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Sample records for superficial perceptual features

  1. Generalized perceptual features for animal vocalization classification

    Science.gov (United States)

    Clemins, Patrick J.; Johnson, Michael T.

    2001-05-01

    Two sets of generalized, perceptual-based features are investigated for use in classifying animal vocalizations. Since many species, especially mammals, share similar physical sound perception mechanisms which vary in size, two features sets commonly used in human speech processing, mel-frequency cepstral coefficients (MFCCs) and perceptual linear prediction (PLP) analysis, are modified for use in other species. One modification made to the feature extraction process is incorporating the frequency range of hearing and length of the basilar membrane of the animal in order to correctly determine the width and location of the critical band filters used for signal processing. Experimentally determined critical bands (equivalent rectangular bandwidth) and equal loudness curves (audiograms) can also be incorporated directly into the feature extraction process. Experiments are performed on African elephant (Loxodonta africana) vocalizations using a hidden Markov model (HMM) based classifier showing increased classification accuracy when using features sets based on the specific animals perceptual abilities compared to the original human perception-based feature sets.

  2. The perceptual basis of the feature vowel height

    NARCIS (Netherlands)

    Chládková, K.; Boersma, P.; Benders, T.

    2015-01-01

    The present study investigated whether listeners perceptually map phonetic information to phonological feature categories or to phonemes. The test case is a phonological feature that occurs in most of the world’s languages, namely vowel height, and its acoustic correlate, the first formant (F1). We

  3. Perceptual image hashing via feature points: performance evaluation and tradeoffs.

    Science.gov (United States)

    Monga, Vishal; Evans, Brian L

    2006-11-01

    We propose an image hashing paradigm using visually significant feature points. The feature points should be largely invariant under perceptually insignificant distortions. To satisfy this, we propose an iterative feature detector to extract significant geometry preserving feature points. We apply probabilistic quantization on the derived features to introduce randomness, which, in turn, reduces vulnerability to adversarial attacks. The proposed hash algorithm withstands standard benchmark (e.g., Stirmark) attacks, including compression, geometric distortions of scaling and small-angle rotation, and common signal-processing operations. Content changing (malicious) manipulations of image data are also accurately detected. Detailed statistical analysis in the form of receiver operating characteristic (ROC) curves is presented and reveals the success of the proposed scheme in achieving perceptual robustness while avoiding misclassification.

  4. Perceptual approaches to finding features in data

    Science.gov (United States)

    Rogowitz, Bernice E.

    2013-03-01

    Electronic imaging applications hinge on the ability to discover features in data. For example, doctors examine diagnostic images for tumors, broken bones and changes in metabolic activity. Financial analysts explore visualizations of market data to find correlations, outliers and interaction effects. Seismologists look for signatures in geological data to tell them where to drill or where an earthquake may begin. These data are very diverse, including images, numbers, graphs, 3-D graphics, and text, and are growing exponentially, largely through the rise in automatic data collection technologies such as sensors and digital imaging. This paper explores important trends in the art and science of finding features in data, such as the tension between bottom-up and top-down processing, the semantics of features, and the integration of human- and algorithm-based approaches. This story is told from the perspective of the IS and T/SPIE Conference on Human Vision and Electronic Imaging (HVEI), which has fostered research at the intersection between human perception and the evolution of new technologies.

  5. Perceptual separability of featural and configural information in congenital prosopagnosia.

    Science.gov (United States)

    Kimchi, Ruth; Behrmann, Marlene; Avidan, Galia; Amishav, Rama

    2012-01-01

    The deficit in face recognition in individuals with prosopagnosia has often been attributed to an underlying impairment in holistic processing. Exactly what constitutes holistic processing has remained controversial, however. Here, we compare how configural information and featural information interact during face processing in a group of individuals with congenital prosopagnosia (CP) and matched controls. We adopted Amishav and Kimchi's version of Garner's speeded classification task, in which observers classify upright faces based on configural (intereyes and nose-mouth spacing) or featural (shape of eyes, nose, and mouth) information while the other dimension remains constant or varied randomly. We replicated the finding that normal observers evince symmetric Garner interference--failure to selectively attend to features without being influenced by irrelevant variation in configuration, and vice versa--indicating that featural and configural information are integral in normal face processing. In contrast, the CPs showed no Garner interference: They were able to attend to configural information without interference from irrelevant variation in featural information, and they were able to attend to featural information without interference from irrelevant variation in configural information. The absence of Garner interference in CP provides strong evidence that featural information and configural information are perceptually separable in CP's face processing. These findings indicate that CPs do not perceive faces holistically; rather, they process featural and configural information independently.

  6. Unexpected diagnosis of superficial neurofibroma in a lesion with imaging features of a vascular malformation

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Patrick; Reid, Janet; Morrison, Stuart [Cleveland Clinic Foundation, Department of Radiology, Cleveland, OH (United States); Vidimos, Allison [Cleveland Clinic Foundation, Department of Dermatology, Cleveland, OH (United States); DiFiore, John [Cleveland Clinic Foundation, Department of Pediatric Surgery, Cleveland, OH (United States)

    2005-12-01

    Plexiform neurofibroma is a pathognomonic, often disabling feature of neurofibromatosis type I. Although the target-like appearance of deep plexiform neurofibroma on T2-weighted MRI has been well-described, a second superficial form of plexiform neurofibroma has differing imaging features. We report a 15-year-old boy who presented with multiple cutaneous lesions exhibiting clinical and imaging characteristics of a venolymphatic malformation. These lesions were histologically proved to represent superficial plexiform neurofibromas. We wish to emphasize the unique MR findings of superficial plexiform neurofibromas; these findings are different from the imaging characteristics of the deep form and can be confused with a low-flow vascular malformation. (orig.)

  7. The Effects of Goal Relevance and Perceptual Features on Emotional Items and Associative Memory

    Directory of Open Access Journals (Sweden)

    Wei B. Mao

    2017-07-01

    Full Text Available Showing an emotional item in a neutral background scene often leads to enhanced memory for the emotional item and impaired associative memory for background details. Meanwhile, both top–down goal relevance and bottom–up perceptual features played important roles in memory binding. We conducted two experiments and aimed to further examine the effects of goal relevance and perceptual features on emotional items and associative memory. By manipulating goal relevance (asking participants to categorize only each item image as living or non-living or to categorize each whole composite picture consisted of item image and background scene as natural scene or manufactured scene and perceptual features (controlling visual contrast and visual familiarity in two experiments, we found that both high goal relevance and salient perceptual features (high salience of items vs. high familiarity of items could promote emotional item memory, but they had different effects on associative memory for emotional items and neutral backgrounds. Specifically, high goal relevance and high perceptual-salience of items could jointly impair the associative memory for emotional items and neutral backgrounds, while the effect of item familiarity on associative memory for emotional items would be modulated by goal relevance. High familiarity of items could increase associative memory for negative items and neutral backgrounds only in the low goal relevance condition. These findings suggest the effect of emotion on associative memory is not only related to attentional capture elicited by emotion, but also can be affected by goal relevance and perceptual features of stimulus.

  8. The fate of task-irrelevant visual motion: perceptual load versus feature-based attention.

    Science.gov (United States)

    Taya, Shuichiro; Adams, Wendy J; Graf, Erich W; Lavie, Nilli

    2009-11-18

    We tested contrasting predictions derived from perceptual load theory and from recent feature-based selection accounts. Observers viewed moving, colored stimuli and performed low or high load tasks associated with one stimulus feature, either color or motion. The resultant motion aftereffect (MAE) was used to evaluate attentional allocation. We found that task-irrelevant visual features received less attention than co-localized task-relevant features of the same objects. Moreover, when color and motion features were co-localized yet perceived to belong to two distinct surfaces, feature-based selection was further increased at the expense of object-based co-selection. Load theory predicts that the MAE for task-irrelevant motion would be reduced with a higher load color task. However, this was not seen for co-localized features; perceptual load only modulated the MAE for task-irrelevant motion when this was spatially separated from the attended color location. Our results suggest that perceptual load effects are mediated by spatial selection and do not generalize to the feature domain. Feature-based selection operates to suppress processing of task-irrelevant, co-localized features, irrespective of perceptual load.

