fricke, T; Fritschel, P; Frolov, V V; Fyffe, M; Garofoli, J; Gholami, I; Giaime, J A; Giampanis, S; Giardina, K D; Goda, K; Goetz, E; Goggin, L; González, G; Gossler, S; Gouaty, R; Grant, A; Gras, S; Gray, C; Gray, M; Greenhalgh, R J S; Gretarsson, A M; Grimaldi, F; Grosso, R; Grote, H; Grunewald, S; Guenther, M; Gustafson, E K; Gustafson, R; Hage, B; Hallam, J M; Hammer, D; Hanna, C; Hanson, J; Harms, J; Harry, G; Harstad, E; Hayama, K; Hayler, T; Heefner, J; Heng, I S; Hennessy, M; Heptonstall, A; Hewitson, M; Hild, S; Hirose, E; Hoak, D; Hosken, D; Hough, J; Huttner, S H; Ingram, D; Ito, M; Ivanov, A; Johnson, B; Johnson, W W; Jones, D I; Jones, G; Jones, R; Ju, L; Kalmus, P; Kalogera, V; Kamat, S; Kanner, J; Kasprzyk, D; Katsavounidis, E; Kawabe, K; Kawamura, S; Kawazoe, F; Kells, W; Keppel, D G; Khalili, F Ya; Khan, R; Khazanov, E; Kim, C; King, P; Kissel, J S; Klimenko, S; Kokeyama, K; Kondrashov, V; Kopparapu, R K; Kozak, D; Kozhevatov, I; Krishnan, B; Kwee, P; Lam, P K; Landry, M; Lang, M M; Lantz, B; Lazzarini, A; Lei, M; Leindecker, N; Leonhardt, V; Leonor, I; Libbrecht, K; Lin, H; Lindquist, P; Lockerbie, N A; Lodhia, D; Lormand, M; Lu, P; Lubinski, M; Lucianetti, A; Lück, H; Machenschalk, B; Macinnis, M; Mageswaran, M; Mailand, K; Mandic, V; Márka, S; Márka, Z; Markosyan, A; Markowitz, J; Maros, E; Martin, I; Martin, R M; Marx, J N; Mason, K; Matichard, F; Matone, L; Matzner, R; Mavalvala, N; McCarthy, R; McClelland, D E; McGuire, S C; McHugh, M; McIntyre, G; McIvor, G; McKechan, D; McKenzie, K; Meier, T; Melissinos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C J; Meyers, D; Miller, J; Minelli, J; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Moe, B; Mohanty, S; Moreno, G; Mossavi, K; Mowlowry, C; Mueller, G; Mukherjee, S; Mukhopadhyay, H; Müller-Ebhardt, H; Munch, J; Murray, P; Myers, E; Myers, J; Nash, T; Nelson, J; Newton, G; Nishizawa, A; Numata, K; O'Dell, J; Ogin, G; O'Reilly, B; O'Shaughnessy, R; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Pan, Y; Pankow, C; Papa, M A; Parameshwaraiah, V; Patel, P; Pedraza, M; Penn, S; Perreca, A; Petrie, T; Pinto, I M; Pitkin, M; Pletsch, H J; Plissi, M V; Postiglione, F; Principe, M; Prix, R; Quetschke, V; Raab, F; Rabeling, D S; Radkins, H; Rainer, N; Rakhmanov, M; Ramsunder, M; Rehbein, H; Reid, S; Reitze, D H; Riesen, R; Riles, K; Rivera, B; Robertson, N A; Robinson, C; Robinson, E L; Roddy, S; Rodriguez, A; Rogan, A M; Rollins, J; Romano, J D; Romie, J; Route, R; Rowan, S; Rüdiger, A; Ruet, L; Russell, P; Ryan, K; Sakata, S; Samidi, M; de la Jordana, L Sancho; Sandberg, V; Sannibale, V; Saraf, S; Sarin, P; Sathyaprakash, B S; Sato, S; Saulson, P R; Savage, R; Savov, P; Schediwy, S W; Schilling, R; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seifert, F; Sellers, D; Sengupta, A S; Shawhan, P; Shoemaker, D H; Sibley, A; Siemens, X; Sigg, D; Sinha, S; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, N D; Somiya, K; Sorazu, B; Stein, L C; Stochino, A; Stone, R; Strain, K A; Strom, D M; Stuver, A; Summerscales, T Z; Sun, K-X; Sung, M; Sutton, P J; Takahashi, H; Tanner, D B; Taylor, R; Taylor, R; Thacker, J; Thorne, K A; Thorne, K S; Thüring, A; Tokmakov, K V; Torres, C; Torrie, C; Traylor, G; Trias, M; Tyler, W; Ugolini, D; Ulmen, J; Urbanek, K; Vahlbruch, H; Van Den Broeck, C; van der Sluys, M; Vass, S; Vaulin, R; Vecchio, A; Veitch, J; Veitch, P

    2008-11-21

    We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3x10;{45} and 9x10;{52} erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models.

  9. Review of tandem repeat search tools: a systematic approach to evaluating algorithmic performance

    National Research Council Canada - National Science Library

    Lim, Kian Guan; Kwoh, Chee Keong; Hsu, Li Yang; Wirawan, Adrianto

    2013-01-01

    .... Over the last 10-15 years, numerous tools have been developed for searching tandem repeats, but differences in the search algorithms adopted and difficulties with parameter settings have confounded...

  10. Usability Testing of a Large, Multidisciplinary Library Database: Basic Search and Visual Search

    OpenAIRE

    Fagan, Jody Condit

    2006-01-01

    Visual search interfaces have been shown by researchers to assist users with information search and retrieval. Recently, several major library vendors have added visual search interfaces or functions to their products. For public service librarians, perhaps the most critical area of interest is the extent to which visual search interfaces and text-based search interfaces support research. This study presents the results of eight full-scale usability tests of both the EBSCOhost Basic Search an...

  11. The target effect: visual memory for unnamed search targets.

    Science.gov (United States)

    Thomas, Mark D; Williams, Carrick C

    2014-01-01

    Search targets are typically remembered much better than other objects even when they are viewed for less time. However, targets have two advantages that other objects in search displays do not have: They are identified categorically before the search, and finding them represents the goal of the search task. The current research investigated the contributions of both of these types of information to the long-term visual memory representations of search targets. Participants completed either a predefined search or a unique-object search in which targets were not defined with specific categorical labels before searching. Subsequent memory results indicated that search target memory was better than distractor memory even following ambiguously defined searches and when the distractors were viewed significantly longer. Superior target memory appears to result from a qualitatively different representation from those of distractor objects, indicating that decision processes influence visual memory.

  12. Animating streamlines with repeated asymmetric patterns for steady flow visualization

    Science.gov (United States)

    Yeh, Chih-Kuo; Liu, Zhanping; Lee, Tong-Yee

    2012-01-01

    Animation provides intuitive cueing for revealing essential spatial-temporal features of data in scientific visualization. This paper explores the design of Repeated Asymmetric Patterns (RAPs) in animating evenly-spaced color-mapped streamlines for dense accurate visualization of complex steady flows. We present a smooth cyclic variable-speed RAP animation model that performs velocity (magnitude) integral luminance transition on streamlines. This model is extended with inter-streamline synchronization in luminance varying along the tangential direction to emulate orthogonal advancing waves from a geometry-based flow representation, and then with evenly-spaced hue differing in the orthogonal direction to construct tangential flow streaks. To weave these two mutually dual sets of patterns, we propose an energy-decreasing strategy that adopts an iterative yet efficient procedure for determining the luminance phase and hue of each streamline in HSL color space. We also employ adaptive luminance interleaving in the direction perpendicular to the flow to increase the contrast between streamlines.

  13. Visual instance search from one example

    NARCIS (Netherlands)

    Tao, R.

    2017-01-01

    A visual instance is a visually unique entity (e.g., Brooklyn bridge), or a set of entities with identical visual appearance and hence not visually distinguishable (e.g., a Miffy doll with many identical copies). The same instance may vary tremendously in appearance in different images due to

  14. Visual Search Deficits Are Independent of Magnocellular Deficits in Dyslexia

    Science.gov (United States)

    Wright, Craig M.; Conlon, Elizabeth G.; Dyck, Murray

    2012-01-01

    The aim of this study was to investigate the theory that visual magnocellular deficits seen in groups with dyslexia are linked to reading via the mechanisms of visual attention. Visual attention was measured with a serial search task and magnocellular function with a coherent motion task. A large group of children with dyslexia (n = 70) had slower…

  15. Visual search of illusory contours: an attempt of automatization

    Directory of Open Access Journals (Sweden)

    Gvozdenović Vasilije

    2008-01-01

    Full Text Available Laboratory of Experimental Psychology, University of Belgrade Recent research, which was mostly focused on assessing the types of visual search of illusory contours, showed that visual search is dependent on factors like target configuration and task type. Some experimental research supports the theory of parallel search while other research supports the theory of serial search of illusory contours. The inconsistency is most likely due to the fact that various types of illusory contour configurations were used in set creation. Up to this point, our research indicated that the serial search is used in most cases. Some exceptions of search type have been proven in some modification of task type but nevertheless the search profile remained serial. In this article, we are reporting on two visual search experiments. The first experiment was an investigation of a specific feature of a Kanisza type illusory triangle, orientation. The validity of the profile defined in the first experiment was tested in our second experiment with an attempt to automatize the visual search by the multiplication of the initial experimental trials. Our results confirmed that, regardless of the number of experimental trials, the visual search profile remains serial.

  16. The Serial Process in Visual Search

    Science.gov (United States)

    Gilden, David L.; Thornton, Thomas L.; Marusich, Laura R.

    2010-01-01

    The conditions for serial search are described. A multiple target search methodology (Thornton & Gilden, 2007) is used to home in on the simplest target/distractor contrast that effectively mandates a serial scheduling of attentional resources. It is found that serial search is required when (a) targets and distractors are mirror twins, and…

  17. Perceptual Dependencies in Information Visualization Assessed by Complex Visual Search

    NARCIS (Netherlands)

    Berg, Ronald van den; Cornelissen, Frans W.; Roerdink, Jos B.T.M.

    2008-01-01

    A common approach for visualizing data sets is to map them to images in which distinct data dimensions are mapped to distinct visual features, such as color, size and orientation. Here, we consider visualizations in which different data dimensions should receive equal weight and attention. Many of t

  18. Training Techniques for Visual Search in Complex Task Environments.

    Science.gov (United States)

    Guznov, Svyatoslav; Matthews, Gerald; Warm, Joel S; Pfahler, Marc

    2017-06-01

    The goal for this study was to evaluate several visual search training techniques in an unmanned aerial vehicle (UAV) simulated task environment. Operators controlling remote unmanned vehicles often must perform complex visual search tasks (e.g., target search). These tasks may pose substantial demands on the operator due to various environmental factors. Visual search training may reduce errors and mitigate stress, but the most effective form of training has not been determined. Participants were assigned to one of four training conditions: target, cue, visual scanning, or control. After the training, the effectiveness of the training techniques was tested during a 30-minute simulated UAV flight. A secondary task manipulation was included to further simulate the demands of a realistic UAV control and target search task. Subjective stress and fatigue were also assessed. Target training produced superior target search performances in more hits and fewer false alarms (FAs) when compared to the control condition. The visual scanning and cue trainings were moderately effective. Only target training performance was vulnerable to the secondary task load. The task was stressful, but training did not mitigate stress response. Training participants on the target and the cue appearance as well as active scanning of the visual field is promising for promoting effective target search for this simulated UAV environment. These training techniques could be used in preparation for intelligence, surveillance, and reconnaissance (ISR) missions that involve target search, especially where target appearance change is likely.

  19. Visual search demands dictate reliance on working memory storage.

    Science.gov (United States)

    Luria, Roy; Vogel, Edward K

    2011-04-20

    Previous research suggested that working memory (WM) does not play any significant role in visual search. In three experiments, we investigated the search difficulty and individual differences in WM capacity as determinants of WM involvement during visual search tasks, using both behavioral and electrophysiological markers [i.e., the contralateral delay activity (CDA), which is a marker for WM capacity allocation]. Human participants performed a visual search task that contained a target, neutral distractors, and a flanker distractor. Overall, we found that, as the search difficulty increased (as indicated by longer reaction times), so did the role of WM in performing the search task (as indicated by larger CDA amplitudes). Moreover, the results pinpoint a dissociation between the two types of factors that determined the WM involvement in the search process. Namely, individual differences in WM capacity and search difficulty independently affected the degree to which the search process relied on WM. Instead of showing a progressive role, individual differences in WM capacity correlated with the search efficiency in all search conditions (i.e., easy, medium, and difficult). Counterintuitively, individuals with high WM capacity generally relied less on WM during the search task.

  20. Saccadic selection and crowding in visual search : stronger lateral masking leads to shorter search times

    NARCIS (Netherlands)

    de Vries, Jelmer P.; Hooge, Ignace T. C.; Wiering, Marco A.; Verstraten, Frans A. J.

    2011-01-01

    We investigated the role of crowding in saccadic selection during visual search. To guide eye movements, often information from the visual periphery is used. Crowding is known to deteriorate the quality of peripheral information. In four search experiments, we studied the role of crowding, by accomp

  1. Visual similarity is stronger than semantic similarity in guiding visual search for numbers.

    Science.gov (United States)

    Godwin, Hayward J; Hout, Michael C; Menneer, Tamaryn

    2014-06-01

    Using a visual search task, we explored how behavior is influenced by both visual and semantic information. We recorded participants' eye movements as they searched for a single target number in a search array of single-digit numbers (0-9). We examined the probability of fixating the various distractors as a function of two key dimensions: the visual similarity between the target and each distractor, and the semantic similarity (i.e., the numerical distance) between the target and each distractor. Visual similarity estimates were obtained using multidimensional scaling based on the independent observer similarity ratings. A linear mixed-effects model demonstrated that both visual and semantic similarity influenced the probability that distractors would be fixated. However, the visual similarity effect was substantially larger than the semantic similarity effect. We close by discussing the potential value of using this novel methodological approach and the implications for both simple and complex visual search displays.

  2. Key Technologies in Mobile Visual Search and MPEG Standardization Activities

    Institute of Scientific and Technical Information of China (English)

    Ling- Yu Duan; Jie Chen; Chunyu Wang; Rongrong Ji; Tiejun Huang; Wen Gao

    2012-01-01

    Visual search has been a long-standing problem in applications such as location recognition and product search. Much research has been done on image representation, matching, indexing, and retrieval. Key component technologies for visual search have been developed, and numerous real-world applications are emerging. To ensure application interoperability, the Moving Picture Experts Group (MPEG) has begun standardizing visuaJ search technologies and is developing the compact descriptors for visua) search (CDVS) standard. MPEG seeks to develop a collaborative platform for evaluating existing visual search technologies. Peking University has participated in this standardization since the 94th MPEG meeting, and significant progress has been made with the various proposals. A test model (TM) has been selected to determine the basic pipeline and key components of visual search. However, the first-version TM has high computational complexity and imperfect retrieval and matching. Core experiments have therefore been set up to improve TM. In this article, we summarize key technologies for visual search and report the progress of MPEG CDVS. We discuss Peking University' s efforts in CDVS and also discuss unresolved issues.

  3. Individual differences predict low prevalence visual search performance.

    Science.gov (United States)

    Peltier, Chad; Becker, Mark W

    2017-01-01

    Critical real-world visual search tasks such as radiology and baggage screening rely on the detection of rare targets. When targets are rare, observers search for a relatively short amount of time and have a high miss rate, a pattern of results known as the low prevalence effect. Attempts to improve the search for rare targets have been unsuccessful or resulted in an increase in detections at the price of more false alarms. As an alternative to improving visual search performance through experimental manipulations, an individual differences approach found that those with higher working memory capacity were better at finding rare targets. We build on the individual differences approach and assess 141 observers' visual working memory capacity (vWMC), vigilance, attentional control, big five personality traits, and performance in both high and low prevalence search tasks. vWMC, vigilance, attentional control, high prevalence visual search performance, and level of introversion were all significant predictors of low prevalence search accuracy, and together account for more than 50% of the variance in search performance. With the exception of vigilance, these factors are also significant predictors of reaction time; better performance was associated with longer reaction times, suggesting these factors identify observers who maintain relatively high quitting thresholds, even with low target prevalence. Our results suggest that a quick and easy-to-administer battery of tasks can identify observers who are likely to perform well in low prevalence search tasks, and these predictor variables are associated with higher quitting thresholds, leading to higher accuracy.

  4. Conjunctive Visual Search in Individuals with and without Mental Retardation

    Science.gov (United States)

    Carlin, Michael; Chrysler, Christina; Sullivan, Kate

    2007-01-01

    A comprehensive understanding of the basic visual and cognitive abilities of individuals with mental retardation is critical for understanding the basis of mental retardation and for the design of remediation programs. We assessed visual search abilities in individuals with mild mental retardation and in MA- and CA-matched comparison groups. Our…

  5. Semantic Map Based Web Search Result Visualization

    OpenAIRE

    2007-01-01

    The problem of information overload has become more pressing with the emergence of the increasingly more popular Internet services. The main information retrieval mechanisms provided by the prevailing Internet Web software are based on either keyword search (e.g., Google and Yahoo) or hypertext browsing (e.g., Internet Explorer and Netscape). The research presented in this paper is aimed at providing an alternative concept-based categorization and search capability based on a combination of m...

  6. Probing the Feature Map for Faces in Visual Search

    Directory of Open Access Journals (Sweden)

    Hua Yang

    2011-05-01

    Full Text Available Controversy surrounds the mechanisms underlying the pop-out effect for faces in visual search. Is there a feature map for faces? If so, does it rely on the categorical distinction between faces and nonfaces, or on image-level face semblance? To probe the feature map, we compared search efficiency for faces, and nonface stimuli with high, low, and no face semblance. First, subjects performed a visual search task with objects as distractors. Only faces popped-out. Moreover, search efficiency for nonfaces correlated with image-level face semblance of the target. In a second experiment, faces were used as distractors but nonfaces did not pop-out. Interestingly, search efficiency for nonfaces was not modulated by face semblance, although searching for a face among faces was particularly difficult, reflecting a categorical boundary between nonfaces and faces. Finally, inversion and contrast negation significantly interacted with the effect of face semblance, ruling out the possibility that search efficiency solely depends on low-level features. Our study supports a parallel search for faces that is perhaps preattentive. Like other features (color, orientation etc., there appears to be a continuous face feature map for visual search. Our results also suggest that this map may include both image-level face semblance and face categoricity.

  7. Individual differences and metacognitive knowledge of visual search strategy.

    Science.gov (United States)

    Proulx, Michael J

    2011-01-01

    A crucial ability for an organism is to orient toward important objects and to ignore temporarily irrelevant objects. Attention provides the perceptual selectivity necessary to filter an overwhelming input of sensory information to allow for efficient object detection. Although much research has examined visual search and the 'template' of attentional set that allows for target detection, the behavior of individual subjects often reveals the limits of experimental control of attention. Few studies have examined important aspects such as individual differences and metacognitive strategies. The present study analyzes the data from two visual search experiments for a conjunctively defined target (Proulx, 2007). The data revealed attentional capture blindness, individual differences in search strategies, and a significant rate of metacognitive errors for the assessment of the strategies employed. These results highlight a challenge for visual attention studies to account for individual differences in search behavior and distractibility, and participants that do not (or are unable to) follow instructions.

  8. Individual differences and metacognitive knowledge of visual search strategy.

    Directory of Open Access Journals (Sweden)

    Michael J Proulx

    Full Text Available A crucial ability for an organism is to orient toward important objects and to ignore temporarily irrelevant objects. Attention provides the perceptual selectivity necessary to filter an overwhelming input of sensory information to allow for efficient object detection. Although much research has examined visual search and the 'template' of attentional set that allows for target detection, the behavior of individual subjects often reveals the limits of experimental control of attention. Few studies have examined important aspects such as individual differences and metacognitive strategies. The present study analyzes the data from two visual search experiments for a conjunctively defined target (Proulx, 2007. The data revealed attentional capture blindness, individual differences in search strategies, and a significant rate of metacognitive errors for the assessment of the strategies employed. These results highlight a challenge for visual attention studies to account for individual differences in search behavior and distractibility, and participants that do not (or are unable to follow instructions.

  9. LoyalTracker: Visualizing Loyalty Dynamics in Search Engines.

    Science.gov (United States)

    Shi, Conglei; Wu, Yingcai; Liu, Shixia; Zhou, Hong; Qu, Huamin

    2014-12-01

    The huge amount of user log data collected by search engine providers creates new opportunities to understand user loyalty and defection behavior at an unprecedented scale. However, this also poses a great challenge to analyze the behavior and glean insights into the complex, large data. In this paper, we introduce LoyalTracker, a visual analytics system to track user loyalty and switching behavior towards multiple search engines from the vast amount of user log data. We propose a new interactive visualization technique (flow view) based on a flow metaphor, which conveys a proper visual summary of the dynamics of user loyalty of thousands of users over time. Two other visualization techniques, a density map and a word cloud, are integrated to enable analysts to gain further insights into the patterns identified by the flow view. Case studies and the interview with domain experts are conducted to demonstrate the usefulness of our technique in understanding user loyalty and switching behavior in search engines.

  10. Selection-for-action in visual search

    NARCIS (Netherlands)

    Hannus, A; Cornelissen, FW; Lindemann, O; Bekkering, H

    2005-01-01

    Grasping an object rather than pointing to it enhances processing of its orientation but not its color. Apparently, visual discrimination is selectively enhanced for a behaviorally relevant feature. In two experiments we investigated the limitations and targets of this bias. Specifically, in Experim

  11. The impact of expert visual guidance on trainee visual search strategy, visual attention and motor skills.

    Science.gov (United States)

    Leff, Daniel R; James, David R C; Orihuela-Espina, Felipe; Kwok, Ka-Wai; Sun, Loi Wah; Mylonas, George; Athanasiou, Thanos; Darzi, Ara W; Yang, Guang-Zhong

    2015-01-01

    Minimally invasive and robotic surgery changes the capacity for surgical mentors to guide their trainees with the control customary to open surgery. This neuroergonomic study aims to assess a "Collaborative Gaze Channel" (CGC); which detects trainer gaze-behavior and displays the point of regard to the trainee. A randomized crossover study was conducted in which twenty subjects performed a simulated robotic surgical task necessitating collaboration either with verbal (control condition) or visual guidance with CGC (study condition). Trainee occipito-parietal (O-P) cortical function was assessed with optical topography (OT) and gaze-behavior was evaluated using video-oculography. Performance during gaze-assistance was significantly superior [biopsy number: (mean ± SD): control = 5.6 ± 1.8 vs. CGC = 6.6 ± 2.0; p visual search, and alleviates the burden in brain centers subserving visual attention and does not induce changes in the trainee's O-P functional network observable with the current OT technique. The results imply that through visual guidance, attentional resources may be liberated, potentially improving the capability of trainees to attend to other safety critical events during the procedure.

  12. Visual search of illusory contours: Shape and orientation effects

    Directory of Open Access Journals (Sweden)

    Gvozdenović Vasilije

    2008-01-01

    Full Text Available Illusory contours are specific class of visual stimuli that represent stimuli configurations perceived as integral irrespective of the fact that they are given in fragmented uncompleted wholes. Due to their specific features, illusory contours gained much attention in last decade representing prototype of stimuli used in investigations focused on binding problem. On the other side, investigations of illusory contours are related to problem of the level of their visual processing. Neurophysiologic studies show that processing of illusory contours proceed relatively early, on the V2 level, on the other hand most of experimental studies claim that illusory contours are perceived with engagement of visual attention, binding their elements to whole percept. This research is focused on two experiments in which visual search of illusory contours are based on shape and orientation. The main experimental procedure evolved the task proposed by Bravo and Nakayama where instead of detection, subjects were performing identification of one among two possible targets. In the first experiment subjects detected the presence of illusory square or illusory triangle, while in the second experiment subject were detecting two different orientations of illusory triangle. The results are interpreted in terms of visual search and feature integration theory. Beside the type of visual search task, search type proved to be dependent of specific features of illusory shapes which further complicate theoretical interpretation of the level of their perception.

  13. Inter-trial priming does not affect attentional priority in asymmetric visual search

    Directory of Open Access Journals (Sweden)

    Liana eAmunts

    2014-08-01

    Full Text Available Visual search is considerably speeded when the target’s characteristics remain constant across successive selections. Here, we investigated whether such inter-trial priming increases the target’s attentional priority, by examining whether target repetition reduces search efficiency during serial search. As the study of inter-trial priming requires the target and distractors to exchange roles unpredictably, it has mostly been confined to singleton searches, which typically yield efficient search. We therefore resorted to two singleton searches known to yield relatively inefficient performance, that is, searches in which the target does not pop out. Participants searched for a veridical angry face among neutral ones or vice-versa, either upright or inverted (Experiment 1 or for a Q among Os or vice-versa (Experiment 2. In both experiments, we found substantial intertrial priming that did not improve search efficiency. In addition, intertrial priming was asymmetric and occurred only when the more salient target repeated. We conclude that intertrial priming does not modulate attentional priority allocation and that it occurs in asymmetric search only when the target is characterized by an additional feature that is consciously perceived.

  14. Rapid Resumption of Interrupted Search Is Independent of Age-Related Improvements in Visual Search

    Science.gov (United States)

    Lleras, Alejandro; Porporino, Mafalda; Burack, Jacob A.; Enns, James T.

    2011-01-01

    In this study, 7-19-year-olds performed an interrupted visual search task in two experiments. Our question was whether the tendency to respond within 500 ms after a second glimpse of a display (the "rapid resumption" effect ["Psychological Science", 16 (2005) 684-688]) would increase with age in the same way as overall search efficiency. The…

  15. From foreground to background: how task-neutral context influences contextual cueing of visual search

    Directory of Open Access Journals (Sweden)

    Xuelian eZang

    2016-06-01

    Full Text Available Selective attention determines the effectiveness of implicit contextual learning (e.g., Jiang & Leung, 2005. Visual foreground-background segmentation, on the other hand, is a key process in the guidance of attention (Wolfe, 2003. In the present study, we examined the impact of foreground-background segmentation on contextual cueing of visual search in three experiments. A visual search display, consisting of distractor ‘L’s and a target ‘T’, was overlaid on a task-neutral cuboid on the same depth plane (Experiment 1, on stereoscopically separated depth planes (Experiment 2, or spread over the entire display on the same depth plane (Experiment 3. Half of the search displays contained repeated target-distractor arrangements, whereas the other half was always newly generated. The task-neutral cuboid was constant during an initial training session, but was either rotated by 90º or entirely removed in the subsequent test sessions. We found that the gains resulting from repeated presentation of display arrangements during training (i.e., contextual-cueing effects were diminished when the cuboid was changed or removed in Experiment 1, but remained intact in Experiments 2 and 3 when the cuboid was placed in a different depth plane, or when the items were randomly spread over the whole display but not on the edges of the cuboid. These findings suggest that foreground-background segmentation occurs prior to contextual learning, and only objects/arrangements that are grouped as foreground are learned over the course of repeated visual search.

  16. Agarose gel electrophoresis and polyacrylamide gel electrophoresis for visualization of simple sequence repeats.

    Science.gov (United States)

    Anderson, James; Wright, Drew; Meksem, Khalid

    2013-01-01

    In the modern age of genetic research there is a constant search for ways to improve the efficiency of plant selection. The most recent technology that can result in a highly efficient means of selection and still be done at a low cost is through plant selection directed by simple sequence repeats (SSRs or microsatellites). The molecular markers are used to select for certain desirable plant traits without relying on ambiguous phenotypic data. The best way to detect these is the use of gel electrophoresis. Gel electrophoresis is a common technique in laboratory settings which is used to separate deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) by size. Loading DNA and RNA onto gels allows for visualization of the size of fragments through the separation of DNA and RNA fragments. This is achieved through the use of the charge in the particles. As the fragments separate, they form into distinct bands at set sizes. We describe the ability to visualize SSRs on slab gels of agarose and polyacrylamide gel electrophoresis.

  17. Segmentation by depth does not always facilitate visual search.

    Science.gov (United States)

    Finlayson, Nonie J; Remington, Roger W; Retell, James D; Grove, Philip M

    2013-07-11

    In visual search, target detection times are relatively insensitive to set size when targets and distractors differ on a single feature dimension. Search can be confined to only those elements sharing a single feature, such as color (Egeth, Virzi, & Garbart, 1984). These findings have been taken as evidence that elementary feature dimensions support a parallel segmentation of a scene into discrete sets of items. Here we explored if relative depth (signaled by binocular disparity) could support a similar parallel segmentation by examining the effects of distributing distracting elements across two depth planes. Three important empirical findings emerged. First, when the target was a feature singleton on the target depth plane, but a conjunction search among distractors on the nontarget plane, search efficiency increased compared to a single depth plane. Second, benefits of segmentation in depth were only observed when the target depth plane was known in advance. Third, no benefit of segmentation in depth was observed when both planes required a conjunction search, even with prior knowledge of the target depth plane. Overall, the benefit of distributing the elements of a search set across two depth planes was observed only when the two planes differed both in binocular disparity and in the elementary feature composition of individual elements. We conclude that segmentation of the search array into two depth planes can facilitate visual search, but unlike color or other elementary properties, does not provide an automatic, preattentive segmentation.

  18. Visual exploratory search of relationship graphs on smartphones.

    Science.gov (United States)

    Ouyang, Jianquan; Zheng, Hao; Kong, Fanbin; Liu, Tianming

    2013-01-01

    This paper presents a novel framework for Visual Exploratory Search of Relationship Graphs on Smartphones (VESRGS) that is composed of three major components: inference and representation of semantic relationship graphs on the Web via meta-search, visual exploratory search of relationship graphs through both querying and browsing strategies, and human-computer interactions via the multi-touch interface and mobile Internet on smartphones. In comparison with traditional lookup search methodologies, the proposed VESRGS system is characterized with the following perceived advantages. 1) It infers rich semantic relationships between the querying keywords and other related concepts from large-scale meta-search results from Google, Yahoo! and Bing search engines, and represents semantic relationships via graphs; 2) the exploratory search approach empowers users to naturally and effectively explore, adventure and discover knowledge in a rich information world of interlinked relationship graphs in a personalized fashion; 3) it effectively takes the advantages of smartphones' user-friendly interfaces and ubiquitous Internet connection and portability. Our extensive experimental results have demonstrated that the VESRGS framework can significantly improve the users' capability of seeking the most relevant relationship information to their own specific needs. We envision that the VESRGS framework can be a starting point for future exploration of novel, effective search strategies in the mobile Internet era.

  19. Visual exploratory search of relationship graphs on smartphones.

    Directory of Open Access Journals (Sweden)

    Jianquan Ouyang

    Full Text Available This paper presents a novel framework for Visual Exploratory Search of Relationship Graphs on Smartphones (VESRGS that is composed of three major components: inference and representation of semantic relationship graphs on the Web via meta-search, visual exploratory search of relationship graphs through both querying and browsing strategies, and human-computer interactions via the multi-touch interface and mobile Internet on smartphones. In comparison with traditional lookup search methodologies, the proposed VESRGS system is characterized with the following perceived advantages. 1 It infers rich semantic relationships between the querying keywords and other related concepts from large-scale meta-search results from Google, Yahoo! and Bing search engines, and represents semantic relationships via graphs; 2 the exploratory search approach empowers users to naturally and effectively explore, adventure and discover knowledge in a rich information world of interlinked relationship graphs in a personalized fashion; 3 it effectively takes the advantages of smartphones' user-friendly interfaces and ubiquitous Internet connection and portability. Our extensive experimental results have demonstrated that the VESRGS framework can significantly improve the users' capability of seeking the most relevant relationship information to their own specific needs. We envision that the VESRGS framework can be a starting point for future exploration of novel, effective search strategies in the mobile Internet era.

  20. Crowded visual search in children with normal vision and children with visual impairment

    NARCIS (Netherlands)

    Huurneman, Bianca; Cox, Ralf F. A.; Vlaskamp, Björn N. S.; Boonstra, F. Nienke

    2014-01-01

    This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n = 11), children with visual impairment without nystagmus ([VI-nys], n = 11), and children with VI with accompanying nystagmus ([VI+nys], n = 26). Ex

  1. Crowded visual search in children with normal vision and children with visual impairment

    NARCIS (Netherlands)

    Huurneman, B.; Cox, R.F.; Vlaskamp, B.N.; Boonstra, F.N.

    2014-01-01

    This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n=11), children with visual impairment without nystagmus ([VI-nys], n=11), and children with VI with accompanying nystagmus ([VI+nys], n=26). Exclusio

  2. Crowded visual search in children with normal vision and children with visual impairment

    NARCIS (Netherlands)

    Huurneman, B.; Cox, R.F.A.; Vlaskamp, B.N.S.; Boonstra, F.N.

    2014-01-01

    This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n = 11), children with visual impairment without nystagmus ([VI−nys], n = 11), and children with VI with accompanying nystagmus ([VI+nys], n = 26). Ex

  3. Crowded visual search in children with normal vision and children with visual impairment

    NARCIS (Netherlands)

    Huurneman, Bianca; Cox, Ralf F. A.; Vlaskamp, Björn N. S.; Boonstra, F. Nienke

    2014-01-01

    This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n = 11), children with visual impairment without nystagmus ([VI-nys], n = 11), and children with VI with accompanying nystagmus ([VI+nys], n = 26). Ex

  4. The Impact of Expert Visual Guidance on Trainee Visual Search Strategy, Visual Attention and Motor Skills

    Directory of Open Access Journals (Sweden)

    Daniel Richard Leff

    2015-10-01

    Full Text Available Minimally invasive and robotic surgery changes the capacity for surgical mentors to guide their trainees with the control customary to open surgery. This neuroergonomic study aims to assess a Collaborative Gaze Channel (CGC; which detects trainer gaze-behaviour and displays the point of regard to the trainee. A randomised crossover study was conducted in which twenty subjects performed a simulated robotic surgical task necessitating collaboration either with verbal (control condition or visual guidance with CGC (study condition. Trainee occipito-parietal (O-P cortical function was assessed with optical topography (OT and gaze-behaviour was evaluated using video-oculography. Performance during gaze-assistance was significantly superior [biopsy number: (mean ± SD: control=5·6±1·8 vs. CGC=6·6±2·0; p< 0.05] and was associated with significantly lower O-P cortical activity [∆HbO2 mMol x cm [median (IQR] control = 2.5 (12.0 vs. CGC 0.63 (11.2, p < 0.001]. A random effect model confirmed the association between guidance mode and O-P excitation. Network cost and global efficiency and global efficiency were not significantly influenced by guidance mode. A gaze channel enhances performance, modulates visual search, and alleviates the burden in brain centres subserving visual attention and does not induce changes in the trainee's O-P functional network observable with the current OT technique. The results imply that through visual guidance, attentional resources may be liberated, potentially improving the capability trainees to attend to other safety critical events during the procedure.

  5. Aurally Aided Visual Search Performance Comparing Virtual Audio Systems

    DEFF Research Database (Denmark)

    Larsen, Camilla Horne; Lauritsen, David Skødt; Larsen, Jacob Junker;

    2014-01-01

    Due to increased computational power, reproducing binaural hearing in real-time applications, through usage of head-related transfer functions (HRTFs), is now possible. This paper addresses the differences in aurally-aided visual search performance between a HRTF enhanced audio system (3D......) and an amplitude panning audio system (panning) in a virtual environment. We present a performance study involving 33 participants locating aurally-aided visual targets placed at fixed positions, under different audio conditions. A varying amount of visual distractors were present, represented as black circles...

  6. Vigilance, visual search and attention in an agricultural task.

    Science.gov (United States)

    Hartley, L R; Arnold, P K; Kobryn, H; Macleod, C

    1989-03-01

    In a fragile agricultural environment, such as Western Australia (WA), introduced exotic plant species present a serious environmental and economic threat. Skeleton weed, centaurea juncea, a Mediterranean daisy, was accidentally introduced into WA in 1963. It competes with cash crops such as wheat. When observed in the fields, farms are quarantined and mechanised teams search for the infestations in order to destroy them. Since the search process requires attention, visual search and vigilance, the present investigators conducted a number of controlled field trials to identify the importance of these factors in detection of the weed. The paper describes the basic hit rate, vigilance decrement, effect of search party size, effect of target size, and some data on the effect of solar illumination of the target. Several recommendations have been made and incorporated in the search programme and some laboratory studies undertaken to answer questions arising.

  7. In search of the emotional face: anger versus happiness superiority in visual search.

    Science.gov (United States)

    Savage, Ruth A; Lipp, Ottmar V; Craig, Belinda M; Becker, Stefanie I; Horstmann, Gernot

    2013-08-01

    Previous research has provided inconsistent results regarding visual search for emotional faces, yielding evidence for either anger superiority (i.e., more efficient search for angry faces) or happiness superiority effects (i.e., more efficient search for happy faces), suggesting that these results do not reflect on emotional expression, but on emotion (un-)related low-level perceptual features. The present study investigated possible factors mediating anger/happiness superiority effects; specifically search strategy (fixed vs. variable target search; Experiment 1), stimulus choice (Nimstim database vs. Ekman & Friesen database; Experiments 1 and 2), and emotional intensity (Experiment 3 and 3a). Angry faces were found faster than happy faces regardless of search strategy using faces from the Nimstim database (Experiment 1). By contrast, a happiness superiority effect was evident in Experiment 2 when using faces from the Ekman and Friesen database. Experiment 3 employed angry, happy, and exuberant expressions (Nimstim database) and yielded anger and happiness superiority effects, respectively, highlighting the importance of the choice of stimulus materials. Ratings of the stimulus materials collected in Experiment 3a indicate that differences in perceived emotional intensity, pleasantness, or arousal do not account for differences in search efficiency. Across three studies, the current investigation indicates that prior reports of anger or happiness superiority effects in visual search are likely to reflect on low-level visual features associated with the stimulus materials used, rather than on emotion.

  8. Visual attention to repeated print advertising : A test of scanpath theory

    NARCIS (Netherlands)

    Pieters, R; Rosbergen, E; Wedel, M

    1999-01-01

    The authors examine consumers' visual attention during repeated exposures to print advertisements using eye-tracking methodology. The authors propose a statistical model comprising submodels for two key measures of visual attention to elements of the advertisement: attention duration and inter- and

  9. Visual search deficits in Williams-Beuren syndrome.

    Science.gov (United States)

    Montfoort, I; Frens, M A; Hooge, I Th C; Haselen, G C Lagers-van; van der Geest, J N

    2007-03-14

    Williams-Beuren syndrome (WBS) is a rare genetic condition characterized by several physical and mental traits, such as a poor visuo-spatial processing and a relative strength in language. In this study we investigated how WBS subjects search and scan their visual environment. We presented 10 search displays on a computer screen to WBS subjects as well as control subjects, with the instruction to find a target out of several stimulus elements. We analyzed the eye movement patterns for fixation characteristics and systematicy of search. Fixations generally lasted longer in WBS subjects than in control subjects. WBS subjects made more fixations at a stimulus element they had already looked at and more fixations that were not aimed at a stimulus element at all, decreasing the efficiency of search. These outcomes lead to the conclusion that visual search of individuals with Williams-Beuren syndrome is less effective than in control subjects. This finding may be related to their motor deficits, an impaired processing of global visual information and/or deficits in working memory and could reflect impairments within the dorsal stream.

  10. Eye movements during visual search in patients with glaucoma

    Directory of Open Access Journals (Sweden)

    Smith Nicholas D

    2012-08-01

    Full Text Available Abstract Background Glaucoma has been shown to lead to disability in many daily tasks including visual search. This study aims to determine whether the saccadic eye movements of people with glaucoma differ from those of people with normal vision, and to investigate the association between eye movements and impaired visual search. Methods Forty patients (mean age: 67 [SD: 9] years with a range of glaucomatous visual field (VF defects in both eyes (mean best eye mean deviation [MD]: –5.9 (SD: 5.4 dB and 40 age-related people with normal vision (mean age: 66 [SD: 10] years were timed as they searched for a series of target objects in computer displayed photographs of real world scenes. Eye movements were simultaneously recorded using an eye tracker. Average number of saccades per second, average saccade amplitude and average search duration across trials were recorded. These response variables were compared with measurements of VF and contrast sensitivity. Results The average rate of saccades made by the patient group was significantly smaller than the number made by controls during the visual search task (P = 0.02; mean reduction of 5.6% (95% CI: 0.1 to 10.4%. There was no difference in average saccade amplitude between the patients and the controls (P = 0.09. Average number of saccades was weakly correlated with aspects of visual function, with patients with worse contrast sensitivity (PR logCS; Spearman’s rho: 0.42; P = 0.006 and more severe VF defects (best eye MD; Spearman’s rho: 0.34; P = 0.037 tending to make less eye movements during the task. Average detection time in the search task was associated with the average rate of saccades in the patient group (Spearman’s rho = −0.65; P  Conclusions The average rate of saccades made during visual search by this group of patients was fewer than those made by people with normal vision of a similar average age. There was wide variability in saccade rate in the patients

  11. Visualization for Information Retrieval based on Fast Search Technology

    Directory of Open Access Journals (Sweden)

    Mamoon H. Mamoon

    2013-03-01

    Full Text Available The core of search engine is information retrieval technique. Using information retrieval system backs more retrieval results, some of them more relevant than other, and some is not relevant. While using search engine to retrieve information has grown very substantially, there remain problems with the information retrieval systems. The interface of the systems does not help them to perceive the precision of these results. It is therefore not surprising that graphical visualizations have been employed in search engines to assist users. The main objective of Internet users is to find the required information with high efficiency and effectiveness. In this paper we present brief sides of information visualization's role in enhancing web information retrieval system as in some of its techniques such as tree view, title view, map view, bubble view and cloud view and its tools such as highlighting and Colored Query Result.

  12. Functional Connectivity Between Superior Parietal Lobule and Primary Visual Cortex "at Rest" Predicts Visual Search Efficiency.

    Science.gov (United States)

    Bueichekú, Elisenda; Ventura-Campos, Noelia; Palomar-García, María-Ángeles; Miró-Padilla, Anna; Parcet, María-Antonia; Ávila, César

    2015-10-01

    Spatiotemporal activity that emerges spontaneously "at rest" has been proposed to reflect individual a priori biases in cognitive processing. This research focused on testing neurocognitive models of visual attention by studying the functional connectivity (FC) of the superior parietal lobule (SPL), given its central role in establishing priority maps during visual search tasks. Twenty-three human participants completed a functional magnetic resonance imaging session that featured a resting-state scan, followed by a visual search task based on the alphanumeric category effect. As expected, the behavioral results showed longer reaction times and more errors for the within-category (i.e., searching a target letter among letters) than the between-category search (i.e., searching a target letter among numbers). The within-category condition was related to greater activation of the superior and inferior parietal lobules, occipital cortex, inferior frontal cortex, dorsal anterior cingulate cortex, and the superior colliculus than the between-category search. The resting-state FC analysis of the SPL revealed a broad network that included connections with the inferotemporal cortex, dorsolateral prefrontal cortex, and dorsal frontal areas like the supplementary motor area and frontal eye field. Noteworthy, the regression analysis revealed that the more efficient participants in the visual search showed stronger FC between the SPL and areas of primary visual cortex (V1) related to the search task. We shed some light on how the SPL establishes a priority map of the environment during visual attention tasks and how FC is a valuable tool for assessing individual differences while performing cognitive tasks.

  13. Mandatory processing of irrelevant fearful face features in visual search.

    Science.gov (United States)

    Fenker, Daniela B; Heipertz, Dorothee; Boehler, Carsten N; Schoenfeld, Mircea A; Noesselt, Tömme; Heinze, Hans-Jochen; Duezel, Emrah; Hopf, Jens-Max

    2010-12-01

    Faces expressing fear may attract attention in an automatic bottom-up fashion. Here we address this issue with magneto-encephalographic (MEG) recordings in subjects performing a demanding visual search combined with the presentation of irrelevant neutral or fearful faces. The impact of the faces' emotional expression on attentional selection was assessed by analyzing the N2pc component--a modulation of the event-related magnetic field response known to reflect attentional focusing in visual search. We observed that lateralized fearful faces elicited an N2pc approximately between 240 and 400 msec in ventral extrastriate cortex that was independent of the N2pc reflecting target selection in visual search. Despite their clear influence on neural processing, fearful faces did not significantly influence behavioral performance. To clarify this discrepancy, we further performed an MEG experiment in which the demands of the search task were reduced. Under those conditions, lateralized fearful faces elicited an N2pc response that was again independent of the N2pc response to the search target. Behavioral performance was, however, influenced in a significant manner, suggesting that for behavioral effects to appear, sufficient attentional resources need to be left unoccupied by the search task--a notion put forward by the perceptual load theory. Our observations are taken to indicate that irrelevant fearful faces influence attentional processing in extrastriate visual cortex in an automatic fashion and independent of other task-relevant attentional operations. However, this may not necessarily be echoed at the behavioral level as long as task-relevant selection operations exhaust attentional resources.

  14. The Mechanisms Underlying the ASD Advantage in Visual Search.

    Science.gov (United States)

    Kaldy, Zsuzsa; Giserman, Ivy; Carter, Alice S; Blaser, Erik

    2016-05-01

    A number of studies have demonstrated that individuals with autism spectrum disorders (ASDs) are faster or more successful than typically developing control participants at various visual-attentional tasks (for reviews, see Dakin and Frith in Neuron 48:497-507, 2005; Simmons et al. in Vis Res 49:2705-2739, 2009). This "ASD advantage" was first identified in the domain of visual search by Plaisted et al. (J Child Psychol Psychiatry 39:777-783, 1998). Here we survey the findings of visual search studies from the past 15 years that contrasted the performance of individuals with and without ASD. Although there are some minor caveats, the overall consensus is that-across development and a broad range of symptom severity-individuals with ASD reliably outperform controls on visual search. The etiology of the ASD advantage has not been formally specified, but has been commonly attributed to 'enhanced perceptual discrimination', a superior ability to visually discriminate between targets and distractors in such tasks (e.g. O'Riordan in Cognition 77:81-96, 2000). As well, there is considerable evidence for impairments of the attentional network in ASD (for a review, see Keehn et al. in J Child Psychol Psychiatry 37:164-183, 2013). We discuss some recent results from our laboratory that support an attentional, rather than perceptual explanation for the ASD advantage in visual search. We speculate that this new conceptualization may offer a better understanding of some of the behavioral symptoms associated with ASD, such as over-focusing and restricted interests.

  15. Neural correlates of context-dependent feature conjunction learning in visual search tasks.

    Science.gov (United States)

    Reavis, Eric A; Frank, Sebastian M; Greenlee, Mark W; Tse, Peter U

    2016-06-01

    Many perceptual learning experiments show that repeated exposure to a basic visual feature such as a specific orientation or spatial frequency can modify perception of that feature, and that those perceptual changes are associated with changes in neural tuning early in visual processing. Such perceptual learning effects thus exert a bottom-up influence on subsequent stimulus processing, independent of task-demands or endogenous influences (e.g., volitional attention). However, it is unclear whether such bottom-up changes in perception can occur as more complex stimuli such as conjunctions of visual features are learned. It is not known whether changes in the efficiency with which people learn to process feature conjunctions in a task (e.g., visual search) reflect true bottom-up perceptual learning versus top-down, task-related learning (e.g., learning better control of endogenous attention). Here we show that feature conjunction learning in visual search leads to bottom-up changes in stimulus processing. First, using fMRI, we demonstrate that conjunction learning in visual search has a distinct neural signature: an increase in target-evoked activity relative to distractor-evoked activity (i.e., a relative increase in target salience). Second, we demonstrate that after learning, this neural signature is still evident even when participants passively view learned stimuli while performing an unrelated, attention-demanding task. This suggests that conjunction learning results in altered bottom-up perceptual processing of the learned conjunction stimuli (i.e., a perceptual change independent of the task). We further show that the acquired change in target-evoked activity is contextually dependent on the presence of distractors, suggesting that search array Gestalts are learned. Hum Brain Mapp 37:2319-2330, 2016. © 2016 Wiley Periodicals, Inc.

  16. Statistical patterns of visual search for hidden objects

    Science.gov (United States)

    Credidio, Heitor F.; Teixeira, Elisângela N.; Reis, Saulo D. S.; Moreira, André A.; Andrade, José S., Jr.

    2012-12-01

    The movement of the eyes has been the subject of intensive research as a way to elucidate inner mechanisms of cognitive processes. A cognitive task that is rather frequent in our daily life is the visual search for hidden objects. Here we investigate through eye-tracking experiments the statistical properties associated with the search of target images embedded in a landscape of distractors. Specifically, our results show that the twofold process of eye movement, composed of sequences of fixations (small steps) intercalated by saccades (longer jumps), displays characteristic statistical signatures. While the saccadic jumps follow a log-normal distribution of distances, which is typical of multiplicative processes, the lengths of the smaller steps in the fixation trajectories are consistent with a power-law distribution. Moreover, the present analysis reveals a clear transition between a directional serial search to an isotropic random movement as the difficulty level of the searching task is increased.

  17. An Experimental Report on Asymmetry in Visual Search

    Institute of Scientific and Technical Information of China (English)

    陈咏媛

    2006-01-01

    The search rate for a target among distractors may vary dramatically depending on which stimulus plays the role of target and which that of distractors. In this experiment, we found that the time required to find a closed circle was significantly shorter than that of a circle with a gap.The results are completely the same as Triesman's research in 1985, which predicts that searching for a circle should be parallel and fast. We infer that it may due to the small quantity of subjects and the subjects' poor performance caused by the lack of strictness in manipulation of experiment.Generally speaking, there absolutely exists an asymmetry in visual search, and the reaction time is significantly effected by the display size in the search of feature.

  18. Crowded visual search in children with normal vision and children with visual impairment.

    Science.gov (United States)

    Huurneman, Bianca; Cox, Ralf F A; Vlaskamp, Björn N S; Boonstra, F Nienke

    2014-03-01

    This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n=11), children with visual impairment without nystagmus ([VI-nys], n=11), and children with VI with accompanying nystagmus ([VI+nys], n=26). Exclusion criteria for children with VI were: multiple impairments and visual acuity poorer than 20/400 or better than 20/50. Three search conditions were presented: a row with homogeneous distractors, a matrix with homogeneous distractors, and a matrix with heterogeneous distractors. Element spacing was manipulated in 5 steps from 2 to 32 minutes of arc. Symbols were sized 2 times the threshold acuity to guarantee visibility for the VI groups. During simple row and matrix search with homogeneous distractors children in the VI+nys group were less accurate than children with NV at smaller spacings. Group differences were even more pronounced during matrix search with heterogeneous distractors. Search times were longer in children with VI compared to children with NV. The more extended impairments during serial search reveal greater dependence on oculomotor control during serial compared to parallel search. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Macular degeneration affects eye movement behaviour during visual search

    Directory of Open Access Journals (Sweden)

    Stefan eVan Der Stigchel

    2013-09-01

    Full Text Available Patients with a scotoma in their central vision (e.g. due to macular degeneration, MD commonly adopt a strategy to direct the eyes such that the image falls onto a peripheral location on the retina. This location is referred to as the preferred retinal locus (PRL. Although previous research has investigated the characteristics of this PRL, it is unclear whether eye movement metrics are modulated by peripheral viewing with a PRL as measured during a visual search paradigm. To this end, we tested four MD patients in a visual search paradigm and contrasted their performance with a healthy control group and a healthy control group performing the same experiment with a simulated scotoma. The experiment contained two conditions. In the first condition the target was an unfilled circle hidden among c-shaped distractors (serial condition and in the second condition the target was a filled circle (pop-out condition. Saccadic search latencies for the MD group were significantly longer in both conditions compared to both control groups. Results of a subsequent experiment indicated that this difference between the MD and the control groups could not be explained by a difference in target selection sensitivity. Furthermore, search behaviour of MD patients was associated with saccades with smaller amplitudes towards the scotoma, an increased intersaccadic interval and an increased number of eye movements necessary to locate the target. Some of these characteristics, such as the increased intersaccadic interval, were also observed in the simulation group, which indicate that these characteristics are related to the peripheral viewing itself. We suggest that the combination of the central scotoma and peripheral viewing can explain the altered search behaviour and no behavioural evidence was found for a possible reorganization of the visual system associated with the use of a PRL. Thus the switch from a fovea-based to a PRL-based reference frame impairs search

  20. Aurally Aided Visual Search Performance Comparing Virtual Audio Systems

    DEFF Research Database (Denmark)

    Larsen, Camilla Horne; Lauritsen, David Skødt; Larsen, Jacob Junker;

    2014-01-01

    Due to increased computational power reproducing binaural hearing in real-time applications, through usage of head-related transfer functions (HRTFs), is now possible. This paper addresses the differences in aurally-aided visual search performance between an HRTF enhanced audio system (3D...... with white dots. The results indicate that 3D audio yields faster search latencies than panning audio, especially with larger amounts of distractors. The applications of this research could fit virtual environments such as video games or virtual simulations....

  1. Perspective: n-type oxide thermoelectrics via visual search strategies

    Directory of Open Access Journals (Sweden)

    Guangzong Xing

    2016-05-01

    Full Text Available We discuss and present search strategies for finding new thermoelectric compositions based on first principles electronic structure and transport calculations. We illustrate them by application to a search for potential n-type oxide thermoelectric materials. This includes a screen based on visualization of electronic energy isosurfaces. We report compounds that show potential as thermoelectric materials along with detailed properties, including SrTiO3, which is a known thermoelectric, and appropriately doped KNbO3 and rutile TiO2.

  2. The effects of visual realism on search tasks in mixed reality simulation.

    Science.gov (United States)

    Lee, Cha; Rincon, Gustavo A; Meyer, Greg; Höllerer, Tobias; Bowman, Doug A

    2013-04-01

    In this paper, we investigate the validity of Mixed Reality (MR) Simulation by conducting an experiment studying the effects of the visual realism of the simulated environment on various search tasks in Augmented Reality (AR). MR Simulation is a practical approach to conducting controlled and repeatable user experiments in MR, including AR. This approach uses a high-fidelity Virtual Reality (VR) display system to simulate a wide range of equal or lower fidelity displays from the MR continuum, for the express purpose of conducting user experiments. For the experiment, we created three virtual models of a real-world location, each with a different perceived level of visual realism. We designed and executed an AR experiment using the real-world location and repeated the experiment within VR using the three virtual models we created. The experiment looked into how fast users could search for both physical and virtual information that was present in the scene. Our experiment demonstrates the usefulness of MR Simulation and provides early evidence for the validity of MR Simulation with respect to AR search tasks performed in immersive VR.

  3. Synchronized audio-visual transients drive efficient visual search for motion-in-depth.

    Directory of Open Access Journals (Sweden)

    Marina Zannoli

    Full Text Available In natural audio-visual environments, a change in depth is usually correlated with a change in loudness. In the present study, we investigated whether correlating changes in disparity and loudness would provide a functional advantage in binding disparity and sound amplitude in a visual search paradigm. To test this hypothesis, we used a method similar to that used by van der Burg et al. to show that non-spatial transient (square-wave modulations of loudness can drastically improve spatial visual search for a correlated luminance modulation. We used dynamic random-dot stereogram displays to produce pure disparity modulations. Target and distractors were small disparity-defined squares (either 6 or 10 in total. Each square moved back and forth in depth in front of the background plane at different phases. The target's depth modulation was synchronized with an amplitude-modulated auditory tone. Visual and auditory modulations were always congruent (both sine-wave or square-wave. In a speeded search task, five observers were asked to identify the target as quickly as possible. Results show a significant improvement in visual search times in the square-wave condition compared to the sine condition, suggesting that transient auditory information can efficiently drive visual search in the disparity domain. In a second experiment, participants performed the same task in the absence of sound and showed a clear set-size effect in both modulation conditions. In a third experiment, we correlated the sound with a distractor instead of the target. This produced longer search times, indicating that the correlation is not easily ignored.

  4. The influence of attention, learning, and motivation on visual search.

    Science.gov (United States)

    Dodd, Michael D; Flowers, John H

    2012-01-01

    The 59th Annual Nebraska Symposium on Motivation (The Influence of Attention, Learning, and Motivation on Visual Search) took place April 7-8, 2011, on the University of Nebraska-Lincoln campus. The symposium brought together leading scholars who conduct research related to visual search at a variety levels for a series of talks, poster presentations, panel discussions, and numerous additional opportunities for intellectual exchange. The Symposium was also streamed online for the first time in the history of the event, allowing individuals from around the world to view the presentations and submit questions. The present volume is intended to both commemorate the event itself and to allow our speakers additional opportunity to address issues and current research that have since arisen. Each of the speakers (and, in some cases, their graduate students and post docs) has provided a chapter which both summarizes and expands on their original presentations. In this chapter, we sought to a) provide additional context as to how the Symposium came to be, b) discuss why we thought that this was an ideal time to organize a visual search symposium, and c) to briefly address recent trends and potential future directions in the field. We hope you find the volume both enjoyable and informative, and we thank the authors who have contributed a series of engaging chapters.

  5. How mammographic breast density affects radiologists' visual search patterns.

    Science.gov (United States)

    Al Mousa, Dana S; Brennan, Patrick C; Ryan, Elaine A; Lee, Warwick B; Tan, Jennifer; Mello-Thoms, Claudia

    2014-11-01

    To determine the impact of mammographic breast density on the visual search process of radiologists when reading digital mammograms. Institutional review board approval was obtained. A set of 149 craniocaudal digital mammograms were read by seven radiologists, and observer search patterns were recorded. Total time examining each case, time to first hit the lesion, dwell time, and number of hits per area were calculated. The nonparametric Mann-Whitney U test was used for statistical evaluation. In both low- and high-mammographic density cases, significant increases were observed in the time to first hit lesions when they were located outside, compared to overlying fibroglandular dense tissue (P = .001). Significantly longer dwell time (P = .003) and greater number of fixations (P = .0003) were observed when the lesions were situated within--rather than outside--the dense fibroglandular tissue. Increased mammographic breast density changes radiologists' visual search patterns. Dense areas of the parenchyma attracted greater visual attention in both high- and low-mammographic density cases, resulting in faster detection of lesions overlying the fibroglandular dense tissue, along with longer dwell times and greater number of fixations, as compared to lesions located outside the dense fibroglandular regions. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

  6. Reading and visual search: a developmental study in normal children.

    Directory of Open Access Journals (Sweden)

    Magali Seassau

    Full Text Available Studies dealing with developmental aspects of binocular eye movement behaviour during reading are scarce. In this study we have explored binocular strategies during reading and during visual search tasks in a large population of normal young readers. Binocular eye movements were recorded using an infrared video-oculography system in sixty-nine children (aged 6 to 15 and in a group of 10 adults (aged 24 to 39. The main findings are (i in both tasks the number of progressive saccades (to the right and regressive saccades (to the left decreases with age; (ii the amplitude of progressive saccades increases with age in the reading task only; (iii in both tasks, the duration of fixations as well as the total duration of the task decreases with age; (iv in both tasks, the amplitude of disconjugacy recorded during and after the saccades decreases with age; (v children are significantly more accurate in reading than in visual search after 10 years of age. Data reported here confirms and expands previous studies on children's reading. The new finding is that younger children show poorer coordination than adults, both while reading and while performing a visual search task. Both reading skills and binocular saccades coordination improve with age and children reach a similar level to adults after the age of 10. This finding is most likely related to the fact that learning mechanisms responsible for saccade yoking develop during childhood until adolescence.

  7. Visual working memory simultaneously guides facilitation and inhibition during visual search.

    Science.gov (United States)

    Dube, Blaire; Basciano, April; Emrich, Stephen M; Al-Aidroos, Naseem

    2016-07-01

    During visual search, visual working memory (VWM) supports the guidance of attention in two ways: It stores the identity of the search target, facilitating the selection of matching stimuli in the search array, and it maintains a record of the distractors processed during search so that they can be inhibited. In two experiments, we investigated whether the full contents of VWM can be used to support both of these abilities simultaneously. In Experiment 1, participants completed a preview search task in which (a) a subset of search distractors appeared before the remainder of the search items, affording participants the opportunity to inhibit them, and (b) the search target varied from trial to trial, requiring the search target template to be maintained in VWM. We observed the established signature of VWM-based inhibition-reduced ability to ignore previewed distractors when the number of distractors exceeds VWM's capacity-suggesting that VWM can serve this role while also representing the target template. In Experiment 2, we replicated Experiment 1, but added to the search displays a singleton distractor that sometimes matched the color (a task-irrelevant feature) of the search target, to evaluate capture. We again observed the signature of VWM-based preview inhibition along with attentional capture by (and, thus, facilitation of) singletons matching the target template. These findings indicate that more than one VWM representation can bias attention at a time, and that these representations can separately affect selection through either facilitation or inhibition, placing constraints on existing models of the VWM-based guidance of attention.

  8. The Efficiency of a Visual Skills Training Program on Visual Search Performance

    Directory of Open Access Journals (Sweden)

    Krzepota Justyna

    2015-06-01

    Full Text Available In this study, we conducted an experiment in which we analyzed the possibilities to develop visual skills by specifically targeted training of visual search. The aim of our study was to investigate whether, for how long and to what extent a training program for visual functions could improve visual search. The study involved 24 healthy students from the Szczecin University who were divided into two groups: experimental (12 and control (12. In addition to regular sports and recreational activities of the curriculum, the subjects of the experimental group also participated in 8-week long training with visual functions, 3 times a week for 45 min. The Signal Test of the Vienna Test System was performed four times: before entering the study, after first 4 weeks of the experiment, immediately after its completion and 4 weeks after the study terminated. The results of this experiment proved that an 8-week long perceptual training program significantly differentiated the plot of visual detecting time. For the visual detecting time changes, the first factor, Group, was significant as a main effect (F(1,22=6.49, p<0.05 as well as the second factor, Training (F(3,66=5.06, p<0.01. The interaction between the two factors (Group vs. Training of perceptual training was F(3,66=6.82 (p<0.001. Similarly, for the number of correct reactions, there was a main effect of a Group factor (F(1,22=23.40, p<0.001, a main effect of a Training factor (F(3,66=11.60, p<0.001 and a significant interaction between factors (Group vs. Training (F(3,66=10.33, p<0.001. Our study suggests that 8-week training of visual functions can improve visual search performance.

  9. The Efficiency of a Visual Skills Training Program on Visual Search Performance.

    Science.gov (United States)

    Krzepota, Justyna; Zwierko, Teresa; Puchalska-Niedbał, Lidia; Markiewicz, Mikołaj; Florkiewicz, Beata; Lubiński, Wojciech

    2015-06-27

    In this study, we conducted an experiment in which we analyzed the possibilities to develop visual skills by specifically targeted training of visual search. The aim of our study was to investigate whether, for how long and to what extent a training program for visual functions could improve visual search. The study involved 24 healthy students from the Szczecin University who were divided into two groups: experimental (12) and control (12). In addition to regular sports and recreational activities of the curriculum, the subjects of the experimental group also participated in 8-week long training with visual functions, 3 times a week for 45 min. The Signal Test of the Vienna Test System was performed four times: before entering the study, after first 4 weeks of the experiment, immediately after its completion and 4 weeks after the study terminated. The results of this experiment proved that an 8-week long perceptual training program significantly differentiated the plot of visual detecting time. For the visual detecting time changes, the first factor, Group, was significant as a main effect (F(1,22)=6.49, pperceptual training was F(3,66)=6.82 (p<0.001). Similarly, for the number of correct reactions, there was a main effect of a Group factor (F(1,22)=23.40, p<0.001), a main effect of a Training factor (F(3,66)=11.60, p<0.001) and a significant interaction between factors (Group vs. Training) (F(3,66)=10.33, p<0.001). Our study suggests that 8-week training of visual functions can improve visual search performance.

  10. Feedback strategies for visual search in airframe structural inspection.

    Science.gov (United States)

    Gramopadhye, A K; Drury, C G; Sharit, J

    1997-05-01

    Feedback of information has consistently shown positive results in human inspection, provided it is given in a timely and appropriate manner. Feedback serves as the basis of most training schemes; traditionally this has been performance feedback. Other forms of feedback which provide strategy information rather than performance information may have a role in improving inspection. This study compared performance feedback and cognitive feedback in a realistic simulation of an aircraft structural inspection task. Performance (time, errors) feedback showed the greatest improvements in performance measures. Cognitive feedback enhanced efficiency measures of search strategy. When cognitive feedback consisted of visual representations of the path and the coverage of the search sequence, subjects also were able to use this task information to improve their search performance.

  11. Information-Limited Parallel Processing in Difficult Heterogeneous Covert Visual Search

    Science.gov (United States)

    Dosher, Barbara Anne; Han, Songmei; Lu, Zhong-Lin

    2010-01-01

    Difficult visual search is often attributed to time-limited serial attention operations, although neural computations in the early visual system are parallel. Using probabilistic search models (Dosher, Han, & Lu, 2004) and a full time-course analysis of the dynamics of covert visual search, we distinguish unlimited capacity parallel versus serial…

  12. Understanding visual search patterns of dermatologists assessing pigmented skin lesions before and after online training.

    Science.gov (United States)

    Krupinski, Elizabeth A; Chao, Joseph; Hofmann-Wellenhof, Rainer; Morrison, Lynne; Curiel-Lewandrowski, Clara

    2014-12-01

    The goal of this investigation was to explore the feasibility of characterizing the visual search characteristics of dermatologists evaluating images corresponding to single pigmented skin lesions (PSLs) (close-ups and dermoscopy) as a venue to improve training programs for dermoscopy. Two Board-certified dermatologists and two dermatology residents participated in a phased study. In phase I, they viewed a series of 20 PSL cases ranging from benign nevi to melanoma. The close-up and dermoscopy images of the PSL were evaluated sequentially and rated individually as benign or malignant, while eye position was recorded. Subsequently, the participating subjects completed an online dermoscopy training module that included a pre- and post-test assessing their dermoscopy skills (phase 2). Three months later, the subjects repeated their assessment on the 20 PSLs presented during phase I of the study. Significant differences in viewing time and eye-position parameters were observed as a function of level of expertise. Dermatologists overall have more efficient search than residents generating fewer fixations with shorter dwells. Fixations and dwells associated with decisions changing from benign to malignant or vice versa from photo to dermatoscopic viewing were longer than any other decision, indicating increased visual processing for those decisions. These differences in visual search may have implications for developing tools to teach dermatologists and residents about how to better utilize dermoscopy in clinical practice.

  13. Visual-search models for location-known detection tasks

    Science.gov (United States)

    Gifford, H. C.; Karbaschi, Z.; Banerjee, K.; Das, M.

    2017-03-01

    Lesion-detection studies that analyze a fixed target position are generally considered predictive of studies involving lesion search, but the extent of the correlation often goes untested. The purpose of this work was to develop a visual-search (VS) model observer for location-known tasks that, coupled with previous work on localization tasks, would allow efficient same-observer assessments of how search and other task variations can alter study outcomes. The model observer featured adjustable parameters to control the search radius around the fixed lesion location and the minimum separation between suspicious locations. Comparisons were made against human observers, a channelized Hotelling observer and a nonprewhitening observer with eye filter in a two-alternative forced-choice study with simulated lumpy background images containing stationary anatomical and quantum noise. These images modeled single-pinhole nuclear medicine scans with different pinhole sizes. When the VS observer's search radius was optimized with training images, close agreement was obtained with human-observer results. Some performance differences between the humans could be explained by varying the model observer's separation parameter. The range of optimal pinhole sizes identified by the VS observer was in agreement with the range determined with the channelized Hotelling observer.

  14. Mortality estimates from repeated visual censuses of a parrotfish (Sparisoma viride) population : Demographic implications

    NARCIS (Netherlands)

    vanRooij, JM; Videler, JJ

    1997-01-01

    Repeated visual censuses of different categories (juveniles, females, territorial and group males) of the stoplight parrotfish (Sparisoma viride, a protogynous hermaphrodite) over a 3-year period indicated a relatively stable size and structure of the adult population. This allowed estimates of size

  15. Drivers’ Visual Search Patterns during Overtaking Maneuvers on Freeway

    Directory of Open Access Journals (Sweden)

    Wenhui Zhang

    2016-11-01

    Full Text Available Drivers gather traffic information primarily by means of their vision. Especially during complicated maneuvers, such as overtaking, they need to perceive a variety of characteristics including the lateral and longitudinal distances with other vehicles, the speed of others vehicles, lane occupancy, and so on, to avoid crashes. The primary object of this study is to examine the appropriate visual search patterns during overtaking maneuvers on freeways. We designed a series of driving simulating experiments in which the type and speed of the leading vehicle were considered as two influential factors. One hundred and forty participants took part in the study. The participants overtook the leading vehicles just like they would usually do so, and their eye movements were collected by use of the Eye Tracker. The results show that participants’ gaze durations and saccade durations followed normal distribution patterns and that saccade angles followed a log-normal distribution pattern. It was observed that the type of leading vehicle significantly impacted the drivers’ gaze duration and gaze frequency. As the speed of a leading vehicle increased, subjects’ saccade durations became longer and saccade angles became larger. In addition, the initial and destination lanes were found to be key areas with the highest visual allocating proportion, accounting for more than 65% of total visual allocation. Subjects tended to more frequently shift their viewpoints between the initial lane and destination lane in order to search for crucial traffic information. However, they seldom directly shifted their viewpoints between the two wing mirrors.

  16. Cuckoo Search Algorithm Based on Repeat-Cycle Asymptotic Self-Learning and Self-Evolving Disturbance for Function Optimization

    OpenAIRE

    Jie-sheng Wang; Shu-xia Li; Jiang-di Song

    2015-01-01

    In order to improve convergence velocity and optimization accuracy of the cuckoo search (CS) algorithm for solving the function optimization problems, a new improved cuckoo search algorithm based on the repeat-cycle asymptotic self-learning and self-evolving disturbance (RC-SSCS) is proposed. A disturbance operation is added into the algorithm by constructing a disturbance factor to make a more careful and thorough search near the bird’s nests location. In order to select a reasonable repeat-...

  17. Visual tracking method based on cuckoo search algorithm

    Science.gov (United States)

    Gao, Ming-Liang; Yin, Li-Ju; Zou, Guo-Feng; Li, Hai-Tao; Liu, Wei

    2015-07-01

    Cuckoo search (CS) is a new meta-heuristic optimization algorithm that is based on the obligate brood parasitic behavior of some cuckoo species in combination with the Lévy flight behavior of some birds and fruit flies. It has been found to be efficient in solving global optimization problems. An application of CS is presented to solve the visual tracking problem. The relationship between optimization and visual tracking is comparatively studied and the parameters' sensitivity and adjustment of CS in the tracking system are experimentally studied. To demonstrate the tracking ability of a CS-based tracker, a comparative study of tracking accuracy and speed of the CS-based tracker with six "state-of-art" trackers, namely, particle filter, meanshift, PSO, ensemble tracker, fragments tracker, and compressive tracker are presented. Comparative results show that the CS-based tracker outperforms the other trackers.

  18. WORDGRAPH: Keyword-in-Context Visualization for NETSPEAK's Wildcard Search.

    Science.gov (United States)

    Riehmann, Patrick; Gruendl, Henning; Potthast, Martin; Trenkmann, Martin; Stein, Benno; Froehlich, Benno

    2012-09-01

    The WORDGRAPH helps writers in visually choosing phrases while writing a text. It checks for the commonness of phrases and allows for the retrieval of alternatives by means of wildcard queries. To support such queries, we implement a scalable retrieval engine, which returns high-quality results within milliseconds using a probabilistic retrieval strategy. The results are displayed as WORDGRAPH visualization or as a textual list. The graphical interface provides an effective means for interactive exploration of search results using filter techniques, query expansion, and navigation. Our observations indicate that, of three investigated retrieval tasks, the textual interface is sufficient for the phrase verification task, wherein both interfaces support context-sensitive word choice, and the WORDGRAPH best supports the exploration of a phrase's context or the underlying corpus. Our user study confirms these observations and shows that WORDGRAPH is generally the preferred interface over the textual result list for queries containing multiple wildcards.

  19. Visual Search Revived: The Slopes Are Not That Slippery: A Reply to Kristjansson (2015).

    Science.gov (United States)

    Wolfe, Jeremy M

    2016-05-01

    Kristjansson (2015) suggests that standard research methods in the study of visual search should be "reconsidered." He reiterates a useful warning against treating reaction time x set size functions as simple metrics that can be used to label search tasks as "serial" or "parallel." However, I argue that he goes too far with a broad attack on the use of slopes in the study of visual search. Used wisely, slopes do provide us with insight into the mechanisms of visual search.

  20. Online multiple kernel similarity learning for visual search.

    Science.gov (United States)

    Xia, Hao; Hoi, Steven C H; Jin, Rong; Zhao, Peilin

    2014-03-01

    Recent years have witnessed a number of studies on distance metric learning to improve visual similarity search in content-based image retrieval (CBIR). Despite their successes, most existing methods on distance metric learning are limited in two aspects. First, they usually assume the target proximity function follows the family of Mahalanobis distances, which limits their capacity of measuring similarity of complex patterns in real applications. Second, they often cannot effectively handle the similarity measure of multimodal data that may originate from multiple resources. To overcome these limitations, this paper investigates an online kernel similarity learning framework for learning kernel-based proximity functions which goes beyond the conventional linear distance metric learning approaches. Based on the framework, we propose a novel online multiple kernel similarity (OMKS) learning method which learns a flexible nonlinear proximity function with multiple kernels to improve visual similarity search in CBIR. We evaluate the proposed technique for CBIR on a variety of image data sets in which encouraging results show that OMKS outperforms the state-of-the-art techniques significantly.

  1. Visual search performance in infants associates with later ASD diagnosis.

    Science.gov (United States)

    Cheung, C H M; Bedford, R; Johnson, M H; Charman, T; Gliga, T

    2016-09-30

    An enhanced ability to detect visual targets amongst distractors, known as visual search (VS), has often been documented in Autism Spectrum Disorders (ASD). Yet, it is unclear when this behaviour emerges in development and if it is specific to ASD. We followed up infants at high and low familial risk for ASD to investigate how early VS abilities links to later ASD diagnosis, the potential underlying mechanisms of this association and the specificity of superior VS to ASD. Clinical diagnosis of ASD as well as dimensional measures of ASD, attention-deficit/hyperactivity disorder (ADHD) and anxiety symptoms were ascertained at 3 years. At 9 and 15 months, but not at age 2 years, high-risk children who later met clinical criteria for ASD (HR-ASD) had better VS performance than those without later diagnosis and low-risk controls. Although HR-ASD children were also more attentive to the task at 9 months, this did not explain search performance. Superior VS specifically predicted 3 year-old ASD but not ADHD or anxiety symptoms. Our results demonstrate that atypical perception and core ASD symptoms of social interaction and communication are closely and selectively associated during early development, and suggest causal links between perceptual and social features of ASD. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  2. Electroencephalogram assessment of mental fatigue in visual search.

    Science.gov (United States)

    Fan, Xiaoli; Zhou, Qianxiang; Liu, Zhongqi; Xie, Fang

    2015-01-01

    Mental fatigue is considered to be a contributing factor responsible for numerous road accidents and various medical conditions and the efficiency and performance could be impaired during fatigue. Hence, determining how to evaluate mental fatigue is very important. In the present study, ten subjects performed a long-term visual search task with electroencephalogram recorded, and self-assessment and reaction time (RT) were combined to verify if mental fatigue had been induced and were also used as confirmatory tests for the proposed measures. The changes in relative energy in four wavebands (δ,θ,α, and β), four ratio formulas [(α+θ)/β,α/β,(α+θ)/(α+β), and θ/β], and Shannon's entropy (SE) were compared and analyzed between the beginning and end of the task. The results showed that a significant increase occurred in alpha activity in the frontal, central, posterior temporal, parietal, and occipital lobes, and a dip occurred in the beta activity in the pre-frontal, inferior frontal, posterior temporal, and occipital lobes. The ratio formulas clearly increased in all of these brain regions except the temporal region, where only α/β changed obviously after finishing the 60-min visual search task. SE significantly increased in the posterior temporal, parietal, and occipital lobes. These results demonstrate some potential indicators for mental fatigue detection and evaluation, which can be applied in the future development of countermeasures to fatigue.

  3. "Hot" Facilitation of "Cool" Processing: Emotional Distraction Can Enhance Priming of Visual Search

    Science.gov (United States)

    Kristjansson, Arni; Oladottir, Berglind; Most, Steven B.

    2013-01-01

    Emotional stimuli often capture attention and disrupt effortful cognitive processing. However, cognitive processes vary in the degree to which they require effort. We investigated the impact of emotional pictures on visual search and on automatic priming of search. Observers performed visual search after task-irrelevant neutral or emotionally…

  4. How visual search relates to visual diagnostic performance: a narrative systematic review of eye-tracking research in radiology.

    Science.gov (United States)

    van der Gijp, A; Ravesloot, C J; Jarodzka, H; van der Schaaf, M F; van der Schaaf, I C; van Schaik, J P J; Ten Cate, Th J

    2017-08-01

    Eye tracking research has been conducted for decades to gain understanding of visual diagnosis such as in radiology. For educational purposes, it is important to identify visual search patterns that are related to high perceptual performance and to identify effective teaching strategies. This review of eye-tracking literature in the radiology domain aims to identify visual search patterns associated with high perceptual performance. Databases PubMed, EMBASE, ERIC, PsycINFO, Scopus and Web of Science were searched using 'visual perception' OR 'eye tracking' AND 'radiology' and synonyms. Two authors independently screened search results and included eye tracking studies concerning visual skills in radiology published between January 1, 1994 and July 31, 2015. Two authors independently assessed study quality with the Medical Education Research Study Quality Instrument, and extracted study data with respect to design, participant and task characteristics, and variables. A thematic analysis was conducted to extract and arrange study results, and a textual narrative synthesis was applied for data integration and interpretation. The search resulted in 22 relevant full-text articles. Thematic analysis resulted in six themes that informed the relation between visual search and level of expertise: (1) time on task, (2) eye movement characteristics of experts, (3) differences in visual attention, (4) visual search patterns, (5) search patterns in cross sectional stack imaging, and (6) teaching visual search strategies. Expert search was found to be characterized by a global-focal search pattern, which represents an initial global impression, followed by a detailed, focal search-to-find mode. Specific task-related search patterns, like drilling through CT scans and systematic search in chest X-rays, were found to be related to high expert levels. One study investigated teaching of visual search strategies, and did not find a significant effect on perceptual performance. Eye

  5. Searching for the right word: Hybrid visual and memory search for words.

    Science.gov (United States)

    Boettcher, Sage E P; Wolfe, Jeremy M

    2015-05-01

    In "hybrid search" (Wolfe Psychological Science, 23(7), 698-703, 2012), observers search through visual space for any of multiple targets held in memory. With photorealistic objects as the stimuli, response times (RTs) increase linearly with the visual set size and logarithmically with the memory set size, even when over 100 items are committed to memory. It is well-established that pictures of objects are particularly easy to memorize (Brady, Konkle, Alvarez, & Oliva Proceedings of the National Academy of Sciences, 105, 14325-14329, 2008). Would hybrid-search performance be similar if the targets were words or phrases, in which word order can be important, so that the processes of memorization might be different? In Experiment 1, observers memorized 2, 4, 8, or 16 words in four different blocks. After passing a memory test, confirming their memorization of the list, the observers searched for these words in visual displays containing two to 16 words. Replicating Wolfe (Psychological Science, 23(7), 698-703, 2012), the RTs increased linearly with the visual set size and logarithmically with the length of the word list. The word lists of Experiment 1 were random. In Experiment 2, words were drawn from phrases that observers reported knowing by heart (e.g., "London Bridge is falling down"). Observers were asked to provide four phrases, ranging in length from two words to no less than 20 words (range 21-86). All words longer than two characters from the phrase, constituted the target list. Distractor words were matched for length and frequency. Even with these strongly ordered lists, the results again replicated the curvilinear function of memory set size seen in hybrid search. One might expect to find serial position effects, perhaps reducing the RTs for the first (primacy) and/or the last (recency) members of a list (Atkinson & Shiffrin, 1968; Murdock Journal of Experimental Psychology, 64, 482-488, 1962). Surprisingly, we showed no reliable effects of word order

  6. Repeating Pulsed Magnet System for Axion-like Particle Searches and Vacuum Birefringence Experiments

    CERN Document Server

    Yamazaki, T; Namba, T; Asai, S; Kobayashi, T; Matsuo, A; Kindo, K; Nojiri, H

    2016-01-01

    We have developed a repeating pulsed magnet system which generates magnetic fields of about 10 T in a direction transverse to an incident beam over a length of 0.8 m with a repetition rate of 0.2 Hz. Its repetition rate is by two orders of magnitude higher than usual pulsed magnets. It is composed of four low resistance racetrack coils and a 30 kJ transportable capacitor bank as a power supply. The system aims at axion-like particle searches with a pulsed light source and vacuum birefringence measurements. We report on the details of the system and its performances.

  7. Repeating pulsed magnet system for axion-like particle searches and vacuum birefringence experiments

    Science.gov (United States)

    Yamazaki, T.; Inada, T.; Namba, T.; Asai, S.; Kobayashi, T.; Matsuo, A.; Kindo, K.; Nojiri, H.

    2016-10-01

    We have developed a repeating pulsed magnet system which generates magnetic fields of about 10 T in a direction transverse to an incident beam over a length of 0.8 m with a repetition rate of 0.2 Hz. Its repetition rate is by two orders of magnitude higher than usual pulsed magnets. It is composed of four low resistance racetrack coils and a 30 kJ transportable capacitor bank as a power supply. The system aims at axion-like particle searches with a pulsed light source and vacuum birefringence measurements. We report on the details of the system and its performances.

  8. Search for soft gamma repeaters in the SMM/HXRBS data

    Science.gov (United States)

    Kouveliotou, C.; Norris, J. P.; Wood, K. S.; Cline, T. L.; Dennis, B. R.; Desal, U. D.; Orwig, L. E.

    1992-01-01

    The triggered fast memory of the hard X-ray burst spectrometer (HXRBS) on board the SMM is used to describe the results of a search for short transients resembling soft gamma repeater (SGR) bursts. Memory data for a total of about 4000 burst triggers, out of which only a very few could be considered as valid SGR candidate events, are analyzed. The search methodology is outlined, the HXRBS exposure and sensitivity to SGR bursts are calculated, and the criteria which constrain the number of candidate events are described. An upper limit is given for the SGR source number density. This limit, combined with results from other relevant observations and the assumption of a neutron star origin, are applied to obtain a constraint on SGR-active lifetimes.

  9. Pupil diameter reflects uncertainty in attentional selection during visual search

    Directory of Open Access Journals (Sweden)

    Joy J. Geng

    2015-08-01

    Full Text Available Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones & Cohen, 2005b; Yu & Dayan, 2005. In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time and performance accuracy (Experiments 1-2. Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes.

  10. Electrophysiological measurement of information flow during visual search.

    Science.gov (United States)

    Cosman, Joshua D; Arita, Jason T; Ianni, Julianna D; Woodman, Geoffrey F

    2016-04-01

    The temporal relationship between different stages of cognitive processing is long debated. This debate is ongoing, primarily because it is often difficult to measure the time course of multiple cognitive processes simultaneously. We employed a manipulation that allowed us to isolate ERP components related to perceptual processing, working memory, and response preparation, and then examined the temporal relationship between these components while observers performed a visual search task. We found that, when response speed and accuracy were equally stressed, our index of perceptual processing ended before both the transfer of information into working memory and response preparation began. However, when we stressed speed over accuracy, response preparation began before the completion of perceptual processing or transfer of information into working memory on trials with the fastest reaction times. These findings show that individuals can control the flow of information transmission between stages, either waiting for perceptual processing to be completed before preparing a response or configuring these stages to overlap in time.

  11. Age-related changes in conjunctive visual search in children with and without ASD.

    Science.gov (United States)

    Iarocci, Grace; Armstrong, Kimberly

    2014-04-01

    Visual-spatial strengths observed among people with autism spectrum disorder (ASD) may be associated with increased efficiency of selective attention mechanisms such as visual search. In a series of studies, researchers examined the visual search of targets that share features with distractors in a visual array and concluded that people with ASD showed enhanced performance on visual search tasks. However, methodological limitations, the small sample sizes, and the lack of developmental analysis have tempered the interpretations of these results. In this study, we specifically addressed age-related changes in visual search. We examined conjunctive visual search in groups of children with (n = 34) and without ASD (n = 35) at 7-9 years of age when visual search performance is beginning to improve, and later, at 10-12 years, when performance has improved. The results were consistent with previous developmental findings; 10- to 12-year-old children were significantly faster visual searchers than their 7- to 9-year-old counterparts. However, we found no evidence of enhanced search performance among the children with ASD at either the younger or older ages. More research is needed to understand the development of visual search in both children with and without ASD.

  12. Repeatability of Detecting Visual Cortex Activity in Functional Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Mahboubeh Ma'soumbeigi

    2012-03-01

    Full Text Available Introduction As functional magnetic resonance imaging (fMRI is too expensive and time consuming, its frequent implementation is difficult. The aim of this study is to evaluate repeatability of detecting visual cortex activity in fMRI. Materials and Methods In this study, 15 normal volunteers (10 female, 5 male; Mean age±SD: 24.7±3.8 years attended. Functional magnetic resonance images were obtained during a visual task of sine-wave with spatial frequency of 1.84 cpd and temporal frequency of 8 Hz in three scan runs. Two runs of functional images were provided consecutively in a session, and the third run was provided 1-6 weeks later. The activation map was created using the data obtained from the block-designed fMRI study. Voxels whose Z value was above a threshold of 2.3, at a significance level p=0.05, were considered activated. After image processing, the blood oxygen level dependent (BOLD signal changes and the number of activated voxels in response to visual stimuli were compared in different runs. Results The results of this study demonstrate no significant difference between the number of activated voxels and BOLD signal in first and second runs in one session (Paired t-test, p>0.05. Moreover, there is a considerable correlation between first and second scan runs (rsignal=0.74, p=0.006 and rvoxel=0.62, p=0.03, while the correlation between the runs in separate sessions is weak (rsignal=0.28, p=0.38 and rvoxel=0.32, p=0.31. Conclusion Since the repeatability of BOLD signal and number of activated voxels in one session is considerably better than that in the separate sessions, it is suggested that in fMRI visual studies that need repeated scanning, scans should be acquired during a single session.

  13. The effect of spectrally selective filters on visual search performance.

    Science.gov (United States)

    Chisum, G T; Sheehy, J B; Morway, P E; Askew, G K

    1987-05-01

    The effect of five spectrally selective filters on the performance of an acuity-dependent visual search task was evaluated. The filters were: A) a neutral density filter (control condition); B) a 5200A green interference filter; C) a 3215-250 red filter; D) a neodymium visor; and E) a holographic visor. The observers were presented with 5 blocks of 10 slides per filter. Each slide projected a 6 degrees X 6 degrees field of 900 letter O's--each 10' of arc--which contained a single Landolt C. The observers were required to find the C and indicate the position of the opening in the C. The opening in the C subtended 2.64' corresponding to an acuity of 0.38. Response time, error rate, accommodative accuracy, and the number and duration of fixations were recorded for each slide presentation. The results demonstrated that filter type had no effect on any of the response measures. During the first three trial blocks, the observers appeared to optimize their search strategies, after which they began to revert to their initial performance levels. However, this effect was not supported statistically.

  14. Visual imagery in autobiographical memory: The role of repeated retrieval in shifting perspective.

    Science.gov (United States)

    Butler, Andrew C; Rice, Heather J; Wooldridge, Cynthia L; Rubin, David C

    2016-05-01

    Recent memories are generally recalled from a first-person perspective whereas older memories are often recalled from a third-person perspective. We investigated how repeated retrieval affects the availability of visual information, and whether it could explain the observed shift in perspective with time. In Experiment 1, participants performed mini-events and nominated memories of recent autobiographical events in response to cue words. Next, they described their memory for each event and rated its phenomenological characteristics. Over the following three weeks, they repeatedly retrieved half of the mini-event and cue-word memories. No instructions were given about how to retrieve the memories. In Experiment 2, participants were asked to adopt either a first- or third-person perspective during retrieval. One month later, participants retrieved all of the memories and again provided phenomenology ratings. When first-person visual details from the event were repeatedly retrieved, this information was retained better and the shift in perspective was slowed.

  15. Task specificity and the influence of memory on visual search: comment on Võ and Wolfe (2012).

    Science.gov (United States)

    Hollingworth, Andrew

    2012-12-01

    Recent results from Võ and Wolfe (2012b) suggest that the application of memory to visual search may be task specific: Previous experience searching for an object facilitated later search for that object, but object information acquired during a different task did not appear to transfer to search. The latter inference depended on evidence that a preview task did not improve later search, but Võ and Wolfe used a relatively insensitive, between-subjects design. Here, we replicated the Võ and Wolfe study using a within-subject manipulation of scene preview. A preview session (focused either on object location memory or on the assessment of object semantics) reliably facilitated later search. In addition, information acquired from distractors in a scene-facilitated search when the distractor later became the target. Instead of being strongly constrained by task, visual memory is applied flexibly to guide attention and gaze during visual search.

  16. Visual search near threshold : Some features are more equal than others

    NARCIS (Netherlands)

    van den Berg, R; Bekkering, H.; Roerdink, J.B.T.M.; Cornelissen, F.W

    2006-01-01

    While searching for objects, we combine information from multiple visual modalities. Classical theories of visual search assume that features are processed independently prior to an integration stage. Based on this, one would predict that features that are equally discriminable in single feature

  17. Visual search near threshold: Some features are more equal than others

    NARCIS (Netherlands)

    Hannus, A.; Berg, R. van den; Bekkering, H.; Roerdink, J.B.T.M.; Cornelissen, F.W.

    2006-01-01

    While searching for objects, we combine information from multiple visual modalities. Classical theories of visual search assume that features are processed independently prior to an integration stage. Based on this, one would predict that features that are equally discriminable in single feature

  18. Visual search near threshold: some features are more equal than others

    NARCIS (Netherlands)

    van den Berg, R; Bekkering, H.; Roerdink, J.B.T.M.; Cornelissen, F.W

    2006-01-01

    While searching for objects, we combine information from multiple visual modalities. Classical theories of visual search assume that features are processed independently prior to an integration stage. Based on this, one would predict that features that are equally discriminable in single feature sea

  19. Priming of pop-out on multiple time scales during visual search.

    Science.gov (United States)

    Brascamp, Jan W; Pels, Elmar; Kristjánsson, Arni

    2011-09-01

    When target-color repeats in pop-out visual search performance is faster than otherwise. While various characteristics of such priming of pop-out (PoP) are well known, relatively little is known about the temporal character of the memory traces underlying the effect. Recent findings on the perception of ambiguous stimuli show that the percept at any given moment is affected by perception over a long period, as well as by immediately preceding percepts. Intrigued by the existence of various parallels between this perceptual priming phenomenon and PoP, we here investigate whether similar multiplicity in timescales is seen for PoP. We contrasted long-term PoP build-up of a particular target color against shorter-term build-up for a different color. The priming effects from the two colors indeed reflect memory traces at different timescales: long-term priming build-up results in a more gradual decay than brief buildup, which is followed by faster decay. This is clearly demonstrated in Experiment 2 where sustained repetition of one target color is followed by a few repetitions of a second color. Following such a sequence, priming is initially stronger for the second target color, which was primed most recently; however, as more time passes longer-term priming starts to dominate, resulting in better search performance for the first color later on. Our results suggest that priming effects in visual search contain both transient and more sustained components. Similarities between the time courses of attentional priming and perception of ambiguous stimuli are striking and suggest compelling avenues of further research into the relation between the two effects. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. The effect of search condition and advertising type on visual attention to Internet advertising.

    Science.gov (United States)

    Kim, Gho; Lee, Jang-Han

    2011-05-01

    This research was conducted to examine the level of consumers' visual attention to Internet advertising. It was predicted that consumers' search type would influence visual attention to advertising. Specifically, it was predicted that more attention to advertising would be attracted in the exploratory search condition than in the goal-directed search condition. It was also predicted that there would be a difference in visual attention depending on the advertisement type (advertising type: text vs. pictorial advertising). An eye tracker was used for measurement. Results revealed that search condition and advertising type influenced advertising effectiveness.

  1. How visual search relates to visual diagnostic performance : a narrative systematic review of eye-tracking research in radiology

    NARCIS (Netherlands)

    van der Gijp, A; Ravesloot, C J; Jarodzka, H; van der Schaaf, M F; van der Schaaf, I C; van Schaik, J P J; ten Cate, Olle

    Eye tracking research has been conducted for decades to gain understanding of visual diagnosis such as in radiology. For educational purposes, it is important to identify visual search patterns that are related to high perceptual performance and to identify effective teaching strategies. This review

  2. Transformation of an uncertain video search pipeline to a sketch-based visual analytics loop.

    Science.gov (United States)

    Legg, Philip A; Chung, David H S; Parry, Matthew L; Bown, Rhodri; Jones, Mark W; Griffiths, Iwan W; Chen, Min

    2013-12-01

    Traditional sketch-based image or video search systems rely on machine learning concepts as their core technology. However, in many applications, machine learning alone is impractical since videos may not be semantically annotated sufficiently, there may be a lack of suitable training data, and the search requirements of the user may frequently change for different tasks. In this work, we develop a visual analytics systems that overcomes the shortcomings of the traditional approach. We make use of a sketch-based interface to enable users to specify search requirement in a flexible manner without depending on semantic annotation. We employ active machine learning to train different analytical models for different types of search requirements. We use visualization to facilitate knowledge discovery at the different stages of visual analytics. This includes visualizing the parameter space of the trained model, visualizing the search space to support interactive browsing, visualizing candidature search results to support rapid interaction for active learning while minimizing watching videos, and visualizing aggregated information of the search results. We demonstrate the system for searching spatiotemporal attributes from sports video to identify key instances of the team and player performance.

  3. Acute effects of caffeine on selective attention and visual search processes

    NARCIS (Netherlands)

    Lorist, M.M.; Snel, J.; Kok, A; Mulder, G.

    1996-01-01

    The influence of a single dose of caffeine was evaluated in focused and divided attention conditions of a visual selective search task in which subjects had to perform controlled search processes to locate a target item. Search processes were manipulated by varying display load. A dose of 3 mg/kg bo

  4. Interactions of visual odometry and landmark guidance during food search in honeybees

    NARCIS (Netherlands)

    Vladusich, T; Hemmi, JM; Srinivasan, MV; Zeil, J

    2005-01-01

    How do honeybees use visual odometry and goal-defining landmarks to guide food search? In one experiment, bees were trained to forage in an optic-flow-rich tunnel with a landmark positioned directly above the feeder. Subsequent food-search tests indicated that bees searched much more accurately when

  5. Acute effects of caffeine on selective attention and visual search processes

    NARCIS (Netherlands)

    Lorist, M.M.; Snel, J.; Kok, A; Mulder, G.

    The influence of a single dose of caffeine was evaluated in focused and divided attention conditions of a visual selective search task in which subjects had to perform controlled search processes to locate a target item. Search processes were manipulated by varying display load. A dose of 3 mg/kg

  6. Evaluation of patient visual comfort and repeatability of refractive values in non-presbyopic healthy eyes

    Directory of Open Access Journals (Sweden)

    Francisco Segura

    2015-10-01

    Full Text Available AIM: To evaluate the intra-operator repeatability in healthy subjects using the WAM-5500 auto-kerato/refractometer and the iTrace aberrometer, to compare the refractive values and the subjective refraction obtained with both devices and to determine which of these three spherocylindrical corrections allows the subject to achieve the best visual comfort. METHODS: Forty-two non-presbyopic healthy eyes of 42 subjects were enrolled in this prospective study. Refractive values were compared, evaluating the repeatability, the relationship between the methods and the best visual comfort obtained. RESULTS: Sphere, cylinder and axis results showed good intraclass correlation coefficients (ICC; the highest ICC was obtained using the spherical refraction with the autorefractometer and the aberrometer, achieving levels of 0.999 and 0.998, respectively. The power vector (PV was calculated for each refraction method, and the results indicated that there were no statistically significant differences between them (P>0.05. Direct comparison of PV measurements using the three methods showed that aberrometer refraction gave the highest values, followed by the subjective values; the autorefractometer gave the lowest values. The subjective method correction was most frequently chosen as the first selection. Equal values were found for the autorefractometer and the aberrometer as the second selection. CONCLUSION: The iTrace aberrometer and the WAM-5500 auto-kerato/refractometer showed high levels of repeatability in healthy eyes. Refractive corrections with the aberrometer, the autorefractometer and subjective methods presented similar results, but spherocylindrical subjective correction was the most frequently selected option. These technologies can be used as complements in refractive evaluation, but they should not replace subjective refraction.

  7. Cuckoo Search Algorithm Based on Repeat-Cycle Asymptotic Self-Learning and Self-Evolving Disturbance for Function Optimization.

    Science.gov (United States)

    Wang, Jie-sheng; Li, Shu-xia; Song, Jiang-di

    2015-01-01

    In order to improve convergence velocity and optimization accuracy of the cuckoo search (CS) algorithm for solving the function optimization problems, a new improved cuckoo search algorithm based on the repeat-cycle asymptotic self-learning and self-evolving disturbance (RC-SSCS) is proposed. A disturbance operation is added into the algorithm by constructing a disturbance factor to make a more careful and thorough search near the bird's nests location. In order to select a reasonable repeat-cycled disturbance number, a further study on the choice of disturbance times is made. Finally, six typical test functions are adopted to carry out simulation experiments, meanwhile, compare algorithms of this paper with two typical swarm intelligence algorithms particle swarm optimization (PSO) algorithm and artificial bee colony (ABC) algorithm. The results show that the improved cuckoo search algorithm has better convergence velocity and optimization accuracy.

  8. Cuckoo Search Algorithm Based on Repeat-Cycle Asymptotic Self-Learning and Self-Evolving Disturbance for Function Optimization

    Directory of Open Access Journals (Sweden)

    Jie-sheng Wang

    2015-01-01

    Full Text Available In order to improve convergence velocity and optimization accuracy of the cuckoo search (CS algorithm for solving the function optimization problems, a new improved cuckoo search algorithm based on the repeat-cycle asymptotic self-learning and self-evolving disturbance (RC-SSCS is proposed. A disturbance operation is added into the algorithm by constructing a disturbance factor to make a more careful and thorough search near the bird’s nests location. In order to select a reasonable repeat-cycled disturbance number, a further study on the choice of disturbance times is made. Finally, six typical test functions are adopted to carry out simulation experiments, meanwhile, compare algorithms of this paper with two typical swarm intelligence algorithms particle swarm optimization (PSO algorithm and artificial bee colony (ABC algorithm. The results show that the improved cuckoo search algorithm has better convergence velocity and optimization accuracy.

  9. Orthographic versus semantic matching in visual search for words within lists.

    Science.gov (United States)

    Léger, Laure; Rouet, Jean-François; Ros, Christine; Vibert, Nicolas

    2012-03-01

    An eye-tracking experiment was performed to assess the influence of orthographic and semantic distractor words on visual search for words within lists. The target word (e.g., "raven") was either shown to participants before the search (literal search) or defined by its semantic category (e.g., "bird", categorical search). In both cases, the type of words included in the list affected visual search times and eye movement patterns. In the literal condition, the presence of orthographic distractors sharing initial and final letters with the target word strongly increased search times. Indeed, the orthographic distractors attracted participants' gaze and were fixated for longer times than other words in the list. The presence of semantic distractors related to the target word also increased search times, which suggests that significant automatic semantic processing of nontarget words took place. In the categorical condition, semantic distractors were expected to have a greater impact on the search task. As expected, the presence in the list of semantic associates of the target word led to target selection errors. However, semantic distractors did not significantly increase search times any more, whereas orthographic distractors still did. Hence, the visual characteristics of nontarget words can be strong predictors of the efficiency of visual search even when the exact target word is unknown. The respective impacts of orthographic and semantic distractors depended more on the characteristics of lists than on the nature of the search task.

  10. Detailed analysis of distraction induced by in-vehicle verbal interactions on visual search performance

    Directory of Open Access Journals (Sweden)

    Kazumitsu Shinohara

    2010-07-01

    Full Text Available We examined the negative effect of in-vehicle verbal interaction on visual search performance. Twenty participants performed a primary visual search task and a secondary verbal interaction task concurrently. We found that visual search performance deteriorated when the secondary task involving memory retrieval and speech production was performed concurrently. Moreover, a detailed analysis of the reaction time as a function of set size revealed that the increased reaction time was attributed not to the slowing of inspecting each item but to the increased processing time other than the inspection of each visual item, possibly due to task switching between the primary visual search task and the secondary verbal task. These findings have implications for providing information from in-vehicle information devices while reducing the risk of driver distraction.

  11. Evolutionary Visual Exploration: Evaluation of an IEC Framework for Guided Visual Search.

    Science.gov (United States)

    Boukhelifa, N; Bezerianos, A; Cancino, W; Lutton, E

    2017-01-01

    We evaluate and analyse a framework for evolutionary visual exploration (EVE) that guides users in exploring large search spaces. EVE uses an interactive evolutionary algorithm to steer the exploration of multidimensional data sets toward two-dimensional projections that are interesting to the analyst. Our method smoothly combines automatically calculated metrics and user input in order to propose pertinent views to the user. In this article, we revisit this framework and a prototype application that was developed as a demonstrator, and summarise our previous study with domain experts and its main findings. We then report on results from a new user study with a clearly predefined task, which examines how users leverage the system and how the system evolves to match their needs. While we previously showed that using EVE, domain experts were able to formulate interesting hypotheses and reach new insights when exploring freely, our new findings indicate that users, guided by the interactive evolutionary algorithm, are able to converge quickly to an interesting view of their data when a clear task is specified. We provide a detailed analysis of how users interact with an evolutionary algorithm and how the system responds to their exploration strategies and evaluation patterns. Our work aims at building a bridge between the domains of visual analytics and interactive evolution. The benefits are numerous, in particular for evaluating interactive evolutionary computation (IEC) techniques based on user study methodologies.

  12. Task-Dependent Changes in Frontal-Parietal Activation and Connectivity During Visual Search.

    Science.gov (United States)

    Maximo, Jose O; Neupane, Ajaya; Saxena, Nitesh; Joseph, Robert M; Kana, Rajesh K

    2016-05-01

    Visual search is an important skill in navigating and locating objects (a target) among distractors in our environment. Efficient and faster target detection involves reciprocal interaction between a viewer's attentional resources as well as salient target characteristics. The neural correlates of visual search have been extensively investigated over the last decades, suggesting the involvement of a frontal-parietal network comprising the frontal eye fields (FEFs) and intraparietal sulcus (IPS). In addition, activity and connectivity of these network changes as the visual search become complex and more demanding. The current functional magnetic resonance imaging study examined the modulation of the frontal-parietal network in response to cognitive demand in 22 healthy adult participants. In addition to brain activity, changes in functional connectivity and effective connectivity in this network were examined in response to easy and difficult visual search. Results revealed significantly increased activation in FEF, IPS, and supplementary motor area, more so in difficult search than in easy search. Functional and effective connectivity analyses showed enhanced connectivity in the frontal-parietal network during difficult search and enhanced information transfer from left to right hemisphere during the difficult search process. Our overall findings suggest that cognitive demand significantly increases brain resources across all three measures of brain processing. In sum, we found that goal-directed visual search engages a network of frontal-parietal areas that are modulated in relation to cognitive demand.

  13. Integrating Interactive Visualizations in the Search Process of Digital Libraries and IR Systems

    CERN Document Server

    Hienert, Daniel; Schaer, Philipp; Mayr, Philipp

    2012-01-01

    Interactive visualizations for exploring and retrieval have not yet become an integral part of digital libraries and information retrieval systems. We have integrated a set of interactive graphics in a real world social science digital library. These visualizations support the exploration of search queries, results and authors, can filter search results, show trends in the database and can support the creation of new search queries. The use of weighted brushing supports the identification of related metadata for search facets. We discuss some use cases of the combination of IR systems and interactive graphics. In a user study we verify that users can gain insights from statistical graphics intuitively and can adopt interaction techniques.

  14. Visual search patterns in semantic dementia show paradoxical facilitation of binding processes.

    Science.gov (United States)

    Viskontas, Indre V; Boxer, Adam L; Fesenko, John; Matlin, Alisa; Heuer, Hilary W; Mirsky, Jacob; Miller, Bruce L

    2011-02-01

    While patients with Alzheimer's disease (AD) show deficits in attention, manifested by inefficient performance on visual search, new visual talents can emerge in patients with frontotemporal lobar degeneration (FTLD), suggesting that, at least in some of the patients, visual attention is spared, if not enhanced. To investigate the underlying mechanisms for visual talent in FTLD (behavioral variant FTD [bvFTD] and semantic dementia [SD]) patients, we measured performance on a visual search paradigm that includes both feature and conjunction search, while simultaneously monitoring saccadic eye movements. AD patients were impaired relative to healthy controls (NC) and FTLD patients on both feature and conjunction search. BvFTD patients showed less accurate performance only on the conjunction search task, but slower response times than NC on all three tasks. In contrast, SD patients were as accurate as controls and had faster response times when faced with the largest number of distracters in the conjunction search task. Measurement of saccades during visual search showed that AD patients explored more of the image, whereas SD patients explored less of the image before making a decision as to whether the target was present. Performance on the conjunction search task positively correlated with gray matter volume in the superior parietal lobe, precuneus, middle frontal gyrus and superior temporal gyrus. These data suggest that despite the presence of extensive temporal lobe degeneration, visual talent in SD may be facilitated by more efficient visual search under distracting conditions due to enhanced function in the dorsal frontoparietal attention network. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Investigating the role of visual and auditory search in reading and developmental dyslexia

    Directory of Open Access Journals (Sweden)

    Marie eLallier

    2013-09-01

    Full Text Available It has been suggested that auditory and visual sequential processing deficits contribute to phonological disorders in developmental dyslexia. As an alternative explanation to a phonological deficit as the proximal cause for reading disorders, the visual attention span hypothesis (VA Span suggests that difficulties in processing visual elements simultaneously lead to dyslexia, regardless of the presence of a phonological disorder. In this study, we assessed whether deficits in processing simultaneously displayed visual or auditory elements is linked to dyslexia associated with a VA Span impairment. Sixteen children with developmental dyslexia and 16 age-matched skilled readers were assessed on visual and auditory search tasks. Participants were asked to detect a target presented simultaneously with 3, 9 or 15 distracters. In the visual modality, target detection was slower in the dyslexic children than in the control group on a serial search condition only: the intercepts (but not the slopes of the search functions were higher in the dyslexic group than in the control group. In the auditory modality, although no group difference was observed, search performance was influenced by the number of distracters in the control group only. Within the dyslexic group, not only poor visual search (high reaction times and intercepts but also low auditory search performance (d´ strongly correlated with poor irregular word reading accuracy. Moreover, both visual and auditory search performance was associated with the VA Span abilities of dyslexic participants but not with their phonological skills. The present data suggests that some visual mechanisms engaged in serial search contribute to reading and orthographic knowledge via VA Span skills regardless of phonological skills. The present results further open the question of the role of auditory simultaneous processing in reading as well as its link with VA Span skills.

  16. Eye-movement study during visual search in Chinese children with developmental dyslexia

    Institute of Scientific and Technical Information of China (English)

    LI Xiu-hong; JING Jin; YANG De-sheng; WANG Hui; WANG Qing-xiong; SONG Shan-shan; FAN Fang

    2013-01-01

    Background Developmental dyslexia (DD) is a disorder in which children with normal intelligence and sensory abilities show learning deficits in reading.Abnormal eye movements have been found in DD.However,eye-movement abnormalities during visual search among Chinese children with DD remain unknown.We aimed to identify the eyemovement characteristics and search efficiency of Chinese children with DD during visual search for targets of different conceptual categories,under same-category conditions.Methods We compared 32 Chinese dyslexic children and 39 non-dyslexic children in visual search tasks,which were assessed using EyeLink Ⅱ High-Speed Eye Tracker (SR Research Ltd.,Canada).Letters,single Chinese characters,digits,Chinese phrases,figures and facial expressions were used as stimuli.Targets were similar to distractors in meaning,phonology and/or shape.Results A main effect of task on visual search scores and all eye-movement parameters were found.Search scores,average saccade amplitude and saccade distance were significantly smaller in the DD group than in the controls.An interaction between group and task was found for pupil diameter.Conclusions Unlike normal readers,children with DD had a reduction in the visual attention span and search accuracy.Besides,children with DD could not increase their mental workload with increase in task difficulty.The conceptual category of the stimulus materials significantly impacts search speed,accuracy and eye-movement parameters.

  17. Different predictors of multiple-target search accuracy between nonprofessional and professional visual searchers.

    Science.gov (United States)

    Biggs, Adam T; Mitroff, Stephen R

    2014-01-01

    Visual search, locating target items among distractors, underlies daily activities ranging from critical tasks (e.g., looking for dangerous objects during security screening) to commonplace ones (e.g., finding your friends in a crowded bar). Both professional and nonprofessional individuals conduct visual searches, and the present investigation is aimed at understanding how they perform similarly and differently. We administered a multiple-target visual search task to both professional (airport security officers) and nonprofessional participants (members of the Duke University community) to determine how search abilities differ between these populations and what factors might predict accuracy. There were minimal overall accuracy differences, although the professionals were generally slower to respond. However, the factors that predicted accuracy varied drastically between groups; variability in search consistency-how similarly an individual searched from trial to trial in terms of speed-best explained accuracy for professional searchers (more consistent professionals were more accurate), whereas search speed-how long an individual took to complete a search when no targets were present-best explained accuracy for nonprofessional searchers (slower nonprofessionals were more accurate). These findings suggest that professional searchers may utilize different search strategies from those of nonprofessionals, and that search consistency, in particular, may provide a valuable tool for enhancing professional search accuracy.

  18. Efficient Retrieval of Images for Search Engine by Visual Similarity and Re Ranking

    Directory of Open Access Journals (Sweden)

    Viswa S S

    2013-06-01

    Full Text Available Nowadays, web scale image search engines (e.g. Google Image Search, Microsoft Live Image Search rely almost purely on surrounding text features. Users type keywords in hope of finding a certain type of images. The search engine returns thousands of images ranked by the text keywords extracted from the surrounding text. However, many of returned images are noisy, disorganized, or irrelevant. Even Google and Microsoft have no Visual Information for searching of images. Using visual information to re rank and improve text based image search results is the idea. This improves the precision of the text based image search ranking by incorporating the information conveyed by the visual modality. The typical assumption that the top- images in the text-based search result are equally relevant is relaxed by linking the relevance of the images to their initial rank positions. Then, a number of images from the initial search result are employed as the prototypes that serve to visually represent the query and that are subsequently used to construct meta re rankers .i.e. The most relevant images are found by visual similarity and the average scores are calculated. By applying different meta re rankers to an image from the initial result, re ranking scores are generated, which are then used to find the new rank position for an image in the re ranked search result. Human supervision is introduced to learn the model weights offline, prior to the online re ranking process. While model learning requires manual labelling of the results for a few queries, the resulting model is query independent and therefore applicable to any other query. The experimental results on a representative web image search dataset comprising 353 queries demonstrate that the proposed method outperforms the existing supervised and unsupervised Re ranking approaches. Moreover, it improves the performance over the text-based image search engine by more than 25.48%.

  19. Attentional control during visual search: The effect of irrelevant singletons

    NARCIS (Netherlands)

    Theeuwes, J.; Burger, R.

    1998-01-01

    Four experiments investigated whether a highly salient color singleton can be ignored during serial search. Observers searched for a target letter among nontarget letters and were instructed to ignore an irrelevant, highly salient color singleton that was either compatible or incompatible with the r

  20. Information regarding structure and lightness based on phenomenal transparency influences the efficiency of visual search.

    Science.gov (United States)

    Mitsudo, Hiroyuki

    2003-01-01

    Phenomenal transparency reflects a process which makes it possible to recover the structure and lightness of overlapping objects from a fragmented image. This process was investigated by the visual-search paradigm. In three experiments, observers searched for a target that consisted of gray patches among a variable number of distractors and the search efficiency was assessed. Experiments 1 and 2 showed that the search efficiency was greatly improved when the target was distinctive with regard to structure, based on transparency. Experiment 3 showed that the search efficiency was impaired when a target was not distinctive with regard to lightness (ie perceived reflectance), based on transparency. These results suggest that the shape and reflectance of overlapping objects when accompanied by transparency can be calculated in parallel across the visual field, and can be used as a guide for visual attention.

  1. Influence of social presence on eye movements in visual search tasks.

    Science.gov (United States)

    Liu, Na; Yu, Ruifeng

    2017-06-22

    This study employed an eye-tracking technique to investigate the influence of social presence on eye movements in visual search tasks. A total of 20 male subjects performed visual search tasks in a 2 (target presence: present vs. absent) × 2 (task complexity: complex vs. simple) × 2 (social presence: alone vs. a human audience) within-subject experiment. Results indicated that the presence of an audience could evoke a social facilitation effect on response time in visual search tasks. Compared with working alone, the participants made fewer and shorter fixations, larger saccades and shorter scan path in simple search tasks and more and longer fixations, smaller saccades and longer scan path in complex search tasks when working with an audience. The saccade velocity and pupil diameter in the audience-present condition were larger than those in the working-alone condition. No significant change in target fixation number was observed between two social presence conditions. Practitioner Summary: This study employed an eye-tracking technique to examine the influence of social presence on eye movements in visual search tasks. Results clarified the variation mechanism and characteristics of oculomotor scanning induced by social presence in visual search.

  2. Scene analysis for effective visual search in rough three-dimensional-modeling scenes

    Science.gov (United States)

    Wang, Qi; Hu, Xiaopeng

    2016-11-01

    Visual search is a fundamental technology in the computer vision community. It is difficult to find an object in complex scenes when there exist similar distracters in the background. We propose a target search method in rough three-dimensional-modeling scenes based on a vision salience theory and camera imaging model. We give the definition of salience of objects (or features) and explain the way that salience measurements of objects are calculated. Also, we present one type of search path that guides to the target through salience objects. Along the search path, when the previous objects are localized, the search region of each subsequent object decreases, which is calculated through imaging model and an optimization method. The experimental results indicate that the proposed method is capable of resolving the ambiguities resulting from distracters containing similar visual features with the target, leading to an improvement of search speed by over 50%.

  3. A New Tool for Collaborative Video Search via Content-based Retrieval and Visual Inspection

    NARCIS (Netherlands)

    Hürst, W.O.; Ip Vai Ching, Algernon; Hudelist, Marco A.; Primus, Manfred J.; Schoeffmann, Klaus; Beecks, Chrisitan

    2016-01-01

    We present a new approach for collaborative video search and video browsing relying on a combination of traditional, indexbased video retrieval complemented with large-scale human-based visual inspection. In particular, a traditional PC interface is used for query-based search using advanced indexin

  4. Pip and pop : Non-spatial auditory signals improve spatial visual search

    NARCIS (Netherlands)

    Burg, E. van der; Olivers, C.N.L.; Bronkhorst, A.W.; Theeuwes, J.

    2008-01-01

    Searching for an object within a cluttered, continuously changing environment can be a very time-consuming process. The authors show that a simple auditory pip drastically decreases search times for a synchronized visual object that is normally very difficult to find. This effect occurs even though

  5. Training shortens search times in children with visual impairment accompanied by nystagmus

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.