  9. Decoding stimulus features in primate somatosensory cortex during perceptual categorization

    Science.gov (United States)

    Alvarez, Manuel; Zainos, Antonio; Romo, Ranulfo

    2015-01-01

    Neurons of the primary somatosensory cortex (S1) respond as functions of frequency or amplitude of a vibrotactile stimulus. However, whether S1 neurons encode both frequency and amplitude of the vibrotactile stimulus or whether each sensory feature is encoded by separate populations of S1 neurons is not known, To further address these questions, we recorded S1 neurons while trained monkeys categorized only one sensory feature of the vibrotactile stimulus: frequency, amplitude, or duration. The results suggest a hierarchical encoding scheme in S1: from neurons that encode all sensory features of the vibrotactile stimulus to neurons that encode only one sensory feature. We hypothesize that the dynamic representation of each sensory feature in S1 might serve for further downstream processing that leads to the monkey’s psychophysical behavior observed in these tasks. PMID:25825711

  10. Physiological and perceptual features of dysarthria in Moebius syndrome: directions for treatment.

    Science.gov (United States)

    Murdoch, B E; Johnson, S M; Theodoros, D G

    1997-01-01

    The functioning of the major subsystems of the speech production apparatus of a 12 year old female with Moebius syndrome was investigated using a battery of perceptual and physiological instrumental measures. Perceptual tests administered included: The Assessment of Intelligibility of Dysarthric Speech; the Frenchay Dysarthria Assessment; and a perceptual analysis of a speech sample based on a reading of the Grandfather Passage. Instrumental procedures included: spirometric and kinematic analysis of speech breathing; electroglottographic and aerodynamic evaluation of laryngeal function; nasometric assessment of velopharyngeal function; and evaluation of lip and tongue function using a variety of strain-gauge and pressure transducers. Consistent with the pathophysiological basis of Moebius syndrome, the major dysfunctions of the speech production mechanism were found at the level of the articulatory valve. Somewhat unexpectedly, however, impaired function was also identified at the level of the velopharyngeal and laryngeal valves by both the perceptual and instrumental assessments and at the level of the respiratory system by the physiological analysis alone. The results are discussed with reference to the neurological basis and clinical features of Moebius syndrome. The implications of the findings for the treatment of congenital dysarthria associated with Moebius syndrome are also discussed. The advantage of instrumental analysis over perceptual assessments in defining treatment goals for children with congenital dysarthria is highlighted.

  11. A perceptual hashing method based on luminance features

    Science.gov (United States)

    Luo, Siqing

    2011-02-01

    With the rapid development of multimedia technology, content based searching and image authentication has become strong requirements. Image hashing technique has been proposed to meet them. In this paper, an RST (Rotation, Scaling, and Translation) resistant image hash algorithm is presented. In this method, the geometric distortions are extracted and adjusted by normalization. The features of the image are generated from the high-rank moments of luminance distribution. With the help of the efficient image representation capability of high-rank moments, the robustness and discrimination of proposed method are improved. The experimental results show that the proposed method is better than some existing methods in robustness under rotation attack.

  12. Perceptual learning of basic visual features remains task specific with Training-Plus-Exposure (TPE) training.

    Science.gov (United States)

    Cong, Lin-Juan; Wang, Ru-Jie; Yu, Cong; Zhang, Jun-Yun

    2016-01-01

    Visual perceptual learning is known to be specific to the trained retinal location, feature, and task. However, location and feature specificity can be eliminated by double-training or TPE training protocols, in which observers receive additional exposure to the transfer location or feature dimension via an irrelevant task besides the primary learning task Here we tested whether these new training protocols could even make learning transfer across different tasks involving discrimination of basic visual features (e.g., orientation and contrast). Observers practiced a near-threshold orientation (or contrast) discrimination task. Following a TPE training protocol, they also received exposure to the transfer task via performing suprathreshold contrast (or orientation) discrimination in alternating blocks of trials in the same sessions. The results showed no evidence for significant learning transfer to the untrained near-threshold contrast (or orientation) discrimination task after discounting the pretest effects and the suprathreshold practice effects. These results thus do not support a hypothetical task-independent component in perceptual learning of basic visual features. They also set the boundary of the new training protocols in their capability to enable learning transfer.

  13. Interaction features for prediction of perceptual segmentation: Effects of musicianship and experimental task

    DEFF Research Database (Denmark)

    Hartmann, Martin; Lartillot, Olivier; Toiviainen, Petri

    2016-01-01

    was investigated for six musical stimuli via a real-time task and an annotation (non real-time) task. The proposed approach involved computation of novelty curve interaction features and a prediction model of perceptual segmentation boundary density. We found that, compared to non-musicians’, musicians......’ segmentation yielded lower prediction rates, and involved more features for prediction, particularly more interaction features; also non-musicians required a larger time shift for optimal segmentation modelling. Prediction of the annotation task exhibited higher rates, and involved more musical features than...... for the real-time task; in addition, the real-time task required time shifting of the segmentation data for its optimal modelling. We also found that annotation task models that were weighted according to boundary strength ratings exhibited improvements in segmentation prediction rates and involved more...

  14. Emergent features and perceptual objects: re-examining fundamental principles in analogical display design.

    Science.gov (United States)

    Holt, Jerred; Bennett, Kevin B; Flach, John M

    2015-01-01

    Two sets of design principles for analogical visual displays, based on the concepts of emergent features and perceptual objects, are described. An interpretation of previous empirical findings for three displays (bar graph, polar graphic, alphanumeric) is provided from both perspectives. A fourth display (configural coordinate) was designed using principles of ecological interface design (i.e. direct perception). An experiment was conducted to evaluate performance (accuracy and latency of state identification) with these four displays. Numerous significant effects were obtained and a clear rank ordering of performance emerged (from best to worst): configural coordinate, bar graph, alphanumeric and polar graphic. These findings are consistent with principles of design based on emergent features; they are inconsistent with principles based on perceptual objects. Some limitations of the configural coordinate display are discussed and a redesign is provided. Practitioner Summary: Principles of ecological interface design, which emphasise the quality of very specific mappings between domain, display and observer constraints, are described; these principles are applicable to the design of all analogical graphical displays.

  15. Feature modulation search: a novel memory search model that extends the perceptual interference effect to musical stimuli.

    Science.gov (United States)

    Schulkind, Matthew D

    2002-03-01

    Although most research in the perceptual interference literature has used visual stimuli, recent experiments have replicated this effect using musical stimuli. Two experiments investigated whether musical and visual demonstrations of the effect are produced by a common mechanism by examining whether the provision of incorrect cues would impair melodic object identification in the perceptual interference paradigm. Whereas incorrect cues typically do not affect visual object identification, they reduced melody identification both when the subjects generated the cues and when the experimenter provided them. A novel model (feature modulation search) is presented to account for perceptual interference in musical stimuli. The model has potential applications for the larger perceptual interference literature and for related phenomena in which target-related information impairs cognition.