    2014-01-01

    Perceptual learning (PL) can improve near visual acuity (NVA) in 4-9 year old children with visual impairment (VI). However, the mechanisms underlying improved NVA are unknown. The present study compares feature search and oculomotor measures in 4-9 year old children with VI accompanied by nystagmus

  6. Recognition of Facially Expressed Emotions and Visual Search Strategies in Adults with Asperger Syndrome

    Science.gov (United States)

    Falkmer, Marita; Bjallmark, Anna; Larsson, Matilda; Falkmer, Torbjorn

    2011-01-01

    Can the disadvantages persons with Asperger syndrome frequently experience with reading facially expressed emotions be attributed to a different visual perception, affecting their scanning patterns? Visual search strategies, particularly regarding the importance of information from the eye area, and the ability to recognise facially expressed…

  7. The Effects of Presentation Method and Information Density on Visual Search Ability and Working Memory Load

    Science.gov (United States)

    Chang, Ting-Wen; Kinshuk; Chen, Nian-Shing; Yu, Pao-Ta

    2012-01-01

    This study investigates the effects of successive and simultaneous information presentation methods on learner's visual search ability and working memory load for different information densities. Since the processing of information in the brain depends on the capacity of visual short-term memory (VSTM), the limited information processing capacity…

  8. Recognition of Facially Expressed Emotions and Visual Search Strategies in Adults with Asperger Syndrome

    Science.gov (United States)

    Falkmer, Marita; Bjallmark, Anna; Larsson, Matilda; Falkmer, Torbjorn

    2011-01-01

    Can the disadvantages persons with Asperger syndrome frequently experience with reading facially expressed emotions be attributed to a different visual perception, affecting their scanning patterns? Visual search strategies, particularly regarding the importance of information from the eye area, and the ability to recognise facially expressed…

  9. Hand Movement Deviations in a Visual Search Task with Cross Modal Cuing

    Science.gov (United States)

    Aslan, Asli; Aslan, Hurol

    2007-01-01

    The purpose of this study is to demonstrate the cross-modal effects of an auditory organization on a visual search task and to investigate the influence of the level of detail in instructions describing or hinting at the associations between auditory stimuli and the possible locations of a visual target. In addition to measuring the participants'…

  10. PSYCHOPHYSIOLOGICAL EVIDENCE FOR CONTINUOUS INFORMATION-TRANSMISSION BETWEEN VISUAL-SEARCH AND RESPONSE PROCESSES

    NARCIS (Netherlands)

    SMID, HGOM; LAMAIN, W; HOGEBOOM, MM; Mulder, Lambertus; Mulder, Gysbertus

    1991-01-01

    This study was designed to test whether information transmission between the perceptual and motor levels occurs continuously or in discrete steps. Ss performed visual search across nontargets that shared visual features with one of two possible targets, each assigned to a different response. In addi

  11. Visual Search in the Detection of Retinal Injury: A Feasibility Study

    Science.gov (United States)

    2013-04-01

    1996; 73: 621–637. 28. Kuyk T, Elliott JL. Visual factors and mobility in persons with age-related macular degeneration . Journal of Rehabilitation...Avni I, Yassur Y. Replacing the Amsler Grid. A New Method for Monitoring Patients with Age-related Macular Degeneration . Ophthalmology. 2003; 110...Fuhr PSW. Visual search in age-related macular degeneration . Investigative Ophthalmology and Visual Science, 2007; 48: E-abstract 3545. 25. Palankar

  12. Performance of visual search tasks from various types of contour information.

    Science.gov (United States)

    Itan, Liron; Yitzhaky, Yitzhak

    2013-03-01

    A recently proposed visual aid for patients with a restricted visual field (tunnel vision) combines a see-through head-mounted display and a simultaneous minified contour view of the wide-field image of the environment. Such a widening of the effective visual field is helpful for tasks, such as visual search, mobility, and orientation. The sufficiency of image contours for performing everyday visual tasks is of major importance for this application, as well as for other applications, and for basic understanding of human vision. This research aims is to examine and compare the use of different types of automatically created contours, and contour representations, for practical everyday visual operations using commonly observed images. The visual operations include visual searching for items, such as cutlery, housewares, etc. Considering different recognition levels, identification of an object is distinguished from mere detection (when the object is not necessarily identified). Some nonconventional visual-based contour representations were developed for this purpose. Experiments were performed with normal-vision subjects by superposing contours of the wide field of the scene over a narrow field (see-through) background. From the results, it appears that about 85% success is obtained for searched object identification when the best contour versions are employed. Pilot experiments with video simulations are reported at the end of the paper.

  13. Efficient visual search from synchronized auditory signals requires transient audiovisual events.

    Directory of Open Access Journals (Sweden)

    Erik Van der Burg

    Full Text Available BACKGROUND: A prevailing view is that audiovisual integration requires temporally coincident signals. However, a recent study failed to find any evidence for audiovisual integration in visual search even when using synchronized audiovisual events. An important question is what information is critical to observe audiovisual integration. METHODOLOGY/PRINCIPAL FINDINGS: Here we demonstrate that temporal coincidence (i.e., synchrony of auditory and visual components can trigger audiovisual interaction in cluttered displays and consequently produce very fast and efficient target identification. In visual search experiments, subjects found a modulating visual target vastly more efficiently when it was paired with a synchronous auditory signal. By manipulating the kind of temporal modulation (sine wave vs. square wave vs. difference wave; harmonic sine-wave synthesis; gradient of onset/offset ramps we show that abrupt visual events are required for this search efficiency to occur, and that sinusoidal audiovisual modulations do not support efficient search. CONCLUSIONS/SIGNIFICANCE: Thus, audiovisual temporal alignment will only lead to benefits in visual search if the changes in the component signals are both synchronized and transient. We propose that transient signals are necessary in synchrony-driven binding to avoid spurious interactions with unrelated signals when these occur close together in time.

  14. Multisensory brand search: How the meaning of sounds guides consumers' visual attention.

    Science.gov (United States)

    Knoeferle, Klemens M; Knoeferle, Pia; Velasco, Carlos; Spence, Charles

    2016-06-01

    Building on models of crossmodal attention, the present research proposes that brand search is inherently multisensory, in that the consumers' visual search for a specific brand can be facilitated by semantically related stimuli that are presented in another sensory modality. A series of 5 experiments demonstrates that the presentation of spatially nonpredictive auditory stimuli associated with products (e.g., usage sounds or product-related jingles) can crossmodally facilitate consumers' visual search for, and selection of, products. Eye-tracking data (Experiment 2) revealed that the crossmodal effect of auditory cues on visual search manifested itself not only in RTs, but also in the earliest stages of visual attentional processing, thus suggesting that the semantic information embedded within sounds can modulate the perceptual saliency of the target products' visual representations. Crossmodal facilitation was even observed for newly learnt associations between unfamiliar brands and sonic logos, implicating multisensory short-term learning in establishing audiovisual semantic associations. The facilitation effect was stronger when searching complex rather than simple visual displays, thus suggesting a modulatory role of perceptual load. (PsycINFO Database Record

  15. Effects of targets embedded within words in a visual search task.

    Science.gov (United States)

    Grabbe, Jeremy W

    2014-01-01

    Visual search performance can be negatively affected when both targets and distracters share a dimension relevant to the task. This study examined if visual search performance would be influenced by distracters that affect a dimension irrelevant from the task. In Experiment 1 within the letter string of a letter search task, target letters were embedded within a word. Experiment 2 compared targets embedded in words to targets embedded in nonwords. Experiment 3 compared targets embedded in words to a condition in which a word was present in a letter string, but the target letter, although in the letter string, was not embedded within the word. The results showed that visual search performance was negatively affected when a target appeared within a high frequency word. These results suggest that the interaction and effectiveness of distracters is not merely dependent upon common features of the target and distracters, but can be affected by word frequency (a dimension not related to the task demands).

  16. Pop-out in visual search of moving targets in the archer fish.

    Science.gov (United States)

    Ben-Tov, Mor; Donchin, Opher; Ben-Shahar, Ohad; Segev, Ronen

    2015-03-10

    Pop-out in visual search reflects the capacity of observers to rapidly detect visual targets independent of the number of distracting objects in the background. Although it may be beneficial to most animals, pop-out behaviour has been observed only in mammals, where neural correlates are found in primary visual cortex as contextually modulated neurons that encode aspects of saliency. Here we show that archer fish can also utilize this important search mechanism by exhibiting pop-out of moving targets. We explore neural correlates of this behaviour and report the presence of contextually modulated neurons in the optic tectum that may constitute the neural substrate for a saliency map. Furthermore, we find that both behaving fish and neural responses exhibit additive responses to multiple visual features. These findings suggest that similar neural computations underlie pop-out behaviour in mammals and fish, and that pop-out may be a universal search mechanism across all vertebrates.

  17. Towards Visual-Search Model Observers for Mass Detection in Breast Tomosynthesis.

    Science.gov (United States)

    Lau, Beverly A; Das, Mini; Gifford, Howard C

    2013-03-21

    We are investigating human-observer models that perform clinically realistic detection and localization tasks as a means of making reliable assessments of digital breast tomosynthesis images. The channelized non-prewhitening (CNPW) observer uses the background known exactly task for localization and detection. Visual-search observer models attempt to replicate the search patterns of trained radiologists. The visual-search observer described in this paper utilizes a two-phase approach, with an initial holistic search followed by directed analysis and decision making. Gradient template matching is used for the holistic search, and the CNPW observer is used for analysis and decision making. Spherical masses were embedded into anthropomorphic breast phantoms, and simulated projections were made using ray-tracing and a serial cascade model. A localization ROC study was performed on these images using the visual-search model observer and the CNPW observer. Observer performance from the two computer observers was compared to human observer performance. The visual-search observer was able to produce area under the LROC curve values similar to those from human observers; however, more research is needed to increase the robustness of the algorithm.

  18. Pesquisando em fontes visuais = Searching in visual sources

    OpenAIRE

    Proença, Caio de Carvalho

    2012-01-01

    O presente ensaio pretende demonstrar reflexões sobre os usos da fotografia como fonte. Na primeira partedo ensaio procura-se demonstrar a experiência de um primeiro contato com a fonte visual, em especial a fotografia, para posteriormente entrar em contato com as diferentes formas metodológicas presentes na pesquisa desta fonte. Em um segundo momento mostra-se alguns apontamentos sobre o método de pesquisa voltado à fonte visual fotográfica que auxiliam a pesquisa, contemplando a discussão s...

  19. Spacing affects some but not all visual searches: implications for theories of attention and crowding.

    Science.gov (United States)

    Reddy, Lavanya; VanRullen, Rufin

    2007-02-02

    We investigated the effect of varying interstimulus spacing on an upright among inverted face search and a red-green among green-red bisected disk search. Both tasks are classic examples of serial search; however, spacing affects them very differently: As spacing increased, face discrimination performance improved significantly, whereas performance on the bisected disks remained poor. (No effect of spacing was observed for either a red among green or an L among + search tasks, two classic examples of parallel search.) In a second experiment, we precued the target location so that attention was no longer a limiting factor: Both serial search tasks were now equally affected by spacing, a result we attribute to a more classical form of crowding. The observed spacing effect in visual search suggests that for certain tasks, serial search may result from local neuronal competition between target and distractors, soliciting attentional resources; in other cases, serial search must occur for another reason, for example, because an item-by-item, attention-mediated recognition must take place. We speculate that this distinction may be based on whether or not there exist neuronal populations tuned to the relevant target-distractor distinction, and we discuss the possible relations between this spacing effect in visual search and other forms of crowding.

  20. Playing shooter and driving videogames improves top-down guidance in visual search.

    Science.gov (United States)

    Wu, Sijing; Spence, Ian

    2013-05-01

    Playing action videogames is known to improve visual spatial attention and related skills. Here, we showed that playing action videogames also improves classic visual search, as well as the ability to locate targets in a dual search that mimics certain aspects of an action videogame. In Experiment 1A, first-person shooter (FPS) videogame players were faster than nonplayers in both feature search and conjunction search, and in Experiment 1B, they were faster and more accurate in a peripheral search and identification task while simultaneously performing a central search. In Experiment 2, we showed that 10 h of play could improve the performance of nonplayers on each of these tasks. Three different genres of videogames were used for training: two action games and a 3-D puzzle game. Participants who played an action game (either an FPS or a driving game) achieved greater gains on all search tasks than did those who trained using the puzzle game. Feature searches were faster after playing an action videogame, suggesting that players developed a better target template to guide search in a top-down manner. The results of the dual search suggest that, in addition to enhancing the ability to divide attention, playing an action game improves the top-down guidance of attention to possible target locations. The results have practical implications for the development of training tools to improve perceptual and cognitive skills.

  1. The role of highlighting in visual search through maps

    NARCIS (Netherlands)

    Wickens, C.D.; Alexander, A.L.; Ambinder, M.S.; Martens, M.H.

    2004-01-01

    Two experiments were conducted in which participants performed a vehicle dispatching task. The intensity of one information source (vehicles in Experiment 1, destinations in Experiment 2) was varied to examine the effects of salience and discrimination on both searching for and processing the inform

  2. Matched filtering determines human visual search in natural images

    NARCIS (Netherlands)

    Toet, A.

    2011-01-01

    The structural image similarity index (SSIM), introduced by Wang and Bovik (IEEE Signal Processing Letters 9-3, pp. 81-84, 2002) measures the similarity between images in terms of luminance, contrast en structure. It has successfully been deployed to model human visual perception of image

  3. Searching for Meaning: Visual Culture from an Anthropological Perspective

    Science.gov (United States)

    Stokrocki, Mary

    2006-01-01

    In this article, the author discusses the importance of Viktor Lowenfeld's influence on her research, describes visual anthropology, gives examples of her research, and examines the implications of this type of research for teachers. The author regards Lowenfeld's (1952/1939) early work with children in Austria as a form of participant observation…

  4. Searching for Meaning: Visual Culture from an Anthropological Perspective

    Science.gov (United States)

    Stokrocki, Mary

    2006-01-01

    In this article, the author discusses the importance of Viktor Lowenfeld's influence on her research, describes visual anthropology, gives examples of her research, and examines the implications of this type of research for teachers. The author regards Lowenfeld's (1952/1939) early work with children in Austria as a form of participant observation…

  5. Real-world visual search is dominated by top-down guidance.

    Science.gov (United States)

    Chen, Xin; Zelinsky, Gregory J

    2006-11-01

    How do bottom-up and top-down guidance signals combine to guide search behavior? Observers searched for a target either with or without a preview (top-down manipulation) or a color singleton (bottom-up manipulation) among the display objects. With a preview, reaction times were faster and more initial eye movements were guided to the target; the singleton failed to attract initial saccades under these conditions. Only in the absence of a preview did subjects preferentially fixate the color singleton. We conclude that the search for realistic objects is guided primarily by top-down control. Implications for saliency map models of visual search are discussed.

  6. When is it time to move to the next map? Optimal foraging in guided visual search.

    Science.gov (United States)

    Ehinger, Krista A; Wolfe, Jeremy M

    2016-10-01

    Suppose that you are looking for visual targets in a set of images, each containing an unknown number of targets. How do you perform that search, and how do you decide when to move from the current image to the next? Optimal foraging theory predicts that foragers should leave the current image when the expected value from staying falls below the expected value from leaving. Here, we describe how to apply these models to more complex tasks, like search for objects in natural scenes where people have prior beliefs about the number and locations of targets in each image, and search is guided by target features and scene context. We model these factors in a guided search task and predict the optimal time to quit search. The data come from a satellite image search task. Participants searched for small gas stations in large satellite images. We model quitting times with a Bayesian model that incorporates prior beliefs about the number of targets in each map, average search efficiency (guidance), and actual search history in the image. Clicks deploying local magnification were used as surrogates for deployments of attention and, thus, for time. Leaving times (measured in mouse clicks) were well-predicted by the model. People terminated search when their expected rate of target collection fell to the average rate for the task. Apparently, people follow a rate-optimizing strategy in this task and use both their prior knowledge and search history in the image to decide when to quit searching.

  7. Acute exercise and aerobic fitness influence selective attention during visual search

    Directory of Open Access Journals (Sweden)

    Tom eBullock

    2014-11-01

    Full Text Available Successful goal directed behavior relies on a human attention system that is flexible and able to adapt to different conditions of physiological stress. However, the effects of physical activity on multiple aspects of selective attention and whether these effects are mediated by aerobic capacity, remains unclear. The aim of the present study was to investigate the effects of a prolonged bout of physical activity on visual search performance and perceptual distraction. Two groups of participants completed a hybrid visual search flanker/response competition task in an initial baseline session and then at 17-minute intervals over a 2 hour 16 minute test period. Participants assigned to the exercise group engaged in steady-state aerobic exercise between completing blocks of the visual task, whereas participants assigned to the control group rested in between blocks. The key result was a correlation between individual differences in aerobic capacity and visual search performance, such that those individuals that were more fit performed the search task more quickly. Critically, this relationship only emerged in the exercise group after the physical activity had begun. The relationship was not present in either group at baseline and never emerged in the control group during the test period, suggesting that under these task demands, aerobic capacity may be an important determinant of visual search performance under physical stress. The results enhance current understanding about the relationship between exercise and cognition, and also inform current models of selective attention.

  8. Motivation and short-term memory in visual search: Attention's accelerator revisited.

    Science.gov (United States)

    Schneider, Daniel; Bonmassar, Claudia; Hickey, Clayton

    2017-07-13

    A cue indicating the possibility of cash reward will cause participants to perform memory-based visual search more efficiently. A recent study has suggested that this performance benefit might reflect the use of multiple memory systems: when needed, participants may maintain the to-be-remembered object in both long-term and short-term visual memory, with this redundancy benefitting target identification during search (Reinhart, McClenahan & Woodman, 2016). Here we test this compelling hypothesis. We had participants complete a memory-based visual search task involving a reward cue that either preceded presentation of the to-be-remembered target (pre-cue) or followed it (retro-cue). Following earlier work, we tracked memory representation using two components of the event-related potential (ERP): the contralateral delay activity (CDA), reflecting short-term visual memory, and the anterior P170, reflecting long-term storage. We additionally tracked attentional preparation and deployment in the contingent negative variation (CNV) and N2pc, respectively. Results show that only the reward pre-cue impacted our ERP indices of memory. However, both types of cue elicited a robust CNV, reflecting an influence on task preparation, both had equivalent impact on deployment of attention to the target, as indexed in the N2pc, and both had equivalent impact on visual search behavior. Reward prospect thus has an influence on memory-guided visual search, but this does not appear to be necessarily mediated by a change in the visual memory representations indexed by CDA. Our results demonstrate that the impact of motivation on search is not a simple product of improved memory for target templates. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The Visual Hemifield Asymmetry in the Spatial Blink during Singleton Search and Feature Search

    Science.gov (United States)

    Burnham, Bryan R.; Rozell, Cassandra A.; Kasper, Alex; Bianco, Nicole E.; Delliturri, Antony

    2011-01-01

    The present study examined a visual field asymmetry in the contingent capture of attention that was previously observed by Du and Abrams (2010). In our first experiment, color singleton distractors that matched the color of a to-be-detected target produced a stronger capture of attention when they appeared in the left visual hemifield than in the…

  10. Training shortens search times in children with visual impairment accompanied by nystagmus

    Directory of Open Access Journals (Sweden)

    Bianca eHuurneman

    2014-09-01

    Full Text Available Perceptual learning (PL can improve near visual acuity in 4-9 year old children with visual impairment. However, the mechanisms underlying improved near visual acuity are unknown. The present study compares feature search and oculomotor measures in 4-9 year old children with visual impairment accompanied by nystagmus (VI+nys [n=33] and children with normal vision (NV [n=29]. Children in the VI+nys group were divided into three training groups: an experimental PL group, a control PL group, and a magnifier group. They were seen before (baseline and after six weeks of training. Children with NV were only seen at baseline. The feature search task entailed finding a target E among distractor E’s (pointing right with element spacing varied in four steps: 0.04°, 0.5°, 1°, and 2°. At baseline, children with VI+nys showed longer search times, shorter fixation durations, and larger saccade amplitudes than children with NV. After training, all training groups showed shorter search times. Only the experimental PL group showed prolonged fixation duration after training at 0.5° and 2° spacing, p’s respectively .033 and .021. Prolonged fixation duration was associated with reduced crowding and improved crowded near visual acuity. One of the mechanisms underlying improved crowded near visual acuity after PL in children with VI+nys seems to be prolonged fixation duration.

  11. VisiNav: Visual Web Data Search and Navigation

    Science.gov (United States)

    Harth, Andreas

    Semantic Web technologies facilitate data integration over a large number of sources with decentralised and loose coordination, ideally leading to interlinked datasets which describe objects, their attributes and links to other objects. Such information spaces are amenable to queries that go beyond traditional keyword search over documents. To this end, we present a formal query model comprising six atomic operations over object-structured datasets: keyword search, object navigation, facet selection, path traversal, projection, and sorting. Using these atomic operations, users can incrementally assemble complex queries that yield a set of objects or trees of objects as result. Results can then be either directly displayed or exported to application programs or online services. We report on user experiments carried out during the design phase of the system, and present performance results for a range of queries over 18.5m statements aggregated from 70k sources.

  12. Visually Guiding and Controlling the Search While Mining Chemical Structures

    OpenAIRE

    Max Pereira; Vitor Santos Costa; Rui Camacho; Fonseca, Nuno A.

    2009-01-01

    In this paper we present the work in progress on LogCHEM, an ILP based tool for discriminative interactive mining of chemical fragments. In particular, we describe the integration with a molecule visualisation software that allows the chemist to graphically control the search for interesting patterns in chemical fragments. Furthermore, we show how structured information, such as rings, functional groups like carboxyl, amine, methyl, ester, etc are integrated and exploited in LogCHEM.

  13. Target-present guessing as a function of target prevalence and accumulated information in visual search.

    Science.gov (United States)

    Peltier, Chad; Becker, Mark W

    2017-05-01

    Target prevalence influences visual search behavior. At low target prevalence, miss rates are high and false alarms are low, while the opposite is true at high prevalence. Several models of search aim to describe search behavior, one of which has been specifically intended to model search at varying prevalence levels. The multiple decision model (Wolfe & Van Wert, Current Biology, 20(2), 121--124, 2010) posits that all searches that end before the observer detects a target result in a target-absent response. However, researchers have found very high false alarms in high-prevalence searches, suggesting that prevalence rates may be used as a source of information to make "educated guesses" after search termination. Here, we further examine the ability for prevalence level and knowledge gained during visual search to influence guessing rates. We manipulate target prevalence and the amount of information that an observer accumulates about a search display prior to making a response to test if these sources of evidence are used to inform target present guess rates. We find that observers use both information about target prevalence rates and information about the proportion of the array inspected prior to making a response allowing them to make an informed and statistically driven guess about the target's presence.

  14. Dual-target cost in visual search for multiple unfamiliar faces.

    Science.gov (United States)

    Mestry, Natalie; Menneer, Tamaryn; Cave, Kyle R; Godwin, Hayward J; Donnelly, Nick

    2017-08-01

    The efficiency of visual search for one (single-target) and either of two (dual-target) unfamiliar faces was explored to understand the manifestations of capacity and guidance limitations in face search. The visual similarity of distractor faces to target faces was manipulated using morphing (Experiments 1 and 2) and multidimensional scaling (Experiment 3). A dual-target cost was found in all experiments, evidenced by slower and less accurate search in dual- than single-target conditions. The dual-target cost was unequal across the targets, with performance being maintained on one target and reduced on the other, which we label "preferred" and "non-preferred" respectively. We calculated the capacity for each target face and show reduced capacity for representing the non-preferred target face. However, results show that the capacity for the non-preferred target can be increased when the dual-target condition is conducted after participants complete the single-target conditions. Analyses of eye movements revealed evidence for weak guidance of fixations in single-target search, and when searching for the preferred target in dual-target search. Overall, the experiments show dual-target search for faces is capacity- and guidance-limited, leading to superior search for 1 face over the other in dual-target search. However, learning faces individually may improve capacity with the second face. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  15. Pesquisando em fontes visuais = Searching in visual sources

    Directory of Open Access Journals (Sweden)

    Proença, Caio de Carvalho

    2012-01-01

    Full Text Available O presente ensaio pretende demonstrar reflexões sobre os usos da fotografia como fonte. Na primeira partedo ensaio procura-se demonstrar a experiência de um primeiro contato com a fonte visual, em especial a fotografia, para posteriormente entrar em contato com as diferentes formas metodológicas presentes na pesquisa desta fonte. Em um segundo momento mostra-se alguns apontamentos sobre o método de pesquisa voltado à fonte visual fotográfica que auxiliam a pesquisa, contemplando a discussão sobre Contexto, Iconosfera, Visual e Visível. Assim que discutido estes temas, segue-se para o estudo de caso. É apresentado um exemplo metodológico, seguindo as reflexões dos momentos anteriores, onde a fotografia é utilizada como fonte. Este exemplo está inserido na pesquisa de iniciação científica que está em andamento, procurando compreender a construção da imagem das elites e da modernidade urbana de São Paulo na revista ilustrada Cigarra nos anos 1920

  16. Visual Servoing: A technology in search of an application

    Energy Technology Data Exchange (ETDEWEB)

    Feddema, J.T.

    1994-05-01

    Considerable research has been performed on Robotic Visual Servoing (RVS) over the past decade. Using real-time visual feedback, researchers have demonstrated that robotic systems can pick up moving parts, insert bolts, apply sealant, and guide vehicles. With the rapid improvements being made in computing and image processing hardware, one would expect that every robot manufacturer would have a RVS option by the end of the 1990s. So why aren`t the Fanucs, ABBs, Adepts, and Motomans of the world investing heavily in RVS? I would suggest four seasons: cost, complexity, reliability, and lack of demand. Solutions to the first three are approaching the point where RVS could be commercially available; however, the lack of demand is keeping RVS from becoming a reality in the near future. A new set of applications is needed to focus near term RVS development. These must be applications which currently do not have solutions. Once developed and working in one application area, the technology is more likely to quickly spread to other areas. DOE has several applications that are looking for technological solutions, such as agile weapons production, weapons disassembly, decontamination and dismantlement of nuclear facilities, and hazardous waste remediation. This paper will examine a few of these areas and suggest directions for application-driven visual servoing research.

  17. Working memory load predicts visual search efficiency: Evidence from a novel pupillary response paradigm.

    Science.gov (United States)

    Attar, Nada; Schneps, Matthew H; Pomplun, Marc

    2016-10-01

    An observer's pupil dilates and constricts in response to variables such as ambient and focal luminance, cognitive effort, the emotional stimulus content, and working memory load. The pupil's memory load response is of particular interest, as it might be used for estimating observers' memory load while they are performing a complex task, without adding an interruptive and confounding memory test to the protocol. One important task in which working memory's involvement is still being debated is visual search, and indeed a previous experiment by Porter, Troscianko, and Gilchrist (Quarterly Journal of Experimental Psychology, 60, 211-229, 2007) analyzed observers' pupil sizes during search to study this issue. These authors found that pupil size increased over the course of the search, and they attributed this finding to accumulating working memory load. However, since the pupil response is slow and does not depend on memory load alone, this conclusion is rather speculative. In the present study, we estimated working memory load in visual search during the presentation of intermittent fixation screens, thought to induce a low, stable level of arousal and cognitive effort. Using standard visual search and control tasks, we showed that this paradigm reduces the influence of non-memory-related factors on pupil size. Furthermore, we found an early increase in working memory load to be associated with more efficient search, indicating a significant role of working memory in the search process.

  18. Differential roles of the dorsal prefrontal and posterior parietal cortices in visual search: a TMS study.

    Science.gov (United States)

    Yan, Yulong; Wei, Rizhen; Zhang, Qian; Jin, Zhenlan; Li, Ling

    2016-07-25

    Although previous studies have shown that fronto-parietal attentional networks play a crucial role in bottom-up and top-down processes, the relative contribution of the frontal and parietal cortices to these processes remains elusive. Here we used transcranial magnetic stimulation (TMS) to interfere with the activity of the right dorsal prefrontal cortex (DLPFC) or the right posterior parietal cortex (PPC), immediately prior to the onset of the visual search display. Participants searched a target defined by color and orientation in "pop-out" or "search" condition. Repetitive TMS was applied to either the right DLPFC or the right PPC on different days. Performance was evaluated at baseline (no TMS), during TMS, and after TMS (Post-session). RTs were prolonged when TMS was applied over the DLPFC in the search, but not in the pop-out condition, relative to the baseline session. In comparison, TMS over the PPC prolonged RTs in the pop-out condition, and when the target appeared in the left visual field for the search condition. Taken together these findings provide evidence for a differential role of DLPFC and PPC in the visual search, indicating that DLPFC has a specific involvement in the "search" condition, while PPC is mainly involved in detecting "pop-out" targets.

  19. The Interplay of Episodic and Semantic Memory in Guiding Repeated Search in Scenes

    Science.gov (United States)

    Vo, Melissa L.-H.; Wolfe, Jeremy M.

    2013-01-01

    It seems intuitive to think that previous exposure or interaction with an environment should make it easier to search through it and, no doubt, this is true in many real-world situations. However, in a recent study, we demonstrated that previous exposure to a scene does not necessarily speed search within that scene. For instance, when observers…

  20. Effects of display curvature, display zone, and task duration on legibility and visual fatigue during visual search task.

    Science.gov (United States)

    Park, Sungryul; Choi, Donghee; Yi, Jihhyeon; Lee, Songil; Lee, Ja Eun; Choi, Byeonghwa; Lee, Seungbae; Kyung, Gyouhyung

    2017-04-01

    This study examined the effects of display curvature (400, 600, 1200 mm, and flat), display zone (5 zones), and task duration (15 and 30 min) on legibility and visual fatigue. Each participant completed two 15-min visual search task sets at each curvature setting. The 600-mm and 1200-mm settings yielded better results than the flat setting in terms of legibility and perceived visual fatigue. Relative to the corresponding centre zone, the outermost zones of the 1200-mm and flat settings showed a decrease of 8%-37% in legibility, whereas those of the flat setting showed an increase of 26%-45% in perceived visual fatigue. Across curvatures, legibility decreased by 2%-8%, whereas perceived visual fatigue increased by 22% during the second task set. The two task sets induced an increase of 102% in the eye complaint score and a decrease of 0.3 Hz in the critical fusion frequency, both of which indicated an increase in visual fatigue. In summary, a curvature of around 600 mm, central display zones, and frequent breaks are recommended to improve legibility and reduce visual fatigue.

  1. Abnormal early brain responses during visual search are evident in schizophrenia but not bipolar affective disorder.

    Science.gov (United States)

    VanMeerten, Nicolaas J; Dubke, Rachel E; Stanwyck, John J; Kang, Seung Suk; Sponheim, Scott R

    2016-01-01

    People with schizophrenia show deficits in processing visual stimuli but neural abnormalities underlying the deficits are unclear and it is unknown whether such functional brain abnormalities are present in other severe mental disorders or in individuals who carry genetic liability for schizophrenia. To better characterize brain responses underlying visual search deficits and test their specificity to schizophrenia we gathered behavioral and electrophysiological responses during visual search (i.e., Span of Apprehension [SOA] task) from 38 people with schizophrenia, 31 people with bipolar disorder, 58 biological relatives of people with schizophrenia, 37 biological relatives of people with bipolar disorder, and 65 non-psychiatric control participants. Through subtracting neural responses associated with purely sensory aspects of the stimuli we found that people with schizophrenia exhibited reduced early posterior task-related neural responses (i.e., Span Endogenous Negativity [SEN]) while other groups showed normative responses. People with schizophrenia exhibited longer reaction times than controls during visual search but nearly identical accuracy. Those individuals with schizophrenia who had larger SENs performed more efficiently (i.e., shorter reaction times) on the SOA task suggesting that modulation of early visual cortical responses facilitated their visual search. People with schizophrenia also exhibited a diminished P300 response compared to other groups. Unaffected first-degree relatives of people with bipolar disorder and schizophrenia showed an amplified N1 response over posterior brain regions in comparison to other groups. Diminished early posterior brain responses are associated with impaired visual search in schizophrenia and appear to be specifically associated with the neuropathology of schizophrenia. Published by Elsevier B.V.

  2. Visual Search skills in Task of Spot Difference

    Directory of Open Access Journals (Sweden)

    Watanabe Takayuki

    2011-12-01

    Full Text Available There were few data for spot of the difference searching skilled on eye movement. Especially, it was unknown how to view and recognition of spot difference quickly. The purpose of this study was to investigate the behavior of spot the difference due to the time pressure tasks. Twelve students participated in this study (average 21years old. Every subject equipped eye movement apparatus recorder (NAC EMR-9, Tokyo Japan, it was displayed gaze point of spot the difference as the stimulus pictures. The attention stimuli was same two photos it’s has spot the difference. The device was measured the spot of the difference as x and y coordinated. It was within one minute to each one recorded searching behavior. After recording gaze and eye movement coordinate apparatus was analyzed it with analytical software (EMR-dFactory ver2.12b, Tokyo Japan. The results of this study was the findings of major two skilled patterns. They gaze tracking one side that was not easily to find out the spot of difference like as inattentional blindness. And it was too quickly eye gaze movement to detected difference. The other it was equal time and trajectory on right and left stimulus picture.

  3. Reward association facilitates distractor suppression in human visual search.

    Science.gov (United States)

    Gong, Mengyuan; Yang, Feitong; Li, Sheng

    2016-04-01

    Although valuable objects are attractive in nature, people often encounter situations where they would prefer to avoid such distraction while focusing on the task goal. Contrary to the typical effect of attentional capture by a reward-associated item, we provide evidence for a facilitation effect derived from the active suppression of a high reward-associated stimulus when cuing its identity as distractor before the display of search arrays. Selection of the target is shown to be significantly faster when the distractors were in high reward-associated colour than those in low reward-associated or non-rewarded colours. This behavioural reward effect was associated with two neural signatures before the onset of the search display: the increased frontal theta oscillation and the strengthened top-down modulation from frontal to anterior temporal regions. The former suggests an enhanced working memory representation for the reward-associated stimulus and the increased need for cognitive control to override Pavlovian bias, whereas the latter indicates that the boost of inhibitory control is realized through a frontal top-down mechanism. These results suggest a mechanism in which the enhanced working memory representation of a reward-associated feature is integrated with task demands to modify attentional priority during active distractor suppression and benefit behavioural performance.

  4. Emotional priming of pop-out in visual search.

    Science.gov (United States)

    Lamy, Dominique; Amunts, Liana; Bar-Haim, Yair

    2008-04-01

    When searching for a discrepant target along a simple dimension such as color or shape, repetition of the target feature substantially speeds search, an effect known as feature priming of pop-out (V. Maljkovic and K. Nakayama, 1994). The authors present the first report of emotional priming of pop-out. Participants had to detect the face displaying a discrepant expression of emotion in an array of four face photographs. On each trial, the target when present was either a neutral face among emotional faces (angry in Experiment 1 or happy in Experiment 2), or an emotional face among neutral faces. Target detection was faster when the target displayed the same emotion on successive trials. This effect occurred for angry and for happy faces, not for neutral faces. It was completely abolished when faces were inverted instead of upright, suggesting that emotional categories rather than physical feature properties drive emotional priming of pop-out. The implications of the present findings for theoretical accounts of intertrial priming and for the face-in-the-crowd phenomenon are discussed.

  5. Quantifying peripheral and foveal perceived differences in natural image patches to predict visual search performance.

    Science.gov (United States)

    Hughes, Anna E; Southwell, Rosy V; Gilchrist, Iain D; Tolhurst, David J

    2016-08-01

    Duncan and Humphreys (1989) identified two key factors that affected performance in a visual search task for a target among distractors. The first was the similarity of the target to distractors (TD), and the second was the similarity of distractors to each other (DD). Here we investigate if it is the perceived similarity in foveal or peripheral vision that determines performance. We studied search using stimuli made from patches cut from colored images of natural objects; differences between targets and their modified distractors were estimated using a ratings task peripherally and foveally. We used search conditions in which the targets and distractors were easy to distinguish both foveally and peripherally ("high" stimuli), in which they were difficult to distinguish both foveally and peripherally ("low"), and in which they were easy to distinguish foveally but difficult to distinguish peripherally ("metamers"). In the critical metameric condition, search slopes (change of search time with number of distractors) were similar to the "low" condition, indicating a key role for peripheral information in visual search as both conditions have low perceived similarity peripherally. Furthermore, in all conditions, search slope was well described quantitatively from peripheral TD and DD but not foveal. However, some features of search, such as error rates, do indicate roles for foveal vision too.

  6. Ontology-Driven Search and Triage: Design of a Web-Based Visual Interface for MEDLINE.

    Science.gov (United States)

    Demelo, Jonathan; Parsons, Paul; Sedig, Kamran

    2017-02-02

    Diverse users need to search health and medical literature to satisfy open-ended goals such as making evidence-based decisions and updating their knowledge. However, doing so is challenging due to at least two major difficulties: (1) articulating information needs using accurate vocabulary and (2) dealing with large document sets returned from searches. Common search interfaces such as PubMed do not provide adequate support for exploratory search tasks. Our objective was to improve support for exploratory search tasks by combining two strategies in the design of an interactive visual interface by (1) using a formal ontology to help users build domain-specific knowledge and vocabulary and (2) providing multi-stage triaging support to help mitigate the information overload problem. We developed a Web-based tool, Ontology-Driven Visual Search and Triage Interface for MEDLINE (OVERT-MED), to test our design ideas. We implemented a custom searchable index of MEDLINE, which comprises approximately 25 million document citations. We chose a popular biomedical ontology, the Human Phenotype Ontology (HPO), to test our solution to the vocabulary problem. We implemented multistage triaging support in OVERT-MED, with the aid of interactive visualization techniques, to help users deal with large document sets returned from searches. Formative evaluation suggests that the design features in OVERT-MED are helpful in addressing the two major difficulties described above. Using a formal ontology seems to help users articulate their information needs with more accurate vocabulary. In addition, multistage triaging combined with interactive visualizations shows promise in mitigating the information overload problem. Our strategies appear to be valuable in addressing the two major problems in exploratory search. Although we tested OVERT-MED with a particular ontology and document collection, we anticipate that our strategies can be transferred successfully to other contexts.

  7. Pattern search for the visualization of scalar, vector, and line fields

    OpenAIRE

    Wang, Zhongjie

    2015-01-01

    The main topic of this thesis is pattern search in data sets for the purpose of visual data analysis. By giving a reference pattern, pattern search aims to discover similar occurrences in a data set with invariance to translation, rotation and scaling. To address this problem, we developed algorithms dealing with different types of data: scalar fields, vector fields, and line fields. For scalar fields, we use the SIFT algorithm (Scale-Invariant Feature Transform) to find a sparse sampling ...

  8. Hand movement deviations in a visual search task with cross modal cuing

    OpenAIRE

    Hürol Aslan; Asli Aslan

    2007-01-01

    The purpose of this study is to demonstrate the cross-modal effects of an auditory organization on a visual search task and to investigate the influence of the level of detail in instructions describing or hinting at the associations between auditory stimuli and the possible locations of a visual target. In addition to measuring the participants reaction times, we paid special attention to tracking the hand movements toward the target. According to the results, t...

  9. Memory for found targets interferes with subsequent performance in multiple-target visual search.

    Science.gov (United States)

    Cain, Matthew S; Mitroff, Stephen R

    2013-10-01

    Multiple-target visual searches--when more than 1 target can appear in a given search display--are commonplace in radiology, airport security screening, and the military. Whereas 1 target is often found accurately, additional targets are more likely to be missed in multiple-target searches. To better understand this decrement in 2nd-target detection, here we examined 2 potential forms of interference that can arise from finding a 1st target: interference from the perceptual salience of the 1st target (a now highly relevant distractor in a known location) and interference from a newly created memory representation for the 1st target. Here, we found that removing found targets from the display or making them salient and easily segregated color singletons improved subsequent search accuracy. However, replacing found targets with random distractor items did not improve subsequent search accuracy. Removing and highlighting found targets likely reduced both a target's visual salience and its memory load, whereas replacing a target removed its visual salience but not its representation in memory. Collectively, the current experiments suggest that the working memory load of a found target has a larger effect on subsequent search accuracy than does its perceptual salience.

  10. How do magnitude and frequency of monetary reward guide visual search?

    Science.gov (United States)

    Won, Bo-Yeong; Leber, Andrew B

    2016-07-01

    How does reward guide spatial attention during visual search? In the present study, we examine whether and how two types of reward information-magnitude and frequency-guide search behavior. Observers were asked to find a target among distractors in a search display to earn points. We manipulated multiple levels of value across the search display quadrants in two ways: For reward magnitude, targets appeared equally often in each quadrant, and the value of each quadrant was determined by the average points earned per target; for reward frequency, we varied how often the target appeared in each quadrant but held the average points earned per target constant across the quadrants. In Experiment 1, we found that observers were highly sensitive to the reward frequency information, and prioritized their search accordingly, whereas we did not find much prioritization based on magnitude information. In Experiment 2, we found that magnitude information for a nonspatial feature (color) could bias search performance, showing that the relative insensitivity to magnitude information during visual search is not generalized across all types of information. In Experiment 3, we replicated the negligible use of spatial magnitude information even when we used limited-exposure displays to incentivize the expression of learning. In Experiment 4, we found participants used the spatial magnitude information during a modified choice task-but again not during search. Taken together, these findings suggest that the visual search apparatus does not equally exploit all potential sources of spatial value information; instead, it favors spatial reward frequency information over spatial reward magnitude information.

  11. Efficient Retrieval of Images for Search Engine by Visual Similarity and Re Ranking

    Directory of Open Access Journals (Sweden)

    Viswa S S

    2013-06-01

    Full Text Available Nowadays, web scale image search engines (e.g.Google Image Search, Microsoft Live ImageSearch rely almost purely on surrounding textfeatures. Users type keywords in hope of finding acertain type of images. The search engine returnsthousands of images ranked by the text keywordsextracted from the surrounding text. However,many of returned images are noisy, disorganized, orirrelevant. Even Google and Microsoft have noVisual Information for searching of images. Usingvisual information to re rank and improve textbased image search results is the idea. Thisimproves the precision of the text based imagesearch ranking by incorporating the informationconveyed by the visual modality.The typicalassumption that the top-images in the text-basedsearch result are equally relevant is relaxed bylinking the relevance of the images to their initialrank positions. Then, a number of images from theinitial search result are employed as the prototypesthat serve to visually represent the query and thatare subsequently used to construct meta re rankers.i.e. The most relevant images are found by visualsimilarity and the average scores are calculated. Byapplying different meta re rankers to an image fromthe initial result, re ranking scores are generated,which are then used to find the new rank positionfor an image in the re ranked search result.Humansupervision is introduced to learn the model weightsoffline, prior to the online re ranking process. Whilemodel learning requires manual labelling of theresults for a few queries, the resulting model isquery independent and therefore applicable to anyother query. The experimental results on arepresentative web image search dataset comprising353 queries demonstrate that the proposed methodoutperforms the existing supervised andunsupervised Re ranking approaches. Moreover, itimproves the performance over the text-based imagesearch engine by morethan 25.48%

  12. Increased Complexities in Visual Search Behavior in Skilled Players for a Self-Paced Aiming Task

    Directory of Open Access Journals (Sweden)

    Jingyi S. Chia

    2017-06-01

    Full Text Available The badminton serve is an important shot for winning a rally in a match. It combines good technique with the ability to accurately integrate visual information from the shuttle, racket, opponent, and intended landing point. Despite its importance and repercussive nature, to date no study has looked at the visual search behaviors during badminton service in the singles discipline. Unlike anticipatory tasks (e.g., shot returns, the serve presents an opportunity to explore the role of visual search behaviors in movement control for self-paced tasks. Accordingly, this study examined skill-related differences in visual behavior during the badminton singles serve. Skilled (n = 12 and less skilled (n = 12 participants performed 30 serves to a live opponent, while real-time eye movements were captured using a mobile gaze registration system. Frame-by-frame analyses of 662 serves were made and the skilled players took a longer preparatory time before serving. Visual behavior of the skilled players was characterized by significantly greater number of fixations on more areas of interest per trial than the less skilled. In addition, the skilled players spent a significantly longer time fixating on the court and net, whereas the less skilled players found the shuttle to be more informative. Quiet eye (QE duration (indicative of superior sports performance however, did not differ significantly between groups which has implications on the perceived importance of QE in the badminton serve. Moreover, while visual behavior differed by skill level, considerable individual differences were also observed especially within the skilled players. This augments the need for not just group-level analyses, but individualized analysis for a more accurate representation of visual behavior. Findings from this study thus provide an insight to the possible visual search strategies as players serve in net-barrier games. Moreover, this study highlighted an important aspect of

  13. Neural mechanisms of surround attenuation and distractor competition in visual search.

    Science.gov (United States)

    Boehler, Carsten N; Tsotsos, John K; Schoenfeld, Mircea A; Heinze, Hans-Jochen; Hopf, Jens-Max

    2011-04-06

    Visual attention biases relevant processing in the visual system by amplifying relevant or attenuating irrelevant sensory input. A potential signature of the latter operation, referred to as surround attenuation, has recently been identified in the electromagnetic brain response of human observers performing visual search. It was found that a zone of attenuated cortical excitability surrounds the target when the search required increased spatial resolution for item discrimination. Here we address the obvious hypothesis that surround attenuation serves distractor suppression in the vicinity of the target where interference from irrelevant search items is maximal. To test this hypothesis, surround attenuation was assessed under conditions when the target was presented in isolation versus when it was surrounded by distractors. Surprisingly, substantial and indistinguishable surround attenuation was seen under both conditions, indicating that it reflects an attentional operation independent of the presence of distractors. Adding distractors in the target's surround, however, increased the amplitude of the N2pc--an evoked response known to index distractor competition in visual search. Moreover, adding distractors led to a topographical change of source activity underlying the N2pc toward earlier extrastriate areas. In contrast, the topography of reduced source activity due to surround attenuation remained unaltered with and without distractors in the target's surround. We conclude that surround attenuation is not a direct consequence of the attenuation of distractors in visual search and that it dissociates from attentional operations reflected by the N2pc. A theoretical framework is proposed that links both operations in a common model of top-down attentional selection in visual cortex.

  14. Real-time volumetric visualization of high-resolution array and toroidal volume search sonar data

    Science.gov (United States)

    Cross, Robert A.

    1998-09-01

    The Advanced Volume Visualization Display (AVVD) research program is a joint research program between the Fraunhofer Center for Research in Computer Graphics, Inc. and Innovative Research and Development Corp. It is dedicated the application of the human visual system to real-time visualization of high- resolution volumetric sensor data sets. The AVVD program has successfully demonstrated its application to undersea imaging using data from the Naval Undersea Warfare Center -- Division Newport's High Resolution Array (HRA), and from the Naval Surface Warfare Center -- Coastal System Stations's Toroidal Volume Search Sonar (TVSS).

  15. Posterior α EEG Dynamics Dissociate Current from Future Goals in Working Memory-Guided Visual Search

    Science.gov (United States)

    2017-01-01

    Current models of visual search assume that search is guided by an active visual working memory representation of what we are currently looking for. This attentional template for currently relevant stimuli can be dissociated from accessory memory representations that are only needed prospectively, for a future task, and that should be prevented from guiding current attention. However, it remains unclear what electrophysiological mechanisms dissociate currently relevant (serving upcoming selection) from prospectively relevant memories (serving future selection). We measured EEG of 20 human subjects while they performed two consecutive visual search tasks. Before the search tasks, a cue instructed observers which item to look for first (current template) and which second (prospective template). During the delay leading up to the first search display, we found clear suppression of α band (8–14 Hz) activity in regions contralateral to remembered items, comprising both local power and interregional phase synchronization within a posterior parietal network. Importantly, these lateralization effects were stronger when the memory item was currently relevant (i.e., for the first search) compared with when it was prospectively relevant (i.e., for the second search), consistent with current templates being prioritized over future templates. In contrast, event-related potential analysis revealed that the contralateral delay activity was similar for all conditions, suggesting no difference in storage. Together, these findings support the idea that posterior α oscillations represent a state of increased processing or excitability in task-relevant cortical regions, and reflect enhanced cortical prioritization of memory representations that serve as a current selection filter. SIGNIFICANCE STATEMENT Our days are filled with looking for relevant objects while ignoring irrelevant visual information. Such visual search activity is thought to be driven by current goals activated

  16. Posterior α EEG Dynamics Dissociate Current from Future Goals in Working Memory-Guided Visual Search.

    Science.gov (United States)

    de Vries, Ingmar E J; van Driel, Joram; Olivers, Christian N L

    2017-02-08

    Current models of visual search assume that search is guided by an active visual working memory representation of what we are currently looking for. This attentional template for currently relevant stimuli can be dissociated from accessory memory representations that are only needed prospectively, for a future task, and that should be prevented from guiding current attention. However, it remains unclear what electrophysiological mechanisms dissociate currently relevant (serving upcoming selection) from prospectively relevant memories (serving future selection). We measured EEG of 20 human subjects while they performed two consecutive visual search tasks. Before the search tasks, a cue instructed observers which item to look for first (current template) and which second (prospective template). During the delay leading up to the first search display, we found clear suppression of α band (8-14 Hz) activity in regions contralateral to remembered items, comprising both local power and interregional phase synchronization within a posterior parietal network. Importantly, these lateralization effects were stronger when the memory item was currently relevant (i.e., for the first search) compared with when it was prospectively relevant (i.e., for the second search), consistent with current templates being prioritized over future templates. In contrast, event-related potential analysis revealed that the contralateral delay activity was similar for all conditions, suggesting no difference in storage. Together, these findings support the idea that posterior α oscillations represent a state of increased processing or excitability in task-relevant cortical regions, and reflect enhanced cortical prioritization of memory representations that serve as a current selection filter.SIGNIFICANCE STATEMENT Our days are filled with looking for relevant objects while ignoring irrelevant visual information. Such visual search activity is thought to be driven by current goals activated in

  17. Don't Pack Your iPod in Honey: Lessons from the Study of Visual Search

    Directory of Open Access Journals (Sweden)

    Jeremy M. Wolfe

    2011-05-01

    Full Text Available We are built to search. Our ancestors foraged for food. We search for pens, keys, and cars in parking lots. Even when the stimulus is visible, we must search because we cannot fully process all visual stimuli at once. I will discuss the limits on vision without attention and some of the mechanisms of visual search. I will then turn to real-world tasks like the search for cancer in X-rays or security threats in luggage. I will show how our normal processes of search can lead to serious problems in socially important tasks.

  18. Implicit short- and long-term memory direct our gaze in visual search.

    Science.gov (United States)

    Kruijne, Wouter; Meeter, Martijn

    2016-04-01

    Visual attention is strongly affected by the past: both by recent experience and by long-term regularities in the environment that are encoded in and retrieved from memory. In visual search, intertrial repetition of targets causes speeded response times (short-term priming). Similarly, targets that are presented more often than others may facilitate search, even long after it is no longer present (long-term priming). In this study, we investigate whether such short-term priming and long-term priming depend on dissociable mechanisms. By recording eye movements while participants searched for one of two conjunction targets, we explored at what stages of visual search different forms of priming manifest. We found both long- and short- term priming effects. Long-term priming persisted long after the bias was present, and was again found even in participants who were unaware of a color bias. Short- and long-term priming affected the same stage of the task; both biased eye movements towards targets with the primed color, already starting with the first eye movement. Neither form of priming affected the response phase of a trial, but response repetition did. The results strongly suggest that both long- and short-term memory can implicitly modulate feedforward visual processing.

  19. Training eye movements for visual search in individuals with macular degeneration

    NARCIS (Netherlands)

    Janssen, C.P.; Verghese, Preeti

    2016-01-01

    We report a method to train individuals with central field loss due to macular degeneration improve the efficiency of visual search. Our method requires participants to make a same/different judgment on two simple silhouettes. One silhouette is presented in an area that falls within the binocular sc

  20. The effects of link format and screen location on visual search of web pages.

    Science.gov (United States)

    Ling, Jonathan; Van Schaik, Paul

    2004-06-22

    Navigation of web pages is of critical importance to the usability of web-based systems such as the World Wide Web and intranets. The primary means of navigation is through the use of hyperlinks. However, few studies have examined the impact of the presentation format of these links on visual search. The present study used a two-factor mixed measures design to investigate whether there was an effect of link format (plain text, underlined, bold, or bold and underlined) upon speed and accuracy of visual search and subjective measures in both the navigation and content areas of web pages. An effect of link format on speed of visual search for both hits and correct rejections was found. This effect was observed in the navigation and the content areas. Link format did not influence accuracy in either screen location. Participants showed highest preference for links that were in bold and underlined, regardless of screen area. These results are discussed in the context of visual search processes and design recommendations are given.

  1. Attentional Capture by Salient Distractors during Visual Search Is Determined by Temporal Task Demands

    DEFF Research Database (Denmark)

    Kiss, Monika; Grubert, Anna; Petersen, Anders

    2012-01-01

    The question whether attentional capture by salient but taskirrelevant visual stimuli is triggered in a bottom–up fashion or depends on top–down task settings is still unresolved. Strong support for bottom–up capture was obtained in the additional singleton task, in which search arrays were visib...

  2. Earthdata Search: Combining New Services and Technologies for Earth Science Data Discovery, Visualization, and Access

    Science.gov (United States)

    Quinn, P.; Pilone, D.

    2014-12-01

    A host of new services are revolutionizing discovery, visualization, and access of NASA's Earth science data holdings. At the same time, web browsers have become far more capable and open source libraries have grown to take advantage of these capabilities. Earthdata Search is a web application which combines modern browser features with the latest Earthdata services from NASA to produce a cutting-edge search and access client with features far beyond what was possible only a couple of years ago. Earthdata Search provides data discovery through the Common Metadata Repository (CMR), which provides a high-speed REST API for searching across hundreds of millions of data granules using temporal, spatial, and other constraints. It produces data visualizations by combining CMR data with Global Imagery Browse Services (GIBS) image tiles. Earthdata Search renders its visualizations using custom plugins built on Leaflet.js, a lightweight mobile-friendly open source web mapping library. The client further features an SVG-based interactive timeline view of search results. For data access, Earthdata Search provides easy temporal and spatial subsetting as well as format conversion by making use of OPeNDAP. While the client hopes to drive adoption of these services and standards, it provides fallback behavior for working with data that has not yet adopted them. This allows the client to remain on the cutting-edge of service offerings while still boasting a catalog containing thousands of data collections. In this session, we will walk through Earthdata Search and explain how it incorporates these new technologies and service offerings.

  3. Temporal Binding and Segmentation in Visual Search: A Computational Neuroscience Analysis.

    Science.gov (United States)

    Mavritsaki, Eirini; Humphreys, Glyn

    2016-10-01

    Human visual search operates not only over space but also over time, as old items remain in the visual field and new items appear. Preview search (where one set of distractors appears before the onset of a second set) has been used as a paradigm to study search over time and space [Watson, D. G., & Humphreys, G. W. Visual marking: Prioritizing selection for new objects by top-down attentional inhibition of old objects. Psychological Review, 104, 90-122, 1997], with participants showing efficient search when old distractors can be ignored and new targets prioritized. The benefits of preview search are lost, however, if a temporal gap is introduced between a first presentation of the old items and the re-presentation of all the items in the search display [Kunar, M. A., Humphreys, G. W., & Smith, K. J. History matters: The preview benefit in search is not onset capture. Psychological Science, 14, 181-185, 2003a], consistent with the old items being bound by temporal onset to the new stimuli. This effect of temporal binding can be eliminated if the old items reappear briefly before the new items, indicating also a role for the memory of the old items. Here we simulate these effects of temporal coding in search using the spiking search over time and space model [Mavritsaki, E., Heinke, D., Allen, H., Deco, G., & Humphreys, G. W. Bridging the gap between physiology and behavior: Evidence from the sSoTS model of human visual attention. Psychological Review, 118, 3-41, 2011]. We show that a form of temporal binding by new onsets has to be introduced to the model to simulate the effects of a temporal gap, but that effects of the memory of the old item can stem from continued neural suppression across a temporal gap. We also show that the model can capture the effects of brain lesion on preview search under the different temporal conditions. The study provides a proof-of-principle analysis that neural suppression and temporal binding can be sufficient to account for human

  4. Accelerated damage visualization using binary search with fixed pitch-catch distance laser ultrasonic scanning

    Science.gov (United States)

    Park, Byeongjin; Sohn, Hoon

    2017-07-01

    Laser ultrasonic scanning, especially full-field wave propagation imaging, is attractive for damage visualization thanks to its noncontact nature, sensitivity to local damage, and high spatial resolution. However, its practicality is limited because scanning at a high spatial resolution demands a prohibitively long scanning time. Inspired by binary search, an accelerated damage visualization technique is developed to visualize damage with a reduced scanning time. The pitch-catch distance between the excitation point and the sensing point is also fixed during scanning to maintain a high signal-to-noise ratio (SNR) of measured ultrasonic responses. The approximate damage boundary is identified by examining the interactions between ultrasonic waves and damage observed at the scanning points that are sparsely selected by a binary search algorithm. Here, a time-domain laser ultrasonic response is transformed into a spatial ultrasonic domain response using a basis pursuit approach so that the interactions between ultrasonic waves and damage, such as reflections and transmissions, can be better identified in the spatial ultrasonic domain. Then, the area inside the identified damage boundary is visualized as damage. The performance of the proposed damage visualization technique is validated excusing a numerical simulation performed on an aluminum plate with a notch and experiments performed on an aluminum plate with a crack and a wind turbine blade with delamination. The proposed damage visualization technique accelerates the damage visualization process in three aspects: (1) the number of measurements that is necessary for damage visualization is dramatically reduced by a binary search algorithm; (2) the number of averaging that is necessary to achieve a high SNR is reduced by maintaining the wave propagation distance short; and (3) with the proposed technique, the same damage can be identified with a lower spatial resolution than the spatial resolution required by full

  5. Centre-of-Gravity Fixations in Visual Search: When Looking at Nothing Helps to Find Something

    Directory of Open Access Journals (Sweden)

    Dustin Venini

    2014-01-01

    Full Text Available In visual search, some fixations are made between stimuli on empty regions, commonly referred to as “centre-of-gravity” fixations (henceforth: COG fixations. Previous studies have shown that observers with task expertise show more COG fixations than novices. This led to the view that COG fixations reflect simultaneous encoding of multiple stimuli, allowing more efficient processing of task-related items. The present study tested whether COG fixations also aid performance in visual search tasks with unfamiliar and abstract stimuli. Moreover, to provide evidence for the multiple-item processing view, we analysed the effects of COG fixations on the number and dwell times of stimulus fixations. The results showed that (1 search efficiency increased with increasing COG fixations even in search for unfamiliar stimuli and in the absence of special higher-order skills, (2 COG fixations reliably reduced the number of stimulus fixations and their dwell times, indicating processing of multiple distractors, and (3 the proportion of COG fixations was dynamically adapted to potential information gain of COG locations. A second experiment showed that COG fixations are diminished when stimulus positions unpredictably vary across trials. Together, the results support the multiple-item processing view, which has important implications for current theories of visual search.

  6. Dimension-specific signal modulation in visual search: evidence from inter-stimulus surround suppression.

    Science.gov (United States)

    Chan, Louis K H; Hayward, William G

    2012-04-18

    A fundamental task for the visual system is to determine where to attend next. In general, attention is guided by visual saliency. Computational models suggest that saliency values are estimated through an iterative process in which each visual item suppresses each other item's saliency, especially for those with close proximity. To investigate this proposal, we tested the effect of two salient distractors on visual search for a size target. While fixing the target-to-distractor distance, we manipulated the distance between two distractors. If two salient distractors suppressed each other when they were close together, they should interfere with search less; this was exactly what we found. However, we observed such a distance effect only for distractors of the same dimension (e.g., both defined in color) but not for those of different dimensions (e.g., one defined in color and the other in shape), displaying specificity to a perceptual dimension. Therefore, we conclude that saliency in visual search is calculated through a surround suppression process that occurs at a dimension-specific level.

  7. Active visual search in non-stationary scenes: coping with temporal variability and uncertainty

    Science.gov (United States)

    Ušćumlić, Marija; Blankertz, Benjamin

    2016-02-01

    Objective. State-of-the-art experiments for studying neural processes underlying visual cognition often constrain sensory inputs (e.g., static images) and our behavior (e.g., fixed eye-gaze, long eye fixations), isolating or simplifying the interaction of neural processes. Motivated by the non-stationarity of our natural visual environment, we investigated the electroencephalography (EEG) correlates of visual recognition while participants overtly performed visual search in non-stationary scenes. We hypothesized that visual effects (such as those typically used in human-computer interfaces) may increase temporal uncertainty (with reference to fixation onset) of cognition-related EEG activity in an active search task and therefore require novel techniques for single-trial detection. Approach. We addressed fixation-related EEG activity in an active search task with respect to stimulus-appearance styles and dynamics. Alongside popping-up stimuli, our experimental study embraces two composite appearance styles based on fading-in, enlarging, and motion effects. Additionally, we explored whether the knowledge obtained in the pop-up experimental setting can be exploited to boost the EEG-based intention-decoding performance when facing transitional changes of visual content. Main results. The results confirmed our initial hypothesis that the dynamic of visual content can increase temporal uncertainty of the cognition-related EEG activity in active search with respect to fixation onset. This temporal uncertainty challenges the pivotal aim to keep the decoding performance constant irrespective of visual effects. Importantly, the proposed approach for EEG decoding based on knowledge transfer between the different experimental settings gave a promising performance. Significance. Our study demonstrates that the non-stationarity of visual scenes is an important factor in the evolution of cognitive processes, as well as in the dynamic of ocular behavior (i.e., dwell time and

  8. Neural basis of feature-based contextual effects on visual search behavior

    Directory of Open Access Journals (Sweden)

    Kelly eShen

    2012-01-01

    Full Text Available Searching for a visual object is known to be adaptable to context, and it is thought to result from the selection of neural representations distributed on a visual salience map, wherein stimulus-driven and goal-directed signals are combined. Here we investigated the neural basis of this adaptability by recording superior colliculus (SC neurons while three female rhesus monkeys (Macaca mulatta searched with saccadic eye movements for a target presented in an array of visual stimuli whose feature composition varied from trial to trial. We found that sensory-motor activity associated with distracters was enhanced or suppressed depending on the search array composition and that it corresponded to the monkey's search strategy, as assessed by the distribution of the occasional errant saccades. This feature-related modulation occurred independently from the saccade goal and facilitated the process of saccade target selection. We also observed feature-related enhancement in the activity associated with distracters that had been the search target during the previous session. Consistent with recurrent processing, both feature-related neuronal modulations occurred more than 60 ms after the onset of the visually evoked responses, and their near coincidence with the time of saccade target selection suggests that they are integral to this process. These results suggest that SC neuronal activity is shaped by the visual context as dictated by both stimulus-driven and goal-directed signals. Given the close proximity of the SC to the motor circuit, our findings suggest a direct link between perception and action and no need for distinct salience and motor maps.

  9. Regional differences of repeatability on visual analogue scale with experimental mechanical pain stimuli.

    Science.gov (United States)

    Hayashi, Kazuhiro; Ikemoto, Tatsunori; Ueno, Takefumi; Arai, Young-Chang P; Shimo, Kazuhiro; Nishihara, Makoto; Suzuki, Shigeyuki; Ushida, Takahiro

    2015-01-12

    Pain-VAS is quite subjective as a scale, but has a tendency to assume differences in repeatability in accordance with perceived pain intensity. The aim of the present study was to investigate the repeatability of regional differences with ratings of pain-VAS. Three experimental mechanical stimuli were applied to twenty seven healthy volunteers across four sessions over four weeks within individuals. The same stimuli were also simultaneously measured in the same manner with an electric balance. The magnitude of mechanical stimuli was determined by 100 g, 300 g, and 600 g monofilaments. Standard deviations (SDs) across measurements with an electric balance showed a regular increase with stimulus magnitude, while coefficient variations (CVs) were constant in each stimulus. On the other hand, although SDs across pain-VAS measurements were significantly greater with the 300 g filament than with the 100 g and 600 g filaments, CVs showed a regular decrease in magnitude of stimulus. These results showed that the CVs of repeated measurement with electric balance were consistent regardless of stimulus intensity, in contrast, CVs of pain-VAS decreased with greater pain rating averaged by repeated measurement. These results suggest that a low rating in pain-VAS is inherently less objective, indicating poor repeatability. In contrast, a high rating in pain-VAS is more objective with better repeatability for experimental pain perception.

  10. Differential effects of parietal and frontal inactivations on reaction times distributions in a visual search task

    Directory of Open Access Journals (Sweden)

    Claire eWardak

    2012-06-01

    Full Text Available The posterior parietal cortex participates to numerous cognitive functions, from perceptual to attentional and decisional processes. However, the same functions have also been attributed to the frontal cortex. We previously conducted a series of reversible inactivations of the lateral intraparietal area (LIP and of the frontal eye field (FEF in the monkey which showed impairments in covert visual search performance, characterized mainly by an increase in the mean reaction time (RT necessary to detect a contralesional target. Only subtle differences were observed between the inactivation effects in both areas. In particular, the magnitude of the deficit was dependant of search task difficulty for LIP, but not for FEF.In the present study, we re-examine these data in order to try to dissociate the specific involvement of these two regions, by considering the entire RT distribution instead of mean RT. We use the LATER model to help us interpret the effects of the inactivations with regard to information accumulation rate and decision processes. We show that: 1 different search strategies can be used by monkeys to perform visual search, either by processing the visual scene in parallel, or by combining parallel and serial processes; 2 LIP and FEF inactivations have very different effects on the RT distributions in the two monkeys. Although our results are not conclusive with regards to the exact functional mechanisms affected by the inactivations, the effects we observe on RT distributions could be accounted by an involvement of LIP in saliency representation or decision-making, and an involvement of FEF in attentional shifts and perception. Finally, we observe that the use of the LATER model is limited in the context of a visual search as it cannot fit all the behavioural strategies encountered. We propose that the diversity in search strategies observed in our monkeys also exists in individual human subjects and should be considered in future

  11. The Importance of the Eye Area in Face Identification Abilities and Visual Search Strategies in Persons with Asperger Syndrome

    Science.gov (United States)

    Falkmer, Marita; Larsson, Matilda; Bjallmark, Anna; Falkmer, Torbjorn

    2010-01-01

    Partly claimed to explain social difficulties observed in people with Asperger syndrome, face identification and visual search strategies become important. Previous research findings are, however, disparate. In order to explore face identification abilities and visual search strategies, with special focus on the importance of the eye area, 24…

  12. The Importance of the Eye Area in Face Identification Abilities and Visual Search Strategies in Persons with Asperger Syndrome

    Science.gov (United States)

    Falkmer, Marita; Larsson, Matilda; Bjallmark, Anna; Falkmer, Torbjorn

    2010-01-01

    Partly claimed to explain social difficulties observed in people with Asperger syndrome, face identification and visual search strategies become important. Previous research findings are, however, disparate. In order to explore face identification abilities and visual search strategies, with special focus on the importance of the eye area, 24…

  13. Working Memory Capacity Predicts Selection and Identification Errors in Visual Search.

    Science.gov (United States)

    Peltier, Chad; Becker, Mark W

    2016-11-17

    As public safety relies on the ability of professionals, such as radiologists and baggage screeners, to detect rare targets, it could be useful to identify predictors of visual search performance. Schwark, Sandry, and Dolgov found that working memory capacity (WMC) predicts hit rate and reaction time in low prevalence searches. This link was attributed to higher WMC individuals exhibiting a higher quitting threshold and increasing the probability of finding the target before terminating search in low prevalence search. These conclusions were limited based on the methods; without eye tracking, the researchers could not differentiate between an increase in accuracy due to fewer identification errors (failing to identify a fixated target), selection errors (failing to fixate a target), or a combination of both. Here, we measure WMC and correlate it with reaction time and accuracy in a visual search task. We replicate the finding that WMC predicts reaction time and hit rate. However, our analysis shows that it does so through both a reduction in selection and identification errors. The correlation between WMC and selection errors is attributable to increased quitting thresholds in those with high WMC. The correlation between WMC and identification errors is less clear, though potentially attributable to increased item inspection times in those with higher WMC. In addition, unlike Schwark and coworkers, we find that these WMC effects are fairly consistent across prevalence rates rather than being specific to low-prevalence searches.

  14. A Lifelog Browser for Visualization and Search of Mobile Everyday-Life

    Directory of Open Access Journals (Sweden)

    Keum-Sung Hwang

    2014-01-01

    Full Text Available Mobile devices can now handle a great deal of information thanks to the convergence of diverse functionalities. Mobile environments have already shown great potential in terms of providing customized service to users because they can record meaningful and private information continually for long periods of time. The research for understanding, searching and summarizing the everyday-life of human has received increasing attention in recent years due to the digital convergence. In this paper, we propose a mobile life browser, which visualizes and searches human's mobile life based on the contents and context of lifelog data. The mobile life browser is for searching the personal information effectively collected on his/her mobile device and for supporting the concept-based searching method by using concept networks and Bayesian networks. In the experiments, we collected the real mobile log data from three users for a month and visualized the mobile lives of the users with the mobile life browser developed. Some tests on searching tasks confirmed that the result using the proposed concept-based searching method is promising.

  15. HD CAGnome: a search tool for huntingtin CAG repeat length-correlated genes.

    Directory of Open Access Journals (Sweden)

    Ekaterina I Galkina

    Full Text Available BACKGROUND: The length of the huntingtin (HTT CAG repeat is strongly correlated with both age at onset of Huntington's disease (HD symptoms and age at death of HD patients. Dichotomous analysis comparing HD to controls is widely used to study the effects of HTT CAG repeat expansion. However, a potentially more powerful approach is a continuous analysis strategy that takes advantage of all of the different CAG lengths, to capture effects that are expected to be critical to HD pathogenesis. METHODOLOGY/PRINCIPAL FINDINGS: We used continuous and dichotomous approaches to analyze microarray gene expression data from 107 human control and HD lymphoblastoid cell lines. Of all probes found to be significant in a continuous analysis by CAG length, only 21.4% were so identified by a dichotomous comparison of HD versus controls. Moreover, of probes significant by dichotomous analysis, only 33.2% were also significant in the continuous analysis. Simulations revealed that the dichotomous approach would require substantially more than 107 samples to either detect 80% of the CAG-length correlated changes revealed by continuous analysis or to reduce the rate of significant differences that are not CAG length-correlated to 20% (n = 133 or n = 206, respectively. Given the superior power of the continuous approach, we calculated the correlation structure between HTT CAG repeat lengths and gene expression levels and created a freely available searchable website, "HD CAGnome," that allows users to examine continuous relationships between HTT CAG and expression levels of ∼20,000 human genes. CONCLUSIONS/SIGNIFICANCE: Our results reveal limitations of dichotomous approaches compared to the power of continuous analysis to study a disease where human genotype-phenotype relationships strongly support a role for a continuum of CAG length-dependent changes. The compendium of HTT CAG length-gene expression level relationships found at the HD CAGnome now provides

  16. The downside of choice: Having a choice benefits enjoyment, but at a cost to efficiency and time in visual search.

    Science.gov (United States)

    Kunar, Melina A; Ariyabandu, Surani; Jami, Zaffran

    2016-04-01

    The efficiency of how people search for an item in visual search has, traditionally, been thought to depend on bottom-up or top-down guidance cues. However, recent research has shown that the rate at which people visually search through a display is also affected by cognitive strategies. In this study, we investigated the role of choice in visual search, by asking whether giving people a choice alters both preference for a cognitively neutral task and search behavior. Two visual search conditions were examined: one in which participants were given a choice of visual search task (the choice condition), and one in which participants did not have a choice (the no-choice condition). The results showed that the participants in the choice condition rated the task as both more enjoyable and likeable than did the participants in the no-choice condition. However, despite their preferences, actual search performance was slower and less efficient in the choice condition than in the no-choice condition (Exp. 1). Experiment 2 showed that the difference in search performance between the choice and no-choice conditions disappeared when central executive processes became occupied with a task-switching task. These data concur with a choice-impaired hypothesis of search, in which having a choice leads to more motivated, active search involving executive processes.

  17. Priming of Visual Search Facilitates Attention Shifts: Evidence From Object-Substitution Masking.

    Science.gov (United States)

    Kristjánsson, Árni

    2016-03-01

    Priming of visual search strongly affects visual function, releasing items from crowding and during free-choice primed targets are chosen over unprimed ones. Two accounts of priming have been proposed: attentional facilitation of primed features and postperceptual episodic memory retrieval that involves mapping responses to visual events. Here, well-known masking effects were used to assess the two accounts. Object-substitution masking has been considered to reflect attentional processing: It does not occur when a target is precued and is strengthened when distractors are present. Conversely, metacontrast masking has been connected to lower level processing where attention exerts little effect. If priming facilitates attention shifts, it should mitigate object-substitution masking, while lower level masking might not be similarly influenced. Observers searched for an odd-colored target among distractors. Unpredictably (on 20% of trials), object-substitution masks or metacontrast masks appeared around the target. Object-substitution masking was strongly mitigated for primed target colors, while metacontrast masking was mostly unaffected. This argues against episodic retrieval accounts of priming, placing the priming locus firmly within the realm of attentional processing. The results suggest that priming of visual search facilitates attention shifts to the target, which allows better spatiotemporal resolution that overcomes object-substitution masking.

  18. Integrating space and time in visual search: how the preview benefit is modulated by stereoscopic depth.

    Science.gov (United States)

    Dent, Kevin; Braithwaite, Jason J; He, Xun; Humphreys, Glyn W

    2012-07-15

    We examined visual search for letters that were distributed across both 3 dimensional space, and time. In Experiment 1, when participants had foreknowledge of the depth plane and time interval where targets could appear, search was more efficient if the items could be segmented either by depth or by time (with a 1000 ms preview), and there were increased benefits when the two cues (depth and time) were combined. In Experiments 2 and 3 the target depth plane was always unknown to the participant. In this case, depth cues alone did not facilitate search, though they continued to increase the preview benefit. In Experiment 4 new items in preview search could fall at the same depth as preview items or a new depth. There was a substantial cost to search if the target appeared at a previewed depth. Experiment 5 showed that this cost remained even when participants knew the target would appear at the old depth on 75% of trials. The results indicate that spatial (depth) and temporal cues combine to enhance visual segmentation and selection, and this is accomplished by inhibition of distractors in irrelevant depth planes.

  19. Blaming the victims of your own mistakes: How visual search accuracy influences evaluation of stimuli.

    Science.gov (United States)

    Chetverikov, Andrey; Jóhannesson, Ómar I; Kristjánsson, Árni

    2015-01-01

    Even without explicit positive or negative reinforcement, experiences may influence preferences. According to the affective feedback in hypotheses testing account preferences are determined by the accuracy of hypotheses: correct hypotheses evoke positive affect, while incorrect ones evoke negative affect facilitating changes of hypotheses. Applying this to visual search, we suggest that accurate search should lead to more positive ratings of targets than distractors, while for errors targets should be rated more negatively. We test this in two experiments using time-limited search for a conjunction of gender and tint of faces. Accurate search led to more positive ratings for targets as compared to distractors or targets following errors. Errors led to more negative ratings for targets than for distractors. Critically, eye tracking revealed that the longer the fixation dwell times in target regions, the higher the target ratings for correct responses, and the lower the ratings for errors. The longer observers look at targets, the more positive their ratings if they answer correctly, and less positive, following errors. The findings support the affective feedback account and provide the first demonstration of negative effects on liking ratings following errors in visual search.

  20. Adding a Visualization Feature to Web Search Engines: It’s Time

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Pak C.

    2008-11-11

    Since the first world wide web (WWW) search engine quietly entered our lives in 1994, the “information need” behind web searching has rapidly grown into a multi-billion dollar business that dominates the internet landscape, drives e-commerce traffic, propels global economy, and affects the lives of the whole human race. Today’s search engines are faster, smarter, and more powerful than those released just a few years ago. With the vast investment pouring into research and development by leading web technology providers and the intense emotion behind corporate slogans such as “win the web” or “take back the web,” I can’t help but ask why are we still using the very same “text-only” interface that was used 13 years ago to browse our search engine results pages (SERPs)? Why has the SERP interface technology lagged so far behind in the web evolution when the corresponding search technology has advanced so rapidly? In this article I explore some current SERP interface issues, suggest a simple but practical visual-based interface design approach, and argue why a visual approach can be a strong candidate for tomorrow’s SERP interface.

  1. Neural Correlates of Inter-trial Priming and Role-Reversal in Visual Search

    Directory of Open Access Journals (Sweden)

    Chris eRorden

    2011-11-01

    Full Text Available Studies of priming of visual perception demonstrate that observers respond more quickly to targets in a field of distractors when relevant features are repeated versus novel or role-reversed. In a recent brain imaging study participants were presented with two items of one color and a single item in a different color with the task of reporting the orientation of the uniquely colored item. Consistent with previous behavioral reports, they found that observers were faster to respond when the target and distractor colors were identical to the previous trial than when they were reversed. They found reduced BOLD activity in brain areas linked with attentional control on trials where the target and distractor colors were repeated relative to reversed, which they interpreted as reflecting response suppression (decreased BOLD signal for repeated stimuli. However, since their design only compared repeated versus reversed task demands, it is logically possible that this pattern reflects increased BOLD signal for role-reversed stimuli: activity required to inhibit previously facilitated information and select previously inhibited information. We explored this possibility with a task where we contrasted the signal generated by repeated, reversed and novel features. Our data suggest that the majority of the change in neural signal elicited by priming of pop-out reflects increased activation when selection criteria are reversed.

  2. Evaluation of a dichromatic color-appearance simulation by a visual search task

    Science.gov (United States)

    Sunaga, Shoji; Ogura, Tomomi; Seno, Takeharu

    2013-03-01

    We used a visual search task to investigate the validity of the dichromatic simulation model proposed by Brettel et al. Although the dichromatic simulation could qualitatively predict reaction times for color-defective observers, the reaction times for color-defective observers tended to be longer than those of the trichromatic observers in Experiment 1. In Experiment 2, we showed that a reduction of purity excitation of simulated colors can provide a good prediction. Further, we propose an adaptive dichromatic simulation model based on the color differences between a simulated target color and simulated distractor colors in order to obtain a better quantitative prediction of reaction times in the visual search task for color defects.

  3. Human visual search does not maximize the post-saccadic probability of identifying targets.

    Directory of Open Access Journals (Sweden)

    Camille Morvan

    2012-02-01

    Full Text Available Researchers have conjectured that eye movements during visual search are selected to minimize the number of saccades. The optimal Bayesian eye movement strategy minimizing saccades does not simply direct the eye to whichever location is judged most likely to contain the target but makes use of the entire retina as an information gathering device during each fixation. Here we show that human observers do not minimize the expected number of saccades in planning saccades in a simple visual search task composed of three tokens. In this task, the optimal eye movement strategy varied, depending on the spacing between tokens (in the first experiment or the size of tokens (in the second experiment, and changed abruptly once the separation or size surpassed a critical value. None of our observers changed strategy as a function of separation or size. Human performance fell far short of ideal, both qualitatively and quantitatively.

  4. Visual search for emotional expressions: Effect of stimulus set on anger and happiness superiority.

    Science.gov (United States)

    Savage, Ruth A; Becker, Stefanie I; Lipp, Ottmar V

    2016-01-01

    Prior reports of preferential detection of emotional expressions in visual search have yielded inconsistent results, even for face stimuli that avoid obvious expression-related perceptual confounds. The current study investigated inconsistent reports of anger and happiness superiority effects using face stimuli drawn from the same database. Experiment 1 excluded procedural differences as a potential factor, replicating a happiness superiority effect in a procedure that previously yielded an anger superiority effect. Experiments 2a and 2b confirmed that image colour or poser gender did not account for prior inconsistent findings. Experiments 3a and 3b identified stimulus set as the critical variable, revealing happiness or anger superiority effects for two partially overlapping sets of face stimuli. The current results highlight the critical role of stimulus selection for the observation of happiness or anger superiority effects in visual search even for face stimuli that avoid obvious expression related perceptual confounds and are drawn from a single database.

  5. Searching for Grendel: origin and global spread of the C9ORF72 repeat expansion.

    Science.gov (United States)

    Pliner, Hannah A; Mann, David M; Traynor, Bryan J

    2014-03-01

    Recent advances are uncovering more and more of the genetic architecture underlying amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative condition that affects ~6,000 Americans annually. Chief among these was the discovery that a large repeat expansion in the C9ORF72 gene is responsible for an unprecedented portion of familial and sporadic ALS cases. Much has been published on how this expansion disrupts neuronal homeostasis and how gene-based therapy might be an effective treatment in the future. Nevertheless, it is instructive to look back at the origins of this important mutation. In this opinion piece, we attempt to answer three key questions concerning C9ORF72. First, how many times did the expansion occur throughout human history? Second, how old is the expansion? And finally and perhaps most importantly, how did the expansion spread throughout Europe? We speculate that the expansion occurred only once in the past, that this event took place in the Finnish population and that the Vikings and their descendants were responsible for disseminating this mutation throughout the rest of the continent.

  6. Improving Target Detection in Visual Search Through the Augmenting Multi-Sensory Cues

    Science.gov (United States)

    2013-01-01

    target detection, visual search James Merlo , Joseph E. Mercado, Jan B.F. Van Erp, Peter A. Hancock University of Central Florida 12201 Research Parkway...cued control condition (e.g. Fisher et al. 1989; Fisher and Tan 1989; Hofer, Palen, and Possolo 1993; Merlo and Hancock 2011; Sklar and Sarter 1999...by the improvements encountered in bi-modal forms of presentation ( Merlo , Duley, and Hancock 2010) and thus the present extension into the exploration

  7. Age-Related Changes in Selective Attention and Perceptual Load During Visual Search

    OpenAIRE

    Madden, David J.; Langley, Linda K.

    2003-01-01

    Three visual search experiments were conducted to test the hypothesis that age differences in selective attention vary as a function of perceptual load (E. A. Maylor & N. Lavie, 1998). Under resource-limited conditions (Experiments 1 and 2), the distraction from irrelevant display items generally decreased as display size (perceptual load) increased. This perceptual load effect was similar for younger and older adults, contrary to the findings of Maylor and Lavie. Distraction at low perceptua...

  8. The Speed of Serial Attention Shifts in Visual Search: Evidence from the N2pc Component.

    Science.gov (United States)

    Grubert, Anna; Eimer, Martin

    2016-02-01

    Finding target objects among distractors in visual search display is often assumed to be based on sequential movements of attention between different objects. However, the speed of such serial attention shifts is still under dispute. We employed a search task that encouraged the successive allocation of attention to two target objects in the same search display and measured N2pc components to determine how fast attention moved between these objects. Each display contained one digit in a known color (fixed-color target) and another digit whose color changed unpredictably across trials (variable-color target) together with two gray distractor digits. Participants' task was to find the fixed-color digit and compare its numerical value with that of the variable-color digit. N2pc components to fixed-color targets preceded N2pc components to variable-color digits, demonstrating that these two targets were indeed selected in a fixed serial order. The N2pc to variable-color digits emerged approximately 60 msec after the N2pc to fixed-color digits, which shows that attention can be reallocated very rapidly between different target objects in the visual field. When search display durations were increased, thereby relaxing the temporal demands on serial selection, the two N2pc components to fixed-color and variable-color targets were elicited within 90 msec of each other. Results demonstrate that sequential shifts of attention between different target locations can operate very rapidly at speeds that are in line with the assumptions of serial selection models of visual search.

  9. I can see what you are saying: Auditory labels reduce visual search times.

    Science.gov (United States)

    Cho, Kit W

    2016-10-01

    The present study explored the self-directed-speech effect, the finding that relative to silent reading of a label (e.g., DOG), saying it aloud reduces visual search reaction times (RTs) for locating a target picture among distractors. Experiment 1 examined whether this effect is due to a confound in the differences in the number of cues in self-directed speech (two) vs. silent reading (one) and tested whether self-articulation is required for the effect. The results showed that self-articulation is not required and that merely hearing the auditory label reduces visual search RTs relative to silent reading. This finding also rules out the number of cues confound. Experiment 2 examined whether hearing an auditory label activates more prototypical features of the label's referent and whether the auditory-label benefit is moderated by the target's imagery concordance (the degree to which the target picture matches the mental picture that is activated by a written label for the target). When the target imagery concordance was high, RTs following the presentation of a high prototypicality picture or auditory cue were comparable and shorter than RTs following a visual label or low prototypicality picture cue. However, when the target imagery concordance was low, RTs following an auditory cue were shorter than the comparable RTs following the picture cues and visual-label cue. The results suggest that an auditory label activates both prototypical and atypical features of a concept and can facilitate visual search RTs even when compared to picture primes. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. On-the-fly learning for visual search of large-scale image and video datasets.

    Science.gov (United States)

    Chatfield, Ken; Arandjelović, Relja; Parkhi, Omkar; Zisserman, Andrew

    The objective of this work is to visually search large-scale video datasets for semantic entities specified by a text query. The paradigm we explore is constructing visual models for such semantic entities on-the-fly, i.e. at run time, by using an image search engine to source visual training data for the text query. The approach combines fast and accurate learning and retrieval, and enables videos to be returned within seconds of specifying a query. We describe three classes of queries, each with its associated visual search method: object instances (using a bag of visual words approach for matching); object categories (using a discriminative classifier for ranking key frames); and faces (using a discriminative classifier for ranking face tracks). We discuss the features suitable for each class of query, for example Fisher vectors or features derived from convolutional neural networks (CNNs), and how these choices impact on the trade-off between three important performance measures for a real-time system of this kind, namely: (1) accuracy, (2) memory footprint, and (3) speed. We also discuss and compare a number of important implementation issues, such as how to remove 'outliers' in the downloaded images efficiently, and how to best obtain a single descriptor for a face track. We also sketch the architecture of the real-time on-the-fly system. Quantitative results are given on a number of large-scale image and video benchmarks (e.g.  TRECVID INS, MIRFLICKR-1M), and we further demonstrate the performance and real-world applicability of our methods over a dataset sourced from 10,000 h of unedited footage from BBC News, comprising 5M+ key frames.

  11. Early ERP effects on the scaling of spatial attention in visual search

    Institute of Scientific and Technical Information of China (English)

    Ya-Nan Niu; Jing-Han Wei; Yue-Jia Luo

    2008-01-01

    This article describes the examination of the spatial 'scaling' effect of visual attention with the technique of event-related potential (ERP). Eighteen participants were involved in a visual search task in which the cue-target paradigm was used. The search array was three concentric circles consisting of randomly selected English letters that were equally distributed in each circle. The behavioral and ERP data were recorded, respectively. The behavioral results showed that the response time increased and the response accuracy decreased with the increase of precue size. The ERPs amplitude of PI and Nl components evoked by search array increased with the reduction of precue size. However, the latencies of these ERP components did not show significant differences between conditions. The hierarchical data of both behavioral assessment and ERPs provided evidence for the spatial 'scaling' effect of visual attention. The amplitudes of PI and Nl components may be used as indices to examine the effect of spatial 'scaling'. In different tasks, the display-set size of stimuli and the task complexity may be important factors that affect the attention allocation.

  12. Object integration requires attention: Visual search for Kanizsa figures in parietal extinction.

    Science.gov (United States)

    Gögler, Nadine; Finke, Kathrin; Keller, Ingo; Müller, Hermann J; Conci, Markus

    2016-11-01

    The contribution of selective attention to object integration is a topic of debate: integration of parts into coherent wholes, such as in Kanizsa figures, is thought to arise either from pre-attentive, automatic coding processes or from higher-order processes involving selective attention. Previous studies have attempted to examine the role of selective attention in object integration either by employing visual search paradigms or by studying patients with unilateral deficits in selective attention. Here, we combined these two approaches to investigate object integration in visual search in a group of five patients with left-sided parietal extinction. Our search paradigm was designed to assess the effect of left- and right-grouped nontargets on detecting a Kanizsa target square. The results revealed comparable reaction time (RT) performance in patients and controls when they were presented with displays consisting of a single to-be-grouped item that had to be classified as target vs. nontarget. However, when display size increased to two items, patients showed an extinction-specific pattern of enhanced RT costs for nontargets that induced a partial shape grouping on the right, i.e., in the attended hemifield (relative to the ungrouped baseline). Together, these findings demonstrate a competitive advantage for right-grouped objects, which in turn indicates that in parietal extinction, attentional competition between objects particularly limits integration processes in the contralesional, i.e., left hemifield. These findings imply a crucial contribution of selective attentional resources to visual object integration.

  13. White matter hyperintensities are associated with visual search behavior independent of generalized slowing in aging

    Science.gov (United States)

    Lockhart, Samuel N.; Roach, Alexandra E.; Luck, Steven J.; Geng, Joy; Beckett, Laurel; Carmichael, Owen; DeCarli, Charles

    2014-01-01

    A fundamental controversy is whether cognitive decline with advancing age can be entirely explained by decreased processing speed, or whether specific neural changes can elicit cognitive decline, independent of slowing. These hypotheses are anchored by studies of healthy older individuals where age is presumed the sole influence. Unfortunately, advancing age is also associated with asymptomatic brain white matter injury. We hypothesized that differences in white matter injury extent, manifest by MRI white matter hyperintensities (WMH), mediate differences in visual attentional control in healthy aging, beyond processing speed differences. We tested young and cognitively healthy older adults on search tasks indexing speed and attentional control. Increasing age was associated with generally slowed performance. WMH was also associated with slowed search times independent of processing speed differences. Consistent with evidence attributing reduced network connectivity to WMH, these results conclusively demonstrate that clinically silent white matter injury contributes to slower search performance indicative of compromised cognitive control, independent of generalized slowing of processing speed. PMID:24183716

  14. Visual Search and Attention in Blue Jays (Cyanocitta cristata): Associative Cuing and Sequential Priming

    Science.gov (United States)

    Goto, Kazuhiro; Bond, Alan B.; Burks, Marianna; Kamil, Alan C.

    2014-01-01

    Visual search for complex natural targets requires focal attention, either cued by predictive stimulus associations or primed by a representation of the most recently detected target. Since both processes can focus visual attention, cuing and priming were compared in an operant search task to evaluate their relative impacts on performance and to determine the nature of their interaction in combined treatments. Blue jays were trained to search for pairs of alternative targets among distractors. Informative or ambiguous color cues were provided prior to each trial, and targets were presented either in homogeneous blocked sequences or in constrained random order. Initial task acquisition was facilitated by priming in general, but was significantly retarded when targets were both cued and primed, indicating that the two processes interfered with each other during training. At asymptote, attentional effects were manifested mainly in inhibition, increasing latency in miscued trials and decreasing accuracy on primed trials following an unexpected target switch. A combination of cuing and priming was found to interfere with performance in such unexpected trials, apparently a result of the limited capacity of working memory. Because the ecological factors that promote priming and cuing are rather disparate, it is not clear whether they ever jointly and simultaneously contribute to natural predatory search. PMID:24893217

  15. Visualization of information: a proposal to improve the search and access to digital resources in repositories

    Directory of Open Access Journals (Sweden)

    Paulo Alonso Gaona García

    2014-03-01

    Full Text Available Normal 0 21 false false false ES-CO X-NONE X-NONE Presently, the most notable challenges associated with repositories in resolving problems of searches of digital resources, lie in providing an understanding of resource classification according to a knowledge representation scheme and the relationship between them. However, one of the areas with very little research in the field is the study of visual search interfaces that provide access to relevant materials in digital repositories; more specifically, in the access of digital resources according to areas and sub-areas of a particular knowledge domain through a taxonomy classification. In this article, we focus in proposing a best practice for the search and access to relevant digital resources in repositories through visualization techniques. The article presents a prototype tool as one possible approach to facilitate searches and access to digital resources. Finally, we present the conclusions and future work in the field in order to improve access to relevant materials in digital repositories.

  16. Modeling the Effect of Selection History on Pop-Out Visual Search

    Science.gov (United States)

    Tseng, Yuan-Chi; Glaser, Joshua I.; Caddigan, Eamon; Lleras, Alejandro

    2014-01-01

    While attentional effects in visual selection tasks have traditionally been assigned “top-down” or “bottom-up” origins, more recently it has been proposed that there are three major factors affecting visual selection: (1) physical salience, (2) current goals and (3) selection history. Here, we look further into selection history by investigating Priming of Pop-out (POP) and the Distractor Preview Effect (DPE), two inter-trial effects that demonstrate the influence of recent history on visual search performance. Using the Ratcliff diffusion model, we model observed saccadic selections from an oddball search experiment that included a mix of both POP and DPE conditions. We find that the Ratcliff diffusion model can effectively model the manner in which selection history affects current attentional control in visual inter-trial effects. The model evidence shows that bias regarding the current trial's most likely target color is the most critical parameter underlying the effect of selection history. Our results are consistent with the view that the 3-item color-oddball task used for POP and DPE experiments is best understood as an attentional decision making task. PMID:24595032

  17. Modeling the effect of selection history on pop-out visual search.

    Science.gov (United States)

    Tseng, Yuan-Chi; Glaser, Joshua I; Caddigan, Eamon; Lleras, Alejandro

    2014-01-01

    While attentional effects in visual selection tasks have traditionally been assigned "top-down" or "bottom-up" origins, more recently it has been proposed that there are three major factors affecting visual selection: (1) physical salience, (2) current goals and (3) selection history. Here, we look further into selection history by investigating Priming of Pop-out (POP) and the Distractor Preview Effect (DPE), two inter-trial effects that demonstrate the influence of recent history on visual search performance. Using the Ratcliff diffusion model, we model observed saccadic selections from an oddball search experiment that included a mix of both POP and DPE conditions. We find that the Ratcliff diffusion model can effectively model the manner in which selection history affects current attentional control in visual inter-trial effects. The model evidence shows that bias regarding the current trial's most likely target color is the most critical parameter underlying the effect of selection history. Our results are consistent with the view that the 3-item color-oddball task used for POP and DPE experiments is best understood as an attentional decision making task.

  18. Visualization and quantitative analysis of extrachromosomal telomere-repeat DNA in individual human cells by Halo-FISH.

    Science.gov (United States)

    Komosa, Martin; Root, Heather; Meyn, M Stephen

    2015-02-27

    Current methods for characterizing extrachromosomal nuclear DNA in mammalian cells do not permit single-cell analysis, are often semi-quantitative and frequently biased toward the detection of circular species. To overcome these limitations, we developed Halo-FISH to visualize and quantitatively analyze extrachromosomal DNA in single cells. We demonstrate Halo-FISH by using it to analyze extrachromosomal telomere-repeat (ECTR) in human cells that use the Alternative Lengthening of Telomeres (ALT) pathway(s) to maintain telomere lengths. We find that GM847 and VA13 ALT cells average ∼80 detectable G/C-strand ECTR DNA molecules/nucleus, while U2OS ALT cells average ∼18 molecules/nucleus. In comparison, human primary and telomerase-positive cells contain 300), range widely in length (200 kb) and are composed of primarily G- or C-strand telomere-repeat DNA. Halo-FISH enables, for the first time, the simultaneous analysis of ECTR DNA and chromosomal telomeres in a single cell. We find that ECTR DNA comprises ∼15% of telomere-repeat DNA in GM847 and VA13 cells, but FISH can facilitate the study of a wide variety of extrachromosomal DNA in mammalian cells.

  19. The effects of single and repeated psychiatric occupational therapy on psychiatric symptoms: assessment using a visual analogue scale.

    Science.gov (United States)

    Yamashita, Hitomi; Terao, Takeshi; Mizokami, Yoshinori

    2012-04-01

    The main aims of psychiatric occupational therapy are to improve daily activity, to enhance communication with others and to reinforce social adaptation. Also, substantial improvements in psychiatric symptoms have been reported, but the effects on psychiatric symptoms are yet to be established. In the present study, we investigated the effects of single and repeated administrations of psychiatric occupational therapy on psychiatric symptoms and determined whether the effects can be predicted. Our subjects were 215 inpatients or outpatients at our university hospital who participated in psychiatric occupational therapy. Five psychiatric symptoms (i.e. depressive mood, tension, irritability, anxiety and fatigue) were subjectively measured just before and just after each psychiatric occupational therapy by using a visual analogue scale (VAS). As a result, there was a significant short-term effect from single psychiatric occupational therapy, but there was no significant further improvement of any psychiatric symptom from repeated psychiatric occupational therapy. The VAS value at the beginning stage significantly predicted improvement of each psychiatric symptom. These findings suggest that single psychiatric occupational therapy can bring about a short-term effect, whereas repeated psychiatric occupational therapy cannot induce long-term effect (accumulated effect) on psychiatric symptoms, and that the improvement can be predicted by baseline psychiatric symptoms.

  20. Attentional and visual demands for sprint performance in non-fatigued and fatigued conditions: reliability of a repeated sprint test

    Directory of Open Access Journals (Sweden)

    Diercks Ron L

    2010-05-01

    Full Text Available Abstract Background Physical performance measures are widely used to assess physical function, providing information about physiological and biomechanical aspects of motor performance. However they do not provide insight into the attentional and visual demands for motor performance. A figure-of-eight sprint test was therefore developed to measure the attentional and visual demands for repeated-sprint performance. The aims of the study were: 1 to assess test-retest reliability of the figure-of-eight sprint test, and 2 to study the attentional and visual demands for sprint performance in a non-fatigued and fatigued condition. Methods Twenty-seven healthy athletes were included in the study. To determine test-retest reliability, a subgroup of 19 athletes performed the figure-of-eight sprint test twice. The figure-of-eight sprint test consisted of nine 30-second sprints. The sprint test consisted of three test parts: sprinting without any restriction, with an attention-demanding task, and with restricted vision. Increases in sprint times with the attention-demanding task or restricted vision are reflective of the attentional and visual demands for sprinting. Intraclass correlation coefficients (ICCs and mean difference between test and retest with 95% confidence limits (CL were used to assess test-retest reliability. Repeated-measures ANOVA were used for comparisons between the sprint times and fatigue measurements of the test parts in both a non-fatigued and fatigued condition. Results The figure-of-eight sprint test showed good test-retest reliability, with ICCs ranging from 0.75 to 0.94 (95% CL: 0.40-0.98. Zero lay within the 95% CL of the mean differences, indicating that no bias existed between sprint performance at test and retest. Sprint times during the test parts with attention-demanding task (P = 0.01 and restricted vision (P Conclusions High ICCs and the absence of systematic variation indicate good test-retest reliability of the figure

  1. Multisensory teamwork: using a tactile or an auditory display to exchange gaze information improves performance in joint visual search.

    Science.gov (United States)

    Wahn, Basil; Schwandt, Jessika; Krüger, Matti; Crafa, Daina; Nunnendorf, Vanessa; König, Peter

    2016-06-01

    In joint tasks, adjusting to the actions of others is critical for success. For joint visual search tasks, research has shown that when search partners visually receive information about each other's gaze, they use this information to adjust to each other's actions, resulting in faster search performance. The present study used a visual, a tactile and an auditory display, respectively, to provide search partners with information about each other's gaze. Results showed that search partners performed faster when the gaze information was received via a tactile or auditory display in comparison to receiving it via a visual display or receiving no gaze information. Findings demonstrate the effectiveness of tactile and auditory displays for receiving task-relevant information in joint tasks and are applicable to circumstances in which little or no visual information is available or the visual modality is already taxed with a demanding task such as air-traffic control. Practitioner Summary: The present study demonstrates that tactile and auditory displays are effective for receiving information about actions of others in joint tasks. Findings are either applicable to circumstances in which little or no visual information is available or when the visual modality is already taxed with a demanding task.

  2. Association and dissociation between detection and discrimination of objects of expertise: Evidence from visual search.

    Science.gov (United States)

    Golan, Tal; Bentin, Shlomo; DeGutis, Joseph M; Robertson, Lynn C; Harel, Assaf

    2014-02-01

    Expertise in face recognition is characterized by high proficiency in distinguishing between individual faces. However, faces also enjoy an advantage at the early stage of basic-level detection, as demonstrated by efficient visual search for faces among nonface objects. In the present study, we asked (1) whether the face advantage in detection is a unique signature of face expertise, or whether it generalizes to other objects of expertise, and (2) whether expertise in face detection is intrinsically linked to expertise in face individuation. We compared how groups with varying degrees of object and face expertise (typical adults, developmental prosopagnosics [DP], and car experts) search for objects within and outside their domains of expertise (faces, cars, airplanes, and butterflies) among a variable set of object distractors. Across all three groups, search efficiency (indexed by reaction time slopes) was higher for faces and airplanes than for cars and butterflies. Notably, the search slope for car targets was considerably shallower in the car experts than in nonexperts. Although the mean face slope was slightly steeper among the DPs than in the other two groups, most of the DPs' search slopes were well within the normative range. This pattern of results suggests that expertise in object detection is indeed associated with expertise at the subordinate level, that it is not specific to faces, and that the two types of expertise are distinct facilities. We discuss the potential role of experience in bridging between low-level discriminative features and high-level naturalistic categories.

  3. [Repeatability and reliability of the visual acuity examination on logMAR ETDRS and Snellen chart].

    Science.gov (United States)

    Veselý, P; Synek, S

    2012-05-01

    The main goal of our study was to prove the statistical significant correlation between repeated measurements and test-retest variability TRV expressed with confidence interval CI according to Bland-Altman's method on 95% level of statistical confidence. The methods are threshold interpolation logMAR method on ETDRS chart, whole-line method on Snellen chart and modified threshold interpolation method on Snellen chart with Sloan letters. We had 468 measurements measured with threshold interpolation log MAR method on ETDRS chart, whole-line method on Snellen chart and modified threshold interpolation method on Snellen chart with Sloan letters. The average value of the first sequence of measurements measured with whole-line method on Snellen chart was -0.043 logMAR (min. 1, max. -0.30. SD 0.25) and of the second sequence of measurements was -0.045 logMAR (min. 1, max. -0.30. SD 0.23). The average value of the first sequence of measurements measured with interpolation method on Snellen chart was -0.018 logMAR (min. 0.98, max. -0.30. SD 0.29) and of the second sequence of measurements was -0.024 logMAR (min. 1, max. -0.80. SD 0.29). The average value of the first sequence of measurements measured with interpolation method on ETDRS chart was -0.0612 logMAR (min. 0.72, max. -0.30. SD 0.21) and of the second sequence of measurements was -0.0610 log MAR (min. 0.8, max. -0.28, SD 0.21). We have proved that all methods do not have statistical significant difference between repeated measurements (Wilcoxon paired test, whole-line method on Snellen chart p = 0.74, interpolation method on Snellen chart p = 0.33 and interpolation method on ETDRS p = 0.95) and they also have statistical significant correlations (Spearman correlation coefficient, whole-line method on Snellen chart r = 0.91, p Snellen chart r = 0.89, p Snellen chart +/- 0.11 (i.e., 5 letters), with interpolation method on Snellen chart +/- 0.20 (i.e., 10 letters) and with interpolation method on ETDRS +/- 0.08 (i

  4. Visual search behaviour in skeletal radiographs: a cross-speciality study

    Energy Technology Data Exchange (ETDEWEB)

    Leong, J.J.H.; Nicolaou, M. [Royal Society/Wolfson Foundation Medical Image Computing Laboratory, Imperial College London, London (United Kingdom); Department of Biosurgery and Surgical Technology, Imperial College London, St Mary' s Hospital, London (United Kingdom); Emery, R.J.; Darzi, A.W. [Department of Biosurgery and Surgical Technology, Imperial College London, St Mary' s Hospital, London (United Kingdom); Yang, G.-Z. [Royal Society/Wolfson Foundation Medical Image Computing Laboratory, Imperial College London, London (United Kingdom)], E-mail: g.z.yang@imperial.ac.uk

    2007-11-15

    Aim: To determine whether experience improves the consistency of visual search behaviour in fracture identification in plain radiographs, and the effect of specialization. Material and methods: Twenty-five observers consisting of consultant radiologists, consultant orthopaedic surgeons, orthopaedic specialist registrars, orthopaedic senior house officers, and accident and emergency senior house officers examined 33 skeletal radiographs (shoulder, hand, and knee). Eye movement data were collected using a Tobii 1750 eye tracker with levels of diagnostic confidence collected simultaneously. Kullback-Leibler (KL) divergence and Gaussian mixture model fitting of fixation distance-to-fracture were used to calculate the consistency and the relationship between discovery and reflective visual search phases among different observer groups. Results: Total time spent studying the radiograph was not significantly different between the groups. However, the expert groups had a higher number of true positives (p < 0.001) with less dwell time on the fracture site (p < 0.001) and smaller KL distance (r = 0.062, p < 0.001) between trials. The Gaussian mixture model revealed smaller mean squared error in the expert groups in hand radiographs (r 0.162, p = 0.07); however, the reverse was true in shoulder radiographs (r -0.287, p < 0.001). The relative duration of the reflective phase decreases as the confidence level increased (r = 0.266, p = 0.074). Conclusions: Expert search behaviour exhibited higher accuracy and consistency whilst using less time fixating on fracture sites. This strategy conforms to the discovery and reflective phases of the global-focal model, where the reflective search may be implicated in the cross-referencing and conspicuity of the target, as well as the level of decision-making process involved. The effect of specialization appears to change the search strategy more than the effect of the length of training.

  5. Visual search behaviour in skeletal radiographs: a cross-specialty study.

    Science.gov (United States)

    Leong, J J H; Nicolaou, M; Emery, R J; Darzi, A W; Yang, G-Z

    2007-11-01

    To determine whether experience improves the consistency of visual search behaviour in fracture identification in plain radiographs, and the effect of specialization. Twenty-five observers consisting of consultant radiologists, consultant orthopaedic surgeons, orthopaedic specialist registrars, orthopaedic senior house officers, and accident and emergency senior house officers examined 33 skeletal radiographs (shoulder, hand, and knee). Eye movement data were collected using a Tobii 1750 eye tracker with levels of diagnostic confidence collected simultaneously. Kullback-Leibler (KL) divergence and Gaussian mixture model fitting of fixation distance-to-fracture were used to calculate the consistency and the relationship between discovery and reflective visual search phases among different observer groups. Total time spent studying the radiograph was not significantly different between the groups. However, the expert groups had a higher number of true positives (p<0.001) with less dwell time on the fracture site (p<0.001) and smaller KL distance (r=0.062, p<0.001) between trials. The Gaussian mixture model revealed smaller mean squared error in the expert groups in hand radiographs (r=0.162, p=0.07); however, the reverse was true in shoulder radiographs (r=-0.287, p<0.001). The relative duration of the reflective phase decreases as the confidence level increased (r=0.266, p=0.074). Expert search behaviour exhibited higher accuracy and consistency whilst using less time fixating on fracture sites. This strategy conforms to the discovery and reflective phases of the global-focal model, where the reflective search may be implicated in the cross-referencing and conspicuity of the target, as well as the level of decision-making process involved. The effect of specialization appears to change the search strategy more than the effect of the length of training.

  6. Visual search in ecological and non-ecological displays: evidence for a non-monotonic effect of complexity on performance.

    Directory of Open Access Journals (Sweden)

    Philippe Chassy

    Full Text Available Considerable research has been carried out on visual search, with single or multiple targets. However, most studies have used artificial stimuli with low ecological validity. In addition, little is known about the effects of target complexity and expertise in visual search. Here, we investigate visual search in three conditions of complexity (detecting a king, detecting a check, and detecting a checkmate with chess players of two levels of expertise (novices and club players. Results show that the influence of target complexity depends on level of structure of the visual display. Different functional relationships were found between artificial (random chess positions and ecologically valid (game positions stimuli: With artificial, but not with ecologically valid stimuli, a "pop out" effect was present when a target was visually more complex than distractors but could be captured by a memory chunk. This suggests that caution should be exercised when generalising from experiments using artificial stimuli with low ecological validity to real-life stimuli.

  7. Neural Correlates of Changes in a Visual Search Task due to Cognitive Training in Seniors

    Directory of Open Access Journals (Sweden)

    Nele Wild-Wall

    2012-01-01

    Full Text Available This study aimed to elucidate the underlying neural sources of near transfer after a multidomain cognitive training in older participants in a visual search task. Participants were randomly assigned to a social control, a no-contact control and a training group, receiving a 4-month paper-pencil and PC-based trainer guided cognitive intervention. All participants were tested in a before and after session with a conjunction visual search task. Performance and event-related potentials (ERPs suggest that the cognitive training improved feature processing of the stimuli which was expressed in an increased rate of target detection compared to the control groups. This was paralleled by enhanced amplitudes of the frontal P2 in the ERP and by higher activation in lingual and parahippocampal brain areas which are discussed to support visual feature processing. Enhanced N1 and N2 potentials in the ERP for nontarget stimuli after cognitive training additionally suggest improved attention and subsequent processing of arrays which were not immediately recognized as targets. Possible test repetition effects were confined to processes of stimulus categorisation as suggested by the P3b potential. The results show neurocognitive plasticity in aging after a broad cognitive training and allow pinpointing the functional loci of effects induced by cognitive training.

  8. Fixation and saliency during search of natural scenes: the case of visual agnosia.

    Science.gov (United States)

    Foulsham, Tom; Barton, Jason J S; Kingstone, Alan; Dewhurst, Richard; Underwood, Geoffrey

    2009-07-01

    Models of eye movement control in natural scenes often distinguish between stimulus-driven processes (which guide the eyes to visually salient regions) and those based on task and object knowledge (which depend on expectations or identification of objects and scene gist). In the present investigation, the eye movements of a patient with visual agnosia were recorded while she searched for objects within photographs of natural scenes and compared to those made by students and age-matched controls. Agnosia is assumed to disrupt the top-down knowledge available in this task, and so may increase the reliance on bottom-up cues. The patient's deficit in object recognition was seen in poor search performance and inefficient scanning. The low-level saliency of target objects had an effect on responses in visual agnosia, and the most salient region in the scene was more likely to be fixated by the patient than by controls. An analysis of model-predicted saliency at fixation locations indicated a closer match between fixations and low-level saliency in agnosia than in controls. These findings are discussed in relation to saliency-map models and the balance between high and low-level factors in eye guidance.

  9. Word-Synchronous Optical Sampling of Periodically Repeated OTDM Data Words for True Waveform Visualization

    Science.gov (United States)

    Benkler, Erik; Telle, Harald R.

    2007-06-01

    An improved phase-locked loop (PLL) for versatile synchronization of a sampling pulse train to an optical data stream is presented. It enables optical sampling of the true waveform of repetitive high bit-rate optical time division multiplexed (OTDM) data words such as pseudorandom bit sequences. Visualization of the true waveform can reveal details, which cause systematic bit errors. Such errors cannot be inferred from eye diagrams and require word-synchronous sampling. The programmable direct-digital-synthesis circuit used in our novel PLL approach allows flexible adaption of virtually any problem-specific synchronization scenario, including those required for waveform sampling, for jitter measurements by slope detection, and for classical eye-diagrams. Phase comparison of the PLL is performed at 10-GHz OTDM base clock rate, leading to a residual synchronization jitter of less than 70 fs.

  10. Repeated Nicotine Strengthens Gamma Oscillations in the Prefrontal Cortex and Improves Visual Attention.

    Science.gov (United States)

    Bueno-Junior, Lezio S; Simon, Nicholas W; Wegener, Meredyth A; Moghaddam, Bita

    2017-07-01

    Nicotine has strong addictive as well as procognitive properties. While a large body of research on nicotine continues to inform us about mechanisms related to its reinforcing effects, less is known about clinically relevant mechanisms that subserve its cognitive-enhancing properties. Understanding the latter is critical for developing optimal strategies for treating cognitive deficits. The primary brain region implicated in cognitive functions improved by nicotine is the prefrontal cortex (PFC). Here we assessed the impact of nicotine on unit activity and local field potential oscillations in the PFC of behaving rats. An acute dose of nicotine produced a predominantly inhibitory influence on population activity, a small increase in gamma oscillations, and a decrease in theta and beta oscillations. After a daily dosing regimen, a shift to excitatory-inhibitory balance in single-unit activity and stronger gamma oscillations began to emerge. This pattern of plasticity was specific to the gamma band as lower frequency oscillations were suppressed consistently across daily nicotine treatments. Gamma oscillations are associated with enhanced attentional capacity. Consistent with this mechanism, the repeat dosing regimen in a separate cohort of subjects led to improved performance in an attention task. These data suggest that procognitive effects of nicotine may involve development of enhanced gamma oscillatory activity and a shift to excitatory-inhibitory balance in PFC neural activity. In the context of the clinical use of nicotine and related agonists for treating cognitive deficits, these data suggest that daily dosing may be critical to allow for development of robust gamma oscillations.

  11. Effects of search efficiency on surround suppression during visual selection in frontal eye field.

    Science.gov (United States)

    Schall, Jeffrey D; Sato, Takashi R; Thompson, Kirk G; Vaughn, Amanda A; Juan, Chi-Hung

    2004-06-01

    Previous research has shown that visually responsive neurons in the frontal eye field of macaque monkeys select the target for a saccade during efficient, pop-out visual search through suppression of the representation of the nontarget distractors. For a fraction of these neurons, the magnitude of this distractor suppression varied with the proximity of the target to the receptive field, exhibiting more suppression of the distractor representation when the target was nearby than when the target was distant. The purpose of this study was to determine whether the variation of distractor suppression related to target proximity varied with target-distractor feature similarity. The effect of target proximity on distractor suppression did not vary with target-distractor similarity and therefore may be an endogenous property of the selection process.

  12. Hand movement deviations in a visual search task with cross modal cuing

    Directory of Open Access Journals (Sweden)

    Hürol Aslan

    2007-01-01

    Full Text Available The purpose of this study is to demonstrate the cross-modal effects of an auditory organization on a visual search task and to investigate the influence of the level of detail in instructions describing or hinting at the associations between auditory stimuli and the possible locations of a visual target. In addition to measuring the participants’ reaction times, we paid special attention to tracking the hand movements toward the target. According to the results, the auditory stimuli unassociated with the target locations slightly –but significantly- increased the deviation of the hand movement from the path leading to the target location. The increase in the deviation depended on the degree of association between auditory stimuli and target locations, albeit not on the level of detail in the instructions about the task.

  13. Tracking target and distractor processing in fixed-feature visual search: evidence from human electrophysiology.

    Science.gov (United States)

    Jannati, Ali; Gaspar, John M; McDonald, John J

    2013-12-01

    Salient distractors delay visual search for less salient targets in additional-singleton tasks, even when the features of the stimuli are fixed across trials. According to the salience-driven selection hypothesis, this delay is due to an initial attentional deployment to the distractor. Recent event-related potential (ERP) studies found no evidence for salience-driven selection in fixed-feature search, but the methods employed were not optimized to isolate distractor ERP components such as the N2pc and distractor positivity (PD; indices of selection and suppression, respectively). Here, we isolated target and distractor ERPs in two fixed-feature search experiments. Participants searched for a shape singleton in the presence of a more-salient color singleton (Experiment 1) or for a color singleton in the presence of a less-salient shape singleton (Experiment 2). The salient distractor did not elicit an N2pc, but it did elicit a PD on fast-response trials. Furthermore, distractors had no effect on the timing of the target N2pc. These results indicate that (a) the distractor was prevented from engaging the attentional mechanism associated with N2pc, (b) the distractor did not interrupt the deployment of attention to the target, and (c) competition for attention can be resolved by suppressing locations of irrelevant items on a salience-based priority map.

  14. Adult age differences in visual search from perception to response: Evidence from event-related potentials

    DEFF Research Database (Denmark)

    Wiegand, Iris

    Attentional changes play a major role in age-related behavioral slowing, however, the specific aspects of attention that contribute to this decrement are not clearly defined. To these aims, we combined response times with lateralized ERPs of younger and older adults during a visual compound search...... at multiple stages from perception to response. Furthermore, we explored the implicit influence of recently encountered information in terms of intertrial effects. ERPs could disentangle that, while automatic processes of perceptual-dimension priming and response priming across trials were preserved, older...

  15. The interplay of attention and consciousness in visual search, attentional blink and working memory consolidation.

    Science.gov (United States)

    Raffone, Antonino; Srinivasan, Narayanan; van Leeuwen, Cees

    2014-05-05

    Despite the acknowledged relationship between consciousness and attention, theories of the two have mostly been developed separately. Moreover, these theories have independently attempted to explain phenomena in which both are likely to interact, such as the attentional blink (AB) and working memory (WM) consolidation. Here, we make an effort to bridge the gap between, on the one hand, a theory of consciousness based on the notion of global workspace (GW) and, on the other, a synthesis of theories of visual attention. We offer a theory of attention and consciousness (TAC) that provides a unified neurocognitive account of several phenomena associated with visual search, AB and WM consolidation. TAC assumes multiple processing stages between early visual representation and conscious access, and extends the dynamics of the global neuronal workspace model to a visual attentional workspace (VAW). The VAW is controlled by executive routers, higher-order representations of executive operations in the GW, without the need for explicit saliency or priority maps. TAC leads to newly proposed mechanisms for illusory conjunctions, AB, inattentional blindness and WM capacity, and suggests neural correlates of phenomenal consciousness. Finally, the theory reconciles the all-or-none and graded perspectives on conscious representation.