  16. MRI of superficial soft tissue masses: analysis of features useful in distinguishing between benign and malignant lesions

    Energy Technology Data Exchange (ETDEWEB)

    Calleja, Michele; Dimigen, Marion; Saifuddin, Asif [Royal National Orthopaedic Hospital, Stanmore (United Kingdom)

    2012-12-15

    To identify the MRI features of superficial soft tissue masses, that may allow differentiation between malignant and non-malignant lesions. A total of 136 consecutive patients referred to a supra-regional musculoskeletal oncology center over a 10-year period with the diagnosis of a superficial soft tissue mass were included in this retrospective study. Features analyzed included patient demographics, lesion size, MRI signal characteristics, margins, lobulation, hemorrhage, necrosis, fascial edema, relationship to the fascia, as well as involvement of the skin. Comparison was then made with the final histological diagnosis. Of the patients reviewed, 58 were male and 78 were female, and the mean age was 49.9 years. The mean age for malignant lesions was 57.9 years, and that for non-neoplastic and benign conditions 41.9 years (p < 0.001). A significant relationship was identified between malignancy and lobulation (p < 0.01), hemorrhage (p < 0.001), fascial edema (p < 0.001), hemorrhage (p < 0.0001) and necrosis (p < 0.001). The relationship between skin thickening and skin contact and malignancy was also found to be significant. However, size was not found to be an important determining factor for malignancy, with a significant proportion of malignant superficial sarcomas measuring less than 5 cm in maximal diameter. This study has shown that a significant proportion of malignant superficial sarcomas measured less than 5 cm in maximal diameter. Fascial edema, skin thickening, skin contact, hemorrhage, and necrosis were found to be highly significant factors indicative of malignancy. Lobulation and peritumoral edema were also significant MRI features. (orig.)

  17. Perceptual Confusions Among Consonants, Revisited: Cross-Spectral Integration of Phonetic-Feature Information and Consonant Recognition

    DEFF Research Database (Denmark)

    Christiansen, Thomas Ulrich; Greenberg, Steven

    2012-01-01

    The perceptual basis of consonant recognition was experimentally investigated through a study of how information associated with phonetic features (Voicing, Manner, and Place of Articulation) combines across the acoustic-frequency spectrum. The speech signals, 11 Danish consonants embedded in Con...

  18. Imaging Features of Superficial and Deep Fibromatoses in the Adult Population

    Directory of Open Access Journals (Sweden)

    Eric A. Walker

    2012-01-01

    Full Text Available The fibromatoses are a group of benign fibroblastic proliferations that vary from benign to intermediate in biological behavior. This article will discuss imaging characteristics and patient demographics of the adult type superficial (fascial and deep (musculoaponeurotic fibromatoses. The imaging appearance of these lesions can be characteristic (particularly when using magnetic resonance imaging. Palmar fibromatosis demonstrates multiple nodular or band-like soft tissue masses arising from the proximal palmar aponeurosis and extending along the subcutaneous tissues of the finger in parallel to the flexor tendons. T1 and T2-weighted signal intensity can vary from low (higher collagen to intermediate (higher cellularity, similar to the other fibromatoses. Plantar fibromatosis manifests as superficial lesions along the deep plantar aponeurosis, which typically blend with the adjacent plantar musculature. Linear tails of extension (“fascial tail sign” along the aponeurosis are frequent. Extraabdominal and abdominal wall fibromatosis often appear as a heterogeneous lesion with low signal intensity bands on all pulse sequences and linear fascial extensions (“fascial tail” sign with MR imaging. Mesenteric fibromatosis usually demonstrates a soft tissue density on CT with radiating strands projecting into the adjacent mesenteric fat. When imaging is combined with patient demographics, a diagnosis can frequently be obtained.

  19. Imaging features of superficial and deep fibromatoses in the adult population.

    Science.gov (United States)

    Walker, Eric A; Petscavage, Jonelle M; Brian, Pamela L; Logie, Chika Iloanusi; Montini, Kenneth M; Murphey, Mark D

    2012-01-01

    The fibromatoses are a group of benign fibroblastic proliferations that vary from benign to intermediate in biological behavior. This article will discuss imaging characteristics and patient demographics of the adult type superficial (fascial) and deep (musculoaponeurotic) fibromatoses. The imaging appearance of these lesions can be characteristic (particularly when using magnetic resonance imaging). Palmar fibromatosis demonstrates multiple nodular or band-like soft tissue masses arising from the proximal palmar aponeurosis and extending along the subcutaneous tissues of the finger in parallel to the flexor tendons. T1 and T2-weighted signal intensity can vary from low (higher collagen) to intermediate (higher cellularity), similar to the other fibromatoses. Plantar fibromatosis manifests as superficial lesions along the deep plantar aponeurosis, which typically blend with the adjacent plantar musculature. Linear tails of extension ("fascial tail sign") along the aponeurosis are frequent. Extraabdominal and abdominal wall fibromatosis often appear as a heterogeneous lesion with low signal intensity bands on all pulse sequences and linear fascial extensions ("fascial tail" sign) with MR imaging. Mesenteric fibromatosis usually demonstrates a soft tissue density on CT with radiating strands projecting into the adjacent mesenteric fat. When imaging is combined with patient demographics, a diagnosis can frequently be obtained.

  20. Imaging Features of Superficial and Deep Fibromatoses in the Adult Population

    Science.gov (United States)

    Walker, Eric A.; Petscavage, Jonelle M.; Brian, Pamela L.; Logie, Chika Iloanusi; Montini, Kenneth M.; Murphey, Mark D.

    2012-01-01

    The fibromatoses are a group of benign fibroblastic proliferations that vary from benign to intermediate in biological behavior. This article will discuss imaging characteristics and patient demographics of the adult type superficial (fascial) and deep (musculoaponeurotic) fibromatoses. The imaging appearance of these lesions can be characteristic (particularly when using magnetic resonance imaging). Palmar fibromatosis demonstrates multiple nodular or band-like soft tissue masses arising from the proximal palmar aponeurosis and extending along the subcutaneous tissues of the finger in parallel to the flexor tendons. T1 and T2-weighted signal intensity can vary from low (higher collagen) to intermediate (higher cellularity), similar to the other fibromatoses. Plantar fibromatosis manifests as superficial lesions along the deep plantar aponeurosis, which typically blend with the adjacent plantar musculature. Linear tails of extension (“fascial tail sign”) along the aponeurosis are frequent. Extraabdominal and abdominal wall fibromatosis often appear as a heterogeneous lesion with low signal intensity bands on all pulse sequences and linear fascial extensions (“fascial tail” sign) with MR imaging. Mesenteric fibromatosis usually demonstrates a soft tissue density on CT with radiating strands projecting into the adjacent mesenteric fat. When imaging is combined with patient demographics, a diagnosis can frequently be obtained. PMID:22966216

  1. Distributional Feature of Detrital Minerais in the Superficial Sediment of South Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    王红霞; 林振宏; 郭玉贵

    2004-01-01

    The composition of detrital minerals with grades of 0.063 - 0.25 mm in the superficial sediment of South Yellow Sea is mainly studied in the paper. The research result shows that the minerals can be divided into more than fifty sorts. The light minerals are mainly feldspar, quartz, mica, etc. The heavy minerals are mainly composed of amphibole, epidote, mica, autogeny pyrite, magnetite, hematite, garnet,zircon and so on, which mainly distribute in the sediments of silty clay and lutaceous silt. According to the content and distribution of the main minerals, the research area isdivided into five miteral combination provinces. The assembled types of minerals in every province have close relationship with its hydrodynamic conditions and sedimentary environment. And the sorts of detrital minerals also show that the detrital substances in the sedimentary areas mainly originate from the drainage areas of rivers,bedrock weathering, and transformed sediment, etc.

  2. A Review of Physical and Perceptual Feature Extraction Techniques for Speech, Music and Environmental Sounds

    Directory of Open Access Journals (Sweden)

    Francesc Alías

    2016-05-01

    Full Text Available Endowing machines with sensing capabilities similar to those of humans is a prevalent quest in engineering and computer science. In the pursuit of making computers sense their surroundings, a huge effort has been conducted to allow machines and computers to acquire, process, analyze and understand their environment in a human-like way. Focusing on the sense of hearing, the ability of computers to sense their acoustic environment as humans do goes by the name of machine hearing. To achieve this ambitious aim, the representation of the audio signal is of paramount importance. In this paper, we present an up-to-date review of the most relevant audio feature extraction techniques developed to analyze the most usual audio signals: speech, music and environmental sounds. Besides revisiting classic approaches for completeness, we include the latest advances in the field based on new domains of analysis together with novel bio-inspired proposals. These approaches are described following a taxonomy that organizes them according to their physical or perceptual basis, being subsequently divided depending on the domain of computation (time, frequency, wavelet, image-based, cepstral, or other domains. The description of the approaches is accompanied with recent examples of their application to machine hearing related problems.