  16. Search for high-frequency periodicities in time-tagged event data from gamma ray bursts and soft gamma repeaters

    CERN Document Server

    Kruger, A T; Wasserman, I M; Kruger, Adam T.; Loredo, Thomas J.; Wasserman, Ira

    2002-01-01

    We analyze the Time-Tagged Event (TTE) data from observations of gamma ray bursts (GRBs) and soft gamma repeaters (SGRs) by the Burst and Transient Source Experiment (BATSE). These data provide the best available time resolution for GRBs and SGRs. We have performed an extensive search for weak periodic signals in the frequency range 400 Hz to 2500 Hz using the burst records for 2203 GRBs and 152 SGR flares. The study employs the Rayleigh power as a test statistic to evaluate the evidence for periodic emissions. We find no evidence of periodic emissions from these events at these frequencies. In all but a very few cases the maximum power values obtained are consistent with what would be expected by chance from a non-periodic signal. In those few instances where there is marginal evidence for periodicity there are problems with the data that cast doubt on the reality of the signal. For classical GRBs, the largest Rayleigh power occurs in bursts whose TTE data appear to be corrupted. For SGRs, our largest Raylei...

  17. Evolving the stimulus to fit the brain: a genetic algorithm reveals the brain's feature priorities in visual search.

    Science.gov (United States)

    Van der Burg, Erik; Cass, John; Theeuwes, Jan; Alais, David

    2015-02-06

    How does the brain find objects in cluttered visual environments? For decades researchers have employed the classic visual search paradigm to answer this question using factorial designs. Although such approaches have yielded important information, they represent only a tiny fraction of the possible parametric space. Here we use a novel approach, by using a genetic algorithm (GA) to discover the way the brain solves visual search in complex environments, free from experimenter bias. Participants searched a series of complex displays, and those supporting fastest search were selected to reproduce (survival of the fittest). Their display properties (genes) were crossed and combined to create a new generation of "evolved" displays. Displays evolved quickly over generations towards a stable, efficiently searched array. Color properties evolved first, followed by orientation. The evolved displays also contained spatial patterns suggesting a coarse-to-fine search strategy. We argue that this behavioral performance-driven GA reveals the way the brain selects information during visual search in complex environments. We anticipate that our approach can be adapted to a variety of sensory and cognitive questions that have proven too intractable for factorial designs. © 2015 ARVO.

  18. Putting attention in the spotlight: The influence of APOE genotype on visual search in mid adulthood.

    Science.gov (United States)

    Lancaster, Claire; Forster, Sophie; Tabet, Naji; Rusted, Jennifer

    2017-09-15

    The Apolipoprotein E e4 allele is associated with greater cognitive decline with age, yet effects of this gene are also observed earlier in the lifespan. This research explores genotype differences (e2, e3, e4) in the allocation of visuospatial attention in mid-adulthood. Sixty-six volunteers, aged 45-55 years, completed two paradigms probing the active selection of information at the focus of attention (a dynamic scaling task) and perceptual capacity differences. Two methods of statistical comparison (parametric statistics, Bayesian inference) found no significant difference between e4 carriers and the homozygous e3 group on either the dynamic scaling or perceptual load task. E2 carriers, however, demonstrated less efficient visual search performance on the dynamic scaling task. The lack of an e4 difference in visuospatial attention, despite previous suggestion in the literature of genotype effects, indicates that select attentional processes are intact in e4 carriers in mid-adulthood. The association of e2 genotype with slower visual search performance complicates the premised protective effects of this allele in cognitive ageing. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Developing a Search Algorithm and a Visualization Tool for SNOMED CT

    Directory of Open Access Journals (Sweden)

    Anthony Masi

    2015-04-01

    Full Text Available With electronic health records rising in popularity among hospitals and physicians, the SNOMED CT medical terminology has served as a valuable standard for those looking to exchange a variety of information linked to clinical knowledge bases, information retrieval, and data aggregation. However, SNOMED CT is distributed as a flat file database by the International Health Terminology Standards Development Organization and visualization of data can be a problem. This study describes an algorithm that allows a user to easily search SNOMED CT for identical or partial matches utilizing indexing and wildcard matching through a graphical user interface developed in the cross-platform programming language Java. In addition to this, the algorithm displays corresponding relationships and other relevant information pertaining to the search term. The outcome of this study can serve as a useful visualization tool for those looking to delve into the increasingly standardized world of electronic health records as well as a tool for healthcare providers who may be seeking specific clinical information contained in the SNOMED CT database.

  20. Training eye movements for visual search in individuals with macular degeneration

    Science.gov (United States)

    Janssen, Christian P.; Verghese, Preeti

    2016-01-01

    We report a method to train individuals with central field loss due to macular degeneration to improve the efficiency of visual search. Our method requires participants to make a same/different judgment on two simple silhouettes. One silhouette is presented in an area that falls within the binocular scotoma while they are fixating the center of the screen with their preferred retinal locus (PRL); the other silhouette is presented diametrically opposite within the intact visual field. Over the course of 480 trials (approximately 6 hr), we gradually reduced the amount of time that participants have to make a saccade and judge the similarity of stimuli. This requires that they direct their PRL first toward the stimulus that is initially hidden behind the scotoma. Results from nine participants show that all participants could complete the task faster with training without sacrificing accuracy on the same/different judgment task. Although a majority of participants were able to direct their PRL toward the initially hidden stimulus, the ability to do so varied between participants. Specifically, six of nine participants made faster saccades with training. A smaller set (four of nine) made accurate saccades inside or close to the target area and retained this strategy 2 to 3 months after training. Subjective reports suggest that training increased awareness of the scotoma location for some individuals. However, training did not transfer to a different visual search task. Nevertheless, our study suggests that increasing scotoma awareness and training participants to look toward their scotoma may help them acquire missing information. PMID:28027382

  1. Visual Search Strategies of Soccer Players Executing a Power vs. Placement Penalty Kick

    Science.gov (United States)

    Timmis, Matthew A.; Turner, Kieran; van Paridon, Kjell N.

    2014-01-01

    Introduction When taking a soccer penalty kick, there are two distinct kicking techniques that can be adopted; a ‘power’ penalty or a ‘placement’ penalty. The current study investigated how the type of penalty kick being taken affected the kicker’s visual search strategy and where the ball hit the goal (end ball location). Method Wearing a portable eye tracker, 12 university footballers executed 2 power and placement penalty kicks, indoors, both with and without the presence of a goalkeeper. Video cameras were used to determine initial ball velocity and end ball location. Results When taking the power penalty, the football was kicked significantly harder and more centrally in the goal compared to the placement penalty. During the power penalty, players fixated on the football for longer and more often at the goalkeeper (and by implication the middle of the goal), whereas in the placement penalty, fixated longer at the goal, specifically the edges. Findings remained consistent irrespective of goalkeeper presence. Discussion/conclusion Findings indicate differences in visual search strategy and end ball location as a function of type of penalty kick. When taking the placement penalty, players fixated and kicked the football to the edges of the goal in an attempt to direct the ball to an area that the goalkeeper would have difficulty reaching and saving. Fixating significantly longer on the football when taking the power compared to placement penalty indicates a greater importance of obtaining visual information from the football. This can be attributed to ensuring accurate foot-to-ball contact and subsequent generation of ball velocity. Aligning gaze and kicking the football centrally in the goal when executing the power compared to placement penalty may have been a strategy to reduce the risk of kicking wide of the goal altogether. PMID:25517405

  2. Visual search strategies of soccer players executing a power vs. placement penalty kick.

    Directory of Open Access Journals (Sweden)

    Matthew A Timmis

    Full Text Available When taking a soccer penalty kick, there are two distinct kicking techniques that can be adopted; a 'power' penalty or a 'placement' penalty. The current study investigated how the type of penalty kick being taken affected the kicker's visual search strategy and where the ball hit the goal (end ball location.Wearing a portable eye tracker, 12 university footballers executed 2 power and placement penalty kicks, indoors, both with and without the presence of a goalkeeper. Video cameras were used to determine initial ball velocity and end ball location.When taking the power penalty, the football was kicked significantly harder and more centrally in the goal compared to the placement penalty. During the power penalty, players fixated on the football for longer and more often at the goalkeeper (and by implication the middle of the goal, whereas in the placement penalty, fixated longer at the goal, specifically the edges. Findings remained consistent irrespective of goalkeeper presence.Findings indicate differences in visual search strategy and end ball location as a function of type of penalty kick. When taking the placement penalty, players fixated and kicked the football to the edges of the goal in an attempt to direct the ball to an area that the goalkeeper would have difficulty reaching and saving. Fixating significantly longer on the football when taking the power compared to placement penalty indicates a greater importance of obtaining visual information from the football. This can be attributed to ensuring accurate foot-to-ball contact and subsequent generation of ball velocity. Aligning gaze and kicking the football centrally in the goal when executing the power compared to placement penalty may have been a strategy to reduce the risk of kicking wide of the goal altogether.

  3. A Model of the Superior Colliculus Predicts Fixation Locations during Scene Viewing and Visual Search.

    Science.gov (United States)

    Adeli, Hossein; Vitu, Françoise; Zelinsky, Gregory J

    2017-02-08

    Modern computational models of attention predict fixations using saliency maps and target maps, which prioritize locations for fixation based on feature contrast and target goals, respectively. But whereas many such models are biologically plausible, none have looked to the oculomotor system for design constraints or parameter specification. Conversely, although most models of saccade programming are tightly coupled to underlying neurophysiology, none have been tested using real-world stimuli and tasks. We combined the strengths of these two approaches in MASC, a model of attention in the superior colliculus (SC) that captures known neurophysiological constraints on saccade programming. We show that MASC predicted the fixation locations of humans freely viewing naturalistic scenes and performing exemplar and categorical search tasks, a breadth achieved by no other existing model. Moreover, it did this as well or better than its more specialized state-of-the-art competitors. MASC's predictive success stems from its inclusion of high-level but core principles of SC organization: an over-representation of foveal information, size-invariant population codes, cascaded population averaging over distorted visual and motor maps, and competition between motor point images for saccade programming, all of which cause further modulation of priority (attention) after projection of saliency and target maps to the SC. Only by incorporating these organizing brain principles into our models can we fully understand the transformation of complex visual information into the saccade programs underlying movements of overt attention. With MASC, a theoretical footing now exists to generate and test computationally explicit predictions of behavioral and neural responses in visually complex real-world contexts.SIGNIFICANCE STATEMENT The superior colliculus (SC) performs a visual-to-motor transformation vital to overt attention, but existing SC models cannot predict saccades to visually

  4. The visual search patterns and hazard responses of experienced and inexperienced motorcycle riders.

    Science.gov (United States)

    Hosking, Simon G; Liu, Charles C; Bayly, Megan

    2010-01-01

    Hazard perception is a critical skill for road users. In this study, an open-loop motorcycle simulator was used to examine the effects of motorcycle riding and car driving experience on hazard perception and visual scanning patterns. Three groups of participants were tested: experienced motorcycle riders who were experienced drivers (EM-ED), inexperienced riders/experienced drivers (IM-ED), and inexperienced riders/inexperienced drivers (IM-ID). Participants were asked to search for hazards in simulated scenarios, and click a response button when a hazard was identified. The results revealed a significant monotonic decrease in hazard response times as experience increased from IM-ID to IM-ED to EM-ED. Compared to the IM-ID group, both the EM-ED and IM-ED groups exhibited more flexible visual scanning patterns that were sensitive to the presence of hazards. These results point to the potential benefit of training hazard perception and visual scanning in motorcycle riders, as has been successfully demonstrated in previous studies with car drivers.

  5. Dynamics of target and distractor processing in visual search: evidence from event-related brain potentials.

    Science.gov (United States)

    Hilimire, Matthew R; Mounts, Jeffrey R W; Parks, Nathan A; Corballis, Paul M

    2011-05-20

    When multiple objects are present in a visual scene, salient and behaviorally relevant objects are attentionally selected and receive enhanced processing at the expense of less salient or less relevant objects. Here we examined three lateralized components of the event-related potential (ERP) - the N2pc, Ptc, and SPCN - as indices of target and distractor processing in a visual search paradigm. Participants responded to the orientation of a target while ignoring an attentionally salient distractor and ERPs elicited by the target and the distractor were obtained. Results indicate that both the target and the distractor elicit an N2pc component which may index the initial attentional selection of both objects. In contrast, only the distractor elicited a significant Ptc, which may reflect the subsequent suppression of distracting or irrelevant information. Thus, the Ptc component appears to be similar to another ERP component - the Pd - which is also thought to reflect distractor suppression. Furthermore, only the target elicited an SPCN component which likely reflects the representation of the target in visual short term memory.

  6. iPixel: a visual content-based and semantic search engine for retrieving digitized mammograms by using collective intelligence.

    Science.gov (United States)

    Alor-Hernández, Giner; Pérez-Gallardo, Yuliana; Posada-Gómez, Rubén; Cortes-Robles, Guillermo; Rodríguez-González, Alejandro; Aguilar-Laserre, Alberto A

    2012-09-01

    Nowadays, traditional search engines such as Google, Yahoo and Bing facilitate the retrieval of information in the format of images, but the results are not always useful for the users. This is mainly due to two problems: (1) the semantic keywords are not taken into consideration and (2) it is not always possible to establish a query using the image features. This issue has been covered in different domains in order to develop content-based image retrieval (CBIR) systems. The expert community has focussed their attention on the healthcare domain, where a lot of visual information for medical analysis is available. This paper provides a solution called iPixel Visual Search Engine, which involves semantics and content issues in order to search for digitized mammograms. iPixel offers the possibility of retrieving mammogram features using collective intelligence and implementing a CBIR algorithm. Our proposal compares not only features with similar semantic meaning, but also visual features. In this sense, the comparisons are made in different ways: by the number of regions per image, by maximum and minimum size of regions per image and by average intensity level of each region. iPixel Visual Search Engine supports the medical community in differential diagnoses related to the diseases of the breast. The iPixel Visual Search Engine has been validated by experts in the healthcare domain, such as radiologists, in addition to experts in digital image analysis.

  7. Modeling peripheral visual acuity enables discovery of gaze strategies at multiple time scales during natural scene search

    Science.gov (United States)

    Ramkumar, Pavan; Fernandes, Hugo; Kording, Konrad; Segraves, Mark

    2015-01-01

    Like humans, monkeys make saccades nearly three times a second. To understand the factors guiding this frequent decision, computational models of vision attempt to predict fixation locations using bottom-up visual features and top-down goals. How do the relative influences of these factors evolve over multiple time scales? Here we analyzed visual features at fixations using a retinal transform that provides realistic visual acuity by suitably degrading visual information in the periphery. In a task in which monkeys searched for a Gabor target in natural scenes, we characterized the relative importance of bottom-up and task-relevant influences by decoding fixated from nonfixated image patches based on visual features. At fast time scales, we found that search strategies can vary over the course of a single trial, with locations of higher saliency, target-similarity, edge–energy, and orientedness looked at later on in the trial. At slow time scales, we found that search strategies can be refined over several weeks of practice, and the influence of target orientation was significant only in the latter of two search tasks. Critically, these results were not observed without applying the retinal transform. Our results suggest that saccade-guidance strategies become apparent only when models take into account degraded visual representation in the periphery. PMID:25814545

  8. The effect of computer-aided detection markers on visual search and reader performance during concurrent reading of CT colonography

    Energy Technology Data Exchange (ETDEWEB)

    Helbren, Emma; Taylor, Stuart A. [University College London, Centre for Medical Imaging, London (United Kingdom); Fanshawe, Thomas R.; Mallett, Susan [University of Oxford, Nuffield Department of Primary Care Health Sciences, Oxford (United Kingdom); Phillips, Peter [University of Cumbria, Health and Medical Sciences Group, Lancaster (United Kingdom); Boone, Darren [Colchester Hospital University NHS Foundation Trust and Anglia University, Colchester (United Kingdom); Gale, Alastair [Loughborough University, Applied Vision Research Centre, Loughborough (United Kingdom); Altman, Douglas G. [University of Oxford, Centre for Statistics in Medicine, Oxford (United Kingdom); Manning, David [Lancaster University, Lancaster Medical School, Faculty of Health and Medicine, Lancaster (United Kingdom); Halligan, Steve [University College London, Centre for Medical Imaging, London (United Kingdom); University College Hospital, Gastrointestinal Radiology, University College London, Centre for Medical Imaging, Podium Level 2, London, NW1 2BU (United Kingdom)

    2015-06-01

    We aimed to identify the effect of computer-aided detection (CAD) on visual search and performance in CT Colonography (CTC) of inexperienced and experienced readers. Fifteen endoluminal CTC examinations were recorded, each with one polyp, and two videos were generated, one with and one without a CAD mark. Forty-two readers (17 experienced, 25 inexperienced) interpreted the videos during infrared visual search recording. CAD markers and polyps were treated as regions of interest in data processing. This multi-reader, multi-case study was analysed using multilevel modelling. CAD drew readers' attention to polyps faster, accelerating identification times: median 'time to first pursuit' was 0.48 s (IQR 0.27 to 0.87 s) with CAD, versus 0.58 s (IQR 0.35 to 1.06 s) without. For inexperienced readers, CAD also held visual attention for longer. All visual search metrics used to assess visual gaze behaviour demonstrated statistically significant differences when ''with'' and ''without'' CAD were compared. A significant increase in the number of correct polyp identifications across all readers was seen with CAD (74 % without CAD, 87 % with CAD; p < 0.001). CAD significantly alters visual search and polyp identification in readers viewing three-dimensional endoluminal CTC. For polyp and CAD marker pursuit times, CAD generally exerted a larger effect on inexperienced readers. (orig.)

  9. The Impact of a Modified Repeated-Reading Strategy Paired with Optical Character Recognition on the Reading Rates of Students with Visual Impairments

    Science.gov (United States)

    Pattillo, Suzan Trefry; Heller, Kathryn Wolf; Smith, Maureen

    2004-01-01

    The repeated-reading strategy and optical character recognition were paired to demonstrate a functional relationship between the combined strategies and two factors: the reading rates of students with visual impairments and the students' self-perceptions, or attitudes, toward reading. The results indicated that all five students increased their…

  10. Reliability-based automatic repeat request for short code modulation visual evoked potentials in brain computer interfaces.

    Science.gov (United States)

    Sato, Jun-Ichi; Washizawa, Yoshikazu

    2015-08-01

    We propose two methods to improve code modulation visual evoked potential brain computer interfaces (cVEP BCIs). Most of BCIs average brain signals from several trials in order to improve the classification performance. The number of averaging defines the trade-off between input speed and accuracy, and the optimal averaging number depends on individual, signal acquisition system, and so forth. Firstly, we propose a novel dynamic method to estimate the averaging number for cVEP BCIs. The proposed method is based on the automatic repeat request (ARQ) that is used in communication systems. The existing cVEP BCIs employ rather longer code, such as 63-bit M-sequence. The code length also defines the trade-off between input speed and accuracy. Since the reliability of the proposed BCI can be controlled by the proposed ARQ method, we introduce shorter codes, 32-bit M-sequence and the Kasami-sequence. Thanks to combine the dynamic averaging number estimation method and the shorter codes, the proposed system exhibited higher information transfer rate compared to existing cVEP BCIs.

  11. Visualization of deflagration-to-detonation transitions in a channel with repeated obstacles using a hydrogen-oxygen mixture

    Science.gov (United States)

    Maeda, S.; Minami, S.; Okamoto, D.; Obara, T.

    2016-09-01

    The deflagration-to-detonation transition in a 100 mm square cross-section channel was investigated for a highly reactive stoichiometric hydrogen oxygen mixture at 70 kPa. Obstacles of 5 mm width and 5, 10, and 15 mm heights were equally spaced 60 mm apart at the bottom of the channel. The phenomenon was investigated primarily by time-resolved schlieren visualization from two orthogonal directions using a high-speed video camera. The detonation transition occurred over a remarkably short distance within only three or four repeated obstacles. The global flame speed just before the detonation transition was well below the sound speed of the combustion products and did not reach the sound speed of the initial unreacted gas for tests with an obstacle height of 5 and 10 mm. These results indicate that a detonation transition does not always require global flame acceleration beyond the speed of sound for highly reactive combustible mixtures. A possible mechanism for this detonation initiation was the mixing of the unreacted and reacted gas in the vicinity of the flame front convoluted by the vortex present behind each obstacle, and the formation of a hot spot by the shock wave. The final onset of the detonation originated from the unreacted gas pocket, which was surrounded by the obstacle downstream face and the channel wall.

  12. Event-related potentials dissociate perceptual from response-related age effects in visual search

    DEFF Research Database (Denmark)

    Wiegand, Iris; Müller, Hermann J.; Finke, Kathrin

    2013-01-01

    Attentional decline plays a major role in cognitive changes with aging. However, which specific aspects of attention contribute to this decline is as yet little understood. To identify the contributions of various potential sources of age decrements in visual search, we combined response time...... responses in older participants were associated with age differences in all analyzed event-related potentials from perception to response, indicating that behavioral slowing originates from multiple stages within the information-processing stream. Furthermore, analyses of carry-over effects from one trial...... to the next revealed repetition facilitation of the target-defining dimension and of the motor response—originating from preattentive perceptual and motor execution stages, respectively—to be independent of age. Critically, we demonstrated specific age deficits on intermediate processing stages when...

  13. The Autism-Spectrum Quotient and Visual Search: Shallow and Deep Autistic Endophenotypes.

    Science.gov (United States)

    Gregory, B L; Plaisted-Grant, K C

    2016-05-01

    A high Autism-Spectrum Quotient (AQ) score (Baron-Cohen et al. in J Autism Dev Disord 31(1):5-17, 2001) is increasingly used as a proxy in empirical studies of perceptual mechanisms in autism. Several investigations have assessed perception in non-autistic people measured for AQ, claiming the same relationship exists between performance on perceptual tasks in high-AQ individuals as observed in autism. We question whether the similarity in performance by high-AQ individuals and autistics reflects the same underlying perceptual cause in the context of two visual search tasks administered to a large sample of typical individuals assessed for AQ. Our results indicate otherwise and that deploying the AQ as a proxy for autism introduces unsubstantiated assumptions about high-AQ individuals, the endophenotypes they express, and their relationship to Autistic Spectrum Conditions (ASC) individuals.

  14. Estimation of mental effort in learning visual search by measuring pupil response.

    Directory of Open Access Journals (Sweden)

    Tatsuto Takeuchi

    Full Text Available Perceptual learning refers to the improvement of perceptual sensitivity and performance with training. In this study, we examined whether learning is accompanied by a release from mental effort on the task, leading to automatization of the learned task. For this purpose, we had subjects conduct a visual search for a target, defined by a combination of orientation and spatial frequency, while we monitored their pupil size. It is well known that pupil size reflects the strength of mental effort invested in a task. We found that pupil size increased rapidly as the learning proceeded in the early phase of training and decreased at the later phase to a level half of its maximum value. This result does not support the simple automatization hypothesis. Instead, it suggests that the mental effort and behavioral performance reflect different aspects of perceptual learning. Further, mental effort would be continued to be invested to maintain good performance at a later stage of training.

  15. Age-related changes in selective attention and perceptual load during visual search.

    Science.gov (United States)

    Madden, David J; Langley, Linda K

    2003-03-01

    Three visual search experiments were conducted to test the hypothesis that age differences in selective attention vary as a function of perceptual load (E. A. Maylor & N. Lavie, 1998). Under resource-limited conditions (Experiments 1 and 2), the distraction from irrelevant display items generally decreased as display size (perceptual load) increased. This perceptual load effect was similar for younger and older adults, contrary to the findings of Maylor and Lavie. Distraction at low perceptual loads appeared to reflect both general and specific inhibitory mechanisms. Under more data-limited conditions (Experiment 3), an age-related decline in selective attention was evident, but the age difference was not attributable to capacity limitations as predicted by the perceptual load theory.

  16. HSI-Find: A Visualization and Search Service for Terascale Spectral Image Catalogs

    Science.gov (United States)

    Thompson, D. R.; Smith, A. T.; Castano, R.; Palmer, E. E.; Xing, Z.

    2013-12-01

    Imaging spectrometers are remote sensing instruments commonly deployed on aircraft and spacecraft. They provide surface reflectance in hundreds of wavelength channels, creating data cubes known as hyperspecrtral images. They provide rich compositional information making them powerful tools for planetary and terrestrial science. These data products can be challenging to interpret because they contain datapoints numbering in the thousands (Dawn VIR) or millions (AVIRIS-C). Cross-image studies or exploratory searches involving more than one scene are rare; data volumes are often tens of GB per image and typical consumer-grade computers cannot store more than a handful of images in RAM. Visualizing the information in a single scene is challenging since the human eye can only distinguish three color channels out of the hundreds available. To date, analysis has been performed mostly on single images using purpose-built software tools that require extensive training and commercial licenses. The HSIFind software suite provides a scalable distributed solution to the problem of visualizing and searching large catalogs of spectral image data. It consists of a RESTful web service that communicates to a javascript-based browser client. The software provides basic visualization through an intuitive visual interface, allowing users with minimal training to explore the images or view selected spectra. Users can accumulate a library of spectra from one or more images and use these to search for similar materials. The result appears as an intensity map showing the extent of a spectral feature in a scene. Continuum removal can isolate diagnostic absorption features. The server-side mapping algorithm uses an efficient matched filter algorithm that can process a megapixel image cube in just a few seconds. This enables real-time interaction, leading to a new way of interacting with the data: the user can launch a search with a single mouse click and see the resulting map in seconds

  17. Urinary oxytocin positively correlates with performance in facial visual search in unmarried males, without specific reaction to infant face

    Directory of Open Access Journals (Sweden)

    Atsuko eSaito

    2014-07-01

    Full Text Available The neuropeptide oxytocin plays a central role in prosocial and parental behavior in non-human mammals as well as humans. It has been suggested that oxytocin may affect visual processing of infant faces and emotional reaction to infants. Healthy male volunteers (N = 13 were tested for their ability to detect infant or adult faces among adult or infant faces (facial visual search task. Urine samples were collected from all participants before the study to measure the concentration of oxytocin. Urinary oxytocin positively correlated with performance in the facial visual search task. However, task performance and its correlation with oxytocin concentration did not differ between infant faces and adult faces. Our data suggests that endogenous oxytocin is related to facial visual cognition, but does not promote infant-specific responses in unmarried men who are not fathers.

  18. Toward the influence of temporal attention on the selection of targets in a visual search task: An ERP study.

    Science.gov (United States)

    Rolke, Bettina; Festl, Freya; Seibold, Verena C

    2016-11-01

    We used ERPs to investigate whether temporal attention interacts with spatial attention and feature-based attention to enhance visual processing. We presented a visual search display containing one singleton stimulus among a set of homogenous distractors. Participants were asked to respond only to target singletons of a particular color and shape that were presented in an attended spatial position. We manipulated temporal attention by presenting a warning signal before each search display and varying the foreperiod (FP) between the warning signal and the search display in a blocked manner. We observed distinctive ERP effects of both spatial and temporal attention. The amplitudes for the N2pc, SPCN, and P3 were enhanced by spatial attention indicating a processing benefit of relevant stimulus features at the attended side. Temporal attention accelerated stimulus processing; this was indexed by an earlier onset of the N2pc component and a reduction in reaction times to targets. Most importantly, temporal attention did not interact with spatial attention or stimulus features to influence visual processing. Taken together, the results suggest that temporal attention fosters visual perceptual processing in a visual search task independently from spatial attention and feature-based attention; this provides support for the nonspecific enhancement hypothesis of temporal attention.

  19. Visual search training in occupational therapy:an example of expert practice in community-based stroke rehabilitation

    OpenAIRE

    Turton, A; Angilley, J.; Chapman, M.; Daniel, A.; Longley, V.; Clatworthy, P.; Gilchrist, I. D.

    2015-01-01

    Introduction Visual searching is an essential component of many everyday activities. Search training is practised as part of occupational therapy to improve performance skills both in people with hemianopia and those with spatial inattention post stroke. Evaluation of the effectiveness of such training first requires a systematic and detailed description of the intervention. To this end, this study describes the practice of a specialist occupational therapist. Method Single sessions of inter...

  20. Positional priming of visual pop-out search is supported by multiple spatial reference frames

    Science.gov (United States)

    Gokce, Ahu; Müller, Hermann J.; Geyer, Thomas

    2015-01-01

    The present study investigates the representations(s) underlying positional priming of visual ‘pop-out’ search (Maljkovic and Nakayama, 1996). Three search items (one target and two distractors) were presented at different locations, in invariant (Experiment 1) or random (Experiment 2) cross-trial sequences. By these manipulations it was possible to disentangle retinotopic, spatiotopic, and object-centered priming representations. Two forms of priming were tested: target location facilitation (i.e., faster reaction times – RTs– when the trial n target is presented at a trial n-1 target relative to n-1 blank location) and distractor location inhibition (i.e., slower RTs for n targets presented at n-1 distractor compared to n-1 blank locations). It was found that target locations were coded in positional short-term memory with reference to both spatiotopic and object-centered representations (Experiment 1 vs. 2). In contrast, distractor locations were maintained in an object-centered reference frame (Experiments 1 and 2). We put forward the idea that the uncertainty induced by the experiment manipulation (predictable versus random cross-trial item displacements) modulates the transition from object- to space-based representations in cross-trial memory for target positions. PMID:26136718

  1. Event-related potentials dissociate perceptual from response-related age effects in visual search.

    Science.gov (United States)

    Wiegand, Iris; Finke, Kathrin; Müller, Hermann J; Töllner, Thomas

    2013-03-01

    Attentional decline plays a major role in cognitive changes with aging. However, which specific aspects of attention contribute to this decline is as yet little understood. To identify the contributions of various potential sources of age decrements in visual search, we combined response time measures with lateralized event-related potentials of younger and older adults performing a compound-search task, in which the target-defining dimension of a pop-out target (color/shape) and the response-critical target feature (vertical/horizontal stripes) varied independently across trials. Slower responses in older participants were associated with age differences in all analyzed event-related potentials from perception to response, indicating that behavioral slowing originates from multiple stages within the information-processing stream. Furthermore, analyses of carry-over effects from one trial to the next revealed repetition facilitation of the target-defining dimension and of the motor response-originating from preattentive perceptual and motor execution stages, respectively-to be independent of age. Critically, we demonstrated specific age deficits on intermediate processing stages when intertrial changes required more executively controlled processes, such as flexible stimulus-response (re-)mapping across trials.

  2. Investigation of attentional bias in obsessive compulsive disorder with and without depression in visual search.

    Directory of Open Access Journals (Sweden)

    Sharon Morein-Zamir

    Full Text Available Whether Obsessive Compulsive Disorder (OCD is associated with an increased attentional bias to emotive stimuli remains controversial. Additionally, it is unclear whether comorbid depression modulates abnormal emotional processing in OCD. This study examined attentional bias to OC-relevant scenes using a visual search task. Controls, non-depressed and depressed OCD patients searched for their personally selected positive images amongst their negative distractors, and vice versa. Whilst the OCD groups were slower than healthy individuals in rating the images, there were no group differences in the magnitude of negative bias to concern-related scenes. A second experiment employing a common set of images replicated the results on an additional sample of OCD patients. Although there was a larger bias to negative OC-related images without pre-exposure overall, no group differences in attentional bias were observed. However, OCD patients subsequently rated the images more slowly and more negatively, again suggesting post-attentional processing abnormalities. The results argue against a robust attentional bias in OCD patients, regardless of their depression status and speak to generalized difficulties disengaging from negative valence stimuli. Rather, post-attentional processing abnormalities may account for differences in emotional processing in OCD.

  3. Previously seen and expected stimuli elicit surprise in the context of visual search.

    Science.gov (United States)

    Retell, James D; Becker, Stefanie I; Remington, Roger W

    2016-04-01

    In the context of visual search, surprise is the phenomenon by which a previously unseen and unexpected stimulus exogenously attracts spatial attention. Capture by such a stimulus occurs, by definition, independent of task goals and is thought to be dependent on the extent to which the stimulus deviates from expectations. However, the relative contributions of prior-exposure and explicit knowledge of an unexpected event to the surprise response have not yet been systematically investigated. Here observers searched for a specific color while ignoring irrelevant cues of different colors presented prior to the target display. After a brief familiarization period, we presented an irrelevant motion cue to elicit surprise. Across conditions we varied prior exposure to the motion stimulus - seen versus unseen - and top-down expectations of occurrence - expected versus unexpected - to assess the extent to which each of these factors contributes to surprise. We found no attenuation of the surprise response when observers were pre-exposed to the motion cue and or had explicit knowledge of its occurrence. Our results show that it is neither sufficient nor necessary that a stimulus be new and unannounced to elicit surprise and suggest that the expectations that determine the surprise response are highly context specific.

  4. Visual search behaviors of association football referees during assessment of foul play situations.

    Science.gov (United States)

    Spitz, Jochim; Put, Koen; Wagemans, Johan; Williams, A Mark; Helsen, Werner F

    2016-01-01

    It is well reported that expert athletes have refined perceptual-cognitive skills and fixate on more informative areas during representative tasks. These perceptual-cognitive skills are also crucial to performance within the domain of sports officials. We examined the visual scan patterns of elite and sub-elite association football referees while assessing foul play situations. These foul play situations (open play and corner kick situations) were presented on a Tobii T120 Eye Tracking monitor. The elite referees made more accurate decisions and differences in their visual search behaviors were observed. For the open play situations, referees in the elite group spent significantly more time fixating the most informative area of the attacking player (contact zone) and less time fixating the body part that was not involved in the infringement (non-contact zone). Furthermore, the average total fixation time in the contact zone and non-contact zone tended to differ between the elite and sub-elite referees in corner kick situations. In conclusion, elite level referees have learned to discern relevant from less-relevant information in the same way as expert athletes. Findings have implications for the development of perceptual training programs for sport officials.

  5. Visual search for tropical web spiders: the influence of plot length, sampling effort, and phase of the day on species richness.

    Science.gov (United States)

    Pinto-Leite, C M; Rocha, P L B

    2012-12-01

    Empirical studies using visual search methods to investigate spider communities were conducted with different sampling protocols, including a variety of plot sizes, sampling efforts, and diurnal periods for sampling. We sampled 11 plots ranging in size from 5 by 10 m to 5 by 60 m. In each plot, we computed the total number of species detected every 10 min during 1 hr during the daytime and during the nighttime (0630 hours to 1100 hours, both a.m. and p.m.). We measured the influence of time effort on the measurement of species richness by comparing the curves produced by sample-based rarefaction and species richness estimation (first-order jackknife). We used a general linear model with repeated measures to assess whether the phase of the day during which sampling occurred and the differences in the plot lengths influenced the number of species observed and the number of species estimated. To measure the differences in species composition between the phases of the day, we used a multiresponse permutation procedure and a graphical representation based on nonmetric multidimensional scaling. After 50 min of sampling, we noted a decreased rate of species accumulation and a tendency of the estimated richness curves to reach an asymptote. We did not detect an effect of plot size on the number of species sampled. However, differences in observed species richness and species composition were found between phases of the day. Based on these results, we propose guidelines for visual search for tropical web spiders.

  6. The effect of stimulus duration and motor response in hemispatial neglect during a visual search task.

    Directory of Open Access Journals (Sweden)

    Laura M Jelsone-Swain

    Full Text Available Patients with hemispatial neglect exhibit a myriad of profound deficits. A hallmark of this syndrome is the patients' absence of awareness of items located in their contralesional space. Many studies, however, have demonstrated that neglect patients exhibit some level of processing of these neglected items. It has been suggested that unconscious processing of neglected information may manifest as a fast denial. This theory of fast denial proposes that neglected stimuli are detected in the same way as non-neglected stimuli, but without overt awareness. We evaluated the fast denial theory by conducting two separate visual search task experiments, each differing by the duration of stimulus presentation. Specifically, in Experiment 1 each stimulus remained in the participants' visual field until a response was made. In Experiment 2 each stimulus was presented for only a brief duration. We further evaluated the fast denial theory by comparing verbal to motor task responses in each experiment. Overall, our results from both experiments and tasks showed no evidence for the presence of implicit knowledge of neglected stimuli. Instead, patients with neglect responded the same when they neglected stimuli as when they correctly reported stimulus absence. These findings thus cast doubt on the concept of the fast denial theory and its consequent implications for non-conscious processing. Importantly, our study demonstrated that the only behavior affected was during conscious detection of ipsilesional stimuli. Specifically, patients were slower to detect stimuli in Experiment 1 compared to Experiment 2, suggesting a duration effect occurred during conscious processing of information. Additionally, reaction time and accuracy were similar when reporting verbally versus motorically. These results provide new insights into the perceptual deficits associated with neglect and further support other work that falsifies the fast denial account of non

  7. Active training and driving-specific feedback improve older drivers' visual search prior to lane changes

    Directory of Open Access Journals (Sweden)

    Lavallière Martin

    2012-03-01

    Full Text Available Abstract Background Driving retraining classes may offer an opportunity to attenuate some effects of aging that may alter driving skills. Unfortunately, there is evidence that classroom programs (driving refresher courses do not improve the driving performance of older drivers. The aim of the current study was to evaluate if simulator training sessions with video-based feedback can modify visual search behaviors of older drivers while changing lanes in urban driving. Methods In order to evaluate the effectiveness of the video-based feedback training, 10 older drivers who received a driving refresher course and feedback about their driving performance were tested with an on-road standardized evaluation before and after participating to a simulator training program (Feedback group. Their results were compared to a Control group (12 older drivers who received the same refresher course and in-simulator active practice as the Feedback group without receiving driving-specific feedback. Results After attending the training program, the Control group showed no increase in the frequency of the visual inspection of three regions of interests (rear view and left side mirrors, and blind spot. In contrast, for the Feedback group, combining active training and driving-specific feedbacks increased the frequency of blind spot inspection by 100% (32.3 to 64.9% of verification before changing lanes. Conclusions These results suggest that simulator training combined with driving-specific feedbacks helped older drivers to improve their visual inspection strategies, and that in-simulator training transferred positively to on-road driving. In order to be effective, it is claimed that driving programs should include active practice sessions with driving-specific feedbacks. Simulators offer a unique environment for developing such programs adapted to older drivers' needs.

  8. Searching for biomarkers of CDKL5 disorder: early-onset visual impairment in CDKL5 mutant mice.

    Science.gov (United States)

    Mazziotti, Raffaele; Lupori, Leonardo; Sagona, Giulia; Gennaro, Mariangela; Della Sala, Grazia; Putignano, Elena; Pizzorusso, Tommaso

    2017-06-15

    CDKL5 disorder is a neurodevelopmental disorder still without a cure. Murine models of CDKL5 disorder have been recently generated raising the possibility of preclinical testing of treatments. However, unbiased, quantitative biomarkers of high translational value to monitor brain function are still missing. Moreover, the analysis of treatment is hindered by the challenge of repeatedly and non-invasively testing neuronal function. We analyzed the development of visual responses in a mouse model of CDKL5 disorder to introduce visually evoked responses as a quantitative method to assess cortical circuit function. Cortical visual responses were assessed in CDKL5 null male mice, heterozygous females, and their respective control wild-type littermates by repeated transcranial optical imaging from P27 until P32. No difference between wild-type and mutant mice was present at P25-P26 whereas defective responses appeared from P27-P28 both in heterozygous and homozygous CDKL5 mutant mice. These results were confirmed by visually evoked potentials (VEPs) recorded from the visual cortex of a different cohort. The previously imaged mice were also analyzed at P60-80 using VEPs, revealing a persistent reduction of response amplitude, reduced visual acuity and defective contrast function. The level of adult impairment was significantly correlated with the reduction in visual responses observed during development. Support vector machine showed that multi-dimensional visual assessment can be used to automatically classify mutant and wt mice with high reliability. Thus, monitoring visual responses represents a promising biomarker for preclinical and clinical studies on CDKL5 disorder. © The Author 2017. Published by Oxford University Press.

  9. Target-distractor similarity has a larger impact on visual search in school-age children than spacing

    NARCIS (Netherlands)

    Huurneman, B.; Boonstra, F.N.

    2015-01-01

    In typically developing children, crowding decreases with increasing age. The influence of target-distractor similarity with respect to orientation and element spacing on visual search performance was investigated in 29 school-age children with normal vision (4- to 6-year-olds [N = 16], 7- to 8-year

  10. How Prior Knowledge and Colour Contrast Interfere Visual Search Processes in Novice Learners: An Eye Tracking Study

    Science.gov (United States)

    Sonmez, Duygu; Altun, Arif; Mazman, Sacide Guzin

    2012-01-01

    This study investigates how prior content knowledge and prior exposure to microscope slides on the phases of mitosis effect students' visual search strategies and their ability to differentiate cells that are going through any phases of mitosis. Two different sets of microscope slide views were used for this purpose; with high and low colour…

  11. Fat Content Modulates Rapid Detection of Food: A Visual Search Study Using Fast Food and Japanese Diet

    National Research Council Canada - National Science Library

    Reiko Sawada; Wataru Sato; Motomi Toichi; Tohru Fushiki

    2017-01-01

    .... To investigate these issues, we measured reaction times (RTs) during a visual search task in which participants with normal weight detected high-fat food (i.e., fast food), low-fat food (i.e., Japanese diet), and non-food (i.e., kitchen utensils...

  12. Immaturity of the Oculomotor Saccade and Vergence Interaction in Dyslexic Children: Evidence from a Reading and Visual Search Study

    Science.gov (United States)

    Bucci, Maria Pia; Nassibi, Naziha; Gerard, Christophe-Loic; Bui-Quoc, Emmanuel; Seassau, Magali

    2012-01-01

    Studies comparing binocular eye movements during reading and visual search in dyslexic children are, at our knowledge, inexistent. In the present study we examined ocular motor characteristics in dyslexic children versus two groups of non dyslexic children with chronological/reading age-matched. Binocular eye movements were recorded by an infrared system (mobileEBT®, e(ye)BRAIN) in twelve dyslexic children (mean age 11 years old) and a group of chronological age-matched (N = 9) and reading age-matched (N = 10) non dyslexic children. Two visual tasks were used: text reading and visual search. Independently of the task, the ocular motor behavior in dyslexic children is similar to those reported in reading age-matched non dyslexic children: many and longer fixations as well as poor quality of binocular coordination during and after the saccades. In contrast, chronological age-matched non dyslexic children showed a small number of fixations and short duration of fixations in reading task with respect to visual search task; furthermore their saccades were well yoked in both tasks. The atypical eye movement's patterns observed in dyslexic children suggest a deficiency in the visual attentional processing as well as an immaturity of the ocular motor saccade and vergence systems interaction. PMID:22438934

  13. The Attentional Fields of Visual Search in Simultanagnosia and Healthy Individuals: How Object and Space Attention Interact.

    Science.gov (United States)

    Khan, A Z; Prost-Lefebvre, M; Salemme, R; Blohm, G; Rossetti, Y; Tilikete, C; Pisella, L

    2016-03-01

    Simultanagnosia is a deficit in which patients are unable to perceive multiple objects simultaneously. To date, it remains disputed whether this deficit results from disrupted object or space perception. We asked both healthy participants as well as a patient with simultanagnosia to perform different visual search tasks of variable difficulty. We also modulated the number of objects (target and distracters) presented. For healthy participants, we found that each visual search task was performed with a specific "attentional field" depending on the difficulty of visual object processing but not on the number of objects falling within this "working space." This was demonstrated by measuring the cost in reaction times using different gaze-contingent visible window sizes. We found that bilateral damage to the superior parietal lobule impairs the spatial integration of separable features (within-object processing), shrinking the attentional field in which a target can be detected, but causing no deficit in processing multiple objects per se.

  14. Decision processes in visual search as a function of target prevalence.

    Science.gov (United States)

    Peltier, Chad; Becker, Mark W

    2016-09-01

    The probability of missing a target increases in low target prevalence search tasks. Wolfe and Van Wert (2010) propose 2 causes of this effect: reducing the quitting threshold, and conservatively shifting the decision making criterion used to evaluate each item. Reducing the quitting threshold predicts that target absent responses will be made without fully inspecting the display, increasing misses due to never inspecting the target (selection errors). The shift in decision criterion increases the likelihood of failing to recognize an inspected target (identification errors). Though there is robust evidence that target prevalence rates shift quitting thresholds, the proposed shift in decision making criterion has little support. In Experiment 1 we eye-tracked participants during searches of high, medium, and low prevalence. Eye movements were used to classify misses as selection or identification errors. Identification errors increased as prevalence decreased, supporting the claim that decision criterion becomes more conservative as prevalence decreases. In addition, as prevalence decreased, the dwell time on targets increased while dwell times on distractors decreased. We propose that the effect of prevalence on decision making for individual items is best modeled as a shift in criterion in a drift diffusion model, rather than signal detection, as drift diffusion accounts for this pattern of decision times. In Experiment 2 we replicate these findings while presenting stimuli in an rapid serial visual presentation (RSVP) stream. Experiments 1 and 2 were consistent with the conclusion that prevalence rate influences the item-by-item decision criterion, and are consistent with a drift diffusion model of this decision process. (PsycINFO Database Record

  15. EEG and Eye Tracking Signatures of Target Encoding during Structured Visual Search.

    Science.gov (United States)

    Brouwer, Anne-Marie; Hogervorst, Maarten A; Oudejans, Bob; Ries, Anthony J; Touryan, Jonathan

    2017-01-01

    EEG and eye tracking variables are potential sources of information about the underlying processes of target detection and storage during visual search. Fixation duration, pupil size and event related potentials (ERPs) locked to the onset of fixation or saccade (saccade-related potentials, SRPs) have been reported to differ dependent on whether a target or a non-target is currently fixated. Here we focus on the question of whether these variables also differ between targets that are subsequently reported (hits) and targets that are not (misses). Observers were asked to scan 15 locations that were consecutively highlighted for 1 s in pseudo-random order. Highlighted locations displayed either a target or a non-target stimulus with two, three or four targets per trial. After scanning, participants indicated which locations had displayed a target. To induce memory encoding failures, participants concurrently performed an aurally presented math task (high load condition). In a low load condition, participants ignored the math task. As expected, more targets were missed in the high compared with the low load condition. For both conditions, eye tracking features distinguished better between hits and misses than between targets and non-targets (with larger pupil size and shorter fixations for missed compared with correctly encoded targets). In contrast, SRP features distinguished better between targets and non-targets than between hits and misses (with average SRPs showing larger P300 waveforms for targets than for non-targets). Single trial classification results were consistent with these averages. This work suggests complementary contributions of eye and EEG measures in potential applications to support search and detect tasks. SRPs may be useful to monitor what objects are relevant to an observer, and eye variables may indicate whether the observer should be reminded of them later.

  16. Vanishing point attracts gaze in free-viewing and visual search tasks.

    Science.gov (United States)

    Borji, Ali; Feng, Mengyang; Lu, Huchuan

    2016-11-01

    Several structural scene cues such as gist, layout, horizontal line, openness, and depth have been shown to guide scene perception (e.g., Oliva & Torralba, 2001); Ross & Oliva, 2009). Here, to investigate whether vanishing point (VP) plays a significant role in gaze guidance, we ran two experiments. In the first one, we recorded fixations of 10 observers (six male, four female; mean age 22; SD = 0.84) freely viewing 532 images, out of which 319 had a VP (shuffled presentation; each image for 4 s). We found that the average number of fixations at a local region (80 × 80 pixels) centered at the VP is significantly higher than the average fixations at random locations (t test; n = 319; p search for a target character (T or L) placed randomly on a 3 × 3 imaginary grid overlaid on top of an image. Subjects reported their answers by pressing one of the two keys. Stimuli consisted of 270 color images (180 with a single VP, 90 without). The target happened with equal probability inside each cell (15 times L, 15 times T). We found that subjects were significantly faster (and more accurate) when the target appeared inside the cell containing the VP compared to cells without the VP (median across 14 subjects 1.34 s vs. 1.96 s; Wilcoxon rank-sum test; p = 0.0014). These findings support the hypothesis that vanishing point, similar to face, text (Cerf, Frady, & Koch, 2009), and gaze direction Borji, Parks, & Itti, 2014) guides attention in free-viewing and visual search tasks.

  17. Early experience with multiparametric magnetic resonance imaging-targeted biopsies under visual transrectal ultrasound guidance in patients suspicious for prostate cancer undergoing repeated biopsy

    DEFF Research Database (Denmark)

    Boesen, Lars; Noergaard, Nis; Chabanova, Elizaveta

    2015-01-01

    -RADS) and Likert classification. All underwent repeated TRUS-bx (10 cores) and mp-MRI-bx under visual TRUS guidance of any mp-MRI-suspicious lesion not targeted by systematic TRUS-bx. RESULTS: PCa was found in 39 out of 83 patients (47%) and mp-MRI identified at least one lesion with some degree of suspicion...... in all 39 patients. Both PI-RADS and Likert scoring showed a high correlation between suspicion of malignancy and biopsy results (p

  18. TMS of the right angular gyrus modulates priming of pop-out in visual search: combined TMS-ERP evidence.

    Science.gov (United States)

    Taylor, Paul C J; Muggleton, Neil G; Kalla, Roger; Walsh, Vincent; Eimer, Martin

    2011-12-01

    During priming of pop-out, performance at discriminating a pop-out feature target in visual search is affected by whether the target on the previous trial was defined by the same feature as on the upcoming trial. Recent studies suggest that priming of pop-out relies on attentional processes. With the use of simultaneous, combined transcranial magnetic stimulation and event-related potential recording (TMS-ERP), we tested for any critical role of the right angular gyrus (rANG) and left and right frontal eye fields (FEFs)-key attentional sites-in modulating both performance and the ERPs evoked by such visual events. Intertrial TMS trains were applied while participants discriminated the orientation of a color pop-out element in a visual search array. rANG TMS disrupted priming of pop-out, reducing reaction time costs on switch trials and speeding responses when the color of the pop-out target switched. rANG TMS caused a negativity in the ERP elicited in response to the visual stimulus array, starting 210 ms after stimulus onset. Both behavioral and ERP effects were apparent only after rANG TMS, on switch trials, and when the target in the visual search array was presented in the left visual field, with no effects after left or right FEF TMS. These results provide evidence for an attentional reorienting mechanism, which originates in the rANG and is modulated by the implicit memory of the previous trial. The rANG plays a causal role on switch trials during priming of pop-out by interacting with visual processing, particularly in the ipsilateral hemisphere representing the contralateral hemifield.

  19. Evaluating the effectiveness of Washington state repeated job search services on the employment rate of prime-age female welfare recipients.

    Science.gov (United States)

    Hsiao, Cheng; Shen, Yan; Wang, Boqing; Weeks, Greg

    2008-07-01

    This paper uses an unbalanced panel dataset to evaluate how repeated job search services (JSS) and personal characteristics affect the employment rate of the prime-age female welfare recipients in the State of Washington. We propose a transition probability model to take into account issues of sample attrition, sample refreshment and duration dependence. We also generalize Honoré and Kyriazidou's [Honoré, B.E., Kyriazidou, E., 2000. Panel data discrete choice models with lagged dependent variables. Econometrica 68 (4), 839-874] conditional maximum likelihood estimator to allow for the presence of individual-specific effects. A limited information test is suggested to test for selection issues in non-experimental data. The specification tests indicate that the (conditional on the set of the confounding variables considered) assumptions of no selection due to unobservables and/or no unobserved individual-specific effects are not violated. Our findings indicate that the first job search service does have positive and significant impacts on the employment rate. However, providing repeated JSS to the same client has no significant impact. Further, we find that there are significant experience-enhancing effects. These findings suggest that providing one job search services training to individuals may have a lasting impact on raising their employment rates.

  20. Visualization

    OpenAIRE

    Balon, Andreja

    1990-01-01

    The present thesis entails the field of visualization which is divided into visualization along traditional lines and visualization in computer science. As the psychological aspect of image is of vital importance for visualization, it is shortly described in the beginning. Visualization in computer science is divided into three main fields: scientific visualization, program visualization and visual programming. An explanation and examples of approach to applications are given for each field....

  1. Preserved Suppression of Salient Irrelevant Stimuli During Visual Search in Age-Associated Memory Impairment.

    Science.gov (United States)

    Lorenzo-López, Laura; Maseda, Ana; Buján, Ana; de Labra, Carmen; Amenedo, Elena; Millán-Calenti, José C

    2015-01-01

    Previous studies have suggested that older adults with age-associated memory impairment (AAMI) may show a significant decline in attentional resource capacity and inhibitory processes in addition to memory impairment. In the present paper, the potential attentional capture by task-irrelevant stimuli was examined in older adults with AAMI compared to healthy older adults using scalp-recorded event-related brain potentials (ERPs). ERPs were recorded during the execution of a visual search task, in which the participants had to detect the presence of a target stimulus that differed from distractors by orientation. To explore the automatic attentional capture phenomenon, an irrelevant distractor stimulus defined by a different feature (color) was also presented without previous knowledge of the participants. A consistent N2pc, an electrophysiological indicator of attentional deployment, was present for target stimuli but not for task-irrelevant color stimuli, suggesting that these irrelevant distractors did not attract attention in AAMI older adults. Furthermore, the N2pc for targets was significantly delayed in AAMI patients compared to healthy older controls. Together, these findings suggest a specific impairment of the attentional selection process of relevant target stimuli in these individuals and indicate that the mechanism of top-down suppression of entirely task-irrelevant stimuli is preserved, at least when the target and the irrelevant stimuli are perceptually very different.

  2. Preserved suppression of salient irrelevant stimuli during visual search in Age-Associated Memory Impairment

    Directory of Open Access Journals (Sweden)

    Laura eLorenzo-López

    2016-01-01

    Full Text Available Previous studies have suggested that older adults with age-associated memory impairment (AAMI may show a significant decline in attentional resource capacity and inhibitory processes in addition to memory impairment. In the present paper, the potential attentional capture by task-irrelevant stimuli was examined in older adults with AAMI compared to healthy older adults using scalp-recorded event-related brain potentials (ERPs. ERPs were recorded during the execution of a visual search task, in which the participants had to detect the presence of a target stimulus that differed from distractors by orientation. To explore the automatic attentional capture phenomenon, an irrelevant distractor stimulus defined by a different feature (color was also presented without previous knowledge of the participants. A consistent N2pc, an electrophysiological indicator of attentional deployment, was present for target stimuli but not for task-irrelevant color stimuli, suggesting that these irrelevant distractors did not attract attention in AAMI older adults. Furthermore, the N2pc for targets was significantly delayed in AAMI patients compared to healthy older controls. Together, these findings suggest a specific impairment of the attentional selection process of relevant target stimuli in these individuals and indicate that the mechanism of top-down suppression of entirely task-irrelevant stimuli is preserved, at least when the target and the irrelevant stimuli are perceptually very different.

  3. Task relevance of emotional information affects anxiety-linked attention bias in visual search.

    Science.gov (United States)

    Dodd, Helen F; Vogt, Julia; Turkileri, Nilgun; Notebaert, Lies

    2017-01-01

    Task relevance affects emotional attention in healthy individuals. Here, we investigate whether the association between anxiety and attention bias is affected by the task relevance of emotion during an attention task. Participants completed two visual search tasks. In the emotion-irrelevant task, participants were asked to indicate whether a discrepant face in a crowd of neutral, middle-aged faces was old or young. Irrelevant to the task, target faces displayed angry, happy, or neutral expressions. In the emotion-relevant task, participants were asked to indicate whether a discrepant face in a crowd of middle-aged neutral faces was happy or angry (target faces also varied in age). Trait anxiety was not associated with attention in the emotion-relevant task. However, in the emotion-irrelevant task, trait anxiety was associated with a bias for angry over happy faces. These findings demonstrate that the task relevance of emotional information affects conclusions about the presence of an anxiety-linked attention bias. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Assessment of prostate cancer detection with a visual-search human model observer

    Science.gov (United States)

    Sen, Anando; Kalantari, Faraz; Gifford, Howard C.

    2014-03-01

    Early staging of prostate cancer (PC) is a significant challenge, in part because of the small tumor sizes in- volved. Our long-term goal is to determine realistic diagnostic task performance benchmarks for standard PC imaging with single photon emission computed tomography (SPECT). This paper reports on a localization receiver operator characteristic (LROC) validation study comparing human and model observers. The study made use of a digital anthropomorphic phantom and one-cm tumors within the prostate and pelvic lymph nodes. Uptake values were consistent with data obtained from clinical In-111 ProstaScint scans. The SPECT simulation modeled a parallel-hole imaging geometry with medium-energy collimators. Nonuniform attenua- tion and distance-dependent detector response were accounted for both in the imaging and the ordered-subset expectation-maximization (OSEM) iterative reconstruction. The observer study made use of 2D slices extracted from reconstructed volumes. All observers were informed about the prostate and nodal locations in an image. Iteration number and the level of postreconstruction smoothing were study parameters. The results show that a visual-search (VS) model observer correlates better with the average detection performance of human observers than does a scanning channelized nonprewhitening (CNPW) model observer.

  5. Visual-search model observer for assessing mass detection in CT

    Science.gov (United States)

    Karbaschi, Zohreh; Gifford, Howard C.

    2017-03-01

    Our aim is to devise model observers (MOs) to evaluate acquisition protocols in medical imaging. To optimize protocols for human observers, an MO must reliably interpret images containing quantum and anatomical noise under aliasing conditions. In this study of sampling parameters for simulated lung CT, the lesion-detection performance of human observers was compared with that of visual-search (VS) observers, a channelized nonprewhitening (CNPW) observer, and a channelized Hoteling (CH) observer. Scans of a mathematical torso phantom modeled single-slice parallel-hole CT with varying numbers of detector pixels and angular projections. Circular lung lesions had a fixed radius. Twodimensional FBP reconstructions were performed. A localization ROC study was conducted with the VS, CNPW and human observers, while the CH observer was applied in a location-known ROC study. Changing the sampling parameters had negligible effect on the CNPW and CH observers, whereas several VS observers demonstrated a sensitivity to sampling artifacts that was in agreement with how the humans performed.