  3. Evaluation of Superficial and Dimensional Quality Features in Metallic Micro-Channels Manufactured by Micro-End-Milling

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    Claudio Giardini

    2013-04-01

    Full Text Available Miniaturization encourages the development of new manufacturing processes capable of fabricating features, like micro-channels, in order to use them for different applications, such as in fuel cells, heat exchangers, microfluidic devices and micro-electromechanical systems (MEMS. Many studies have been conducted on heat and fluid transfer in micro-channels, and they appeared significantly deviated from conventional theory, due to measurement errors and fabrication methods. The present research, in order to deal with this opportunity, is focused on a set of experiments in the micro-milling of channels made of aluminum, titanium alloys and stainless steel, varying parameters, such as spindle speed, depth of cut per pass (ap, channel depth (d, feed per tooth (fz and coolant application. The experimental results were analyzed in terms of dimensional error, channel profile shape deviation from rectangular and surface quality (burr and roughness. The micro-milling process was capable of offering quality features required on the micro-channeled devices. Critical phenomena, like run-out, ploughing, minimum chip thickness and tool wear, were encountered as an explanation for the deviations in shape and for the surface quality of the micro-channels. The application of coolant and a low depth of cut per pass were significant to obtain better superficial quality features and a smaller dimensional error. In conclusion, the integration of superficial and geometrical features on the study of the quality of micro-channeled devices made of different metallic materials contributes to the understanding of the impact of calibrated cutting conditions in MEMS applications.

  4. Evaluation of Superficial and Dimensional Quality Features in Metallic Micro-Channels Manufactured by Micro-End-Milling

    Science.gov (United States)

    Monroy-Vázquez, Karla P.; Attanasio, Aldo; Ceretti, Elisabetta; Siller, Héctor R.; Hendrichs-Troeglen, Nicolás J.; Giardini, Claudio

    2013-01-01

    Miniaturization encourages the development of new manufacturing processes capable of fabricating features, like micro-channels, in order to use them for different applications, such as in fuel cells, heat exchangers, microfluidic devices and micro-electromechanical systems (MEMS). Many studies have been conducted on heat and fluid transfer in micro-channels, and they appeared significantly deviated from conventional theory, due to measurement errors and fabrication methods. The present research, in order to deal with this opportunity, is focused on a set of experiments in the micro-milling of channels made of aluminum, titanium alloys and stainless steel, varying parameters, such as spindle speed, depth of cut per pass (ap), channel depth (d), feed per tooth (fz) and coolant application. The experimental results were analyzed in terms of dimensional error, channel profile shape deviation from rectangular and surface quality (burr and roughness). The micro-milling process was capable of offering quality features required on the micro-channeled devices. Critical phenomena, like run-out, ploughing, minimum chip thickness and tool wear, were encountered as an explanation for the deviations in shape and for the surface quality of the micro-channels. The application of coolant and a low depth of cut per pass were significant to obtain better superficial quality features and a smaller dimensional error. In conclusion, the integration of superficial and geometrical features on the study of the quality of micro-channeled devices made of different metallic materials contributes to the understanding of the impact of calibrated cutting conditions in MEMS applications. PMID:28809219

  5. Non-retinotopic feature processing in the absence of retinotopic spatial layout and the construction of perceptual space from motion.

    Science.gov (United States)

    Ağaoğlu, Mehmet N; Herzog, Michael H; Oğmen, Haluk

    2012-10-15

    The spatial representation of a visual scene in the early visual system is well known. The optics of the eye map the three-dimensional environment onto two-dimensional images on the retina. These retinotopic representations are preserved in the early visual system. Retinotopic representations and processing are among the most prevalent concepts in visual neuroscience. However, it has long been known that a retinotopic representation of the stimulus is neither sufficient nor necessary for perception. Saccadic Stimulus Presentation Paradigm and the Ternus-Pikler displays have been used to investigate non-retinotopic processes with and without eye movements, respectively. However, neither of these paradigms eliminates the retinotopic representation of the spatial layout of the stimulus. Here, we investigated how stimulus features are processed in the absence of a retinotopic layout and in the presence of retinotopic conflict. We used anorthoscopic viewing (slit viewing) and pitted a retinotopic feature-processing hypothesis against a non-retinotopic feature-processing hypothesis. Our results support the predictions of the non-retinotopic feature-processing hypothesis and demonstrate the ability of the visual system to operate non-retinotopically at a fine feature processing level in the absence of a retinotopic spatial layout. Our results suggest that perceptual space is actively constructed from the perceptual dimension of motion. The implications of these findings for normal ecological viewing conditions are discussed.

  6. Extending the Simultaneous-Sequential Paradigm to Measure Perceptual Capacity for Features and Words

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    Scharff, Alec; Palmer, John; Moore, Cathleen M.

    2011-01-01

    In perception, divided attention refers to conditions in which multiple stimuli are relevant to an observer. To measure the effect of divided attention in terms of perceptual capacity, we introduce an extension of the simultaneous-sequential paradigm. The extension makes predictions for fixed-capacity models as well as for unlimited-capacity…

  7. Perceptual Visual Distortions in Adult Amblyopia and Their Relationship to Clinical Features

    Science.gov (United States)

    Piano, Marianne E. F.; Bex, Peter J.; Simmers, Anita J.

    2015-01-01

    Purpose Develop a paradigm to map binocular perceptual visual distortions in adult amblyopes and visually normal controls, measure their stability over time, and determine the relationship between strength of binocular single vision and distortion magnitude. Methods Perceptual visual distortions were measured in 24 strabismic, anisometropic, or microtropic amblyopes (interocular acuity difference ≥ 0.200 logMAR or history of amblyopia treatment) and 10 controls (mean age 27.13 ± 10.20 years). The task was mouse-based target alignment on a stereoscopic liquid crystal display monitor, measured binocularly five times during viewing dichoptically through active shutter glasses, amblyopic eye viewing cross-hairs, fellow eye viewing single target dots (16 locations within central 5°), and five times nondichoptically, with all stimuli visible to either eye. Measurements were repeated over time (1 week, 1 month) in eight amblyopic subjects, evaluating test–retest reliability. Measurements were also correlated against logMAR visual acuity, horizontal prism motor fusion range, Frisby/Preschool Randot stereoacuity, and heterophoria/heterotropia prism cover test measurement. Results Sixty-seven percent (16/24) of amblyopes had significant perceptual visual distortions under dichoptic viewing conditions compared to nondichoptic viewing conditions and dichoptic control group performance. Distortions correlated with the strength of motor fusion (r = −0.417, P = 0.043) and log stereoacuity (r = 0.492, P = 0.015), as well as near angle of heterotropic/heterophoric deviation (r = 0.740, P amblyopia depth (r = 0.405, P = 0.049). Global distortion index (GDI, mean displacement) remained, overall, consistent over time (median change in GDI between baseline and 1 week = −0.03°, 1 month = −0.08°; x-axis Z = 4.4256, P amblyopia depth, and larger angles of ocular deviation. Assessment of distortions may be relevant for recent perceptual learning paradigms specifically

  8. The relationship between superficial muscle activity during the cranio-cervical flexion test and clinical features in patients with chronic neck pain.

    Science.gov (United States)

    O'Leary, Shaun; Falla, Deborah; Jull, Gwendolen

    2011-10-01

    Changes in motor behavior are a known feature of chronic mechanical neck pain disorders. This study examined the strength of the association between reported levels of pain and disability from 84 individuals (63 women, 21 men) with chronic mechanical neck pain and levels of electromyographic activity recorded from superficial cervical flexor (sternocleidomastoid; SCM and anterior scalene; AS) muscles during progressive stages of the cranio-cervical flexion muscle test. A significant positive association was observed between superficial muscle activity and pain intensity (P 0.5) or perceived disability (P > 0.21). The strongest relationship between pain intensity and superficial muscle activity occurred at the final increment of the cranio-cervical flexion test (inner-range test position) for both the SCM and AS muscles (R(2) = 0.16). Although a positive and significant relationship between pain intensity and superficial muscle activity was shown, the relationship was only modest (16% explained variance), indicating that multiple factors contribute to the altered motor function observed in individuals with chronic mechanical neck pain.