  6. A comparison of visual search strategies of elite and non-elite tennis players through cluster analysis.

    Science.gov (United States)

    Murray, Nicholas P; Hunfalvay, Melissa

    2017-02-01

    Considerable research has documented that successful performance in interceptive tasks (such as return of serve in tennis) is based on the performers' capability to capture appropriate anticipatory information prior to the flight path of the approaching object. Athletes of higher skill tend to fixate on different locations in the playing environment prior to initiation of a skill than their lesser skilled counterparts. The purpose of this study was to examine visual search behaviour strategies of elite (world ranked) tennis players and non-ranked competitive tennis players (n = 43) utilising cluster analysis. The results of hierarchical (Ward's method) and nonhierarchical (k means) cluster analyses revealed three different clusters. The clustering method distinguished visual behaviour of high, middle-and low-ranked players. Specifically, high-ranked players demonstrated longer mean fixation duration and lower variation of visual search than middle-and low-ranked players. In conclusion, the results demonstrated that cluster analysis is a useful tool for detecting and analysing the areas of interest for use in experimental analysis of expertise and to distinguish visual search variables among participants'.

  7. Target-distractor similarity has a larger impact on visual search in school-age children than spacing.

    Science.gov (United States)

    Huurneman, Bianca; Boonstra, F Nienke

    2015-01-22

    In typically developing children, crowding decreases with increasing age. The influence of target-distractor similarity with respect to orientation and element spacing on visual search performance was investigated in 29 school-age children with normal vision (4- to 6-year-olds [N = 16], 7- to 8-year-olds [N = 13]). Children were instructed to search for a target E among distractor Es (feature search: all flanking Es pointing right; conjunction search: flankers in three orientations). Orientation of the target was manipulated in four directions: right (target absent), left (inversed), up, and down (vertical). Spacing was varied in four steps: 0.04°, 0.5°, 1°, and 2°. During feature search, high target-distractor similarity had a stronger impact on performance than spacing: Orientation affected accuracy until spacing was 1°, and spacing only influenced accuracy for identifying inversed targets. Spatial analyses showed that orientation affected oculomotor strategy: Children made more fixations in the "inversed" target area (4.6) than the vertical target areas (1.8 and 1.9). Furthermore, age groups differed in fixation duration: 4- to 6-year-old children showed longer fixation durations than 7- to 8-year-olds at the two largest element spacings (p = 0.039 and p = 0.027). Conjunction search performance was unaffected by spacing. Four conclusions can be drawn from this study: (a) Target-distractor similarity governs visual search performance in school-age children, (b) children make more fixations in target areas when target-distractor similarity is high, (c) 4- to 6-year-olds show longer fixation durations than 7- to 8-year-olds at 1° and 2° element spacing, and (d) spacing affects feature but not conjunction search-a finding that might indicate top-down control ameliorates crowding in children.

  8. Exploratory search in an audio-visual archive: evaluating a professional search tool for non-professional users

    NARCIS (Netherlands)

    Bron, M.; van Gorp, J.; Nack, F.; de Rijke, M.

    2011-01-01

    As archives are opening up and publishing their content online, the general public can now directly access archive collections. To support access, archives typically provide the public with their internal search tools that were originally intended for professional archivists. We conduct a small-scal

  9. Intrinsic motivation and attentional capture from gamelike features in a visual search task.

    Science.gov (United States)

    Miranda, Andrew T; Palmer, Evan M

    2014-03-01

    In psychology research studies, the goals of the experimenter and the goals of the participants often do not align. Researchers are interested in having participants who take the experimental task seriously, whereas participants are interested in earning their incentive (e.g., money or course credit) as quickly as possible. Creating experimental methods that are pleasant for participants and that reward them for effortful and accurate data generation, while not compromising the scientific integrity of the experiment, would benefit both experimenters and participants alike. Here, we explored a gamelike system of points and sound effects that rewarded participants for fast and accurate responses. We measured participant engagement at both cognitive and perceptual levels and found that the point system (which invoked subtle, anonymous social competition between participants) led to positive intrinsic motivation, while the sound effects (which were pleasant and arousing) led to attentional capture for rewarded colors. In a visual search task, points were awarded after each trial for fast and accurate responses, accompanied by short, pleasant sound effects. We adapted a paradigm from Anderson, Laurent, and Yantis (Proceedings of the National Academy of Sciences 108(25):10367-10371, 2011b), in which participants completed a training phase during which red and green targets were probabilistically associated with reward (a point bonus multiplier). During a test phase, no points or sounds were delivered, color was irrelevant to the task, and previously rewarded targets were sometimes presented as distractors. Significantly longer response times on trials in which previously rewarded colors were present demonstrated attentional capture, and positive responses to a five-question intrinsic-motivation scale demonstrated participant engagement.

  10. Separate evaluation of target facilitation and distractor suppression in the activity of macaque lateral intraparietal neurons during visual search.

    Science.gov (United States)

    Nishida, Satoshi; Tanaka, Tomohiro; Ogawa, Tadashi

    2013-12-01

    During visual search, neurons in the lateral intraparietal area (LIP) discriminate the target from distractors by exhibiting stronger activation when the target appears within the receptive field than when it appears outside the receptive field. It is generally thought that such target-discriminative activity is produced by the combination of target-related facilitation and distractor-related suppression. However, little is known about how the target-discriminative activity is constituted by these two types of neural modulation. To address this issue, we recorded activity from LIP of monkeys performing a visual search task that consisted of target-present and target-absent trials. Monkeys had to make a saccade to a target in the target-present trials, whereas they had to maintain fixation in the target-absent trials, in which only distractors were presented. By introducing the activity from the latter trials as neutral activity, we were able to separate the target-discriminative activity into target-related elevation and distractor-related reduction components. We found that the target-discriminative activity of most LIP neurons consisted of the combination of target-related elevation and distractor-related reduction or only target-related elevation. In contrast, target-discriminative activity composed of only distractor-related reduction was observed for very few neurons. We also found that, on average, target-related elevation was stronger and occurred earlier compared with distractor-related reduction. Finally, we consider possible underlying mechanisms, including lateral inhibitory interactions, responsible for target-discriminative activity in visual search. The present findings provide insight into how neuronal modulations shape target-discriminative activity during visual search.

  11. Do synesthetes have a general advantage in visual search and episodic memory? A case for group studies.

    Directory of Open Access Journals (Sweden)

    Nicolas Rothen

    Full Text Available BACKGROUND: Some studies, most of them case-reports, suggest that synesthetes have an advantage in visual search and episodic memory tasks. The goal of this study was to examine this hypothesis in a group study. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we tested thirteen grapheme-color synesthetes and we compared their performance on a visual search task and a memory test to an age-, handedness-, education-, and gender-matched control group. The results showed no significant group differences (all relevant ps>.50. For the visual search task effect sizes indicated a small advantage for synesthetes (Cohen's d between .19 and .32. No such advantage was found for episodic memory (Cohen's d<.05. CONCLUSIONS/SIGNIFICANCE: The results indicate that synesthesia per se does not seem to lead to a strong performance advantage. Rather, the superior performance of synesthetes observed in some case-report studies may be due to individual differences, to a selection bias or to a strategic use of synesthesia as a mnemonic. In order to establish universal effects of synesthesia on cognition single-case studies must be complemented by group studies.

  12. Computer vision enhances mobile eye-tracking to expose expert cognition in natural-scene visual-search tasks

    Science.gov (United States)

    Keane, Tommy P.; Cahill, Nathan D.; Tarduno, John A.; Jacobs, Robert A.; Pelz, Jeff B.

    2014-02-01

    Mobile eye-tracking provides the fairly unique opportunity to record and elucidate cognition in action. In our research, we are searching for patterns in, and distinctions between, the visual-search performance of experts and novices in the geo-sciences. Traveling to regions resultant from various geological processes as part of an introductory field studies course in geology, we record the prima facie gaze patterns of experts and novices when they are asked to determine the modes of geological activity that have formed the scene-view presented to them. Recording eye video and scene video in natural settings generates complex imagery that requires advanced applications of computer vision research to generate registrations and mappings between the views of separate observers. By developing such mappings, we could then place many observers into a single mathematical space where we can spatio-temporally analyze inter- and intra-subject fixations, saccades, and head motions. While working towards perfecting these mappings, we developed an updated experiment setup that allowed us to statistically analyze intra-subject eye-movement events without the need for a common domain. Through such analyses we are finding statistical differences between novices and experts in these visual-search tasks. In the course of this research we have developed a unified, open-source, software framework for processing, visualization, and interaction of mobile eye-tracking and high-resolution panoramic imagery.

  13. Properties of V1 neurons tuned to conjunctions of visual features: application of the V1 saliency hypothesis to visual search behavior.

    Directory of Open Access Journals (Sweden)

    Li Zhaoping

    Full Text Available From a computational theory of V1, we formulate an optimization problem to investigate neural properties in the primary visual cortex (V1 from human reaction times (RTs in visual search. The theory is the V1 saliency hypothesis that the bottom-up saliency of any visual location is represented by the highest V1 response to it relative to the background responses. The neural properties probed are those associated with the less known V1 neurons tuned simultaneously or conjunctively in two feature dimensions. The visual search is to find a target bar unique in color (C, orientation (O, motion direction (M, or redundantly in combinations of these features (e.g., CO, MO, or CM among uniform background bars. A feature singleton target is salient because its evoked V1 response largely escapes the iso-feature suppression on responses to the background bars. The responses of the conjunctively tuned cells are manifested in the shortening of the RT for a redundant feature target (e.g., a CO target from that predicted by a race between the RTs for the two corresponding single feature targets (e.g., C and O targets. Our investigation enables the following testable predictions. Contextual suppression on the response of a CO-tuned or MO-tuned conjunctive cell is weaker when the contextual inputs differ from the direct inputs in both feature dimensions, rather than just one. Additionally, CO-tuned cells and MO-tuned cells are often more active than the single feature tuned cells in response to the redundant feature targets, and this occurs more frequently for the MO-tuned cells such that the MO-tuned cells are no less likely than either the M-tuned or O-tuned neurons to be the most responsive neuron to dictate saliency for an MO target.

  14. Comparing the Precision of Information Retrieval of MeSH-Controlled Vocabulary Search Method and a Visual Method in the Medline Medical Database.

    Science.gov (United States)

    Hariri, Nadjla; Ravandi, Somayyeh Nadi

    2014-01-01

    Medline is one of the most important databases in the biomedical field. One of the most important hosts for Medline is Elton B. Stephens CO. (EBSCO), which has presented different search methods that can be used based on the needs of the users. Visual search and MeSH-controlled search methods are among the most common methods. The goal of this research was to compare the precision of the retrieved sources in the EBSCO Medline base using MeSH-controlled and visual search methods. This research was a semi-empirical study. By holding training workshops, 70 students of higher education in different educational departments of Kashan University of Medical Sciences were taught MeSH-Controlled and visual search methods in 2012. Then, the precision of 300 searches made by these students was calculated based on Best Precision, Useful Precision, and Objective Precision formulas and analyzed in SPSS software using the independent sample T Test, and three precisions obtained with the three precision formulas were studied for the two search methods. The mean precision of the visual method was greater than that of the MeSH-Controlled search for all three types of precision, i.e. Best Precision, Useful Precision, and Objective Precision, and their mean precisions were significantly different (P EBSCO Medline host than to use the controlled method, which requires users to use special keywords. The potential reason for their preference was that the visual method allowed them more freedom of action.

  15. Discovering intrinsic properties of human observers' visual search and mathematical observers' scanning.

    Science.gov (United States)

    He, Xin; Samuelson, Frank; Zeng, Rongping; Sahiner, Berkman

    2014-11-01

    There is a lack of consensus in measuring observer performance in search tasks. To pursue a consensus, we set our goal to obtain metrics that are practical, meaningful, and predictive. We consider a metric practical if it can be implemented to measure human and computer observers' performance. To be meaningful, we propose to discover intrinsic properties of search observers and formulate the metrics to characterize these properties. If the discovered properties allow verifiable predictions, we consider them predictive. We propose a theory and a conjecture toward two intrinsic properties of search observers: rationality in classification as measured by the location-known-exactly (LKE) receiver operating characteristic (ROC) curve and location uncertainty as measured by the effective set size (M*). These two properties are used to develop search models in both single-response and free-response search tasks. To confirm whether these properties are "intrinsic," we investigate their ability in predicting search performance of both human and scanning channelized Hotelling observers. In particular, for each observer, we designed experiments to measure the LKE-ROC curve and M*, which were then used to predict the same observer's performance in other search tasks. The predictions were then compared to the experimentally measured observer performance. Our results indicate that modeling the search performance using the LKE-ROC curve and M* leads to successful predictions in most cases.

  16. Visual search and line bisection in hemianopia: computational modelling of cortical compensatory mechanisms and comparison with hemineglect.

    Science.gov (United States)

    Lanyon, Linda J; Barton, Jason J S

    2013-01-01

    Hemianopia patients have lost vision from the contralateral hemifield, but make behavioural adjustments to compensate for this field loss. As a result, their visual performance and behaviour contrast with those of hemineglect patients who fail to attend to objects contralateral to their lesion. These conditions differ in their ocular fixations and perceptual judgments. During visual search, hemianopic patients make more fixations in contralesional space while hemineglect patients make fewer. During line bisection, hemianopic patients fixate the contralesional line segment more and make a small contralesional bisection error, while hemineglect patients make few contralesional fixations and a larger ipsilesional bisection error. Hence, there is an attentional failure for contralesional space in hemineglect but a compensatory adaptation to attend more to the blind side in hemianopia. A challenge for models of visual attentional processes is to show how compensation is achieved in hemianopia, and why such processes are hindered or inaccessible in hemineglect. We used a neurophysiology-derived computational model to examine possible cortical compensatory processes in simulated hemianopia from a V1 lesion and compared results with those obtained with the same processes under conditions of simulated hemineglect from a parietal lesion. A spatial compensatory bias to increase attention contralesionally replicated hemianopic scanning patterns during visual search but not during line bisection. To reproduce the latter required a second process, an extrastriate lateral connectivity facilitating form completion into the blind field: this allowed accurate placement of fixations on contralesional stimuli and reproduced fixation patterns and the contralesional bisection error of hemianopia. Neither of these two cortical compensatory processes was effective in ameliorating the ipsilesional bias in the hemineglect model. Our results replicate normal and pathological patterns of

  17. Visual search and line bisection in hemianopia: computational modelling of cortical compensatory mechanisms and comparison with hemineglect.

    Directory of Open Access Journals (Sweden)

    Linda J Lanyon

    Full Text Available Hemianopia patients have lost vision from the contralateral hemifield, but make behavioural adjustments to compensate for this field loss. As a result, their visual performance and behaviour contrast with those of hemineglect patients who fail to attend to objects contralateral to their lesion. These conditions differ in their ocular fixations and perceptual judgments. During visual search, hemianopic patients make more fixations in contralesional space while hemineglect patients make fewer. During line bisection, hemianopic patients fixate the contralesional line segment more and make a small contralesional bisection error, while hemineglect patients make few contralesional fixations and a larger ipsilesional bisection error. Hence, there is an attentional failure for contralesional space in hemineglect but a compensatory adaptation to attend more to the blind side in hemianopia. A challenge for models of visual attentional processes is to show how compensation is achieved in hemianopia, and why such processes are hindered or inaccessible in hemineglect. We used a neurophysiology-derived computational model to examine possible cortical compensatory processes in simulated hemianopia from a V1 lesion and compared results with those obtained with the same processes under conditions of simulated hemineglect from a parietal lesion. A spatial compensatory bias to increase attention contralesionally replicated hemianopic scanning patterns during visual search but not during line bisection. To reproduce the latter required a second process, an extrastriate lateral connectivity facilitating form completion into the blind field: this allowed accurate placement of fixations on contralesional stimuli and reproduced fixation patterns and the contralesional bisection error of hemianopia. Neither of these two cortical compensatory processes was effective in ameliorating the ipsilesional bias in the hemineglect model. Our results replicate normal and

  18. Attentional and visual demands for sprint performance in non-fatigued and fatigued conditions : reliability of a repeated sprint test

    NARCIS (Netherlands)

    Reininga, Inge H. F.; Lemmink, Koen A. P. M.; Diercks, Ron L.; Buizer, Arina T.; Stevens, Martin

    2010-01-01

    Background: Physical performance measures are widely used to assess physical function, providing information about physiological and biomechanical aspects of motor performance. However they do not provide insight into the attentional and visual demands for motor performance. A figure-of-eight sprint

  19. Binocular Saccade Coordination in Reading and Visual Search: A Developmental Study in Typical Reader and Dyslexic Children

    Directory of Open Access Journals (Sweden)

    Magali eSeassau

    2014-10-01

    Full Text Available Studies dealing with developmental aspects of binocular eye movement behavior during reading are scarce. In this study we have explored binocular strategies during reading and visual search tasks in a large population of dyslexic and typical readers. Binocular eye movements were recorded using a video-oculography system in 43 dyslexic children (aged 8 to 13 and in a group of 42 age-matched typical readers. The main findings are (i ocular motor characteristics of dyslexic children are impaired in comparison to those reported in typical children in reading task ; (ii a developmental effect exists in reading in control children; in dyslexic children the effect of development was observed only on fixation durations ; (iii ocular motor behavior in the visual search tasks is similar for dyslexic children and for typical readers, except for the disconjugacy during and after the saccade: dyslexic children are impaired in comparison to typical children. Data reported here confirms and expands previous studies on children’s reading. Both reading skills and binocular saccades coordination improve with age in typical readers. The atypical eye movement’s patterns observed in dyslexic children suggest a deficiency in the visual attentional processing as well as an impairment of the ocular motor saccade and vergence systems interaction.

  20. Fat Content Modulates Rapid Detection of Food: A Visual Search Study Using Fast Food and Japanese Diet

    Directory of Open Access Journals (Sweden)

    Reiko Sawada

    2017-06-01

    Full Text Available Rapid detection of food is crucial for the survival of organisms. However, previous visual search studies have reported discrepant results regarding the detection speeds for food vs. non-food items; some experiments showed faster detection of food than non-food, whereas others reported null findings concerning any speed advantage for the detection of food vs. non-food. Moreover, although some previous studies showed that fat content can affect visual attention for food, the effect of fat content on the detection of food remains unclear. To investigate these issues, we measured reaction times (RTs during a visual search task in which participants with normal weight detected high-fat food (i.e., fast food, low-fat food (i.e., Japanese diet, and non-food (i.e., kitchen utensils targets within crowds of non-food distractors (i.e., cars. Results showed that RTs for food targets were shorter than those for non-food targets. Moreover, the RTs for high-fat food were shorter than those for low-fat food. These results suggest that food is more rapidly detected than non-food within the environment and that a higher fat content in food facilitates rapid detection.

  1. Binocular saccade coordination in reading and visual search: a developmental study in typical reader and dyslexic children.

    Science.gov (United States)

    Seassau, Magali; Gérard, Christophe Loic; Bui-Quoc, Emmanuel; Bucci, Maria Pia

    2014-01-01

    Studies dealing with developmental aspects of binocular eye movement behavior during reading are scarce. In this study we have explored binocular strategies during reading and visual search tasks in a large population of dyslexic and typical readers. Binocular eye movements were recorded using a video-oculography system in 43 dyslexic children (aged 8-13) and in a group of 42 age-matched typical readers. The main findings are: (i) ocular motor characteristics of dyslexic children are impaired in comparison to those reported in typical children in reading task; (ii) a developmental effect exists in reading in control children, in dyslexic children the effect of development was observed only on fixation durations; and (iii) ocular motor behavior in the visual search tasks is similar for dyslexic children and for typical readers, except for the disconjugacy during and after the saccade: dyslexic children are impaired in comparison to typical children. Data reported here confirms and expands previous studies on children's reading. Both reading skills and binocular saccades coordination improve with age in typical readers. The atypical eye movement's patterns observed in dyslexic children suggest a deficiency in the visual attentional processing as well as an impairment of the ocular motor saccade and vergence systems interaction.

  2. Crystal structures of the human G3BP1 NTF2-like domain visualize FxFG Nup Repeat Specificity

    DEFF Research Database (Denmark)

    Vognsen, Tina Reinholdt; Möller, Ingvar Rúnar; Kristensen, Ole

    2013-01-01

    Ras GTPase Activating Protein SH3 Domain Binding Protein (G3BP) is a potential anti-cancer drug target implicated in several cellular functions. We have used protein crystallography to solve crystal structures of the human G3BP1 NTF2-like domain both alone and in complex with an FxFG Nup repeat...... crystal form might indicate a novel ligand binding site that, however, remains to be validated. The crystal structures give insight into the nuclear transportation mechanisms of G3BP and provide a basis for future structure based drug design....

  3. In (visual) search for a new distraction: the efficiency of a novel attentional deployment versus semantic meaning regulation strategies.

    Science.gov (United States)

    Sheppes, Gal; Brady, William J; Samson, Andrea C

    2014-01-01

    Cognitive emotion regulation strategies are considered the king's highway to control affective reactions. Two broad categories of cognitive regulation are attentional deployment and semantic meaning. The basic distinctive feature between these categories is the type of conflict between regulatory and emotional processes for dominance, with an early attentional selection conflict in attentional deployment and a late appraisal selection conflict in semantic meaning. However, prior studies that tested the relative efficacy of these two regulatory categories varied the type and the degree of conflict. Our major goal was to test the relative efficacy of a novel attentional deployment strategy (visual search distraction) and a classic semantic meaning strategy (reappraisal) that have a different type of conflict but a matched degree of conflict. Specifically, visual search distraction involves a strong degree of attentional selection conflict manifested in attending subtle non-emotional features that are camouflaged within potent negative emotional stimuli. Reappraisal involves a strong degree of appraisal selection conflict manifested in construing neutral reappraisals that rely on potent negative emotional appraisals. Based on our theoretical model we hypothesized and found that visual search distraction was as effective as cognitive reappraisal in down-regulating the experience of low intensity of negative emotion (Study 1), but more effective, less effortful, and more strongly blocking emotional information processing than cognitive reappraisal when regulating high intensity (Study 2). A final study ruled out a demand characteristics explanation by showing that participants' expectations about how they should feel diverged from how they actually reported feeling following regulation (Study 3). Our findings suggest that the basic difference in the type rather than degree of conflict between attentional deployment and semantic meaning determines strategies' outcome.

  4. Textual and Visual Information in eWOM: A Gap Between Preferences in Information Search and Diffusion

    DEFF Research Database (Denmark)

    Lee, Geunhee; Tussyadiah, Iis

    2010-01-01

    This article examines the gap between travel-related information search and diffusion by online users in order to better understand the important role of visual information in electronic word of mouth (eWOM). Several analyses were conducted to investigate differences in travelers' preferences...... spreading eWOM. This study discusses the reasons for this gap and the individual differences in travelers' information format preferences when retrieving and diffusing travel-related information online. Managerial implications for destination marketers and user-generated content platform managers...

  5. Textual and Visual Information in eWOM: A Gap Between Preferences in Information Search and Diffusion

    DEFF Research Database (Denmark)

    Lee, Geunhee; Tussyadiah, Iis

    2010-01-01

    This article examines the gap between travel-related information search and diffusion by online users in order to better understand the important role of visual information in electronic word of mouth (eWOM). Several analyses were conducted to investigate differences in travelers' preferences...... spreading eWOM. This study discusses the reasons for this gap and the individual differences in travelers' information format preferences when retrieving and diffusing travel-related information online. Managerial implications for destination marketers and user-generated content platform managers...

  6. Spatial and temporal dynamics of visual search tasks distinguish subtypes of unilateral spatial neglect: Comparison of two cases with viewer-centered and stimulus-centered neglect.

    Science.gov (United States)

    Mizuno, Katsuhiro; Kato, Kenji; Tsuji, Tetsuya; Shindo, Keiichiro; Kobayashi, Yukiko; Liu, Meigen

    2016-08-01

    We developed a computerised test to evaluate unilateral spatial neglect (USN) using a touchscreen display, and estimated the spatial and temporal patterns of visual search in USN patients. The results between a viewer-centered USN patient and a stimulus-centered USN patient were compared. Two right-brain-damaged patients with USN, a patient without USN, and 16 healthy subjects performed a simple cancellation test, the circle test, a visuomotor search test, and a visual search test. According to the results of the circle test, one USN patient had stimulus-centered neglect and a one had viewer-centered neglect. The spatial and temporal patterns of these two USN patients were compared. The spatial and temporal patterns of cancellation were different in the stimulus-centered USN patient and the viewer-centered USN patient. The viewer-centered USN patient completed the simple cancellation task, but paused when transferring from the right side to the left side of the display. Unexpectedly, this patient did not exhibit rightward attention bias on the visuomotor and visual search tests, but the stimulus-centered USN patient did. The computer-based assessment system provided information on the dynamic visual search strategy of patients with USN. The spatial and temporal pattern of cancellation and visual search were different across the two patients with different subtypes of neglect.

  7. Seek and you shall remember: scene semantics interact with visual search to build better memories.

    Science.gov (United States)

    Draschkow, Dejan; Wolfe, Jeremy M; Võ, Melissa L H

    2014-07-11

    Memorizing critical objects and their locations is an essential part of everyday life. In the present study, incidental encoding of objects in naturalistic scenes during search was compared to explicit memorization of those scenes. To investigate if prior knowledge of scene structure influences these two types of encoding differently, we used meaningless arrays of objects as well as objects in real-world, semantically meaningful images. Surprisingly, when participants were asked to recall scenes, their memory performance was markedly better for searched objects than for objects they had explicitly tried to memorize, even though participants in the search condition were not explicitly asked to memorize objects. This finding held true even when objects were observed for an equal amount of time in both conditions. Critically, the recall benefit for searched over memorized objects in scenes was eliminated when objects were presented on uniform, non-scene backgrounds rather than in a full scene context. Thus, scene semantics not only help us search for objects in naturalistic scenes, but appear to produce a representation that supports our memory for those objects beyond intentional memorization. © 2014 ARVO.

  8. Parasite Lost: Chemical and Visual Cues Used by Pseudacteon in Search of Azteca instabilis.

    Science.gov (United States)

    Mathis, Kaitlyn A; Philpott, Stacy M; Moreira, Rayane F

    2011-05-01

    An undescribed species of phorid fly (genus: Pseudacteon) parasitizes the ant Azteca instabilis F Smith, by first locating these ants through the use of both chemical and visual cues. Experiments were performed in Chiapas, Mexico to examine a) the anatomical source of phorid attractants, b) the specific chemicals produced that attract phorids, and c) the nature of the visual cues used by phorids to locate the ants. We determined that phorid-attracting chemicals were present within the dorsal section of the abdomen, the location of the pygidial gland. Further experiments indicate that a pygidial gland compound, 1-acetyl-2-methylcyclopentane, is at least partially responsible for attracting phorid flies to their host. Finally, although visual cues such as movement were important for host location, size and color of objects did not influence the frequency with which phorids attacked moving targets.

  9. Predicting Glycerophosphoinositol Identities in Lipidomic Datasets Using VaLID (Visualization and Phospholipid Identification—An Online Bioinformatic Search Engine

    Directory of Open Access Journals (Sweden)

    Graeme S. V. McDowell

    2014-01-01

    Full Text Available The capacity to predict and visualize all theoretically possible glycerophospholipid molecular identities present in lipidomic datasets is currently limited. To address this issue, we expanded the search-engine and compositional databases of the online Visualization and Phospholipid Identification (VaLID bioinformatic tool to include the glycerophosphoinositol superfamily. VaLID v1.0.0 originally allowed exact and average mass libraries of 736,584 individual species from eight phospholipid classes: glycerophosphates, glyceropyrophosphates, glycerophosphocholines, glycerophosphoethanolamines, glycerophosphoglycerols, glycerophosphoglycerophosphates, glycerophosphoserines, and cytidine 5′-diphosphate 1,2-diacyl-sn-glycerols to be searched for any mass to charge value (with adjustable tolerance levels under a variety of mass spectrometry conditions. Here, we describe an update that now includes all possible glycerophosphoinositols, glycerophosphoinositol monophosphates, glycerophosphoinositol bisphosphates, and glycerophosphoinositol trisphosphates. This update expands the total number of lipid species represented in the VaLID v2.0.0 database to 1,473,168 phospholipids. Each phospholipid can be generated in skeletal representation. A subset of species curated by the Canadian Institutes of Health Research Training Program in Neurodegenerative Lipidomics (CTPNL team is provided as an array of high-resolution structures. VaLID is freely available and responds to all users through the CTPNL resources web site.

  10. Predicting glycerophosphoinositol identities in lipidomic datasets using VaLID (Visualization and Phospholipid Identification)--an online bioinformatic search engine.

    Science.gov (United States)

    McDowell, Graeme S V; Blanchard, Alexandre P; Taylor, Graeme P; Figeys, Daniel; Fai, Stephen; Bennett, Steffany A L

    2014-01-01

    The capacity to predict and visualize all theoretically possible glycerophospholipid molecular identities present in lipidomic datasets is currently limited. To address this issue, we expanded the search-engine and compositional databases of the online Visualization and Phospholipid Identification (VaLID) bioinformatic tool to include the glycerophosphoinositol superfamily. VaLID v1.0.0 originally allowed exact and average mass libraries of 736,584 individual species from eight phospholipid classes: glycerophosphates, glyceropyrophosphates, glycerophosphocholines, glycerophosphoethanolamines, glycerophosphoglycerols, glycerophosphoglycerophosphates, glycerophosphoserines, and cytidine 5'-diphosphate 1,2-diacyl-sn-glycerols to be searched for any mass to charge value (with adjustable tolerance levels) under a variety of mass spectrometry conditions. Here, we describe an update that now includes all possible glycerophosphoinositols, glycerophosphoinositol monophosphates, glycerophosphoinositol bisphosphates, and glycerophosphoinositol trisphosphates. This update expands the total number of lipid species represented in the VaLID v2.0.0 database to 1,473,168 phospholipids. Each phospholipid can be generated in skeletal representation. A subset of species curated by the Canadian Institutes of Health Research Training Program in Neurodegenerative Lipidomics (CTPNL) team is provided as an array of high-resolution structures. VaLID is freely available and responds to all users through the CTPNL resources web site.

  11. The Development of Visual Search in Infants and Very Young Children.

    Science.gov (United States)

    Gerhardstein, Peter; Rovee-Collier, Carolyn

    2002-01-01

    Trained 1- to 3-year-olds to touch a video screen displaying a unique target and appearing among varying numbers of distracters; correct responses triggered a sound and four animated objects on the screen. Found that children's reaction time patterns resembled those from adults in corresponding search tasks, suggesting that basic perceptual…

  12. The Tug of War between Phonological, Semantic and Shape Information in Language-Mediated Visual Search

    Science.gov (United States)

    Huettig, Falk; McQueen, James M.

    2007-01-01

    Experiments 1 and 2 examined the time-course of retrieval of phonological, visual-shape and semantic knowledge as Dutch participants listened to sentences and looked at displays of four pictures. Given a sentence with "beker," "beaker," for example, the display contained phonological (a beaver, "bever"), shape (a bobbin, "klos"), and semantic (a…

  13. The tug of war between phonological, semantic and shape information in language-mediated visual search

    NARCIS (Netherlands)

    Hüttig, F.; McQueen, J.M.

    2007-01-01

    Experiments 1 and 2 examined the time-course of retrieval of phonological, visual-shape and semantic knowledge as Dutch participants listened to sentences and looked at displays of four pictures. Given a sentence with beker, 'beaker' for example, the display contained phonological (a beaver, bever),

  14. Collaborative Video Search Combining Video Retrieval with Human-Based Visual Inspection

    NARCIS (Netherlands)

    Hudelist, M.A.; Cobârzan, C.; Beecks, C.; van de Werken, Rob; Kletz, S.; Hürst, W.O.; Schoeffmann, K.

    2016-01-01

    We propose a novel video browsing approach that aims at optimally integrating traditional, machine-based retrieval methods with an interface design optimized for human browsing performance. Advanced video retrieval and filtering (e.g., via color and motion signatures, and visual concepts) on a deskt

  15. The tug of war between phonological, semantic and shape information in language-mediated visual search

    NARCIS (Netherlands)

    Hüttig, F.; McQueen, J.M.

    2007-01-01

    Experiments 1 and 2 examined the time-course of retrieval of phonological, visual-shape and semantic knowledge as Dutch participants listened to sentences and looked at displays of four pictures. Given a sentence with beker, 'beaker' for example, the display contained phonological (a beaver, bever),

  16. Beyond metadata: searching your archive based on its audio-visual content

    NARCIS (Netherlands)

    Tommasi, T.; Aly, R.; McGuinness, K.; Chatfield, K.; Arandjelovic, R.; Parkhi, O.; Ordelman, R.; Zisserman, A.; Tuytelaars, T.

    2014-01-01

    The EU FP7 project AXES aims at better understanding the needs of archive users and supporting them with systems that reach beyond the state-of-the-art. Our system allows users to instantaneously retrieve content using metadata, spoken words, or a vocabulary of reliably detected visual concepts comp

  17. PatchMatch Filter: Edge-Aware Filtering Meets Randomized Search for Visual Correspondence.

    Science.gov (United States)

    Lu, Jiangbo; Li, Yu; Yang, Hongsheng; Min, Dongbo; Eng, Weiyong; Do, Minh N

    2017-09-01

    Though many tasks in computer vision can be formulated elegantly as pixel-labeling problems, a typical challenge discouraging such a discrete formulation is often due to computational efficiency. Recent studies on fast cost volume filtering based on efficient edge-aware filters provide a fast alternative to solve discrete labeling problems, with the complexity independent of the support window size. However, these methods still have to step through the entire cost volume exhaustively, which makes the solution speed scale linearly with the label space size. When the label space is huge or even infinite, which is often the case for (subpixel-accurate) stereo and optical flow estimation, their computational complexity becomes quickly unacceptable. Developed to search approximate nearest neighbors rapidly, the PatchMatch method can significantly reduce the complexity dependency on the search space size. But, its pixel-wise randomized search and fragmented data access within the 3D cost volume seriously hinder the application of efficient cost slice filtering. This paper presents a generic and fast computational framework for general multi-labeling problems called PatchMatch Filter (PMF). We explore effective and efficient strategies to weave together these two fundamental techniques developed in isolation, i.e., PatchMatch-based randomized search and efficient edge-aware image filtering. By decompositing an image into compact superpixels, we also propose superpixel-based novel search strategies that generalize and improve the original PatchMatch method. Further motivated to improve the regularization strength, we propose a simple yet effective cross-scale consistency constraint, which handles labeling estimation for large low-textured regions more reliably than a single-scale PMF algorithm. Focusing on dense correspondence field estimation in this paper, we demonstrate PMF's applications in stereo and optical flow. Our PMF methods achieve top-tier correspondence

  18. Target templates specify visual, not semantic, features to guide search: A marked asymmetry between seeking and ignoring.

    Science.gov (United States)

    Daffron, Jennifer L; Davis, Greg

    2016-10-01

    Top-down search templates specify targets' properties, either to guide attention toward the target or, independently, to accelerate the recognition of individual search items. Some previous studies have concluded that target templates can specify semantic categories to guide attention, though dissociating the effects of semantic versus visual features has proven difficult. In the present experiments, we examined the roles of target templates in search performance, by measuring the "two-template costs" incurred when observers did not know which of two types of targets would be presented. For target templates, these costs only varied with set size when a template could specify a target's features. Any semantic influences did not affect the guidance of attention, only the recognition of individual items. In contrast, templates for rejection-specifying the properties of irrelevant nontargets-do appear to specify semantic properties to guide attention away from those items, without affecting recognition. These qualitative differences between the two types of templates suggest that the processes of seeking and ignoring are fundamentally different.

  19. Eyes Do Not Have it: A Collinear Salient Line Interferes with Visual Search Responses but Not Eye Movements

    Directory of Open Access Journals (Sweden)

    Li Jingling

    2011-05-01

    Full Text Available Our previous study found that a task-irrelevant salient line impaired visual search when the salient line was composite of collinear bars (Jingling, 2010. In this study, we further investigated whether this inhibition can be observed in eye movements. The search display was a lattice of 21 by 27 bars. The task was to discriminate the orientation of a target, which was presented on one of seven bars in the central of search display. One of the columns of the bars was vertical, thus bars on this line were collinear to each other. The other bars were horizontal, making the collinear line salient. The target was on the bars at salient line by chance. Eight participants were recruited, and eye movements were recorded by EyeLink 1,000 with 250 Hz sampling rate. Results of hand response times replicated our previous findings: Responses were slower for targets on the bars at the salient line than that in the background. However, saccadic duration was not statistically different for these two types of targets. Our data showed that a collinear salient line interferes with key press but not eye movements, suggesting that the inhibitory effect emerged later than sensory information process.

  20. Target resolution in visual search involves the direct suppression of distractors: evidence from electrophysiology.

    Science.gov (United States)

    Hilimire, Matthew R; Hickey, Clayton; Corballis, Paul M

    2012-04-01

    Attentional selection requires both the enhancement of target stimuli and the suppression of distractors. Target enhancement and distractor suppression have been associated with separable components of the lateralized event-related potential: the target negativity and distractor positivity (Pd). We examined the distractor suppression mechanisms indexed by the Pd. The Pd may reflect mechanisms that guide attention away from distractors during search or mechanisms involved in the subsequent resolution of target features. To determine which of these alternatives was more likely, we had participants view search arrays that contained only a target, only a distractor, or both. The Pd elicited by distractors was substantially larger when the display also contained a target, consistent with the idea that this component reflects a mechanism of distractor suppression activated during the resolution and disambiguation of target features.

  1. Visualizing the search for radiation-damaged DNA bases in real time

    Science.gov (United States)

    Lee, Andrea J.; Wallace, Susan S.

    2016-11-01

    The Base Excision Repair (BER) pathway removes the vast majority of damages produced by ionizing radiation, including the plethora of radiation-damaged purines and pyrimidines. The first enzymes in the BER pathway are DNA glycosylases, which are responsible for finding and removing the damaged base. Although much is known about the biochemistry of DNA glycosylases, how these enzymes locate their specific damage substrates among an excess of undamaged bases has long remained a mystery. Here we describe the use of single molecule fluorescence to observe the bacterial DNA glycosylases, Nth, Fpg and Nei, scanning along undamaged and damaged DNA. We show that all three enzymes randomly diffuse on the DNA molecule and employ a wedge residue to search for and locate damage. The search behavior of the Escherichia coli DNA glycosylases likely provides a paradigm for their homologous mammalian counterparts.

  2. Neural evidence for distracter suppression during visual search in real-world scenes.

    Science.gov (United States)

    Seidl, Katharina N; Peelen, Marius V; Kastner, Sabine

    2012-08-22

    Selecting visual information from cluttered real-world scenes involves the matching of visual input to the observer's attentional set--an internal representation of objects that are relevant for current behavioral goals. When goals change, a new attentional set needs to be instantiated, requiring the suppression of the previous set to prevent distraction by objects that are no longer relevant. In the present fMRI study, we investigated how such suppression is implemented at the neural level. We measured human brain activity in response to natural scene photographs that could contain objects from (1) a currently relevant (target) category, (2) a previously but not presently relevant (distracter) category, and/or (3) a never relevant (neutral) category. Across conditions, multivoxel response patterns in object-selective cortex carried information about objects present in the scenes. However, this information strongly depended on the task relevance of the objects. As expected, information about the target category was significantly increased relative to the neutral category, indicating top-down enhancement of task-relevant information. Importantly, information about the distracter category was significantly reduced relative to the neutral category, indicating that the processing of previously relevant objects was suppressed. Such active suppression at the level of high-order visual cortex may serve to prevent the erroneous selection of, or interference from, objects that are no longer relevant to ongoing behavior. We conclude that the enhancement of relevant information and the suppression of distracting information both contribute to the efficient selection of visual information from cluttered real-world scenes.

  3. Flexible cue combination in the guidance of attention in visual search

    Science.gov (United States)

    Brand, John; Oriet, Chris; Johnson, Aaron P.; Wolfe, Jeremy M.

    2014-01-01

    Hodsoll and Humphreys (2001) have assessed the relative contributions of stimulus-driven and user-driven knowledge on linearly- and nonlinearly separable search. However, the target feature used to determine linear separability in their task (i.e., target size) was required to locate the target. In the present work, we investigated the contributions of stimulus-driven and user-driven knowledge when a linearly- or nonlinearly-separable feature is available but not required for target identification. We asked observers to complete a series of standard color X orientation conjunction searches in which target size was either linearly- or nonlinearly separable from the size of the distractors. When guidance by color X orientation and by size information are both available, observers rely on whichever information results in the best search efficiency. This is the case irrespective of whether we provide target foreknowledge by blocking stimulus conditions, suggesting that feature information is used in both a stimulus-driven and user-driven fashion. PMID:25463553

  4. When and why might a Computer Aided Detection (CAD) system interfere with visual search? An eye-tracking study

    Science.gov (United States)

    Drew, Trafton; Cunningham, Corbin; Wolfe, Jeremy

    2012-01-01

    Rational and Objectives Computer Aided Detection (CAD) systems are intended to improve performance. This study investigates how CAD might actually interfere with a visual search task. This is a laboratory study with implications for clinical use of CAD. Methods 47 naïve observers in two studies were asked to search for a target, embedded in 1/f2.4 noise while we monitored their eye-movements. For some observers, a CAD system marked 75% of targets and 10% of distractors while other observers completed the study without CAD. In Experiment 1, the CAD system’s primary function was to tell observers where the target might be. In Experiment 2, CAD provided information about target identity. Results In Experiment 1, there was a significant enhancement of observer sensitivity in the presence of CAD (t(22)=4.74, pCAD system were missed more frequently than equivalent targets in No CAD blocks of the experiment (t(22)=7.02, pCAD, but also no significant cost on sensitivity to unmarked targets (t(22)=0.6, p=n.s.). Finally, in both experiments, CAD produced reliable changes in eye-movements: CAD observers examined a lower total percentage of the search area than the No CAD observers (Ex 1: t(48)=3.05, pCAD signals do not combine with observers’ unaided performance in a straight-forward manner. CAD can engender a sense of certainty that can lead to incomplete search and elevated chances of missing unmarked stimuli. PMID:22958720

  5. Understanding the contribution of target repetition and target expectation to the emergence of the prevalence effect in visual search.

    Science.gov (United States)

    Godwin, Hayward J; Menneer, Tamaryn; Riggs, Charlotte A; Taunton, Dominic; Cave, Kyle R; Donnel, Nick

    2016-06-01

    Behavior in visual search tasks is influenced by the proportion of trials on which a target is presented (the target prevalence). Previous research has shown that when target prevalence is low (2 % prevalence), participants tend to miss targets, as compared with higher prevalence levels (e.g., 50 % prevalence). There is an ongoing debate regarding the relative contributions of target repetition and the expectation that a target will occur in the emergence of prevalence effects. In order to disentangle these two factors, we went beyond previous studies by directly manipulating participants' expectations regarding how likely a target was to appear on a given trial. This we achieved without using cues or feedback. Our results indicated that both target repetition and target expectation contribute to the emergence of the prevalence effect.

  6. P2-11: Attentional Control Setting Did Not Alter the Interference from Global Collinear Distractor in Visual Search

    Directory of Open Access Journals (Sweden)

    Wan-Chen Chang

    2012-10-01

    Full Text Available A salient item usually captures our attention in visual search. When a distractor is salient, it should help observers to find a target that was overlapping it. However, in Jingling and Tseng (in press Journal of Experimental Psychology: Human Perception and Performance doi: 10.1037/a0027325, a target overlapping with a salient distractor took longer to discriminate than that which was non-overlapped, if the salient distractor was grouped by collinearity. One of the reasons for prolonged responses in overlapping targets is that the collinear distractor was not contingent on the attentional control setting of task requirements. More specifically, the target was a broken bar, which might induce an attentional control setting on searching for discontinuity. Meanwhile, the distractor was grouped continuously, which was against the attentional control setting and generated interference to the overlapping target. In this study, we modified the definition of the target and tested whether the interference was preserved when the attentional control setting was not on discontinuity. The target was either a diamond or a square, and was either overlapping or not with the collinear salient distractor. Participants discriminated the shape of the target. The results replicated our previous study in that overlapping targets were harder to find. Our result argued against the possibility that the interference was induced by conflicts between the collinear distractor and the attentional control setting, implying that the interference might have been generated from earlier perceptual processing.

  7. Accelerating object detection via a visual-feature-directed search cascade: algorithm and field programmable gate array implementation

    Science.gov (United States)

    Kyrkou, Christos; Theocharides, Theocharis

    2016-07-01

    Object detection is a major step in several computer vision applications and a requirement for most smart camera systems. Recent advances in hardware acceleration for real-time object detection feature extensive use of reconfigurable hardware [field programmable gate arrays (FPGAs)], and relevant research has produced quite fascinating results, in both the accuracy of the detection algorithms as well as the performance in terms of frames per second (fps) for use in embedded smart camera systems. Detecting objects in images, however, is a daunting task and often involves hardware-inefficient steps, both in terms of the datapath design and in terms of input/output and memory access patterns. We present how a visual-feature-directed search cascade composed of motion detection, depth computation, and edge detection, can have a significant impact in reducing the data that needs to be examined by the classification engine for the presence of an object of interest. Experimental results on a Spartan 6 FPGA platform for face detection indicate data search reduction of up to 95%, which results in the system being able to process up to 50 1024×768 pixels images per second with a significantly reduced number of false positives.

  8. Towards using eye-tracking data to develop visual-search observers for x-ray breast imaging

    Science.gov (United States)

    Jiang, Zhengqiang; Liang, Zhihua; Das, Mini; Gifford, Howard C.

    2015-03-01

    Visual-search (VS) model observers have the potential to provide reliable predictions of human-observer performance in detection-localization tasks. The purpose of this work was to examine some characteristics of human gaze on breast images with the goal of informing the design of our VS observers. Using a helmet-mounted eye- tracking system, we recording the movement of gaze from human observers as they searched for masses in sets of 2D digital breast tomosynthesis (DBT) images. The masses in this study were of a single profile. The DBT images were extracted from image volumes reconstructed with filtered back-projection and penalized maximum- likelihood methods. Fixation times associated with observer points of interest (POIs) were computed from the observer data. The fixation times were then compared to sets of morphological feature values extracted from the images. These features, extracted as cross-correlations involving the mass profile and the test image, included the matched filter (MF), gradient MF, and Laplacian MF. For this initial investigation, we computed correlation coefficients between the fixation times and the feature values.

  9. Looking for a face in the crowd: fixation-related potentials in an eye-movement visual search task.

    Science.gov (United States)

    Kaunitz, Lisandro N; Kamienkowski, Juan E; Varatharajah, Alexander; Sigman, Mariano; Quiroga, Rodrigo Quian; Ison, Matias J

    2014-04-01

    Despite the compelling contribution of the study of event related potentials (ERPs) and eye movements to cognitive neuroscience, these two approaches have largely evolved independently. We designed an eye-movement visual search paradigm that allowed us to concurrently record EEG and eye movements while subjects were asked to find a hidden target face in a crowded scene with distractor faces. Fixation event-related potentials (fERPs) to target and distractor stimuli showed the emergence of robust sensory components associated with the perception of stimuli and cognitive components associated with the detection of target faces. We compared those components with the ones obtained in a control task at fixation: qualitative similarities as well as differences in terms of scalp topography and latency emerged between the two. By using single trial analyses, fixations to target and distractors could be decoded from the EEG signals above chance level in 11 out of 12 subjects. Our results show that EEG signatures related to cognitive behavior develop across spatially unconstrained exploration of natural scenes and provide a first step towards understanding the mechanisms of target detection during natural search.

  10. How You Move Is What I See: Planning an Action Biases a Partner’s Visual Search

    Science.gov (United States)

    Dötsch, Dominik; Vesper, Cordula; Schubö, Anna

    2017-01-01

    Activating action representations can modulate perceptual processing of action-relevant dimensions, indicative of a common-coding of perception and action. When two or more agents work together in joint action, individual agents often need to consider not only their own actions and their effects on the world, but also predict the actions of a co-acting partner. If in these situations the action of a partner is represented in a functionally equivalent way to the agent’s own actions, one may also expect interaction effects between action and perception across jointly acting individuals. The present study investigated whether the action of a co-acting partner may modulate an agent’s perception. The “performer” prepared a grasping or pointing movement toward a physical target while the “searcher” performed a visual search task. The performer’s planned action impaired the searcher’s perceptual performance when the search target dimension was relevant to the performer’s movement execution. These results demonstrate an action-induced modulation of perceptual processes across participants and indicate that agents represent their partner’s action by employing the same perceptual system they use to represent an own action. We suggest that task representations in joint action operate along multiple levels of a cross-brain predictive coding system, which provides agents with information about a partner’s actions when they coordinate to reach a common goal.

  11. Between-object and within-object saccade programming in a visual search task.

    Science.gov (United States)

    Vergilino-Perez, Dorine; Findlay, John M

    2006-07-01

    The role of the perceptual organization of the visual display on eye movement control was examined in two experiments using a task where a two-saccade sequence was directed toward either a single elongated object or three separate shorter objects. In the first experiment, we examined the consequences for the second saccade of a small displacement of the whole display during the first saccade. We found that between-object saccades compensated for the displacement to aim for a target position on the new object whereas within-object saccades did not show compensation but were coded as a fixed motor vector applied irrespective of wherever the preceding saccade landed. In the second experiment, we extended the paradigm to examine saccades performed in different directions. The results suggest that the within-object and between-object saccade distinction is an essential feature of saccadic planning.

  12. Similarity landscapes: An improved method for scientific visualization of information from protein and DNA database searches

    Energy Technology Data Exchange (ETDEWEB)

    Dogget, N.; Myers, G. [Los Alamos National Lab., NM (United States); Wills, C.J. [Univ. of California, San Diego, CA (United States)

    1998-12-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have used computer simulations and examination of a variety of databases to answer questions about a wide range of evolutionary questions. The authors have found that there is a clear distinction in the evolution of HIV-1 and HIV-2, with the former and more virulent virus evolving more rapidly at a functional level. The authors have discovered highly non-random patterns in the evolution of HIV-1 that can be attributed to a variety of selective pressures. In the course of examination of microsatellite DNA (short repeat regions) in microorganisms, the authors have found clear differences between prokaryotes and eukaryotes in their distribution, differences that can be tied to different selective pressures. They have developed a new method (topiary pruning) for enhancing the phylogenetic information contained in DNA sequences. Most recently, the authors have discovered effects in complex rainforest ecosystems that indicate strong frequency-dependent interactions between host species and their parasites, leading to the maintenance of ecosystem variability.

  13. Response Time, Visual Search Strategy, and Anticipatory Skills in Volleyball Players

    Directory of Open Access Journals (Sweden)

    Alessandro Piras

    2014-01-01

    Full Text Available This paper aimed at comparing expert and novice volleyball players in a visuomotor task using realistic stimuli. Videos of a volleyball setter performing offensive action were presented to participants, while their eye movements were recorded by a head-mounted video based eye tracker. Participants were asked to foresee the direction (forward or backward of the setter’s toss by pressing one of two keys. Key-press response time, response accuracy, and gaze behaviour were measured from the first frame showing the setter’s hand-ball contact to the button pressed by the participants. Experts were faster and more accurate in predicting the direction of the setting than novices, showing accurate predictions when they used a search strategy involving fewer fixations of longer duration, as well as spending less time in fixating all display areas from which they extract critical information for the judgment. These results are consistent with the view that superior performance in experts is due to their ability to efficiently encode domain-specific information that is relevant to the task.

  14. A Multi-Area Stochastic Model for a Covert Visual Search Task.

    Directory of Open Access Journals (Sweden)

    Michael A Schwemmer

    Full Text Available Decisions typically comprise several elements. For example, attention must be directed towards specific objects, their identities recognized, and a choice made among alternatives. Pairs of competing accumulators and drift-diffusion processes provide good models of evidence integration in two-alternative perceptual choices, but more complex tasks requiring the coordination of attention and decision making involve multistage processing and multiple brain areas. Here we consider a task in which a target is located among distractors and its identity reported by lever release. The data comprise reaction times, accuracies, and single unit recordings from two monkeys' lateral interparietal area (LIP neurons. LIP firing rates distinguish between targets and distractors, exhibit stimulus set size effects, and show response-hemifield congruence effects. These data motivate our model, which uses coupled sets of leaky competing accumulators to represent processes hypothesized to occur in feature-selective areas and limb motor and pre-motor areas, together with the visual selection process occurring in LIP. Model simulations capture the electrophysiological and behavioral data, and fitted parameters suggest that different connection weights between LIP and the other cortical areas may account for the observed behavioral differences between the animals.

  15. What Top-Down Task Sets Do for Us: An ERP Study on the Benefits of Advance Preparation in Visual Search

    Science.gov (United States)

    Eimer, Martin; Kiss, Monika; Nicholas, Susan

    2011-01-01

    When target-defining features are specified in advance, attentional target selection in visual search is controlled by preparatory top-down task sets. We used ERP measures to study voluntary target selection in the absence of such feature-specific task sets, and to compare it to selection that is guided by advance knowledge about target features.…

  16. Visual Search for Basic Emotional Expressions in Autism; Impaired Processing of Anger, Fear and Sadness, but a Typical Happy Face Advantage

    Science.gov (United States)

    Farran, Emily K.; Branson, Amanda; King, Ben J.

    2011-01-01

    Facial expression recognition was investigated in 20 males with high functioning autism (HFA) or Asperger syndrome (AS), compared to typically developing individuals matched for chronological age (TD CA group) and verbal and non-verbal ability (TD V/NV group). This was the first study to employ a visual search, "face in the crowd" paradigm with a…

  17. Different target-discrimination times can be followed by the same saccade-initiation timing in different stimulus conditions during visual searches.

    Science.gov (United States)

    Tanaka, Tomohiro; Nishida, Satoshi; Ogawa, Tadashi

    2015-07-01

    The neuronal processes that underlie visual searches can be divided into two stages: target discrimination and saccade preparation/generation. This predicts that the length of time of the prediscrimination stage varies according to the search difficulty across different stimulus conditions, whereas the length of the latter postdiscrimination stage is stimulus invariant. However, recent studies have suggested that the length of the postdiscrimination interval changes with different stimulus conditions. To address whether and how the visual stimulus affects determination of the postdiscrimination interval, we recorded single-neuron activity in the lateral intraparietal area (LIP) when monkeys (Macaca fuscata) performed a color-singleton search involving four stimulus conditions that differed regarding luminance (Bright vs. Dim) and target-distractor color similarity (Easy vs. Difficult). We specifically focused on comparing activities between the Bright-Difficult and Dim-Easy conditions, in which the visual stimuli were considerably different, but the mean reaction times were indistinguishable. This allowed us to examine the neuronal activity when the difference in the degree of search speed between different stimulus conditions was minimal. We found that not only prediscrimination but also postdiscrimination intervals varied across stimulus conditions: the postdiscrimination interval was longer in the Dim-Easy condition than in the Bright-Difficult condition. Further analysis revealed that the postdiscrimination interval might vary with stimulus luminance. A computer simulation using an accumulation-to-threshold model suggested that the luminance-related difference in visual response strength at discrimination time could be the cause of different postdiscrimination intervals.

  18. Exploring the potential of analysing visual search behaviour data using FROC (free-response receiver operating characteristic) method: an initial study

    Science.gov (United States)

    Dong, Leng; Chen, Yan; Dias, Sarah; Stone, William; Dias, Joseph; Rout, John; Gale, Alastair G.

    2017-03-01

    Visual search techniques and FROC analysis have been widely used in radiology to understand medical image perceptual behaviour and diagnostic performance. The potential of exploiting the advantages of both methodologies is of great interest to medical researchers. In this study, eye tracking data of eight dental practitioners was investigated. The visual search measures and their analyses are considered here. Each participant interpreted 20 dental radiographs which were chosen by an expert dental radiologist. Various eye movement measurements were obtained based on image area of interest (AOI) information. FROC analysis was then carried out by using these eye movement measurements as a direct input source. The performance of FROC methods using different input parameters was tested. The results showed that there were significant differences in FROC measures, based on eye movement data, between groups with different experience levels. Namely, the area under the curve (AUC) score evidenced higher values for experienced group for the measurements of fixation and dwell time. Also, positive correlations were found for AUC scores between the eye movement data conducted FROC and rating based FROC. FROC analysis using eye movement measurements as input variables can act as a potential performance indicator to deliver assessment in medical imaging interpretation and assess training procedures. Visual search data analyses lead to new ways of combining eye movement data and FROC methods to provide an alternative dimension to assess performance and visual search behaviour in the area of medical imaging perceptual tasks.

  19. Functional interaction between right parietal and bilateral frontal cortices during visual search tasks revealed using functional magnetic imaging and transcranial direct current stimulation.

    Directory of Open Access Journals (Sweden)

    Amanda Ellison

    Full Text Available The existence of a network of brain regions which are activated when one undertakes a difficult visual search task is well established. Two primary nodes on this network are right posterior parietal cortex (rPPC and right frontal eye fields. Both have been shown to be involved in the orientation of attention, but the contingency that the activity of one of these areas has on the other is less clear. We sought to investigate this question by using transcranial direct current stimulation (tDCS to selectively decrease activity in rPPC and then asking participants to perform a visual search task whilst undergoing functional magnetic resonance imaging. Comparison with a condition in which sham tDCS was applied revealed that cathodal tDCS over rPPC causes a selective bilateral decrease in frontal activity when performing a visual search task. This result demonstrates for the first time that premotor regions within the frontal lobe and rPPC are not only necessary to carry out a visual search task, but that they work together to bring about normal function.

  20. The influence of action video game playing on eye movement behaviour during visual search in abstract, in-game and natural scenes.