  9. The perceptual-mnemonic/feature conjunction model of perirhinal cortex function.

    Science.gov (United States)

    Bussey, Timothy J; Saksida, Lisa M; Murray, Elisabeth A

    2005-01-01

    The perirhinal cortex was once thought to be "silent cortex", virtually ignored by researchers interested in the neurobiology of learning and memory. Following studies of brain damage associated with cases of amnesia, perirhinal cortex is now widely regarded as part of a "medial temporal lobe (MTL) memory system". This system is thought to be more or less functionally homogeneous, having a special role in declarative memory, and making little or no contribution to other functions such as perception. In the present article, we summarize an alternative view. First, we propose that components of the putative MTL system such as the hippocampus and perirhinal cortex have distinct and dissociable functions. Second, we provide evidence that the perirhinal cortex has a role in visual discrimination. In addition, we propose a specific role for perirhinal cortex in visual discrimination: the contribution of complex conjunctive representations to the solution of visual discrimination problems with a high degree of "feature ambiguity". These proposals constitute a new view of perirhinal cortex function, one that does not assume strict modularity of function in the occipito-temporal visual stream, but replaces this idea with the notion of a hierarchical representational continuum.

  10. The effect of additional exposure to the unique features in a perceptual learning task can be attributed to a location bias.

    Science.gov (United States)

    Recio, Sergio A; Iliescu, Adela F; Bergés, Germán D; Gil, Marta; de Brugada, Isabel

    2016-04-01

    It has been suggested that human perceptual learning could be explained in terms of a better memory encoding of the unique features during intermixed exposure. However, it is possible that a location bias could play a relevant role in explaining previous results of perceptual learning studies using complex visual stimuli. If this were the case, the only relevant feature would be the location, rather than the content, of the unique features. To further explore this possibility, we attempted to replicate the results of Lavis, Kadib, Mitchell, and Hall (2011, Experiment 2), which showed that additional exposure to the unique elements resulted in better discrimination than simple intermixed exposure. We manipulated the location of the unique elements during the additional exposure. In one experiment, they were located in the same position as that when presented together with the common element. In another experiment, the unique elements were located in the center of the screen, regardless of where they were located together with the common element. Our results showed that additional exposure only improved discrimination when the unique elements were presented in the same position as when they were presented together with the common element. The results reported here do not provide support for the explanation of the effects of additional exposure of the unique elements in terms of a better memory encoding and instead suggest an explanation in terms of location bias. (c) 2016 APA, all rights reserved).

  11. Perceptual learning and human expertise

    Science.gov (United States)

    Kellman, Philip J.; Garrigan, Patrick

    2009-06-01

    We consider perceptual learning: experience-induced changes in the way perceivers extract information. Often neglected in scientific accounts of learning and in instruction, perceptual learning is a fundamental contributor to human expertise and is crucial in domains where humans show remarkable levels of attainment, such as language, chess, music, and mathematics. In Section 2, we give a brief history and discuss the relation of perceptual learning to other forms of learning. We consider in Section 3 several specific phenomena, illustrating the scope and characteristics of perceptual learning, including both discovery and fluency effects. We describe abstract perceptual learning, in which structural relationships are discovered and recognized in novel instances that do not share constituent elements or basic features. In Section 4, we consider primary concepts that have been used to explain and model perceptual learning, including receptive field change, selection, and relational recoding. In Section 5, we consider the scope of perceptual learning, contrasting recent research, focused on simple sensory discriminations, with earlier work that emphasized extraction of invariance from varied instances in more complex tasks. Contrary to some recent views, we argue that perceptual learning should not be confined to changes in early sensory analyzers. Phenomena at various levels, we suggest, can be unified by models that emphasize discovery and selection of relevant information. In a final section, we consider the potential role of perceptual learning in educational settings. Most instruction emphasizes facts and procedures that can be verbalized, whereas expertise depends heavily on implicit pattern recognition and selective extraction skills acquired through perceptual learning. We consider reasons why perceptual learning has not been systematically addressed in traditional instruction, and we describe recent successful efforts to create a technology of perceptual

  12. Feature Presentation on Category Perceptual Represent ation%特征呈现方式对类别知觉表征的影响

    Institute of Scientific and Technical Information of China (English)

    陈琳; 钟罗金; 李悠; 莫雷

    2014-01-01

    The effect of feature presentation on category perceptual representation was investigated in a blocking paradigm in which one defining dimension could perfectly classify all exemplars into two categories.In experiment 1, partici-pants were assigned to learn two categories with features presented sequentially or randomly, which may require dif-ferent working memory.However, the results showed that some nondefining features were learned regardless of the feature presentation.Experiment 2 fixed the defining feature on the top of each exemplar.A strong blocking was found in the sequential condition and none nondefining feature was learned.It indicated that sequential feature presentation induced overall similarity processing, whereas random feature presentation promoted analytic process-ing.%两个实验采用阻碍效应范式探讨了特征的呈现方式对类别知觉表征的影响。研究结果发现在阻碍效应范式中,改变特征的呈现方式引发了不同的类别知觉表征方式;当固定样例特征的呈现位置时,引发了基于样例整体相似性的表征;而随机样例特征的呈现位置时,引发了基于样例特征的解析表征。该结果支持了类别学习的多系统理论。

  13. Conflict-Induced Perceptual Filtering

    Science.gov (United States)

    Wendt, Mike; Luna-Rodriguez, Aquiles; Jacobsen, Thomas

    2012-01-01

    In a variety of conflict paradigms, target and distractor stimuli are defined in terms of perceptual features. Interference evoked by distractor stimuli tends to be reduced when the ratio of congruent to incongruent trials is decreased, suggesting conflict-induced perceptual filtering (i.e., adjusting the processing weights assigned to stimuli…

  14. Unifying Perceptual Learning

    Directory of Open Access Journals (Sweden)

    Philip J. Kellman

    2011-05-01

    Full Text Available What is the relation between perceptual learning (PL in basic sensory discriminations and in more complex tasks, including real-world learning tasks? Most recent PL work focuses on the former, using simple sensory dimensions and a few specific stimulus values. In contrast, other PL research and virtually all real-world tasks involve discovery of invariance amidst variation, and may also involve PL working synergistically with other cognitive abilities. In this talk I will suggest that, despite superficial differences, low- and high-level PL tasks draw upon—and reveal—a unified type of learning. I will consider several arguments that have been advanced in favor of confining perceptual learning to plasticity at the earliest cortical levels along with models of PL based on receptive field change vs. selection. These analyses do not support the idea of a separate low-level process but do support both the abstract character of PL and its dependence on unifying notions of discovery and selection. In the final part of the talk, I will relate this unified view of PL to direct practical applications. Learning technology based on PL modules (PLMs can address elusive aspects of learning, including pattern recognition, transfer, and fluency, even in high-level, symbolic domains, such as mathematics learning.