    Science.gov (United States)

    Azizi, Elham; Abel, Larry A; Stainer, Matthew J

    2017-02-01

    Action game playing has been associated with several improvements in visual attention tasks. However, it is not clear how such changes might influence the way we overtly select information from our visual world (i.e. eye movements). We examined whether action-video-game training changed eye movement behaviour in a series of visual search tasks including conjunctive search (relatively abstracted from natural behaviour), game-related search, and more naturalistic scene search. Forty nongamers were trained in either an action first-person shooter game or a card game (control) for 10 hours. As a further control, we recorded eye movements of 20 experienced action gamers on the same tasks. The results did not show any change in duration of fixations or saccade amplitude either from before to after the training or between all nongamers (pretraining) and experienced action gamers. However, we observed a change in search strategy, reflected by a reduction in the vertical distribution of fixations for the game-related search task in the action-game-trained group. This might suggest learning the likely distribution of targets. In other words, game training only skilled participants to search game images for targets important to the game, with no indication of transfer to the more natural scene search. Taken together, these results suggest no modification in overt allocation of attention. Either the skills that can be trained with action gaming are not powerful enough to influence information selection through eye movements, or action-game-learned skills are not used when deciding where to move the eyes.

  1. Uploading, Searching and Visualizing of Paleomagnetic and Rock Magnetic Data in the Online MagIC Database

    Science.gov (United States)

    Minnett, R.; Koppers, A.; Tauxe, L.; Constable, C.; Donadini, F.

    2007-12-01

    The Magnetics Information Consortium (MagIC) is commissioned to implement and maintain an online portal to a relational database populated by both rock and paleomagnetic data. The goal of MagIC is to archive all available measurements and derived properties from paleomagnetic studies of directions and intensities, and for rock magnetic experiments (hysteresis, remanence, susceptibility, anisotropy). MagIC is hosted under EarthRef.org at http://earthref.org/MAGIC/ and will soon implement two search nodes, one for paleomagnetism and one for rock magnetism. Currently the PMAG node is operational. Both nodes provide query building based on location, reference, methods applied, material type and geological age, as well as a visual map interface to browse and select locations. Users can also browse the database by data type or by data compilation to view all contributions associated with well known earlier collections like PINT, GMPDB or PSVRL. The query result set is displayed in a digestible tabular format allowing the user to descend from locations to sites, samples, specimens and measurements. At each stage, the result set can be saved and, where appropriate, can be visualized by plotting global location maps, equal area, XY, age, and depth plots, or typical Zijderveld, hysteresis, magnetization and remanence diagrams. User contributions to the MagIC database are critical to achieving a useful research tool. We have developed a standard data and metadata template (version 2.3) that can be used to format and upload all data at the time of publication in Earth Science journals. Software tools are provided to facilitate population of these templates within Microsoft Excel. These tools allow for the import/export of text files and provide advanced functionality to manage and edit the data, and to perform various internal checks to maintain data integrity and prepare for uploading. The MagIC Contribution Wizard at http://earthref.org/MAGIC/upload.htm executes the upload

  2. Online visual search attentional bias modification for adolescents with heightened anxiety and depressive symptoms: A randomized controlled trial.

    Science.gov (United States)

    De Voogd, E L; Wiers, R W; Salemink, E

    2017-05-01

    Anxiety and depression, which are highly prevalent in adolescence, are both characterized by a negative attentional bias. As Attentional Bias Modification (ABM) can reduce such a bias, and might also affect emotional reactivity, it could be a promising early intervention. However, a growing number of studies also report comparable improvements in both active and placebo groups. The current study investigated the effects of eight online sessions of visual search (VS) ABM compared to both a VS placebo-training and a no-training control group in adolescents with heightened symptoms of anxiety and/or depression (n = 108). Attention bias, interpretation bias, and stress-reactivity were assessed pre- and post-training. Primary outcomes of anxiety and depressive symptoms, and secondary measures of emotional resilience were assessed pre- and post-training and at three and six months follow-up. Results revealed that VS training reduced attentional bias compared to both control groups, with stronger effects for participants who completed more training sessions. Irrespective of training condition, an overall reduction in symptoms of anxiety and depression and an increase in emotional resilience were observed up to six months later. The training was evaluated relatively negatively. Results suggest that online ABM as employed in the current study has no added value as an early intervention in adolescents with heightened symptoms.

  3. Face Recognition and Visual Search Strategies in Autism Spectrum Disorders: Amending and Extending a Recent Review by Weigelt et al.

    Directory of Open Access Journals (Sweden)

    Julia Tang

    Full Text Available The purpose of this review was to build upon a recent review by Weigelt et al. which examined visual search strategies and face identification between individuals with autism spectrum disorders (ASD and typically developing peers. Seven databases, CINAHL Plus, EMBASE, ERIC, Medline, Proquest, PsychInfo and PubMed were used to locate published scientific studies matching our inclusion criteria. A total of 28 articles not included in Weigelt et al. met criteria for inclusion into this systematic review. Of these 28 studies, 16 were available and met criteria at the time of the previous review, but were mistakenly excluded; and twelve were recently published. Weigelt et al. found quantitative, but not qualitative, differences in face identification in individuals with ASD. In contrast, the current systematic review found both qualitative and quantitative differences in face identification between individuals with and without ASD. There is a large inconsistency in findings across the eye tracking and neurobiological studies reviewed. Recommendations for future research in face recognition in ASD were discussed.

  4. The Magnetics Information Consortium (MagIC) Online Database: Uploading, Searching and Visualizing Paleomagnetic and Rock Magnetic Data

    Science.gov (United States)

    Minnett, R.; Koppers, A.; Tauxe, L.; Constable, C.; Pisarevsky, S. A.; Jackson, M.; Solheid, P.; Banerjee, S.; Johnson, C.

    2006-12-01

    The Magnetics Information Consortium (MagIC) is commissioned to implement and maintain an online portal to a relational database populated by both rock and paleomagnetic data. The goal of MagIC is to archive all measurements and the derived properties for studies of paleomagnetic directions (inclination, declination) and intensities, and for rock magnetic experiments (hysteresis, remanence, susceptibility, anisotropy). MagIC is hosted under EarthRef.org at http://earthref.org/MAGIC/ and has two search nodes, one for paleomagnetism and one for rock magnetism. Both nodes provide query building based on location, reference, methods applied, material type and geological age, as well as a visual map interface to browse and select locations. The query result set is displayed in a digestible tabular format allowing the user to descend through hierarchical levels such as from locations to sites, samples, specimens, and measurements. At each stage, the result set can be saved and, if supported by the data, can be visualized by plotting global location maps, equal area plots, or typical Zijderveld, hysteresis, and various magnetization and remanence diagrams. User contributions to the MagIC database are critical to achieving a useful research tool. We have developed a standard data and metadata template (Version 2.1) that can be used to format and upload all data at the time of publication in Earth Science journals. Software tools are provided to facilitate population of these templates within Microsoft Excel. These tools allow for the import/export of text files and provide advanced functionality to manage and edit the data, and to perform various internal checks to maintain data integrity and prepare for uploading. The MagIC Contribution Wizard at http://earthref.org/MAGIC/upload.htm executes the upload and takes only a few minutes to process several thousand data records. The standardized MagIC template files are stored in the digital archives of EarthRef.org where they

  5. 微软学术搜索的可视化应用探析%On Visualization Application of Microsoft Academic Search

    Institute of Scientific and Technical Information of China (English)

    刘如; 吴琼; 蔚晓川; 刘彦君

    2014-01-01

    信息可视化技术利用计算机图形图像和数据挖掘的技术与方法,将数据中隐藏的信息以交互方式形象生动地展示给用户。在学术搜索领域,信息可视化技术主要用于辅助用户分析数据,进而发现其中蕴含的规律。因此,研究信息可视化技术与应用,具有重要的理论意义和实用价值。对微软学术搜索的信息可视化应用进行深入的研究,提出了针对学术搜索数据的可视化与分析方法,为解决信息可视化所面临的问题提供了新的思路和技术手段。%Information visualization is the study of visual representations of abstract data to reinforce human cogni-tion. In the field of academic search,information visualization is used to assist users in dataset analysis to find the laws contained in the data. Therefore,the research on the technologies of information visualization has important theoretical significance and practical values. This paper mainly focused on the application of information visualization in Microsoft Academic Search. Methods of visualization and visual analysis were proposed,which may offer new ideas and technical methods for the tackling of current problems in the field of information visualization.

  6. Towards a framework for analysis of eye-tracking studies in the three dimensional environment: a study of visual search by experienced readers of endoluminal CT colonography.

    Science.gov (United States)

    Helbren, E; Halligan, S; Phillips, P; Boone, D; Fanshawe, T R; Taylor, S A; Manning, D; Gale, A; Altman, D G; Mallett, S

    2014-05-01

    Eye tracking in three dimensions is novel, but established descriptors derived from two-dimensional (2D) studies are not transferable. We aimed to develop metrics suitable for statistical comparison of eye-tracking data obtained from readers of three-dimensional (3D) "virtual" medical imaging, using CT colonography (CTC) as a typical example. Ten experienced radiologists were eye tracked while observing eight 3D endoluminal CTC videos. Subsequently, we developed metrics that described their visual search patterns based on concepts derived from 2D gaze studies. Statistical methods were developed to allow analysis of the metrics. Eye tracking was possible for all readers. Visual dwell on the moving region of interest (ROI) was defined as pursuit of the moving object across multiple frames. Using this concept of pursuit, five categories of metrics were defined that allowed characterization of reader gaze behaviour. These were time to first pursuit, identification and assessment time, pursuit duration, ROI size and pursuit frequency. Additional subcategories allowed us to further characterize visual search between readers in the test population. We propose metrics for the characterization of visual search of 3D moving medical images. These metrics can be used to compare readers' visual search patterns and provide a reproducible framework for the analysis of gaze tracking in the 3D environment. This article describes a novel set of metrics that can be used to describe gaze behaviour when eye tracking readers during interpretation of 3D medical images. These metrics build on those established for 2D eye tracking and are applicable to increasingly common 3D medical image displays.

  7. Effects of alprazolam and bromazepam on visual search and verbal recognition memory in humans: a study with event-related brain potentials.

    Science.gov (United States)

    Münte, T F; Gehde, E; Johannes, S; Seewald, M; Heinze, H J

    1996-01-01

    The effects of two benzodiazepines (alprazolam and bromazepam) on performance and event-related brain potentials (ERPs) in visual search and verbal recognition memory paradigms were tested in a placebo-controlled double-blind paradigm employing 12 young healthy subjects. Both drugs exerted similar effects on performance and electrophysiological measures. Reaction times and hit rates were adversely affected in both paradigms. The ERP pattern in the visual search experiment suggested an impairment in selective attention (reduction of N1 component) and of automatic feature registration (posterior N2 reduction). In the world recognition experiment a dramatic reduction of the N400 component was seen under benzodiazepines. This is interpreted as reflecting an impaired ability to perform context integration processes.

  8. Search for and limits on plume activity on Mimas, Tethys, and Dione with the Cassini Visual Infrared Mapping Spectrometer (VIMS)

    Science.gov (United States)

    Buratti, B.J.; Faulk, S.P.; Mosher, J.; Baines, K.H.; Brown, R.H.; Clark, R.N.; Nicholson, P.D.

    2011-01-01

    Cassini Visual Infrared Mapping Spectrometer (VIMS) observations of Mimas, Tethys, and Dione obtained during the nominal and extended missions at large solar phase angles were analyzed to search for plume activity. No forward scattered peaks in the solar phase curves of these satellites were detected. The upper limit on water vapor production for Mimas and Tethys is one order of magnitude less than the production for Enceladus. For Dione, the upper limit is two orders of magnitude less, suggesting this world is as inert as Rhea (Pitman, K.M., Buratti, B.J., Mosher, J.A., Bauer, J.M., Momary, T., Brown, R.H., Nicholson, P.D., Hedman, M.M. [2008]. Astrophys. J. Lett. 680, L65-L68). Although the plumes are best seen at ???2.0. ??m, Imaging Science Subsystem (ISS) Narrow Angle Camera images obtained at the same time as the VIMS data were also inspected for these features. None of the Cassini ISS images shows evidence for plumes. The absence of evidence for any Enceladus-like plumes on the medium-sized saturnian satellites cannot absolutely rule out current geologic activity. The activity may below our threshold of detection, or it may be occurring but not captured on the handful of observations at large solar phase angles obtained for each moon. Many VIMS and ISS images of Enceladus at large solar phase angles, for example, do not contain plumes, as the active "tiger stripes" in the south pole region are pointed away from the spacecraft at these times. The 7-year Cassini Solstice Mission is scheduled to gather additional measurements at large solar phase angles that are capable of revealing activity on the saturnian moons. ?? 2011 Elsevier Inc.

  9. Visual search for real world targets under conditions of high target-background similarity: Exploring training and transfer in younger and older adults.

    Science.gov (United States)

    Neider, Mark B; Boot, Walter R; Kramer, Arthur F

    2010-05-01

    Real world visual search tasks often require observers to locate a target that blends in with its surrounding environment. However, studies of the effect of target-background similarity on search processes have been relatively rare and have ignored potential age-related differences. We trained younger and older adults to search displays comprised of real world objects on either homogenous backgrounds or backgrounds that camouflaged the target. Training was followed by a transfer session in which participants searched for novel camouflaged objects. Although older adults were slower to locate the target compared to younger adults, all participants improved substantially with training. Surprisingly, camouflage-trained younger and older adults showed no performance decrements when transferred to novel camouflage displays, suggesting that observers learned age-invariant, generalizable skills relevant for searching under conditions of high target-background similarity. Camouflage training benefits at transfer for older adults appeared to be related to improvements in attentional guidance and target recognition rather than a more efficient search strategy.

  10. Visual search performance on an lcd monitor: effects of color combination of figure and icon background, shape of icon, and line width of icon border.

    Science.gov (United States)

    Huang, Kuo-Chen; Chiu, Tsai-Lan

    2007-04-01

    This study investigated the effects of color combinations for the figure/icon background, icon shape, and line width of the icon border on visual search performance on a liquid crystal display screen. In a circular stimulus array, subjects had to search for a target item which had a diameter of 20 cm and included one target and 19 distractors. Analysis showed that the icon shape significantly affected search performance. The correct response time was significantly shorter for circular icons than for triangular icons, for icon borders with a line width of 3 pixels than for 1 or 2 pixels, and for 2 pixels than for 1 pixel. The color combination also significantly affected the visual search performance: white/yellow, white/blue, black-red, and black/ yellow color combinations for the figure/icon background had shorter correct response times compared to yellow/blue, red/green, yellow/green, and blue/red. However, no effects were found for the line width of the icon border or the icon shape on the error rate. Results have implications for graphics-based design of interfaces, such as for mobile phones, Web sites, and PDAs, as well as complex industrial processes.

  11. 大数据环境下移动视觉搜索的游戏化机制设计%On Mobile Visual Search Game Mechanism Design in the Big Data Environment

    Institute of Scientific and Technical Information of China (English)

    赵宇翔; 朱庆华

    2016-01-01

    The paper first gives a brief review on the connotation and application of mobile visual search on the basis of the existing literature, and proposes our own definition for mobile visual search from both general and narrow scope. Then the paper elaborates on the various stages of mobile visual search, i.e., visual resources collecting, visual resources organizing, and visual resources presentation. A theoretical mapping is conducted to relate the various gami-fication elements with the main stages of mobile visual search, and the objective of gamification, real examples and motivational affordances are also illustrated. Furthermore, the paper puts forward the design framework of gamification in mobile visual search, and a three-level model has been proposed and explained.%文章首先对移动视觉搜索的内涵和应用进行概述,并从广义和狭义的角度界定移动视觉搜索的概念,同时,对游戏化模式及其应用进行简介。在此基础上,进一步探索移动视觉搜索中各个阶段的游戏化元素及相应的动因示能。最后,提出了大数据时代移动视觉搜索的游戏化框架。

  12. The effects of brief visual interruption tasks on drivers' ability to resume their visual search for a pre-cued hazard.

    Science.gov (United States)

    Borowsky, Avinoam; Horrey, William J; Liang, Yulan; Garabet, Angela; Simmons, Lucinda; Fisher, Donald L

    2016-08-01

    Driver visual distraction is known to increase the likelihood of being involved in a crash, especially for long glances inside the vehicle. The detrimental impact of these in-vehicle glances may carry over and disrupt the ongoing processing of information after the driver glances back up on the road. This study explored the effect of different types of visual tasks inside the vehicle on the top-down processes that guide the detection and monitoring of road hazards after the driver glances back towards the road. Using a driving simulator, 56 participants were monitored with an eye tracking system while they navigated various hazardous scenarios in one of four experimental conditions. In all conditions, a potential hazard was visible 4-5s before the driver could strike the potential hazard were it to materialize. All interruptions were exactly two seconds in length. After the interruption the potential hazard again became visible for about a half-second after which the driver passed by the hazard. The nature of the in-vehicle visual interruption presented to the participants was varied across conditions: (1) Visual interruptions comprised of spatial, driving unrelated, tasks; (2) visual interruptions comprised of non-spatial, driving unrelated, tasks; (3) visual interruptions with no tasks added; and (4) no visual interruptions. In the first three conditions drivers glancing on the forward roadway was momentarily interrupted (either with or without a task) just after the potential hazard first became visible by the occurrence of an in-vehicle task lasting two seconds. In the last condition (no interruptions) the driver could not see the potential hazard after it just became visible because of obstructions in the built or natural environment. The obstruction (like the interruption) lasted for two seconds. In other words, across all conditions the hazard was visible, then became invisible, and finally became visible again. Importantly, the results show that the

  13. Honeybees (Apis mellifera exhibit flexible visual search strategies for vertical targets presented at various heights [v2; ref status: indexed, http://f1000r.es/51p

    Directory of Open Access Journals (Sweden)

    Linde Morawetz

    2015-02-01

    Full Text Available When honeybees are presented with a colour discrimination task, they tend to choose swiftly and accurately when objects are presented in the ventral part of their frontal visual field. In contrast, poor performance is observed when objects appear in the dorsal part. Here we investigate if this asymmetry is caused by fixed search patterns or if bees can increase their detection ability of objects in search scenarios when targets appear frequently or exclusively in the dorsal area of the visual field. We trained individual honeybees to choose an orange rewarded target among blue distractors. Target and distractors were presented in the ventral visual field, the dorsal field or both. Bees presented with targets in the ventral visual field consistently had the highest search efficiency, with rapid decisions, high accuracy and direct flight paths. In contrast, search performance for dorsally located targets was inaccurate and slow at the beginning of the experimental phase, but bees increased their search performance significantly after a few foraging bouts: they found the target faster, made fewer errors and flew in a straight line towards the target. However, bees needed thrice as long to improve the search for a dorsally located target when the target’s position changed randomly between the ventral and the dorsal visual field. We propose that honeybees form expectations of the location of the target’s appearance and adapt their search strategy accordingly. A variety of possible mechanisms underlying this behavioural adaptation, for example spatial attention, are discussed.

  14. Strategies of the honeybee Apis mellifera during visual search for vertical targets presented at various heights: a role for spatial attention? [v1; ref status: indexed, http://f1000r.es/3yb

    Directory of Open Access Journals (Sweden)

    Linde Morawetz

    2014-07-01

    Full Text Available When honeybees are presented with a colour discrimination task, they tend to choose swiftly and accurately when objects are presented in the ventral part of their frontal visual field. In contrast, poor performance is observed when objects appear in the dorsal part. Here we investigate if this asymmetry is caused by fixed search patterns or if bees can use alternative search mechanisms such as spatial attention, which allows flexible focusing on different areas of the visual field. We asked individual honeybees to choose an orange rewarded target among blue distractors. Target and distractors were presented in the ventral visual field, the dorsal field or both. Bees presented with targets in the ventral visual field consistently had the highest search efficiency, with rapid decisions, high accuracy and direct flight paths. In contrast, search performance for dorsally located targets was inaccurate and slow at the beginning of the test phase, but bees increased their search performance significantly after a few learning trials: they found the target faster, made fewer errors and flew in a straight line towards the target. However, bees needed thrice as long to improve the search for a dorsally located target when the target’s position changed randomly between the ventral and the dorsal visual field. We propose that honeybees form expectations of the location of the target’s appearance and adapt their search strategy accordingly. Different possible mechanisms of this behavioural adaptation are discussed.

  15. Effects of repeated snowboard exercise in virtual reality with time lags of visual scene behind body rotation on head stability and subjective slalom run performance in healthy young subjects.

    Science.gov (United States)

    Wada, Yoshiro; Nishiike, Suetaka; Kitahara, Tadashi; Yamanaka, Toshiaki; Imai, Takao; Ito, Taeko; Sato, Go; Matsuda, Kazunori; Kitamura, Yoshiaki; Takeda, Noriaki

    2016-11-01

    After repeated snowboard exercises in the virtual reality (VR) world with increasing time lags in trials 3-8, it is suggested that the adaptation to repeated visual-vestibulosomatosensory conflict in the VR world improved dynamic posture control and motor performance in the real world without the development of motion sickness. The VR technology was used and the effects of repeated snowboard exercise examined in the VR world with time lags between visual scene and body rotation on the head stability and slalom run performance during exercise in healthy subjects. Forty-two healthy young subjects participated in the study. After trials 1 and 2 of snowboard exercise in the VR world without time lag, trials 3-8 were conducted with 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 s time lags of the visual scene that the computer creates behind board rotation, respectively. Finally, trial 9 was conducted without time lag. Head linear accelerations and subjective slalom run performance were evaluated. The standard deviations of head linear accelerations in inter-aural direction were significantly increased in trial 8, with a time lag of 0.6 s, but significantly decreased in trial 9 without a time lag, compared with those in trial 2 without a time lag. The subjective scores of slalom run performance were significantly decreased in trial 8, with a time lag of 0.6 s, but significantly increased in trial 9 without a time lag, compared with those in trial 2 without a time lag. Motion sickness was not induced in any subjects.

  16. Age-Related Differences in Sensitivity to Emotional Facial Stimuli but Age-Independent Association between Arousal Ratings and Visual Search Efficiency

    Directory of Open Access Journals (Sweden)

    Daniel Lundqvist

    2013-09-01

    Full Text Available The latter part of the lifespan is commonly associated with a decline of cognitive functions, but also with changes in emotional responding. To explore the effect of age on processing of emotional stimuli, we used a two-task design. In a stimulus-rating task, we investigated the emotional responses to 15 different schematic facial emotional stimuli (one neutral, seven positive, seven negative on Arousal, Valence and Potency measures in 20 younger (21-32 yrs, M=26, SD=3.7 and 20 older (65-81 yrs, M=72, SD=4.9 participants. In a visual attention task, we used the same 15 stimuli in a visual search paradigm to investigate differences between younger and older participants in how the emotional properties of these emotional stimuli influence visual attention.The results from the stimulus-rating task showed significantly reduced range in responses to emotional stimuli in the older compared to the younger group. This difference was found on both emotional Arousal and Potency measures, but not on emotional Valence measures; indicating an age-related flattening of affect on two of the three emotional key dimensions. The results from the visual search task showed – apart from the general extension of response latencies in older – no general emotion-related differences between how emotional stimuli influences attention in the younger and older groups.Analysis of the relationships between attention and emotion measures showed that higher ratings on Arousal and Potency were associated with both shorter reaction times and fewer errors in the attention task. This correlation was age-independent, indicating a similar influence from emotional Arousal on detection of angry faces in younger and older adults.

  17. Seleção e análise de estímulos na tarefa de busca visual Stimuli selection and analysis in the visual search task

    Directory of Open Access Journals (Sweden)

    Joaquim Carlos Rossini

    2008-01-01

    Full Text Available A capacidade de processar simultaneamente vários estágios cognitivos ainda é motivo de discordância entre os modelos que tentam compreender o processamento da informação visual. Muitos resultados experimentais apontam basicamente duas maneiras possíveis de fluxo da informação entre estágios de processamento: uma discreta e outra contínua. No presente estudo, dois experimentos foram delineados para investigar se a informação inicialmente descartada, em um estágio pré-atentivo, pode influenciar o processamento atentivo da informação selecionada em uma tarefa de busca visual. De maneira geral, os resultados observados nestes experimentos mostram que os estímulos inicialmente descartados em um processo automático de seleção não interferem no processamento atentivo dos estímulos na tarefa de busca visual. Este resultado apóia os modelos que predizem uma seleção precoce dos elementos relevantes para o processamento atentivo e uma transmissão discreta da informação entre os estágios cognitivos de processamento.The capacity of processing several cognitive stages simultaneously still generates a considerable disagreement among models that try to understand the processing of visual information. Many experimental results suggest two main possibilities for the information flow between information processing stages: a discrete or a continuous flow. Two experiments have in the present study to investigate were designed attentional processing whether the information at first discarded in a pre-attentive state can influence the of selected information in a visual search task. The results show that the stimuli initially discarded in an automatic process of selection do not interfere in the attention all processing of stimuli in a visual search. The results support the models that predict an early selection of the relevant stimuli and a discrete transmission of the information between the cognitive processing stages.

  18. Positions priming in briefly presented search arrays

    DEFF Research Database (Denmark)

    Asgeirsson, Arni Gunnar; Kristjánsson, Árni; Kyllingsbæk, Søren;

    2011-01-01

    Repetition priming in visual search has been a topic of extensive research since Maljkovic & Nakayama [1994, Memory & Cognition, 22, 657-672] presented the first detailed studies of such effects. Their results showed large reductions in reaction times when target color was repeated on consecutive...... pop-out search trials. Such repetition effects have since been generalized to a multitude of target attributes. Priming has primarily been investigated using self-terminating visual search paradigms, comparing differences in response times. Response accuracy has predominantly served as a control...... variable. Here we present results from experiments where position priming is demonstrated in paradigms involving temporally limited exposures to singleton targets. Position priming of response accuracy was observed in an eye-movement-controlled spatial judgment task and in partial report tasks where...

  19. Attentional capture during visual search is attenuated by target predictability: evidence from the N2pc, Pd, and topographic segmentation.

    Science.gov (United States)

    Burra, Nicolas; Kerzel, Dirk

    2013-05-01

    Attentional capture by salient distractors has been confirmed by the occurrence of an N2pc to the salient distractor. To clarify some failures to replicate this finding, we varied target predictability to induce different search modes. In the unpredictable target condition, the target shape varied randomly from trial to trial, favoring singleton detection mode. In the predictable target condition, the target shape remained the same in a block of trials, favoring feature search mode. With unpredictable targets, we observed an N2pc toward the salient color distractor, confirming attentional capture in singleton search mode. With predictable targets, there was no N2pc to the salient distractor, but a distractor positivity (Pd), suggesting distractor suppression. Also, differences emerged in the topographic segmentation of N2pc and Pd. Further, the amplitude of the N2pc toward the target was larger with predictable than with unpredictable targets.

  20. Psychophysics in a Web browser? Comparing response times collected with JavaScript and Psychophysics Toolbox in a visual search task.

    Science.gov (United States)

    de Leeuw, Joshua R; Motz, Benjamin A

    2016-03-01

    Behavioral researchers are increasingly using Web-based software such as JavaScript to conduct response time experiments. Although there has been some research on the accuracy and reliability of response time measurements collected using JavaScript, it remains unclear how well this method performs relative to standard laboratory software in psychologically relevant experimental manipulations. Here we present results from a visual search experiment in which we measured response time distributions with both Psychophysics Toolbox (PTB) and JavaScript. We developed a methodology that allowed us to simultaneously run the visual search experiment with both systems, interleaving trials between two independent computers, thus minimizing the effects of factors other than the experimental software. The response times measured by JavaScript were approximately 25 ms longer than those measured by PTB. However, we found no reliable difference in the variability of the distributions related to the software, and both software packages were equally sensitive to changes in the response times as a result of the experimental manipulations. We concluded that JavaScript is a suitable tool for measuring response times in behavioral research.

  1. Generating descriptive visual words and visual phrases for large-scale image applications.

    Science.gov (United States)

    Zhang, Shiliang; Tian, Qi; Hua, Gang; Huang, Qingming; Gao, Wen

    2011-09-01

    Bag-of-visual Words (BoWs) representation has been applied for various problems in the fields of multimedia and computer vision. The basic idea is to represent images as visual documents composed of repeatable and distinctive visual elements, which are comparable to the text words. Notwithstanding its great success and wide adoption, visual vocabulary created from single-image local descriptors is often shown to be not as effective as desired. In this paper, descriptive visual words (DVWs) and descriptive visual phrases (DVPs) are proposed as the visual correspondences to text words and phrases, where visual phrases refer to the frequently co-occurring visual word pairs. Since images are the carriers of visual objects and scenes, a descriptive visual element set can be composed by the visual words and their combinations which are effective in representing certain visual objects or scenes. Based on this idea, a general framework is proposed for generating DVWs and DVPs for image applications. In a large-scale image database containing 1506 object and scene categories, the visual words and visual word pairs descriptive to certain objects or scenes are identified and collected as the DVWs and DVPs. Experiments show that the DVWs and DVPs are informative and descriptive and, thus, are more comparable with the text words than the classic visual words. We apply the identified DVWs and DVPs in several applications including large-scale near-duplicated image retrieval, image search re-ranking, and object recognition. The combination of DVW and DVP performs better than the state of the art in large-scale near-duplicated image retrieval in terms of accuracy, efficiency and memory consumption. The proposed image search re-ranking algorithm: DWPRank outperforms the state-of-the-art algorithm by 12.4% in mean average precision and about 11 times faster in efficiency.

  2. Express attentional re-engagement but delayed entry into consciousness following invalid spatial cues in visual search.

    Directory of Open Access Journals (Sweden)

    Benoit Brisson

    Full Text Available BACKGROUND: In predictive spatial cueing studies, reaction times (RT are shorter for targets appearing at cued locations (valid trials than at other locations (invalid trials. An increase in the amplitude of early P1 and/or N1 event-related potential (ERP components is also present for items appearing at cued locations, reflecting early attentional sensory gain control mechanisms. However, it is still unknown at which stage in the processing stream these early amplitude effects are translated into latency effects. METHODOLOGY/PRINCIPAL FINDINGS: Here, we measured the latency of two ERP components, the N2pc and the sustained posterior contralateral negativity (SPCN, to evaluate whether visual selection (as indexed by the N2pc and visual-short term memory processes (as indexed by the SPCN are delayed in invalid trials compared to valid trials. The P1 was larger contralateral to the cued side, indicating that attention was deployed to the cued location prior to the target onset. Despite these early amplitude effects, the N2pc onset latency was unaffected by cue validity, indicating an express, quasi-instantaneous re-engagement of attention in invalid trials. In contrast, latency effects were observed for the SPCN, and these were correlated to the RT effect. CONCLUSIONS/SIGNIFICANCE: Results show that latency differences that could explain the RT cueing effects must occur after visual selection processes giving rise to the N2pc, but at or before transfer in visual short-term memory, as reflected by the SPCN, at least in discrimination tasks in which the target is presented concurrently with at least one distractor. Given that the SPCN was previously associated to conscious report, these results further show that entry into consciousness is delayed following invalid cues.

  3. Visual paired-associate learning: in search of material-specific effects in adult patients who have undergone temporal lobectomy.

    Science.gov (United States)

    Smith, Mary Lou; Bigel, Marla; Miller, Laurie A

    2011-02-01

    The mesial temporal lobes are important for learning arbitrary associations. It has previously been demonstrated that left mesial temporal structures are involved in learning word pairs, but it is not yet known whether comparable lesions in the right temporal lobe impair visually mediated associative learning. Patients who had undergone left (n=16) or right (n=18) temporal lobectomy for relief of intractable epilepsy and healthy controls (n=13) were administered two paired-associate learning tasks assessing their learning and memory of pairs of abstract designs or pairs of symbols in unique locations. Both patient groups had deficits in learning the designs, but only the right temporal group was impaired in recognition. For the symbol location task, differences were not found in learning, but again a recognition deficit was found for the right temporal group. The findings implicate the mesial temporal structures in relational learning. They support a material-specific effect for recognition but not for learning and recall of arbitrary visual and visual-spatial associative information. Copyright © 2010 Elsevier Inc. All rights reserved.

  4. Deployment Repeatability

    Science.gov (United States)

    2016-04-01

    controlled to great precision, but in a Cubesat , there may be no attitude determination at all. Such a Cubesat might treat sun angle and tumbling rates as...could be sensitive to small differences in motor controller timing. In these cases, the analyst might choose to model the entire deployment path, with...knowledge of the material damage model or motor controller timing precision. On the other hand, if many repeated and environmentally representative

  5. Research on Visual Information Processing with Special Reference to Oculomotor Behavior in the Areas of Exploration, Recognition and Search.

    Science.gov (United States)

    1987-03-01

    7 0-Ai86 598 RESEARCH ON VISUAL INFORMATION PROCESSING WdITH SPECIAL t/IREFERENCE TO OCULO (U) GULF AND WESTER APPLIED SCIENCE LABS WALTHAM MA L F...indicate a strong effect, (i.e. distance from foveal center), p=.O00 for axis and the data blot in affects recognition Performance (see figure Q would...the four axes ar- trend is present. The question remains given in table 7 below. These data are as to wnv tnere should be a difference also blotted in

  6. A visualization environment for an on-line monitoring and control system for an experiment to search for T-violation in $K^{+}$ decay

    CERN Document Server

    Grigoriev, M P; Ivashkin, A P; Kudenko, Yu G; Mineev, O V; Khabibullin, M M; Aoki, M; Imazato, J; Kuno, Y; Watanabe, A; Igarashi, Y; Yokoi, T; Shimizu, S

    1999-01-01

    The main goal of experiment E246 at the KEK 12-GeV proton synchrotron is the search for the T-odd muon polarization in the decay K/sup +/ to pi /sup 0/ mu /sup +/ nu (K/sub mu 3/). To satisfy the experimental requirements, a graphic user-oriented on-line system for data monitoring and graphic representation of the most significant experimental parameters in the form of histograms, indicators, and 2D-displays has been developed. This paper describes the E246 data acquisition system, on-line system environment, obtained monitoring capabilities, set of graphic user displays, and the GUI development methodology for the high-energy physics on-line visualization. (16 refs).

  7. The Behavioral Effects of tDCS on Visual Search Performance Are Not Influenced by the Location of the Reference Electrode

    Directory of Open Access Journals (Sweden)

    Amanda Ellison

    2017-09-01

    Full Text Available We investigated the role of reference electrode placement (ipsilateral v contralateral frontal pole on conjunction visual search task performance when the transcranial direct current stimulation (tDCS cathode is placed over right posterior parietal cortex (rPPC and over right frontal eye fields (rFEF, both of which have been shown to be causally involved in the processing of this task using TMS. This resulted in four experimental manipulations in which sham tDCS was applied in week one followed by active tDCS the following week. Another group received sham stimulation in both sessions to investigate practice effects over 1 week in this task. Results show that there is no difference between effects seen when the anode is placed ipsi or contralaterally. Cathodal stimulation of rPPC increased search times straight after stimulation similarly for ipsi and contralateral references. This finding does not extend to rFEF stimulation. However, for both sites and both montages, practice effects as seen in the sham/sham condition were negated. This can be taken as evidence that for this task, reference placement on either frontal pole is not important, but also that care needs to be taken when contextualizing tDCS “effects” that may not be immediately apparent particularly in between-participant designs.

  8. The effects of visual discriminability and rotation angle on 30-month-olds’ search performance in spatial rotation tasks

    Directory of Open Access Journals (Sweden)

    Mirjam Ebersbach

    2016-10-01

    Full Text Available Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29 performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children.

  9. The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds’ Search Performance in Spatial Rotation Tasks

    Science.gov (United States)

    Ebersbach, Mirjam; Nawroth, Christian

    2016-01-01

    Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children. PMID:27812346

  10. Visual Impairment, Including Blindness

    Science.gov (United States)

    ... Who Knows What? Survey Item Bank Search for: Visual Impairment, Including Blindness Links updated, April 2017 En ... doesn’t wear his glasses. Back to top Visual Impairments in Children Vision is one of our ...

  11. Processing Priority for Self-related Information: Evidence from Visual Search of Screen Names%自我相关信息的加工优势:来自网名识别的证据

    Institute of Scientific and Technical Information of China (English)

    杨红升; 王芳; 顾念君; 黄希庭

    2012-01-01

    no difference between hit rates in the two kinds of trials. Experiment 3 made direct comparisons between visual search performance for own screen name and real name. There was no significant difference in either response time or accuracy for these two names. However, they were both more accurately and quickly detected than famous names. Taken together, results of the three experiments showed that as target stimuli, own screen name can be detected more quickly and accurately than control screen name while as distracters, they do not show any larger interference effect on target stimuli. These results completely replicated those of studies using real name stimuli. These similar patterns suggested that recognition of own screen names might share the same mechanism as own real name. In conclusion, the current research provided preliminary evidences on the cognitive priority of self-related online material. As a result of its self-relevance and repeated use, one's own screen name obtains strong personal salience and the consequent preferential processing. Based on the existence of such an online cocktail party effect, processing priority about self-related information can be extended from real world to the virtual online environment. In future studies, the possible individual difference and the effect of familiarity in screen name recognition constitutes two important issues which deserves to be directly explored.%以网名为材料,通过三项视觉搜索实验考察了与自我相关的网络信息可能存在的加工优势.结果发现,自己的网名在作为靶刺激时可以更快且更准确地被探测出来;而在作为干扰刺激时,其对于靶刺激却并未表现出比对照刺激更强的抑制作用.在与真实人名进行的直接比较中,自己的网名与真实人名的加工成绩未出现显著差异,且都好于作为对照的名人名字.这些结果证明了与自我相关的网络信息具有和物理世界中的自我信息相似的加工

  12. Hyperspecificity in Visual Implicit Learning: Learning of Spatial Layout Is Contingent on Item Identity

    Science.gov (United States)

    Jiang, Yuhong; Song, Joo-Hyun

    2005-01-01

    Humans conduct visual search faster when the same display is presented for a 2nd time, showing implicit learning of repeated displays. This study examines whether learning of a spatial layout transfers to other layouts that are occupied by items of new shapes or colors. The authors show that spatial context learning is sometimes contingent on item…

  13. 视觉搜索中的情绪干扰项预习效应%The Emotional Distractor Previewing Effect in Visual Search

    Institute of Scientific and Technical Information of China (English)

    牟兵兵; 宛小昂

    2014-01-01

    The Distractor Previewing Effect (DPE) is one of the inter-trial effects in visual search based on features or categories. In the DPE tasks, oddball-present and oddball-absent trials are intermixed to present. The target is defined by one feature (e.g., a green diamond among red ones) or category (e.g., a face picture among house pictures), and the response is defined by another feature, such as the shape of the color oddball or which side of the face pictures has a red dot next to it. The DPE is indicated by faster responses on the current oddball-present trial when the distractors are congruent with the stimuli on the preceding oddball-absent trial than when the target does so. Both behavioral and neuroscience studies have revealed that the DPE reflects an attentional bias caused by past unsuccessful experience. In this study, participants were shown three emotional stimuli on each display, with or without one picture having a different valence from the other two. They searched for this emotional oddball and identified its non-affective feature if an oddball was present. If the RTs on the current oddball-present trial are faster when the valence of the target is congruent with that of the stimuli on the preceding oddball-absent trial than when the target does so, this inter-trial effect is the emotional DPE. Pictures of veridical faces of emotional expressions were shown in Experiment 1, whereas pictures of threat-relevant and threat-irrelevant animals were shown in Experiment 2. The emotional DPE was elicited in both experiments. In Experiment 1, the emotional DPE was significant in visual search for an angry face among neutral faces, but this effect was eliminated when these faces were inverted, suggesting that the DPE was due to the emotional category of the faces. In addition, the DPE was not significant in visual search for a neutral face (among angry or happy ones) or for a happy face among neutral distractors, suggesting the asymmetry of the emotional DPE

  14. Evaluating color deficiency simulation and daltonization methods through visual search and sample-to-match: SaMSEM and ViSDEM

    Science.gov (United States)

    Simon-Liedtke, Joschua T.; Farup, Ivar; Laeng, Bruno

    2015-01-01

    Color deficient people might be confronted with minor difficulties when navigating through daily life, for example when reading websites or media, navigating with maps, retrieving information from public transport schedules and others. Color deficiency simulation and daltonization methods have been proposed to better understand problems of color deficient individuals and to improve color displays for their use. However, it remains unclear whether these color prosthetic" methods really work and how well they improve the performance of color deficient individuals. We introduce here two methods to evaluate color deficiency simulation and daltonization methods based on behavioral experiments that are widely used in the field of psychology. Firstly, we propose a Sample-to-Match Simulation Evaluation Method (SaMSEM); secondly, we propose a Visual Search Daltonization Evaluation Method (ViSDEM). Both methods can be used to validate and allow the generalization of the simulation and daltonization methods related to color deficiency. We showed that both the response times (RT) and the accuracy of SaMSEM can be used as an indicator of the success of color deficiency simulation methods and that performance in the ViSDEM can be used as an indicator for the efficacy of color deficiency daltonization methods. In future work, we will include comparison and analysis of different color deficiency simulation and daltonization methods with the help of SaMSEM and ViSDEM.

  15. Web页面视觉搜索与浏览策略的眼动研究%Exploring Visual Search and Browsing Strategies on Web Pages Using the Eye-tracking

    Institute of Scientific and Technical Information of China (English)

    栗觅; 钟宁; 吕胜富

    2011-01-01

    利用眼动跟踪技术,探讨Web页面视觉搜索和浏览的视觉特征,并分析2种视觉行为对应策略的差异.实验结果发现,视觉搜索时,周边区域的注视时间和注视次数显著大于中心区域;而视觉浏览时,周边区域和中心区域没有显著差异.而且,视觉搜索时的瞳孔直径显著大于浏览时的瞳孔直径,说明视觉搜索时的心理负荷显著大于浏览时的心理负荷.结果表明,在Web页面上视觉搜索呈现周边区域的视觉搜索策略,而对于视觉浏览更多采用无明显规律的自由随机浏览策略.这种视觉搜索与浏览策略的差异主要是来自目标驱动和心理负荷大小的影响.%This study investigates the characteristics of visual search and browsing, and analyzes the differences of those strategies on Web pages using the eye tracking. When participants search on Web pages, the peripheral area is significantly higher than the central area on fixation duration and fixation count; when participants brows information on Web pages, there is no significant difference between the peripheral area and the central area on fixation duration and fixation count. Visual search is significantly larger than browsing on the average pupil diameter, which shows that the mental load on visual search is significantly greater than that on browsing.Results show that the visual search strategy pays more attention to the peripheral area than the central area;however, the visual browsing strategy freely run their eyes over the peripheral area and the central area in equality. The differences between the visual search and the browsing strategies are mainly due to the goal-driven and the mental load.

  16. Investigating visual analogies for visual insight problems

    OpenAIRE

    Corina Sas; Eric Luchian; Linden Ball

    2010-01-01

    Much research has focused on the impact of analogies in insight problem solving, but less work has investigated how the visual analogies for insight are actually constructed. Thus, it appears that in the search for their facilitative impact on the incubation effect, the understanding of what makes good visual analogies has somehow been lost. This paper presents preliminary work of constructing a set of 6 visual analogies and evaluating their impact on solving the visual problem of eight coins...

  17. Modeling Efficient Serial Visual Search

    Science.gov (United States)

    2012-08-01

    OH 45431 USA Wayne D. Gray (grayw@rpi.edu) Cognitive Science Department, Rensselaer Polytechnic Institute Troy, NY 12180 USA Abstract Humans perform...ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Research Laboratory, Wright-Patterson Air Force Base Dayton, OH 45431 USA 8. PERFORMING ORGANIZATION

  18. Spatial Selectivity in Visual Search.

    Science.gov (United States)

    1980-10-01

    Technical Director AFHRL(OT) Williams AFB, AZ 58224 2 3700 TCHTW/TTGH Stop 32 Sheppard AFB, TX 76311 1 Jack A. Thorp, Maj., USAF Life Sciences...Boulder, CO 80302 Dr. Erik McWilliams Science Education Dev. and Research 1 DR. PETER POLSON National Science Foundation DEPT. OF PSYCHOLOGY

  19. Parieto-occipital areas involved in efficient filtering in search: a time course analysis of visual marking using behavioural and functional imaging procedures

    DEFF Research Database (Denmark)

    Humphreys, Glyn W; Kyllingsbæk, Søren; Watson, Derrick G.

    2004-01-01

    . Furthermore, the reductions in reaction time across time in the preview condition varied nonlinearly with the display size, suggesting that old items were discounted from search in parallel. In Experiment 2 we examined the neural locus of this filtering effect over time, using positron emission tomography...... (PET). We show that regions of parieto-occipital cortex are selectively activated in a preview search condition relative to a detection baseline. These regions also increase in activation as the preview interval increases (and search then becomes easier), consistent with them modulating the parallel...... filtering of distractors from targets in spatial search. Interestingly, the same areas as those activated in preview search were also active in conjunction search relative to its own detection baseline. Thus these regions either modulate parallel filtering in conjunction search too, or they modulate...

  20. Reward modulation of contextual cueing: Repeated context overshadows repeated target location.

    Science.gov (United States)

    Sharifian, Fariba; Contier, Oliver; Preuschhof, Claudia; Pollmann, Stefan

    2017-08-07

    Contextual cueing can be enhanced by reward. However, there is a debate if reward is associated with the repeated target-distractor configurations or with the repeated target locations that occur in both repeated and new displays. Based on neuroimaging evidence, we hypothesized that reward becomes associated with the target location only in new displays, but not in repeated displays, where the repeated target location is overshadowed by the more salient repeated target-distractor configuration. To test this hypothesis, we varied the reward value associated with the same target location in repeated and new displays. The results confirmed the overshadowing hypothesis in that search facilitation in repeated target-distractor configurations was modulated by the variable value associated with the target location. This effect was observed mainly in early learning.

  1. 公路平面线形与驾驶员视觉搜索模式相关性分析%Correlation analysis between highway horizontal alignment and drivers visual search behavior

    Institute of Scientific and Technical Information of China (English)

    王芳; 陈飞; 倪富健; 戈若愚; 程迎迎

    2009-01-01

    In order to quantitatively describe the correlation between drivers' visual search behavior and highway horizontal alignment, the study of drives' visual search behavior based on eye movement experimental was carried out. Firstly, the eye movement indexes under different highway horizontal alignment conditions were obtained by laboratory test; Secondly, the correlation between drivers' visual search behavior and highway horizontal alignment were analyzed from macroscopic level to microcosmic level. Finally, the laboratory testing' effectiveness and the results' reliability were verified by outdoor testing. The results show that the index of fixation duration has significant difference under different horizontal alignment condition. Moreover, drivers' fixation duration has remarkable correlation with horizontal radius R and the value of A. Using Lagrange mean value theorem, it is found that drivers' visual search behavior will change obviously when radius is greater than 1. 5 km or when distance between line section and curve section is less than 100 m. It would be a crucial point in drivers' visual search behavior.%为定量描述驾驶员视觉搜索模式与公路平面线形的相关性,基于眼动试验展开对驾驶员视觉搜索模式的研究.首先通过室内试验获得驾驶员在不同公路平面线形条件下的眼动指标;其次,从宏观层面到微观层面分析驾驶员视觉搜索模式与平面线形的相关性;最后,通过室外试验分析验证室内试验的有效性和结论的可靠性.结果表明:在不同平面线形条件下,驾驶员注视持续时间具有显著差异性.此外,平曲线半径、缓和曲线A值与驾驶员注视持续时间有明显的相关性.应用拉格朗日中值定理发现,当平曲线半径R>1.5 km或直线段结束前100 m时驾驶员注视持续时间变化显著,即为驾驶员视觉搜索变化的关键点.

  2. Repeat-until-success quantum repeaters

    Science.gov (United States)

    Bruschi, David Edward; Barlow, Thomas M.; Razavi, Mohsen; Beige, Almut

    2014-09-01

    We propose a repeat-until-success protocol to improve the performance of probabilistic quantum repeaters. Conventionally, these rely on passive static linear-optics elements and photodetectors to perform Bell-state measurements (BSMs) with a maximum success rate of 50%. This is a strong impediment for entanglement swapping between distant quantum memories. Every time a BSM fails, entanglement needs to be redistributed between the corresponding memories in the repeater link. The key ingredients of our scheme are repeatable BSMs. Under ideal conditions, these turn probabilistic quantum repeaters into deterministic ones. Under realistic conditions, our protocol too might fail. However, using additional threshold detectors now allows us to improve the entanglement generation rate by almost orders of magnitude, at a nominal distance of 1000 km, compared to schemes that rely on conventional BSMs. This improvement is sufficient to make the performance of our scheme comparable to the expected performance of some deterministic quantum repeaters.

  3. Joint Text and Visual Information with Learning to Rank for Image Search%基于文本与视觉特征聚合的图像排序学习模型

    Institute of Scientific and Technical Information of China (English)

    李静; 李贺

    2011-01-01

    An important problem in image search is how to efficiently rank the search results. However, the ranking models of existing image search engines are generally based on associated text while neglecting the visual content. Because sometimes the textual features cannot match the actual visual content, the search results will be mixed with some false images. In order to fix this problem, visual re-ranking has been proposed recently, in which visual information is applied to refine text based search results. However, the improvement for effectiveness brought by visual re-ranking is limited. This is mainly caused by that the errors in the text-based results will propagate to the refinement stage in visual re-ranking. In this work, we propose a Joint Visual and Text information for Learning to Ranking ( JLR) model based on " learning to rank" framework, in which textual and visual information are simultaneously leveraged in one step for ranking learning processing. This only processing step can avoid the error propagation. We formulate the JLR based on large margin structured output learning, by modeling the visual information into a regularization term. Because the number of constraints is huge, direct optimization of the learning problem is nearly infeasible. The efficient cutting plane algorithm is adopted to learn the model by iteratively adding the most violated constraints. The experimental results demonstrate that the proposed ranking model significantly outperforms the state-of-the-art re-ranking methods.%图像搜索中重要的问题之一是如何有效地对搜索结果进行排序.现有图像搜索引擎的排序模型一般都基于相关文本而没有考虑图像的视觉特征.由于文本特征有时并不能很好地匹配图像的内容,所以搜索结果中会包含被错误排序的图像.针对该问题已经提出了视觉重排序方法,通过视觉信息来精炼基于文本的搜索结果.然而视觉重排序带来的性能提升有限,主要

  4. Reading wiring diagrams made easier for maintenance operators: contribution from research in visual attention and visual search; Aide a la lecture des schemas electriques pour le depannage: apport de la recherche sur l`attention visuelle

    Energy Technology Data Exchange (ETDEWEB)

    Ponthieu, L.; Wolfe, J.M.

    1994-07-01

    This work has been carried out while the author was visiting the Visual Psychophysics lab at the Center for Ophthalmic Research, Harvard Medical School. The general framework is the design of a wiring diagrams visualization system for maintenance operators in electric plants. This study concentrates on how knowledge and experimental techniques from visual attention can help this goal. From this standpoint, the visualization system must best exploit the human visual system abilities. As electronic databases containing all the diagrams will soon be available, it is important to think in advance the display techniques. Presently, maintenance operators favor working with paper printouts even where such databases are already available. The study shows why such an approach is valuable for the design of a display that fits the operator`s tasks. Beyond that, this work has been a mean to learn the experimental techniques of cognitive sciences in an applied frame. (authors). 9 figs., 5 annexes.

  5. 数字图书馆移动视觉搜索的众包模式初探%A Probe into Crowdsourcing Model of Digital Library Mobile Visual Search

    Institute of Scientific and Technical Information of China (English)

    张亭亭; 赵宇翔; 朱庆华

    2016-01-01

    文章对数字图书馆移动视觉搜索的资源库建设机制进行分析,提出通过众包的理念和方法来获取新的视觉资源,主要从众包任务的设计、用户参与的激励机制以及众包结果的质量控制三方面展开深入探讨,并与传统的信息搜索模式进行了对比,最终提出了数字图书馆移动视觉搜索的资源建设机制。%This paper proposes a resource construction mechanism of mobile visual search in digital library, and presents the method of constructing new visual resources based on crowdsourcing approach. Specifically, three aspects are further investigated in this study, namely crowdsourcing task design, incentive mechanism of user participation and quality control of task results, and then a comparison analysis is conducted with the traditional information search mode. Finally, the authors conclude with the visual resource construction mechanism in digital library setting.

  6. A New Generation of 3G Mobile e-Commerce Based on Visual Search Technology%基于可视化搜索技术的新一代3G移动电子商务

    Institute of Scientific and Technical Information of China (English)

    黄辉; 张涛; 谈玺; 杨德利

    2011-01-01

    论述了可视化搜索技术的基本原理及其在3G互联网电子商务中的应用.通过把可视化搜索技术与3G电子商务结合起来,形成崭新的移动可视化电子商务模式,该模式利用了3G网络的优点,同时也充分利用了手机及其摄像头这一信息获取方式,是对传统无线电子商务的突破性扩展.%The paper presents the basic theory of visual search technology, and discusses its application over 3G mobile Intemet. By integrating 3G and e-commerce with visual search technology, we can create a brand new mobile visual e-commerce business model. This business model breaks through the limitation of traditional mobile e-commerce while it gives us the chance to make full use of the high speed advantage of 3G mobile network, and maximizes the human-computer interaction benefit of cellular phone' s camera to snap the image of an object to further do understanding and shopping.

  7. 不同状态焦虑水平下跆拳道运动员视觉搜索效率研究%Visual search efficiency of taekwondo athletes under various status anxiety levels

    Institute of Scientific and Technical Information of China (English)

    周文芳; 刘尚礼

    2015-01-01

    探讨不同状态焦虑水平下跆拳道运动员视觉搜索效率。被试为60名跆拳道运动员,通过情绪诱发程序,以威胁性和中性图片为刺激材料,分别对不同状态焦虑水平下跆拳道运动员的视觉搜索反应时和反应正确率进行考察。结果发现:高状态焦虑被试的视觉搜索反应时长于低状态焦虑被试;高状态焦虑被试的反应正确率低于低状态焦虑被试;在有威胁刺激条件下的反应时长于无威胁刺激条件下的反应时;高状态焦虑条件下,男性被试的反应时要长于女性被试。%In order to discuss the efficiency of visual search of taekwondo athletes with different status anxiety levels,this article has selected 60 taekwondo athletes as the testees and taken threatening and neutral pictures as the stimulus material so as to respectively conduct investigations on the visual search reaction time and accuracy of taekwondo athletes at different anxiety levels through emotion induction programs.The results show that the visual search reaction time of individuals with high status anxieties is longer than that with low status anxieties;the reaction accuracy of individuals of high status anxieties is lower than that with low status anxieties;and the reaction time under threatening stimuli is longer than that under no conditions of threatening stimuli.In addition,under the condition of high status anxiety the male's reaction time is longer than the female's,and there is no significant gender difference in the aspects of both the visual search reaction time and reaction accuracy among the testees.

  8. Low Intelligence People Visual Search Target Speed Interference Experiment Research%智力低下人群视觉搜寻目标中运行速度干扰实验研究

    Institute of Scientific and Technical Information of China (English)

    周凯

    2016-01-01

    Objective: to study the mental retardation crowd the influence factors of visual search target speed. Methods:Special education school in Dalian in the male, the female student with low intelligence selected randomly 15, a total of 30;At the same time, choose Dalian a ordinary primary school students 30 as control group. With the method of knowledge chart for two experiments students with visual search target speed interference experiment. To identify the image can be divided into two groups, the first set of image set to search in geometry, and image will be similar to the shape of furniture as the interference terms;Only in a second set of images to be searching for geometry. Results:compared with the students of normal intelligence, mental retardation students' visual search speed slower, more susceptible to interference of interference. The experimental results show that the ability of the mental retardation students is low.%目的:探讨智力低下人群视觉搜索目标中运行速度的影响因素。方法:在大连某市特殊教育学校中随机选取智力低下的男、女学生各15名,共30名;同时选取大连某市某普通小学的学生30名作为对照组。采用识图的方式对两组实验学生进行视觉搜寻目标中运行速度干扰实验。将待识别图像分为两组,第一组图像中设置待搜寻的几何形状,并将相似形状的家具图像作为干扰项;第二组图像中只有待搜寻的几何形状。结果:与智力正常的学生相比,智力低下学生的视觉搜寻中运行速度更慢,更容易受到特定干扰项的干扰。结论:智力低下学生的各项能力均较低,可针对性加强培训。

  9. Adaptive Large Neighbourhood Search

    DEFF Research Database (Denmark)

    Røpke, Stefan

    Large neighborhood search is a metaheuristic that has gained popularity in recent years. The heuristic repeatedly moves from solution to solution by first partially destroying the solution and then repairing it. The best solution observed during this search is presented as the final solution....... This tutorial introduces the large neighborhood search metaheuristic and the variant adaptive large neighborhood search that dynamically tunes parameters of the heuristic while it is running. Both heuristics belong to a broader class of heuristics that are searching a solution space using very large...... neighborhoods. The tutorial also present applications of the adaptive large neighborhood search, mostly related to vehicle routing problems for which the heuristic has been extremely successful. We discuss how the heuristic can be parallelized and thereby take advantage of modern desktop computers...

  10. Search effort and imperfect detection: Influence on timed-search mussel (Bivalvia: Unionidae surveys in Canadian rivers

    Directory of Open Access Journals (Sweden)

    Reid S. M.

    2016-01-01

    Full Text Available Inventories and population monitoring are essential activities supporting the conservation of freshwater mussel diversity in Canadian rivers. Despite widespread use of timed-search methods to survey river mussels, the relationship between species detection and search effort has received limited study. In this study, repeat-sampling data from 54 Ontario river sites were used to estimate: (1 species detection probabilities; (2 the number of sampling events required to confidently detect species; and, (3 the power of timed-search surveys to detect future distribution declines. Mussels were collected using visual and tactile methods, and collection data were recorded separately for each 1.5 h of search time (up to 4.5 h. Thirteen species were collected; including two endangered species (Rainbow Villosa iris and Eastern Pondmussel Ligumia nasuta. In all cases, species detection was imperfect. However, detection probabilities (p for most species were high (>0.69. Two repeat 4.5 h surveys are required to confidently assess whether most (83% species are present at a site. Search effort had a positive effect on estimates of species richness, detection probability and site occupancy, and the power to detect future distribution declines. At all levels of sampling effort, detection probability and site occupancy estimates were positively correlated to mussel abundance.