  15. 浅表器官结外淋巴瘤的超声表现%Ultrasonic feature of superficial organ extranodal lymphoma

    Institute of Scientific and Technical Information of China (English)

    宋琳琳; 詹维伟; 周建桥; 周伟

    2012-01-01

    Objective To analyze the ultrasound image and evaluate its diagnostic value for superficial organ extranodal lymphoma. Methods The ultrasonograms of 24 patients with superficial organ extranodal lymphoma confirmed by surgical or core needle biopsy were analyzed retrospectively. Results There were 24 patients with extranodal lymphoma,including 3 cases of salivary glands,7 cases of thyroid,7 cases of breast,6 cases of testis and 1 case of penis, including lymphoma on both side for one case each of testis and breast lymphoma. Altogether there were 28 superficial organ extranodal lymphoma,including 3 of salivary glands ,7 of thyroid,8 of breast,7 of testis and 3 of penis.The ultrasonographic findings were classified as focal type in 19 lymphoma and diffuse type in 9 lymphoma. The gray scale imaging showed hypoechogenicity, marked hypoechogenicity and cystoid echogenecity. Posterior enhancement was observed in 22 lymphoma (78.6%). Color Doppler ultrasonography showed markedly increased vascularity in 23 lymphoma (82.1% ). Peripheral lymphadenopathy was noted in 9 lymphoma (32.1% ),tended to be round with marked hypoechogenecity. Conclusions The ultrasonogram of superficial organ extranodal lymphoma has characteristic appearance. Ultrasonography is a useful tool for the screening,diagnosis and following up of superficial organ extranodal lymphoma.%目的:分析浅表器官结外淋巴瘤超声声像图特点,评价超声检查在诊断浅表器官结外淋巴瘤中的价值.方法:回顾性分析我院经手术或粗针穿刺活检病理证实的24例浅表器官结外淋巴瘤患者的超声声像图.结果:24例浅表器官结外淋巴瘤患者中,腮腺受累3例,甲状腺受累7例,乳房受累7例(其中1例双侧受累),睾丸受累6例(其中1例双侧受累),阴茎受累1例.24例浅表器官结外淋巴瘤患者共28个病灶,分别为腮腺3个,甲状腺7个,乳腺8个,睾丸7个,阴茎3个.超声声像图表现为局灶型19个,弥漫型9个.灰阶超声表

  16. An Improved Perceptual Hashing Algorithm of Image Based on Discrete Cosine Transform and Speeded Up Robust Features%一种由DCT和SURF改进的图像感知哈希算法

    Institute of Scientific and Technical Information of China (English)

    丁旭; 何建忠

    2014-01-01

    In order to solve the problem of poor robustness of global features and high complexity of local features in image perceptual hashing algorithm,the author proposed an improved perceptual hashing algorithm based on DCT and SURF.Using DCT as global fea tures and SURF as local features,the author gave the hashing functions and the fusion of two features.Then,the author provided the application in image authentication.Experimental results showed that this algorithm has good robustness and efficiency.%针对感知哈希技术中图像全局特征鲁棒性低和局部特征算法复杂度高的特点,提出一种由离散余弦变换(DCT)和SURF算子改进的感知哈希算法.本文以DCT为全局特征,以SURF描述子为局部特征,分别给出了两者的哈希编码算法及两者的融合方式,接着给出在图像认证时的算法流程.实验表明本文算法具有较好的鲁棒性和实时性.

  17. Superficial topography feature of fiber in poplar 107 determined by AFM%基于AFM的107杨纤维表面形貌特征研究

    Institute of Scientific and Technical Information of China (English)

    熊福全; 周亮; 刘盛全

    2013-01-01

    以107杨为研究对象,采用过氧化氢和冰醋酸混合液对应拉木和正常木进行处理获得2种离析纤维;采用铬酸对正常木进行处理获得1种离析纤维;采用硫酸盐制备正常木化学浆获得1种化学浆纤维,并取出一半化学浆进行打浆处理获得1种打浆纤维.使用原子力显微镜(AFM)对上述5种不同处理方法获得的纤维表面形貌进行观察比较.结果表明,应拉木纤维比正常木纤维容易观测到清晰初生壁表面;铬酸离析方法比过氧化氢和冰醋酸混合液离析方法容易观测到清晰初生壁表面;相比离析纤维,化学浆纤维次生壁微纤丝的定向排列方式清晰可见;打浆后纤维较化学浆纤维,微纤丝定向排列被干扰,出现分丝帚化.%In this paper, two kinds of fibers of poplar 107 (fibers of tension wood and fibers of normal wood) were obtained by macerating with mixture of hydrogen peroxide and glacial acetic acid, respectively. The macerating fibers were obtained by chromic acid. Meanwhile, other two kinds of fibers in normal wood, I.e., chemical pulp fibers was obtained with kraft pulping and refining chemical pulp fibers was prepared by further pulping the chemical pulp fibers . Topography features of five kinds of different treatment fiber surfaces were scanned by atomic force microscope (AFM), and that were further observed and compared. The results showed that the primary wall surfaces of fibers in tension wood were clearer to observe than those in normal wood, and the primary wall surfaces of fibers macerated by chromic acid were clearer to observe than that by mixture of hydrogen peroxide and glacial acetic acid. Compared with macerating fibers, the arrangement of microfibrils in secondary wall of chemical pulp fibers could be revealed clearly. Compared with chemical pulp fibers, the arrangement of the microfibrils was disordered, which presented fibrillating.

  18. Superficies de segundo orden

    OpenAIRE

    Salazar Salazar, Luis Álvaro

    1987-01-01

    Este trabajo se propone poner al alcance de estudiantes de primeros semestres de carreras de aplicación de la matemática, un algoritmo proporcionado por el álgebra lineal, para tratar con mas generalidad, agilidad y libertad unos objetos de la geometría analítica de no fácil manipulación por otros métodos y que se conocen como superficies de segundo orden o superficies cuádricas. En este orden de ideas, el autor considera importante que con este tratamiento se incluya este tema en una asignat...

  19. Common Superficial Bursitis.

    Science.gov (United States)

    Khodaee, Morteza

    2017-02-15

    Superficial bursitis most often occurs in the olecranon and prepatellar bursae. Less common locations are the superficial infrapatellar and subcutaneous (superficial) calcaneal bursae. Chronic microtrauma (e.g., kneeling on the prepatellar bursa) is the most common cause of superficial bursitis. Other causes include acute trauma/hemorrhage, inflammatory disorders such as gout or rheumatoid arthritis, and infection (septic bursitis). Diagnosis is usually based on clinical presentation, with a particular focus on signs of septic bursitis. Ultrasonography can help distinguish bursitis from cellulitis. Blood testing (white blood cell count, inflammatory markers) and magnetic resonance imaging can help distinguish infectious from noninfectious causes. If infection is suspected, bursal aspiration should be performed and fluid examined using Gram stain, crystal analysis, glucose measurement, blood cell count, and culture. Management depends on the type of bursitis. Acute traumatic/hemorrhagic bursitis is treated conservatively with ice, elevation, rest, and analgesics; aspiration may shorten the duration of symptoms. Chronic microtraumatic bursitis should be treated conservatively, and the underlying cause addressed. Bursal aspiration of microtraumatic bursitis is generally not recommended because of the risk of iatrogenic septic bursitis. Although intrabursal corticosteroid injections are sometimes used to treat microtraumatic bursitis, high-quality evidence demonstrating any benefit is unavailable. Chronic inflammatory bursitis (e.g., gout, rheumatoid arthritis) is treated by addressing the underlying condition, and intrabursal corticosteroid injections are often used. For septic bursitis, antibiotics effective against Staphylococcus aureus are generally the initial treatment, with surgery reserved for bursitis not responsive to antibiotics or for recurrent cases. Outpatient antibiotics may be considered in those who are not acutely ill; patients who are acutely ill

  20. SUPERFICIAL CERVICAL PLEXUS BLOCK

    Directory of Open Access Journals (Sweden)

    Komang Mega Puspadisari

    2014-01-01

    Full Text Available Superficial cervical plexus block is one of the regional anesthesia in  neck were limited to thesuperficial fascia. Anesthesia is used to relieve pain caused either during or after the surgery iscompleted. This technique can be done by landmark or with ultrasound guiding. The midpointof posterior border of the Sternocleidomastoid was identified and the prosedure done on thatplace or on the level of cartilage cricoid.

  1. Superficial cervicovaginal myofibroblastoma: report of four cases and literature review

    Institute of Scientific and Technical Information of China (English)

    WANG Qi-feng; WU Yu-yu; WANG Jian

    2010-01-01

    @@ In 2001, Laskin et al~1 firstly described a series of 14 seemly distinctive mesenchymal tumors that occurred exclusively in the superficial lamina propria of the vagina and cervix of middle to old-aged women. They proposed the term "superficial cervicovaginal myofibroblastoma (SCVM)" to highlight the unique features of this tumor: the superficial subepithelial location and myofibroblastic differentiation of the tumor cells. SCVM appears less well recognized with only three additional reports have been documented in the English literatures.~(2-4) In this study, we described four new cases of SCVM to further characterize the clinical and pathological features of this rare entity.

  2. Referenceless Prediction of Perceptual Fog Density and Perceptual Image Defogging.

    Science.gov (United States)

    Choi, Lark Kwon; You, Jaehee; Bovik, Alan Conrad

    2015-11-01

    We propose a referenceless perceptual fog density prediction model based on natural scene statistics (NSS) and fog aware statistical features. The proposed model, called Fog Aware Density Evaluator (FADE), predicts the visibility of a foggy scene from a single image without reference to a corresponding fog-free image, without dependence on salient objects in a scene, without side geographical camera information, without estimating a depth-dependent transmission map, and without training on human-rated judgments. FADE only makes use of measurable deviations from statistical regularities observed in natural foggy and fog-free images. Fog aware statistical features that define the perceptual fog density index derive from a space domain NSS model and the observed characteristics of foggy images. FADE not only predicts perceptual fog density for the entire image, but also provides a local fog density index for each patch. The predicted fog density using FADE correlates well with human judgments of fog density taken in a subjective study on a large foggy image database. As applications, FADE not only accurately assesses the performance of defogging algorithms designed to enhance the visibility of foggy images, but also is well suited for image defogging. A new FADE-based referenceless perceptual image defogging, dubbed DEnsity of Fog Assessment-based DEfogger (DEFADE) achieves better results for darker, denser foggy images as well as on standard foggy images than the state of the art defogging methods. A software release of FADE and DEFADE is available online for public use: http://live.ece.utexas.edu/research/fog/index.html.

  3. Superficies de placer

    OpenAIRE

    Delli Gatti, Romina

    2012-01-01

    La presente tesis cuenta con 28 pinturas en distintos formatos y tama- ños a través de los cuales la artista investiga diferentes objetos de su entorno cotidiano que le resultan agradables y pueden llegar a transformar anímicamente. De esta manera se van construyendo superficies ideales, relacionadas principalmente con lo cotidiano y lo intimo, lo orgánico, lo industrial, el diseño textil y lo abstracto. Es un intento por generar o prolongar una sensación visual de agrado y placer a tra...

  4. Delayed perceptual awareness in rapid perceptual decisions.

    Directory of Open Access Journals (Sweden)

    Regina Gregori-Grgič

    Full Text Available The flourishing of studies on the neural correlates of decision-making calls for an appraisal of the relation between perceptual decisions and conscious perception. By exploiting the long integration time of noisy motion stimuli, and by forcing human observers to make difficult speeded decisions--sometimes a blind guess--about stimulus direction, we traced the temporal buildup of motion discrimination capability and perceptual awareness, as assessed trial by trial through direct rating. We found that both increased gradually with motion coherence and viewing time, but discrimination was systematically leading awareness, reaching a plateau much earlier. Sensitivity and criterion changes contributed jointly to the slow buildup of perceptual awareness. It made no difference whether motion discrimination was accomplished by saccades or verbal responses. These findings suggest that perceptual awareness emerges on the top of a developing or even mature perceptual decision. We argue that the middle temporal (MT cortical region does not confer us the full phenomenic depth of motion perception, although it may represent a precursor stage in building our subjective sense of visual motion.

  5. The Influence of Perceptual Features, Ethnic Labels, and Sociocultural Information on the Development of Ethnic/Racial Bias in Young Children.

    Science.gov (United States)

    Kowalski, Kurt; Lo, Ya-Fen

    2001-01-01

    Taiwanese children identified their racial group membership and selected potential playmates from racially diverse photographs. Children displayed some Asian bias. Perception of racial features influenced children's choices more than recognition of ethnic labels, and both factors triggered some bias via knowledge of own-group membership. Age,…

  6. Perceptually-Inspired Computing

    Directory of Open Access Journals (Sweden)

    Ming Lin

    2015-08-01

    Full Text Available Human sensory systems allow individuals to see, hear, touch, and interact with the surrounding physical environment. Understanding human perception and its limit enables us to better exploit the psychophysics of human perceptual systems to design more efficient, adaptive algorithms and develop perceptually-inspired computational models. In this talk, I will survey some of recent efforts on perceptually-inspired computing with applications to crowd simulation and multimodal interaction. In particular, I will present data-driven personality modeling based on the results of user studies, example-guided physics-based sound synthesis using auditory perception, as well as perceptually-inspired simplification for multimodal interaction. These perceptually guided principles can be used to accelerating multi-modal interaction and visual computing, thereby creating more natural human-computer interaction and providing more immersive experiences. I will also present their use in interactive applications for entertainment, such as video games, computer animation, and shared social experience. I will conclude by discussing possible future research directions.

  7. Interaction features for prediction of perceptual segmentation

    DEFF Research Database (Denmark)

    Hartmann, Martin; Lartillot, Olivier; Toiviainen, Petri

    2017-01-01

    As music unfolds in time, structure is recognised and understood by listeners, regardless of their level of musical expertise. A number of studies have found spectral and tonal changes to quite successfully model boundaries between structural sections. However, the effects of musical expertise...

  8. The perceptual flow of phonetic feature processing

    DEFF Research Database (Denmark)

    Greenberg, Steven; Christiansen, Thomas Ulrich

    2008-01-01

    How does the brain process spoken language? It is our thesis that word intelligibility and consonant identification are insufficient by themselves to model how the speech signal is decoded - a finer-grained approach is required. In this study, listeners identified 11 different Danish consonants s...

  9. Speech Synthesis Using Perceptually Motivated Features

    Science.gov (United States)

    2012-01-23

    in resetting the phase of theta oscillations (Schroeder and Lakatos , 2009). Oded argued in his recent article that delta oscillations lay outside...from a lower-level oscillation (e.g., each theta cycle being composed of 4 beta cycles, etc.). Schroeder and Lakatos ’ research in auditory and visual...of brain rhythms is the work by Schroeder and Lakatos (2009) who demonstrate that the relationship between theta and delta oscillations is highly

  10. Perceptual grouping in pigeons.

    Science.gov (United States)

    Nagasaka, Yasuo; Hori, Koji; Osada, Yoshihisa

    2005-01-01

    Animal studies reveal that many species perceive partially occluded objects in the same way as do humans. Pigeons have been a notable exception. We re-investigated this anomaly of pigeon perception using a different approach from previous studies. With our method, we show that pigeons perceive occluded objects in the same manner as do other species. In addition, we report that pigeons can recognize perceptually transparent surfaces when the effect is induced by the same perceptual mechanisms as occlusion. These results give behavioral evidence that the perception of both occlusion and transparency is a common visual function shared by pigeons and humans, despite the structural differences between their visual systems.

  11. Acetylcholine and Olfactory Perceptual Learning

    Science.gov (United States)

    Wilson, Donald A.; Fletcher, Max L.; Sullivan, Regina M.

    2004-01-01

    Olfactory perceptual learning is a relatively long-term, learned increase in perceptual acuity, and has been described in both humans and animals. Data from recent electrophysiological studies have indicated that olfactory perceptual learning may be correlated with changes in odorant receptive fields of neurons in the olfactory bulb and piriform…

  12. Perceptual learning in speech

    NARCIS (Netherlands)

    Norris, D.; McQueen, J.M.; Cutler, A.