  11. 网页信息过载时视觉搜索策略与信息加工方式的眼动研究%Strategy and Processing Mode of Visual Search Under Information Overload on Web Pages: an Eye-tracking Study

    Institute of Scientific and Technical Information of China (English)

    栗觅; 卢万譞; 吕胜富; 宋洋洋; 尹静静; 钟宁

    2012-01-01

    Previous studies have demonstrated that visual search on Web pages is impacted by many factors, such as information form and Webpage layout. However, quantitative research about the impact of information overload for visual search on Web pages has not been reported yet. This study quantitatively investigates users' visual search behavior under information overload on Web pages usingeye-tracking. Results suggest that 1 ) under information overload or not, users' visual search strategies are the same that is paying more attention to pictures and peripheral areas; 2 ) Information overload significantly increases the visual search time, which means the decrease of visual search efficiency; and 3) Under information overload, users are more likely to decrease parallel processing and increase serial processing to improve the visual search efficiency.%为了定量研究网页信息过载对视觉搜索的影响,利用眼动技术调查研究了用户在网页信息过载下的视觉搜索行为.实验结果表明:无论网页信息是否过载,用户视觉搜索都是以图为导向的,并且都呈现周边特性;网页信息过载显著延长了视觉搜索时间,造成获取信息的时间成本增加或时间损失;网页信息过载时,用户更倾向于采用减少平行加工、增加系列加工的信息加工方式来提高视觉搜索效率。

  12. Parieto-occipital areas involved in efficient filtering in search: a time course analysis of visual marking using behavioural and functional imaging procedures

    DEFF Research Database (Denmark)

    Humphreys, Glyn W; Kyllingsbæk, Søren; Watson, Derrick G.

    2004-01-01

    Search for a colour-form conjunction target can be facilitated by presenting one set of distractors prior to the second set of distractors and the target: the preview benefit (Watson & Humphreys, 1997). The early presentation of one set of distractors enables them to be efficiently filtered from ...

  13. Adults with Dyslexia Exhibit Large Effects of Crowding, Increased Dependence on Cues, and Detrimental Effects of Distractors in Visual Search Tasks

    Science.gov (United States)

    Moores, Elisabeth; Cassim, Rizan; Talcott, Joel B.

    2011-01-01

    Difficulties in visual attention are increasingly being linked to dyslexia. To date, the majority of studies have inferred functionality of attention from response times to stimuli presented for an indefinite duration. However, in paradigms that use reaction times to investigate the ability to orient attention, a delayed reaction time could also…

  14. 云计算环境下可视化探索式搜索引擎的研究%The Research on Visual Exploratory Search Engine in Cloud Computing Environment

    Institute of Scientific and Technical Information of China (English)

    周莉; 王珏; 周勇

    2015-01-01

    针对目前搜索引擎返回的信息量过大且缺乏语义关联等问题,提出了一种云计算环境下的可视化探索式搜索引擎模型。该模型通过对元搜索引擎返回的原始信息在云计算环境下语义相似度的计算和语义链的构建,采用探索式搜索方法为用户获取个性化的结果。与传统搜索引擎相比,其结果更加直观地表现了目标信息及其之间丰富的语义关系,该方法使用户能够更为自然而有效地在海量的信息中发现更符合其需求的目标。作为实验模型,还需要更多的元搜索引擎的支持,以及进一步计算优化语义相似度的算法,才能使该模型真正实用化。本研究为云计算环境下构建新一代个性化智能搜索引擎提供了理论和实践上的参考。%A visual exploratory search engine model based on cloud computing has been proposed for the enormous numbers information and lack of Semantics relationship of the traditional search engine. The model obtains personal-ized result for users using exploratory search method ,via semantic similarity computation and semantic link con-struction on the raw information returned from meta-search engine. Compared with the traditional search engine,the results are more intuitive on the represent of the target information and their rich semantic relations. Users can more naturally and efficiently found their target in line with their needs in the massive amount of information. As an ex-perimental model,in order to make this model practical,it needs more meta-search engine's support,and further op-timization of semantic similarity computation algorithm. The research of the model provides theoretical and practical reference for the construction of new generation of personalized intelligent search engine on the cloud computing en-vironment.

  15. Repeatability of peripheral aberrations in young emmetropes.

    Science.gov (United States)

    Baskaran, Karthikeyan; Theagarayan, Baskar; Carius, Staffan; Gustafsson, Jörgen

    2010-10-01

    The purpose of this study is to assess the intrasession repeatability of ocular aberration measurements in the peripheral visual field with a commercially available Shack-Hartmann aberrometer (complete ophthalmic analysis system-high definition-vision research). The higher-order off-axis aberrations data in young healthy emmetropic eyes are also reported. The aberrations of the right eye of 18 emmetropes were measured using an aberrometer with an open field of view that allows peripheral measurements. Five repeated measures of ocular aberrations were obtained and assessed in steps of 10° out to ±40° in the horizontal visual field (nasal + and temporal -) and -20° in the inferior visual field. The coefficient of repeatability, coefficient of variation, and the intraclass correlation coefficient were calculated as a measure of intrasession repeatability. In all eccentric angles, the repeatability of the third- and fourth-order aberrations was better than the fifth and sixth order aberrations. The coefficient of variation was coefficient was >0.90 for the third and fourth order but reduced gradually for higher orders. There was no statistical significant difference in variance of total higher-order root mean square between on- and off-axis measurements (p > 0.05). The aberration data in this group of young emmetropes showed that the horizontal coma (C(3)(1)) was most positive at 40° in the temporal field, decreasing linearly toward negative values with increasing off-axis angle into the nasal field, whereas all other higher-order aberrations showed little or no change. The complete ophthalmic analysis system-high definition-vision research provides fast, repeatable, and valid peripheral aberration measurements and can be used efficiently to measure off-axis aberrations in the peripheral visual field.

  16. Quantum repeated games revisited

    CERN Document Server

    Frackiewicz, Piotr

    2011-01-01

    We present a scheme for playing quantum repeated 2x2 games based on the Marinatto and Weber's approach to quantum games. As a potential application, we study twice repeated Prisoner's Dilemma game. We show that results not available in classical game can be obtained when the game is played in the quantum way. Before we present our idea, we comment on the previous scheme of playing quantum repeated games.

  17. Web Search Results Summarization Using Similarity Assessment

    Directory of Open Access Journals (Sweden)

    Sawant V.V.

    2014-06-01

    Full Text Available Now day’s internet has become part of our life, the WWW is most important service of internet because it allows presenting information such as document, imaging etc. The WWW grows rapidly and caters to a diversified levels and categories of users. For user specified results web search results are extracted. Millions of information pouring online, users has no time to surf the contents completely .Moreover the information available is repeated or duplicated in nature. This issue has created the necessity to restructure the search results that could yield results summarized. The proposed approach comprises of different feature extraction of web pages. Web page visual similarity assessment has been employed to address the problems in different fields including phishing, web archiving, web search engine etc. In this approach, initially by enters user query the number of search results get stored. The Earth Mover's Distance is used to assessment of web page visual similarity, in this technique take the web page as a low resolution image, create signature of that web page image with color and co-ordinate features .Calculate the distance between web pages by applying EMD method. Compute the Layout Similarity value by using tag comparison algorithm and template comparison algorithm. Textual similarity is computed by using cosine similarity, and hyperlink analysis is performed to compute outward links. The final similarity value is calculated by fusion of layout, text, hyperlink and EMD value. Once the similarity matrix is found clustering is employed with the help of connected component. Finally group of similar web pages i.e. summarized results get displayed to user. Experiment conducted to demonstrate the effectiveness of four methods to generate summarized result on different web pages and user queries also.

  18. The weight of the visual world is modified by recent experience

    DEFF Research Database (Denmark)

    Ásgeirsson, Árni Gunnar; Kyllingsbæk, Søren; Kristjánsson, Árni;

    Repetition priming of visual search traditionally refers to the reductions in reaction time when a target‚ or a target feature‚ is repeated on consecutive trials. Priming was initially thought to be a facilitated response to the target-defining feature, while repetition of irrelevant target...... features was thought not to benefit visual search. The simple feature facilitation view has later been contested by results where repetition priming was only observed in response to whole-target repetition and results where search-irrelevant features were primed independently of the target-defining feature....... Recent proposals assume that repetition priming operates at multiple levels. Here we focus on two questions: (1) does repetition priming have a purely perceptual component? and (2) how does such a component fit into the TVA framework? (Bundesen, C. 1990. Psychological bulletin and Review, 97, 523...

  19. 基于元搜索的农业信息可视化平台实现研究%Study on Agricultural Information Visualization Platform Based on Meta-search

    Institute of Scientific and Technical Information of China (English)

    赵兰荣; 朱学芳

    2011-01-01

    With the explosively growing of agricultural websites, it is urgent to design a visual information retrieval platform based on meta-search. On the basis of integration of the visualization and search engines, the establishment of the platform architecture was established in the paper. The design methods of data processing and the functional modal realization for the platform were mainly described. Some interaction functions were described also. The experimen- tal operation showed its stability and advantages over traditional retrieval engines in the search results expression. It is helpful not only to the agricultural information users, but also to the information users in the other domains, and the search engine technique development and application themselves.%随着农业信息资源呈爆炸性增长,可视化信息检索平台的研制显得日益迫切。以农业信息资源检索显示为对象,将可视化技术与搜索引擎技术相结合,主要叙述了基于元搜索的农业信息可视化中的数据处理方法和相应功能模块的设计、实现方法,还叙述了平台界面中的一些交互功能,设计实现了一个基于元搜索的农业信息可视化平台,整个系统性能稳定,能够较好地显示搜索结果。本研究不仅对农业信息检索可视化有帮助,对其它领域信息检索以及对信息检索技术本身的应用研究也具有较好的参考价值。

  20. Professional Microsoft search fast search, Sharepoint search, and search server

    CERN Document Server

    Bennett, Mark; Kehoe, Miles; Voskresenskaya, Natalya

    2010-01-01

    Use Microsoft's latest search-based technology-FAST search-to plan, customize, and deploy your search solutionFAST is Microsoft's latest intelligent search-based technology that boasts robustness and an ability to integrate business intelligence with Search. This in-depth guide provides you with advanced coverage on FAST search and shows you how to use it to plan, customize, and deploy your search solution, with an emphasis on SharePoint 2010 and Internet-based search solutions.With a particular appeal for anyone responsible for implementing and managing enterprise search, this book presents t

  1. Reconfigurable multiport EPON repeater

    Science.gov (United States)

    Oishi, Masayuki; Inohara, Ryo; Agata, Akira; Horiuchi, Yukio

    2009-11-01

    An extended reach EPON repeater is one of the solutions to effectively expand FTTH service areas. In this paper, we propose a reconfigurable multi-port EPON repeater for effective accommodation of multiple ODNs with a single OLT line card. The proposed repeater, which has multi-ports in both OLT and ODN sides, consists of TRs, BTRs with the CDR function and a reconfigurable electrical matrix switch, can accommodate multiple ODNs to a single OLT line card by controlling the connection of the matrix switch. Although conventional EPON repeaters require full OLT line cards to accommodate subscribers from the initial installation stage, the proposed repeater can dramatically reduce the number of required line cards especially when the number of subscribers is less than a half of the maximum registerable users per OLT. Numerical calculation results show that the extended reach EPON system with the proposed EPON repeater can save 17.5% of the initial installation cost compared with a conventional repeater, and can be less expensive than conventional systems up to the maximum subscribers especially when the percentage of ODNs in lightly-populated areas is higher.

  2. Revisiting the TALE repeat.

    Science.gov (United States)

    Deng, Dong; Yan, Chuangye; Wu, Jianping; Pan, Xiaojing; Yan, Nieng

    2014-04-01

    Transcription activator-like (TAL) effectors specifically bind to double stranded (ds) DNA through a central domain of tandem repeats. Each TAL effector (TALE) repeat comprises 33-35 amino acids and recognizes one specific DNA base through a highly variable residue at a fixed position in the repeat. Structural studies have revealed the molecular basis of DNA recognition by TALE repeats. Examination of the overall structure reveals that the basic building block of TALE protein, namely a helical hairpin, is one-helix shifted from the previously defined TALE motif. Here we wish to suggest a structure-based re-demarcation of the TALE repeat which starts with the residues that bind to the DNA backbone phosphate and concludes with the base-recognition hyper-variable residue. This new numbering system is consistent with the α-solenoid superfamily to which TALE belongs, and reflects the structural integrity of TAL effectors. In addition, it confers integral number of TALE repeats that matches the number of bound DNA bases. We then present fifteen crystal structures of engineered dHax3 variants in complex with target DNA molecules, which elucidate the structural basis for the recognition of bases adenine (A) and guanine (G) by reported or uncharacterized TALE codes. Finally, we analyzed the sequence-structure correlation of the amino acid residues within a TALE repeat. The structural analyses reported here may advance the mechanistic understanding of TALE proteins and facilitate the design of TALEN with improved affinity and specificity.

  3. Search Cloud

    Science.gov (United States)

    ... of this page: https://medlineplus.gov/cloud.html Search Cloud To use the sharing features on this ... of Top 110 zoster vaccine Share the MedlinePlus search cloud with your users by embedding our search ...

  4. 视觉搜索任务中直视探测优势的眼动研究%The Detection Superiority of Perceived Direct Gaze in Visual Search Task:Evidence from Eye Movements

    Institute of Scientific and Technical Information of China (English)

    胡中华; 赵光; 刘强; 李红

    2012-01-01

    Previous studies have reported that a straight gaze target embedded in averted gaze distracters was detected faster and more accurate than an averted gaze target among straight gaze distracters. The phenomenon of detection superiority of perceived direct gaze was termed as "the stare-in-the-crowd effect". "The stare-in-the-crowd effect" could be explained as that a straight gaze captures visual-spatial attention more effectively than an averted gaze. However, it is also possible that the stimulus items matching process under the direct gaze condition is faster and easier than that under the averted gaze condition. This explanation has not been tested in previous studies. In addition, head orientation was found to be able to affect the detection of gaze direction. However, it is not clear how head orientation affectsthe detection of gaze direction. In view of this, we used eye tracking approach and divided the detection of gaze direction into three behavioral epochs: the preparation, search and response epoch. To investigate: (1) in which epoch the detection advantage of the direct gaze occurred, and whether the more effectiveness of stimulus items matching process under the direct gaze condition contributed to the-stare-in-the-crowd effect, along with the capture visual-spatial attention of direct gaze. (2) How head orientation affected the detection of gaze direction, and in which visual search epoch this effect was mainly manifested. We used a visual search task. The experiment consisted of two factors: gaze direction (direct gaze; averted gaze) and head orientation (frontal head; deviated head). Subjects were instructed to detect as accurately and quickly as possible whether the target gaze direction was present or not. Sixteen volunteers participated in the experiment (6 males and 10 females). Behavioral results showed that the direct gaze targets were detected more rapidly and accurately than the averted gaze targets; Eye movement analysis found: the detection

  5. Synergistic effect of visual and olfactory cues in the food searching behavior of Drosophila melanogaster%视觉和嗅觉信号对果蝇食物搜寻行为的协同作用

    Institute of Scientific and Technical Information of China (English)

    冯波; 王霞; 李岩; 杜永均

    2013-01-01

    To study the roles of olfaction and vision in the food searching behavior of insects,we investigated the number of trapped adults of Drosophila melanogaster with bayberry and orange as attractants,and the effect of pretreatment with olfactory fruits (bayberry or orange) during the behavioral scenario.The results showed that traps with visual and olfactory cues from the same fruit sources attracted more flies than the bayberry picture or olfactory odor from the bayberry.However,the flies attracted by the combination of visual and olfactory cues from different kind of fruits were not significantly more than those attracted by olfactory cues.Experience by olfactory pretreatments with fruit bayberry or orange not only increased the number of flies attracted by olfactory or visual cues,in which the number of flies attracted by olfactory bayberry was the same as that attracted by bayberry with visual and olfactory cues,but also increased the number of flies attracted by traps with visual and olfactory cues from different kind of fruits.However,olfactory pretreatments did not influence the number of flies attracted by traps with visual and olfactory cues from the same fruits.So,olfactory and visual cues were used by flies in food searching behavior and there was synergistic effect of visual and olfactory cues from the same fruits on the attraction of flies.The fly D.melanogaster has strong memory,and can use remembered olfactory cues to facilitate food searching.Our results will not only improve our understanding about the food searching behavior of flies in nature,but also help us to design more efficient fly traps.%为了探索视觉和嗅觉信号在昆虫食物搜寻过程中的作用,本研究利用杨梅和橘子为引诱物,在实验室条件下测定了嗅觉和视觉信号诱集到的黑腹果蝇Drosophila melanogaster数量,分析了嗅觉经历对果蝇嗅觉和视觉食物搜寻的影响.发现同源性嗅觉和视觉信号存在的杨梅诱集到的果蝇数

  6. Recursive quantum repeater networks

    CERN Document Server

    Van Meter, Rodney; Horsman, Clare

    2011-01-01

    Internet-scale quantum repeater networks will be heterogeneous in physical technology, repeater functionality, and management. The classical control necessary to use the network will therefore face similar issues as Internet data transmission. Many scalability and management problems that arose during the development of the Internet might have been solved in a more uniform fashion, improving flexibility and reducing redundant engineering effort. Quantum repeater network development is currently at the stage where we risk similar duplication when separate systems are combined. We propose a unifying framework that can be used with all existing repeater designs. We introduce the notion of a Quantum Recursive Network Architecture, developed from the emerging classical concept of 'recursive networks', extending recursive mechanisms from a focus on data forwarding to a more general distributed computing request framework. Recursion abstracts independent transit networks as single relay nodes, unifies software layer...

  7. Semantic Visualization and Navigation in Textual Corpus

    CERN Document Server

    Kboubi, Férihane; BenAhmed, Mohamed

    2012-01-01

    This paper gives a survey of related work on the information visualization domain and study the real integration of the cartography paradigms in actual information search systems. Based on this study, we propose a semantic visualization and navigation approach which offer to users three search modes: precise search, connotative search and thematic search. The objective is to propose to the users of an information search system, new interaction paradigms which support the semantic aspect of the considered information space and guide users in their searches by assisting them to locate their interest center and to improve serendipity.

  8. MICdb3.0: a comprehensive resource of microsatellite repeats from prokaryotic genomes.

    Science.gov (United States)

    Mudunuri, Suresh B; Patnana, Sujan; Nagarajaram, Hampapathalu A

    2014-01-01

    The MICdb is a comprehensive relational database of perfect microsatellites extracted from completely sequenced and annotated genomes of bacteria and archaea. The current version MICdb3.0 is an updated and revised version of MICdb2.0. As compared with the previous version MICdb2.0, the current release is significantly improved in terms of much larger coverage of genomes, improved presentation of queried results, user-friendly administration module to manage Simple Sequence Repeat (SSR) data such as addition of new genomes, deletion of obsolete data, etc., and also removal of certain features deemed to be redundant. The new web-interface to the database called Microsatellite Analysis Server (MICAS) version 3.0 has been improved by the addition of powerful high-quality visualization tools to view the query results in the form of pie charts and bar graphs. All the query results and graphs can be exported in different formats so that the users can use them for further analysis. MICAS3.0 is also equipped with a unique genome comparison module using which users can do pair-wise comparison of genomes with regard to their microsatellite distribution. The advanced search module can be used to filter the repeats based on certain criteria such as filtering repeats of a particular motif/repeat size, extracting repeats of coding/non-coding regions, sort repeats, etc. The MICdb database has, therefore, been made portable to be administered by a person with the necessary administrative privileges. The MICdb3.0 database and analysis server can be accessed for free from www.cdfd.org.in/micas. Database URL: http://www.cdfd.org.in/micas.

  9. Search Recipes

    Science.gov (United States)

    ... Tips A to Z Map Search Enter your search term 98 results • Advanced Search Everything News Videos e- ... usda.gov https://www.whatscooking.fns.usda.gov/search/solr-results/im_field_term_program/child-nutrition-cnp-163 We would like ...

  10. Search Patterns

    CERN Document Server

    Morville, Peter

    2010-01-01

    What people are saying about Search Patterns "Search Patterns is a delight to read -- very thoughtful and thought provoking. It's the most comprehensive survey of designing effective search experiences I've seen." --Irene Au, Director of User Experience, Google "I love this book! Thanks to Peter and Jeffery, I now know that search (yes, boring old yucky who cares search) is one of the coolest ways around of looking at the world." --Dan Roam, author, The Back of the Napkin (Portfolio Hardcover) "Search Patterns is a playful guide to the practical concerns of search interface design. It cont

  11. Visual search of neuropil-enriched RNAs from brain in situ hybridization data through the image analysis pipeline hippo-ATESC.

    Directory of Open Access Journals (Sweden)

    Roberto Ugolotti

    Full Text Available MOTIVATION: RNA molecules specifically enriched in the neuropil of neuronal cells and in particular in dendritic spines are of great interest for neurobiology in virtue of their involvement in synaptic structure and plasticity. The systematic recognition of such molecules is therefore a very important task. High resolution images of RNA in situ hybridization experiments contained in the Allen Brain Atlas (ABA represent a very rich resource to identify them and have been so far exploited for this task through human-expert analysis. However, software tools that may automatically address the same objective are not very well developed. RESULTS: In this study we describe an automatic method for exploring in situ hybridization data and discover neuropil-enriched RNAs in the mouse hippocampus. We called it Hippo-ATESC (Automatic Texture Extraction from the Hippocampal region using Soft Computing. Bioinformatic validation showed that the Hippo-ATESC is very efficient in the recognition of RNAs which are manually identified by expert curators as neuropil-enriched on the same image series. Moreover, we show that our method can also highlight genes revealed by microdissection-based methods but missed by human visual inspection. We experimentally validated our approach by identifying a non-coding transcript enriched in mouse synaptosomes. The code is freely available on the web at http://ibislab.ce.unipr.it/software/hippo/.

  12. Visualizing pair formation on the atomic scale and the search for the mechanism of superconductivity in high-T{sub c} cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, A [Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08540 (United States)], E-mail: yazdani@princeton.edu

    2009-04-22

    We have developed several new experimental techniques, based on the scanning tunneling microscope, to visualize the process of pair formation on the atomic scale and to probe with high precision what controls the strength of pairing in high-T{sub c} cuprate superconductor compounds. These new experiments provide evidence that pairing in these exotic superconductors occurs above the bulk transition temperature and in nanoscale regions with sizes of 1-3 nm. The high temperature nucleation and proliferation of these nanoscale puddles have a strong connection to the temperature-doping phase diagram of these superconductors. On average we have found that the pairing gap {delta} and the temperature at which they first nucleate T{sub p} follow the simple relation: 2{delta}/k{sub B}T{sub p}{approx}8. Moreover, the variations of the pairing strength on the nanoscale can be examined to find microscopic clues to the mechanism of pairing. Specifically, we have found evidence that suggests that strong electronic correlation, as opposed to coupling of electrons to bosons, is responsible for the pairing mechanism in the cuprates. Surprisingly, we have found that nanoscale measurements of electronic correlations in the normal state (at temperatures as high as twice T{sub c}) can be used to predict the strength of the local pairing interaction at low temperatures.

  13. Do Gamma-Ray Burst Sources Repeat?

    OpenAIRE

    Meegan, Charles A.; Hartmann, Dieter H.; Brainerd, J. J.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey; Kouveliotou, Chryssa; Fishman, Gerald; Blumenthal, George; Brock, Martin

    1995-01-01

    The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports (Quashnock and Lamb 1993; Wang and Lingenfelter 1993) of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al. 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic and...

  14. Visual Impairment

    Science.gov (United States)

    ... Surgery? Choosing the Right Sport for You Shyness Visual Impairment KidsHealth > For Teens > Visual Impairment Print A A ... with the brain, making vision impossible. What Is Visual Impairment? Many people have some type of visual problem ...

  15. Visual field

    Science.gov (United States)

    Perimetry; Tangent screen exam; Automated perimetry exam; Goldmann visual field exam; Humphrey visual field exam ... Confrontation visual field exam : This is a quick and basic check of the visual field. The health care provider ...

  16. Automated search for supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Kare, J.T.

    1984-11-15

    This thesis describes the design, development, and testing of a search system for supernovae, based on the use of current computer and detector technology. This search uses a computer-controlled telescope and charge coupled device (CCD) detector to collect images of hundreds of galaxies per night of observation, and a dedicated minicomputer to process these images in real time. The system is now collecting test images of up to several hundred fields per night, with a sensitivity corresponding to a limiting magnitude (visual) of 17. At full speed and sensitivity, the search will examine some 6000 galaxies every three nights, with a limiting magnitude of 18 or fainter, yielding roughly two supernovae per week (assuming one supernova per galaxy per 50 years) at 5 to 50 percent of maximum light. An additional 500 nearby galaxies will be searched every night, to locate about 10 supernovae per year at one or two percent of maximum light, within hours of the initial explosion.

  17. A method for real-time visual stimulus selection in the study of cortical object perception.

    Science.gov (United States)

    Leeds, Daniel D; Tarr, Michael J

    2016-06-01

    The properties utilized by visual object perception in the mid- and high-level ventral visual pathway are poorly understood. To better establish and explore possible models of these properties, we adopt a data-driven approach in which we repeatedly interrogate neural units using functional Magnetic Resonance Imaging (fMRI) to establish each unit's image selectivity. This approach to imaging necessitates a search through a broad space of stimulus properties using a limited number of samples. To more quickly identify the complex visual features underlying human cortical object perception, we implemented a new functional magnetic resonance imaging protocol in which visual stimuli are selected in real-time based on BOLD responses to recently shown images. Two variations of this protocol were developed, one relying on natural object stimuli and a second based on synthetic object stimuli, both embedded in feature spaces based on the complex visual properties of the objects. During fMRI scanning, we continuously controlled stimulus selection in the context of a real-time search through these image spaces in order to maximize neural responses across pre-determined 1cm(3) rain regions. Elsewhere we have reported the patterns of cortical selectivity revealed by this approach (Leeds et al., 2014). In contrast, here our objective is to present more detailed methods and explore the technical and biological factors influencing the behavior of our real-time stimulus search. We observe that: 1) Searches converged more reliably when exploring a more precisely parameterized space of synthetic objects; 2) real-time estimation of cortical responses to stimuli is reasonably consistent; 3) search behavior was acceptably robust to delays in stimulus displays and subject motion effects. Overall, our results indicate that real-time fMRI methods may provide a valuable platform for continuing study of localized neural selectivity, both for visual object representation and beyond.

  18. The Pentapeptide Repeat Proteins

    Energy Technology Data Exchange (ETDEWEB)

    Vetting,M.; Hegde, S.; Fajardo, J.; Fiser, A.; Roderick, S.; Takiff, H.; Blanchard, J.

    2006-01-01

    The Pentapeptide Repeat Protein (PRP) family has over 500 members in the prokaryotic and eukaryotic kingdoms. These proteins are composed of, or contain domains composed of, tandemly repeated amino acid sequences with a consensus sequence of [S, T,A, V][D, N][L, F]-[S, T,R][G]. The biochemical function of the vast majority of PRP family members is unknown. The three-dimensional structure of the first member of the PRP family was determined for the fluoroquinolone resistance protein (MfpA) from Mycobacterium tuberculosis. The structure revealed that the pentapeptide repeats encode the folding of a novel right-handed quadrilateral {beta}-helix. MfpA binds to DNA gyrase and inhibits its activity. The rod-shaped, dimeric protein exhibits remarkable size, shape and electrostatic similarity to DNA.

  19. Repeating the Past

    Science.gov (United States)

    Moore, John W.

    1998-05-01

    As part of the celebration of the Journal 's 75th year, we are scanning each Journal issue from 25, 50, and 74 years ago. Many of the ideas and practices described are so similar to present-day "innovations" that George Santayana's adage (1) "Those who cannot remember the past are condemned to repeat it" comes to mind. But perhaps "condemned" is too strong - sometimes it may be valuable to repeat something that was done long ago. One example comes from the earliest days of the Division of Chemical Education and of the Journal.

  20. All-optical repeater.

    Science.gov (United States)

    Silberberg, Y

    1986-06-01

    An all-optical device containing saturable gain, saturable loss, and unsaturable loss is shown to transform weak, distorted optical pulses into uniform standard-shape pulses. The proposed device performs thresholding, amplification, and pulse shaping as required from an optical repeater. It is shown that such a device could be realized by existing semiconductor technology.

  1. Bidirectional Manchester repeater

    Science.gov (United States)

    Ferguson, J.

    1980-01-01

    Bidirectional Manchester repeater is inserted at periodic intervals along single bidirectional twisted pair transmission line to detect, amplify, and transmit bidirectional Manchester 11 code signals. Requiring only 18 TTL 7400 series IC's, some line receivers and drivers, and handful of passive components, circuit is simple and relatively inexpensive to build.

  2. Personalized Search

    CERN Document Server

    AUTHOR|(SzGeCERN)749939

    2015-01-01

    As the volume of electronically available information grows, relevant items become harder to find. This work presents an approach to personalizing search results in scientific publication databases. This work focuses on re-ranking search results from existing search engines like Solr or ElasticSearch. This work also includes the development of Obelix, a new recommendation system used to re-rank search results. The project was proposed and performed at CERN, using the scientific publications available on the CERN Document Server (CDS). This work experiments with re-ranking using offline and online evaluation of users and documents in CDS. The experiments conclude that the personalized search result outperform both latest first and word similarity in terms of click position in the search result for global search in CDS.

  3. Search Combinators

    CERN Document Server

    Schrijvers, Tom; Wuille, Pieter; Samulowitz, Horst; Stuckey, Peter J

    2012-01-01

    The ability to model search in a constraint solver can be an essential asset for solving combinatorial problems. However, existing infrastructure for defining search heuristics is often inadequate. Either modeling capabilities are extremely limited or users are faced with a general-purpose programming language whose features are not tailored towards writing search heuristics. As a result, major improvements in performance may remain unexplored. This article introduces search combinators, a lightweight and solver-independent method that bridges the gap between a conceptually simple modeling language for search (high-level, functional and naturally compositional) and an efficient implementation (low-level, imperative and highly non-modular). By allowing the user to define application-tailored search strategies from a small set of primitives, search combinators effectively provide a rich domain-specific language (DSL) for modeling search to the user. Remarkably, this DSL comes at a low implementation cost to the...

  4. Millennial Students’ Online Search Strategies are Associated With Their Mental Models of Search. A Review of: Holman, L. (2011. Millennial students’ mental models of search: Implications for academic librarians and database developers. Journal of Academic Librarianship, 37(1, 19-27. doi:10.1016/j.acalib.2010.10.003

    Directory of Open Access Journals (Sweden)

    Leslie Bussert

    2011-09-01

    Full Text Available Objective – To examine first-year college students’ information seeking behaviours and determine whether their mental models of the search process influence their ability to effectively search for and find scholarly materials.Design – Mixed methods including contextual inquiry, concept mapping, observation, and interviews.Setting – University of Baltimore, a public institution in Maryland, United States of America, offering undergraduate, graduate, and professional degrees.Subjects – A total of 21 first-year undergraduate students, ages 16 to 19 years, undertaking research assignments for which they chose to use online resources.Methods – First-year students were recruited in the fall of 2008 and met with the researcher in a university usability lab for about one hour over a three week period. The researcher observed and videotaped the students as they conducted research in their chosen search engines or article databases. The searches were captured using software, and students were encouraged to think aloud about their research process, search strategies, and anticipated search results. Observation sessions concluded with a 10-question interview incorporating a review of the keywords the student used, the student’s reflection on the success of his or her searches, and possible alternate keywords. The interview also offered prompts to help the researcher learn about students’ conceptualizations of search tools’ utilization of keywords to generate results. The researcher then asked the students to provide a visual diagram of the relationship between their search terms and the items retrieved in the search tool.Data were analyzed by identifying the 21 different search tools used by the students and categorizing all 210 searches and student diagrams for further analysis. A scheme similar to Guinee, Eagleton, and Hall’s (2003 characterized the student searches into four categories: simple single-term searches, topic plus focus

  5. Duct Leakage Repeatability Testing

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-01-01

    Duct leakage often needs to be measured to demonstrate compliance with requirements or to determine energy or Indoor Air Quality (IAQ) impacts. Testing is often done using standards such as ASTM E1554 (ASTM 2013) or California Title 24 (California Energy Commission 2013 & 2013b), but there are several choices of methods available within the accepted standards. Determining which method to use or not use requires an evaluation of those methods in the context of the particular needs. Three factors that are important considerations are the cost of the measurement, the accuracy of the measurement and the repeatability of the measurement. The purpose of this report is to evaluate the repeatability of the three most significant measurement techniques using data from the literature and recently obtained field data. We will also briefly discuss the first two factors. The main question to be answered by this study is to determine if differences in the repeatability of these tests methods is sufficient to indicate that any of these methods is so poor that it should be excluded from consideration as an allowed procedure in codes and standards.

  6. Slowed Search in the Context of Unimpaired Grouping in Autism: Evidence from Multiple Conjunction Search.

    Science.gov (United States)

    Keehn, Brandon; Joseph, Robert M

    2016-03-01

    In multiple conjunction search, the target is not known in advance but is defined only with respect to the distractors in a given search array, thus reducing the contributions of bottom-up and top-down attentional and perceptual processes during search. This study investigated whether the superior visual search skills typically demonstrated by individuals with autism spectrum disorder (ASD) would be evident in multiple conjunction search. Thirty-two children with ASD and 32 age- and nonverbal IQ-matched typically developing (TD) children were administered a multiple conjunction search task. Contrary to findings from the large majority of studies on visual search in ASD, response times of individuals with ASD were significantly slower than those of their TD peers. Evidence of slowed performance in ASD suggests that the mechanisms responsible for superior ASD performance in other visual search paradigms are not available in multiple conjunction search. Although the ASD group failed to exhibit superior performance, they showed efficient search and intertrial priming levels similar to the TD group. Efficient search indicates that ASD participants were able to group distractors into distinct subsets. In summary, while demonstrating grouping and priming effects comparable to those exhibited by their TD peers, children with ASD were slowed in their performance on a multiple conjunction search task, suggesting that their usual superior performance in visual search tasks is specifically dependent on top-down and/or bottom-up attentional and perceptual processes.

  7. Computerized Screening for Visual Stress in Children with Dyslexia

    Science.gov (United States)

    Singleton, Chris; Henderson, Lisa-Marie

    2007-01-01

    Visual stress--a condition in which unpleasant visual symptoms are experienced when reading--has been reported to be more prevalent in dyslexic individuals but at the present time the relationship between dyslexia and visual stress remains controversial. ViSS, a computerized visual stress screener that incorporates reading-like visual search, has…

  8. Gambling in the visual periphery: a conjoint-measurement analysis of human ability to judge visual uncertainty.

    Directory of Open Access Journals (Sweden)

    Hang Zhang

    Full Text Available Recent work in motor control demonstrates that humans take their own motor uncertainty into account, adjusting the timing and goals of movement so as to maximize expected gain. Visual sensitivity varies dramatically with retinal location and target, and models of optimal visual search typically assume that the visual system takes retinal inhomogeneity into account in planning eye movements. Such models can then use the entire retina rather than just the fovea to speed search. Using a simple decision task, we evaluated human ability to compensate for retinal inhomogeneity. We first measured observers' sensitivity for targets, varying contrast and eccentricity. Observers then repeatedly chose between targets differing in eccentricity and contrast, selecting the one they would prefer to attempt: e.g., a low contrast target at 2° versus a high contrast target at 10°. Observers knew they would later attempt some of their chosen targets and receive rewards for correct classifications. We evaluated performance in three ways. Equivalence: Do observers' judgments agree with their actual performance? Do they correctly trade off eccentricity and contrast and select the more discriminable target in each pair? Transitivity: Are observers' choices self-consistent? Dominance: Do observers understand that increased contrast improves performance? Decreased eccentricity? All observers exhibited patterned failures of equivalence, and seven out of eight observers failed transitivity. There were significant but small failures of dominance. All these failures together reduced their winnings by 10%-18%.

  9. Deep First Formal Concept Search

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2014-01-01

    Full Text Available The calculation of formal concepts is a very important part in the theory of formal concept analysis (FCA; however, within the framework of FCA, computing all formal concepts is the main challenge because of its exponential complexity and difficulty in visualizing the calculating process. With the basic idea of Depth First Search, this paper presents a visualization algorithm by the attribute topology of formal context. Limited by the constraints and calculation rules, all concepts are achieved by the visualization global formal concepts searching, based on the topology degenerated with the fixed start and end points, without repetition and omission. This method makes the calculation of formal concepts precise and easy to operate and reflects the integrity of the algorithm, which enables it to be suitable for visualization analysis.

  10. Faceted Search

    CERN Document Server

    Tunkelang, Daniel

    2009-01-01

    We live in an information age that requires us, more than ever, to represent, access, and use information. Over the last several decades, we have developed a modern science and technology for information retrieval, relentlessly pursuing the vision of a "memex" that Vannevar Bush proposed in his seminal article, "As We May Think." Faceted search plays a key role in this program. Faceted search addresses weaknesses of conventional search approaches and has emerged as a foundation for interactive information retrieval. User studies demonstrate that faceted search provides more

  11. Olfaction spontaneously highlights visual saliency map.

    Science.gov (United States)

    Chen, Kepu; Zhou, Bin; Chen, Shan; He, Sheng; Zhou, Wen

    2013-10-01

    Attention is intrinsic to our perceptual representations of sensory inputs. Best characterized in the visual domain, it is typically depicted as a spotlight moving over a saliency map that topographically encodes strengths of visual features and feedback modulations over the visual scene. By introducing smells to two well-established attentional paradigms, the dot-probe and the visual-search paradigms, we find that a smell reflexively directs attention to the congruent visual image and facilitates visual search of that image without the mediation of visual imagery. Furthermore, such effect is independent of, and can override, top-down bias. We thus propose that smell quality acts as an object feature whose presence enhances the perceptual saliency of that object, thereby guiding the spotlight of visual attention. Our discoveries provide robust empirical evidence for a multimodal saliency map that weighs not only visual but also olfactory inputs.

  12. Repeatability of Cryogenic Multilayer Insulation

    Science.gov (United States)

    Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

    2017-01-01

    Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between multiple identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five GRC provided coupons with 25 layers was shown to be +/- 8.4 whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0. A second group of 10 coupons have been fabricated by Yetispace and tested by Florida State University, through the first 4 tests, the repeatability has been shown to be +/- 16. Based on detailed statistical analysis, the data has been shown to be statistically significant.

  13. Object attributes combine additively in visual search.

    Science.gov (United States)

    Pramod, R T; Arun, S P

    2016-01-01

    We perceive objects as containing a variety of attributes: local features, relations between features, internal details, and global properties. But we know little about how they combine. Here, we report a remarkably simple additive rule that governs how these diverse object attributes combine in vision. The perceived dissimilarity between two objects was accurately explained as a sum of (a) spatially tuned local contour-matching processes modulated by part decomposition; (b) differences in internal details, such as texture; (c) differences in emergent attributes, such as symmetry; and (d) differences in global properties, such as orientation or overall configuration of parts. Our results elucidate an enduring question in object vision by showing that the whole object is not a sum of its parts but a sum of its many attributes.

  14. Impaired visual competition in patients with homonymous visual field defects.

    Science.gov (United States)

    Geuzebroek, A C; van den Berg, A V

    2017-03-01

    Intense visual training can lead to partial recovery of visual field defects caused by lesions of the primary visual cortex. However, the standard visual detection and discrimination tasks, used to assess this recovery process tend to ignore the complexity of the natural visual environment, where multiple stimuli continuously interact. Visual competition is an essential component for natural search tasks and detecting unexpected events. Our study focused on visual decision-making and to what extent the recovered visual field can compete for attention with the 'intact' visual field. Nine patients with visual field defects who had previously received visual discrimination training, were compared to healthy age-matched controls using a saccade target-selection paradigm, in which participants actively make a saccade towards the brighter of two flashed targets. To further investigate the nature of competition (feed-forward or feedback inhibition), we presented two flashes that reversed their intensity difference during the flash. Both competition between recovered visual field and intact visual field, as well as competition within the intact visual field, were assessed. Healthy controls showed the expected primacy effect; they preferred the initially brighter target. Surprisingly, choice behaviour, even in the patients' supposedly 'intact' visual field, was significantly different from the control group for all but one. In the latter patient, competition was comparable to the controls. All other patients showed a significantly reduced preference to the brighter target, but still showed a small hint of primacy in the reversal conditions. The present results indicate that patients and controls have similar decision-making mechanisms but patients' choices are affected by a strong tendency to guess, even in the intact visual field. This tendency likely reveals slower integration of information, paired with a lower threshold. Current rehabilitation should therefore also

  15. Brain Vulnerability to Repeated Blast Overpressure and Polytrauma

    Science.gov (United States)

    2013-11-01

    discrimination procedures were developed, refined and implemented to test visual acuity and visually based cognitive performance and reaction time. Telemetric...exposure: The shock tube consists of a 2.5 ft long compression chamber that is separated from a 15 ft long expansion chamber by polyester Mylar...single BOP (figs 8 & 9) or 2 BOPs separated by 24 hr (not shown), closely coupled repeated BOP exposure increased reaction times (fig 11

  16. Orienting attention to objects in visual short-term memory

    NARCIS (Netherlands)

    Dell'Acqua, Roberto; Sessa, Paola; Toffanin, Paolo; Luria, Roy; Joliccoeur, Pierre

    2010-01-01

    We measured electroencephalographic activity during visual search of a target object among objects available to perception or among objects held in visual short-term memory (VSTM). For perceptual search, a single shape was shown first (pre-cue) followed by a search-array and the task was to decide w

  17. Orienting attention to objects in visual short-term memory

    NARCIS (Netherlands)

    Dell'Acqua, Roberto; Sessa, Paola; Toffanin, Paolo; Luria, Roy; Joliccoeur, Pierre

    2010-01-01

    We measured electroencephalographic activity during visual search of a target object among objects available to perception or among objects held in visual short-term memory (VSTM). For perceptual search, a single shape was shown first (pre-cue) followed by a search-array and the task was to decide w

  18. Orienting attention to objects in visual short-term memory

    NARCIS (Netherlands)

    Dell'Acqua, Roberto; Sessa, Paola; Toffanin, Paolo; Luria, Roy; Joliccoeur, Pierre

    We measured electroencephalographic activity during visual search of a target object among objects available to perception or among objects held in visual short-term memory (VSTM). For perceptual search, a single shape was shown first (pre-cue) followed by a search-array and the task was to decide

  19. Visual agnosia.

    Science.gov (United States)

    Álvarez, R; Masjuan, J

    2016-03-01

    Visual agnosia is defined as an impairment of object recognition, in the absence of visual acuity or cognitive dysfunction that would explain this impairment. This condition is caused by lesions in the visual association cortex, sparing primary visual cortex. There are 2 main pathways that process visual information: the ventral stream, tasked with object recognition, and the dorsal stream, in charge of locating objects in space. Visual agnosia can therefore be divided into 2 major groups depending on which of the two streams is damaged. The aim of this article is to conduct a narrative review of the various visual agnosia syndromes, including recent developments in a number of these syndromes.

  20. Ontologies in biological data visualization.

    Science.gov (United States)

    Carpendale, Sheelagh; Chen, Min; Evanko, Daniel; Gehlenborg, Nils; Gorg, Carsten; Hunter, Larry; Rowland, Francis; Storey, Margaret-Anne; Strobelt, Hendrik

    2014-01-01

    In computer science, an ontology is essentially a graph-based knowledge representation in which each node corresponds to a concept and each edge specifies a relation between two concepts. Ontological development in biology can serve as a focus to discuss the challenges and possible research directions for ontologies in visualization. The principle challenges are the dynamic and evolving nature of ontologies, the ever-present issue of scale, the diversity and richness of the relationships in ontologies, and the need to better understand the relationship between ontologies and the data analysis tasks scientists wish to support. Research directions include visualizing ontologies; visualizing semantically or ontologically annotated texts, documents, and corpora; automated generation of visualizations using ontologies; and visualizing ontological context to support search. Although this discussion uses issues of ontologies in biological data visualization as a springboard, these topics are of general relevance to visualization.

  1. Adaptation and visual salience

    Science.gov (United States)

    McDermott, Kyle C.; Malkoc, Gokhan; Mulligan, Jeffrey B.; Webster, Michael A.

    2011-01-01

    We examined how the salience of color is affected by adaptation to different color distributions. Observers searched for a color target on a dense background of distractors varying along different directions in color space. Prior adaptation to the backgrounds enhanced search on the same background while adaptation to orthogonal background directions slowed detection. Advantages of adaptation were seen for both contrast adaptation (to different color axes) and chromatic adaptation (to different mean chromaticities). Control experiments, including analyses of eye movements during the search, suggest that these aftereffects are unlikely to reflect simple learning or changes in search strategies on familiar backgrounds, and instead result from how adaptation alters the relative salience of the target and background colors. Comparable effects were observed along different axes in the chromatic plane or for axes defined by different combinations of luminance and chromatic contrast, consistent with visual search and adaptation mediated by multiple color mechanisms. Similar effects also occurred for color distributions characteristic of natural environments with strongly selective color gamuts. Our results are consistent with the hypothesis that adaptation may play an important functional role in highlighting the salience of novel stimuli by discounting ambient properties of the visual environment. PMID:21106682

  2. Early vision and visual attention

    Directory of Open Access Journals (Sweden)

    Gvozdenović Vasilije P.

    2003-01-01

    Full Text Available The question whether visual perception is spontaneous, sudden or is running through several phases, mediated by higher cognitive processes, was raised ever since the early work of Gestalt psychologists. In the early 1980s, Treisman proposed the feature integration theory of attention (FIT, based on the findings of neuroscience. Soon after publishing her theory a new scientific approach appeared investigating several visual perception phenomena. The most widely researched were the key constructs of FIT, like types of visual search and the role of the attention. The following review describes the main studies of early vision and visual attention.

  3. Visual art and visual perception

    NARCIS (Netherlands)

    Koenderink, Jan J.

    2015-01-01

    Visual art and visual perception ‘Visual art’ has become a minor cul-de-sac orthogonal to THE ART of the museum directors and billionaire collectors. THE ART is conceptual, instead of visual. Among its cherished items are the tins of artist’s shit (Piero Manzoni, 1961, Merda d’Artista) “worth their

  4. Spatial probability aids visual stimulus discrimination

    Directory of Open Access Journals (Sweden)

    Michael Druker

    2010-08-01

    Full Text Available We investigated whether the statistical predictability of a target's location would influence how quickly and accurately it was classified. Recent results have suggested that spatial probability can be a cue for the allocation of attention in visual search. One explanation for probability cuing is spatial repetition priming. In our two experiments we used probability distributions that were continuous across the display rather than relying on a few arbitrary screen locations. This produced fewer spatial repeats and allowed us to dissociate the effect of a high probability location from that of short-term spatial repetition. The task required participants to quickly judge the color of a single dot presented on a computer screen. In Experiment 1, targets were more probable in an off-center hotspot of high probability that gradually declined to a background rate. Targets garnered faster responses if they were near earlier target locations (priming and if they were near the high probability hotspot (probability cuing. In Experiment 2, target locations were chosen on three concentric circles around fixation. One circle contained 80% of targets. The value of this ring distribution is that it allowed for a spatially restricted high probability zone in which sequentially repeated trials were not likely to be physically close. Participant performance was sensitive to the high-probability circle in addition to the expected effects of eccentricity and the distance to recent targets. These two experiments suggest that inhomogeneities in spatial probability can be learned and used by participants on-line and without prompting as an aid for visual stimulus discrimination and that spatial repetition priming is not a sufficient explanation for this effect. Future models of attention should consider explicitly incorporating the probabilities of targets locations and features.

  5. Analyzing visual attention tot repeated print advertising using scanpath theory

    NARCIS (Netherlands)

    Rosbergen, Edward; Wedel, Michel; Pieters, Rik

    1997-01-01

    The purpose of this paper is to propose a nonparametric interest rate term structure model and investigate its implications on term structure dynamics and prices of interest rate derivative securities. The nonparametric spot interest rate process is estimated from the observed short-term interest ra

  6. Analyzing visual attention tot repeated print advertising using scanpath theory

    NARCIS (Netherlands)

    Rosbergen, Edward; Wedel, Michel; Pieters, Rik

    1997-01-01

    The purpose of this paper is to propose a nonparametric interest rate term structure model and investigate its implications on term structure dynamics and prices of interest rate derivative securities. The nonparametric spot interest rate process is estimated from the observed short-term interest

  7. Flow visualization

    CERN Document Server

    Merzkirch, Wolfgang

    1974-01-01

    Flow Visualization describes the most widely used methods for visualizing flows. Flow visualization evaluates certain properties of a flow field directly accessible to visual perception. Organized into five chapters, this book first presents the methods that create a visible flow pattern that could be investigated by visual inspection, such as simple dye and density-sensitive visualization methods. It then deals with the application of electron beams and streaming birefringence. Optical methods for compressible flows, hydraulic analogy, and high-speed photography are discussed in other cha

  8. Autonomous search

    CERN Document Server

    Hamadi, Youssef; Saubion, Frédéric

    2012-01-01

    Autonomous combinatorial search (AS) represents a new field in combinatorial problem solving. Its major standpoint and originality is that it considers that problem solvers must be capable of self-improvement operations. This is the first book dedicated to AS.

  9. A Novel Algorithm for Finding Interspersed Repeat Regions

    Institute of Scientific and Technical Information of China (English)

    Dongdong Li; Zhengzhi Wang; Qingshan Ni

    2004-01-01

    The analysis of repeats in the DNA sequences is an important subject in bioinformatics. In this paper, we propose a novel projection-assemble algorithm to find unknown interspersed repeats in DNA sequences. The algorithm employs random projection algorithm to obtain a candidate fragment set, and exhaustive search algorithm to search each pair of fragments from the candidate fragment set to find potential linkage, and then assemble them together. The complexity of our projection-assemble algorithm is nearly linear to the length of the genome sequence, and its memory usage is limited by the hardware. We tested our algorithm with both simulated data and real biology data, and the results show that our projection-assemble algorithm is efficient. By means of this algorithm, we found an un-labeled repeat region that occurs five times in Escherichia coli genome, with its length more than 5,000 bp, and a mismatch probability less than 4%.

  10. TRAC Innovative Visualization Techniques

    Science.gov (United States)

    2016-11-14

    Design thinking”. In: Harvard business review 86.6 (2008), p. 84. [6] U.S. Department of the Army. ATP 5-0.1 Army Design Methodology. Washington D.C... business review 86.6 (2008), p. 84. 3 4. What other visualization techniques can assist TRAC analysts with addressing these issues? 5. What are the best...is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and

  11. Visual Servoing

    OpenAIRE

    Chaumette, Francois; Hutchinson, Seth; Corke, Peter

    2016-01-01

    International audience; This chapter introduces visual servo control, using computer vision data in the servo loop to control the motion of a robot. We first describe the basic techniques that are by now well established in the field. We give a general overview of the formulation of the visual servo control problem, and describe the two archetypal visual servo control schemes: image-based and pose-based visual servo control. We then discuss performance and stability issues that pertain to the...

  12. Expansion of protein domain repeats.

    Directory of Open Access Journals (Sweden)

    Asa K Björklund

    2006-08-01

    Full Text Available Many proteins, especially in eukaryotes, contain tandem repeats of several domains from the same family. These repeats have a variety of binding properties and are involved in protein-protein interactions as well as binding to other ligands such as DNA and RNA. The rapid expansion of protein domain repeats is assumed to have evolved through internal tandem duplications. However, the exact mechanisms behind these tandem duplications are not well-understood. Here, we have studied the evolution, function, protein structure, gene structure, and phylogenetic distribution of domain repeats. For this purpose we have assigned Pfam-A domain families to 24 proteomes with more sensitive domain assignments in the repeat regions. These assignments confirmed previous findings that eukaryotes, and in particular vertebrates, contain a much higher fraction of proteins with repeats compared with prokaryotes. The internal sequence similarity in each protein revealed that the domain repeats are often expanded through duplications of several domains at a time, while the duplication of one domain is less common. Many of the repeats appear to have been duplicated in the middle of the repeat region. This is in strong contrast to the evolution of other proteins that mainly works through additions of single domains at either terminus. Further, we found that some domain families show distinct duplication patterns, e.g., nebulin domains have mainly been expanded with a unit of seven domains at a time, while duplications of other domain families involve varying numbers of domains. Finally, no common mechanism for the expansion of all repeats could be detected. We found that the duplication patterns show no dependence on the size of the domains. Further, repeat expansion in some families can possibly be explained by shuffling of exons. However, exon shuffling could not have created all repeats.

  13. Notebook paper: TNO instance search submission 2011

    NARCIS (Netherlands)

    Schavemaker, J.G.M.; Eendebak, P.T.; Staalduinen, M. van; Kraaij, W.

    2011-01-01

    The TNO instance search submission to TRECVID 2011 consisted of three different runs: one is using an exhaustive keypoint search, one is using a bag-of-visual-words approach and one is using open-source face-recognition software. Our run approaches: Briefly, what approach or combination of approache

  14. Audio-visual materials usage preference among agricultural ...

    African Journals Online (AJOL)

    Audio-visual materials usage preference among agricultural extension workers in rivers ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING ... The use of audio-visual materials in the dissemination of agricultural ...

  15. Quantized Visual Awareness

    Directory of Open Access Journals (Sweden)

    W Alexander Escobar

    2013-11-01

    Full Text Available The proposed model holds that, at its most fundamental level, visual awareness is quantized. That is to say that visual awareness arises as individual bits of awareness through the action of neural circuits with hundreds to thousands of neurons in at least the human striate cortex. Circuits with specific topologies will reproducibly result in visual awareness that correspond to basic aspects of vision like color, motion and depth. These quanta of awareness (qualia are produced by the feedforward sweep that occurs through the geniculocortical pathway but are not integrated into a conscious experience until recurrent processing from centers like V4 or V5 select the appropriate qualia being produced in V1 to create a percept. The model proposed here has the potential to shift the focus of the search for visual awareness to the level of microcircuits and these likely exist across the kingdom Animalia. Thus establishing qualia as the fundamental nature of visual awareness will not only provide a deeper understanding of awareness, but also allow for a more quantitative understanding of the evolution of visual awareness throughout the animal kingdom.

  16. Exact Tandem Repeats Analyzer (E-TRA): A new program for DNA sequence mining

    Indian Academy of Sciences (India)

    Mehmet Karaca; Mehmet Bilgen; A. Naci Onus; Ayse Gul Ince; Safinaz Y. Elmasulu

    2005-04-01

    Exact Tandem Repeats Analyzer 1.0 (E-TRA) combines sequence motif searches with keywords such as ‘organs’, ‘tissues’, ‘cell lines’ and ‘development stages’ for finding simple exact tandem repeats as well as non-simple repeats. E-TRA has several advanced repeat search parameters/options compared to other repeat finder programs as it not only accepts GenBank, FASTA and expressed sequence tags (EST) sequence files, but also does analysis of multiple files with multiple sequences. The minimum and maximum tandem repeat motif lengths that E-TRA finds vary from one to one thousand. Advanced user defined parameters/options let the researchers use different minimum motif repeats search criteria for varying motif lengths simultaneously. One of the most interesting features of genomes is the presence of relatively short tandem repeats (TRs). These repeated DNA sequences are found in both prokaryotes and eukaryotes, distributed almost at random throughout the genome. Some of the tandem repeats play important roles in the regulation of gene expression whereas others do not have any known biological function as yet. Nevertheless, they have proven to be very beneficial in DNA profiling and genetic linkage analysis studies. To demonstrate the use of E-TRA, we used 5,465,605 human EST sequences derived from 18,814,550 GenBank EST sequences. Our results indicated that 12.44% (679,800) of the human EST sequences contained simple and non-simple repeat string patterns varying from one to 126 nucleotides in length. The results also revealed that human organs, tissues, cell lines and different developmental stages differed in number of repeats as well as repeat composition, indicating that the distribution of expressed tandem repeats among tissues or organs are not random, thus differing from the un-transcribed repeats found in genomes.

  17. DWI Repeaters and Non-Repeaters: A Comparison.

    Science.gov (United States)

    Weeber, Stan

    1981-01-01

    Discussed how driving-while-intoxicated (DWI) repeaters differed signigicantly from nonrepeaters on 4 of 23 variables tested. Repeaters were more likely to have zero or two dependent children, attend church frequently, drink occasionally and have one or more arrests for public intoxication. (Author)

  18. To Repeat or Not to Repeat a Course

    Science.gov (United States)

    Armstrong, Michael J.; Biktimirov, Ernest N.

    2013-01-01

    The difficult transition from high school to university means that many students need to repeat (retake) 1 or more of their university courses. The authors examine the performance of students repeating first-year core courses in an undergraduate business program. They used data from university records for 116 students who took a total of 232…

  19. $A$ searches

    CERN Document Server

    Beacham, James

    The Standard Model of particle physics encompasses three of the four known fundamental forces of nature, and has remarkably withstood all of the experimental tests of its predictions, a fact solidified by the discovery, in 2012, of the Higgs boson. However, it cannot be the complete picture. Many measurements have been made that hint at physics beyond the Standard Model, and the main task of the high- energy experimental physics community is to conduct searches for new physics in as many di↵erent places and regimes as possible. I present three searches for new phenomena in three di↵erent high-energy collider experiments, namely, a search for events with at least three photons in the final state, which is sensitive to an exotic decay of a Higgs boson into four photons via intermediate pseudoscalar particles, a, with ATLAS, at the Large Hadron Collider; a search for a dark photon, also known as an A0 , with APEX, at Thomas Je↵erson National Accelerator Facility; and a search for a Higgs decaying into four...

  20. Searching and Classifying non-textual information

    OpenAIRE

    Arentz, Will Archer

    2004-01-01

    This dissertation contains a set of contributions that deal with search or classification of non-textual information. Each contribution can be considered a solution to a specific problem, in an attempt to map out a common ground. The problems cover a wide range of research fields, including search in music, classifying digitally sampled music, visualization and navigation in search results, and classifying images and Internet sites.On classification of digitally sample music, as method for ex...