    2003-01-01

    This study demonstrates that listeners use lexical knowledge in perceptual learning of speech sounds. Dutch listeners first made lexical decisions on Dutch words and nonwords. The final fricative of 20 critical words had been replaced by an ambiguous sound, between [f] and [s]. One group of listener

  13. Imaging of the most frequent superficial soft-tissue sarcomas

    Energy Technology Data Exchange (ETDEWEB)

    Morel, Melanie; Taieb, Sophie; Ceugnart, Luc [Centre Oscar Lambret, Department of Radiology, Lille (France); Penel, Nicolas [Centre Oscar Lambret, Department of Oncology, Lille (France); Mortier, Laurent [Centre Hospitalier Universitaire de Lille, Department of Dermatology, Hopital Claude Huriez, Lille (France); Vanseymortier, Luc [Centre Oscar Lambret, Department of Surgery, Lille (France); Robin, Y.M. [Centre Oscar Lambret, Departement of Pathology, Lille (France); Gosset, Pierre [Groupement Hospitalier de l' Institut Catholique-Faculte Libre de Medecine de Lille, Department of Pathology, Hopital Saint-Philibert, Lomme (France); Cotten, Anne [Centre Hospitalier Universitaire de Lille, Department of Musculoskeletal Radiology, Centre Hopital Roger Salengro, Lille (France)

    2011-03-15

    Superficial soft-tissue sarcomas are malignant mesenchymal tumors located within the cutaneous and/or subcutaneous layers. Most superficial soft-tissue sarcomas are low-grade tumors; yet, the risk of local recurrence is high, and initial wide surgery is the main prognostic factor. Some of these superficial sarcomas may grow, following an infiltrative pattern, and their real extent may be underestimated clinically. Imaging techniques are useful to determine precisely the real margins of the tumor, especially in cases of clinically doubtful or recurrent or large superficial lesions. Imaging tools enable one to determine the relationship with the superficial fascia separating the subcutaneous layer from the underlying muscle. In our institution ultrasonographic examination is followed by magnetic resonance (MR) imaging when the size of the lesion exceeds 3-5 cm. Imaging assessment is performed prior to biopsy, enabling optimal surgical management. Imaging features of the main superficial sarcomas are detailed in the following article, according to their major locations: those arising in the epidermis and/or dermis, which are most often diagnosed by dermatologists, and the subcutaneous sarcomas. (orig.)

  14. Notebook Positioning by Perceptual Map and Laddering Method

    Directory of Open Access Journals (Sweden)

    Mehdi Zaribaf

    2012-01-01

    Full Text Available The purpose of this applied paper is to determine positioning of laptops by perceptual map and laddering method. Data collection method was survey using questionnaire. First by using the views of computer experts of selected brands, including Sony, Acer, Asus, Dell and Msi, 5 among 20 attributes, which were considered more important, were selected through application of factor analysis technique. Then, after classification of these features by laddering technique, they were analyzed by using another questionnaire to determine the position of each brand in the perceptual map. We try to show factors and laptop brands position with regard two factors of price and quality in the resulted perceptual map.

  15. Superficial Priming in Episodic Recognition

    Science.gov (United States)

    Dopkins, Stephen; Sargent, Jesse; Ngo, Catherine T.

    2010-01-01

    We explored the effect of superficial priming in episodic recognition and found it to be different from the effect of semantic priming in episodic recognition. Participants made recognition judgments to pairs of items, with each pair consisting of a prime item and a test item. Correct positive responses to the test item were impeded if the prime…

  16. Perceptual learning: toward a comprehensive theory.

    Science.gov (United States)

    Watanabe, Takeo; Sasaki, Yuka

    2015-01-03

    Visual perceptual learning (VPL) is long-term performance increase resulting from visual perceptual experience. Task-relevant VPL of a feature results from training of a task on the feature relevant to the task. Task-irrelevant VPL arises as a result of exposure to the feature irrelevant to the trained task. At least two serious problems exist. First, there is the controversy over which stage of information processing is changed in association with task-relevant VPL. Second, no model has ever explained both task-relevant and task-irrelevant VPL. Here we propose a dual plasticity model in which feature-based plasticity is a change in a representation of the learned feature, and task-based plasticity is a change in processing of the trained task. Although the two types of plasticity underlie task-relevant VPL, only feature-based plasticity underlies task-irrelevant VPL. This model provides a new comprehensive framework in which apparently contradictory results could be explained.

  17. Space and time in perceptual causality

    Directory of Open Access Journals (Sweden)

    Benjamin Straube

    2010-04-01

    Full Text Available Inferring causality is a fundamental feature of human cognition that allows us to theorize about and predict future states of the world. Michotte suggested that humans automatically perceive causality based on certain perceptual features of events. However, individual differences in judgments of perceptual causality cast doubt on Michotte’s view. To gain insights in the neural basis of individual difference in the perception of causality, our participants judged causal relationships in animations of a blue ball colliding with a red ball (a launching event while fMRI-data were acquired. Spatial continuity and temporal contiguity were varied parametrically in these stimuli. We did not find consistent brain activation differences between trials judged as caused and those judged as non-caused, making it unlikely that humans have universal instantiation of perceptual causality in the brain. However, participants were slower to respond to and showed greater neural activity for violations of causality, suggesting that humans are biased to expect causal relationships when moving objects appear to interact. Our participants demonstrated considerable individual differences in their sensitivity to spatial and temporal characteristics in perceiving causality. These qualitative differences in sensitivity to time or space in perceiving causality were instantiated in individual differences in activation of the left basal ganglia or right parietal lobe, respectively. Thus, the perception that the movement of one object causes the movement of another is triggered by elemental spatial and temporal sensitivities, which themselves are instantiated in specific distinct neural networks.

  18. Perceptual Audio Hashing Functions

    Directory of Open Access Journals (Sweden)

    Emin Anarım

    2005-07-01

    Full Text Available Perceptual hash functions provide a tool for fast and reliable identification of content. We present new audio hash functions based on summarization of the time-frequency spectral characteristics of an audio document. The proposed hash functions are based on the periodicity series of the fundamental frequency and on singular-value description of the cepstral frequencies. They are found, on one hand, to perform very satisfactorily in identification and verification tests, and on the other hand, to be very resilient to a large variety of attacks. Moreover, we address the issue of security of hashes and propose a keying technique, and thereby a key-dependent hash function.

  19. Superficie

    OpenAIRE

    Corna, Pablo María

    2015-01-01

    En la época posclásica del derecho romano se buscó, por parte del Estado y ciudadanos, utilizar ciertos terrenos que formaban parte de su patrimonio para arrendarlos por largo término —y a veces a perpetuidad— a personas que tenían el derecho de edificar o plantar mediante el pago de un precio llamado pensio o solárium. En el siglo II de nuestra era ya era utilizado para asentar tribus romanizadas en la frontera del imperio como para el cultivo de vid y los olivos que demoran varios...

  20. Superficie

    OpenAIRE

    Corna, Pablo María

    2015-01-01

    En la época posclásica del derecho romano se buscó, por parte del Estado y ciudadanos, utilizar ciertos terrenos que formaban parte de su patrimonio para arrendarlos por largo término —y a veces a perpetuidad— a personas que tenían el derecho de edificar o plantar mediante el pago de un precio llamado pensio o solárium. En el siglo II de nuestra era ya era utilizado para asentar tribus romanizadas en la frontera del imperio como para el cultivo de vid y los olivos que demoran varios años e...

  1. Metabolomic change precedes apple superficial scald symptoms.

    Science.gov (United States)

    Rudell, David R; Mattheis, James P; Hertog, Maarten L A T M

    2009-09-23

    Untargeted metabolic profiling was employed to characterize metabolomic changes associated with 'Granny Smith' apple superficial scald development following 1-MCP or DPA treatment. Partial least-squares discriminant analyses were used to link metabolites with scald, postharvest treatments, and storage duration. Models revealed metabolomic differentiation between untreated controls and fruit treated with DPA or 1-MCP within 1 week following storage initiation. Metabolic divergence between controls and DPA-treated fruit after 4 weeks of storage preceded scald symptom development by 2 months. alpha-Farnesene oxidation products with known associations to scald, including conjugated trienols, 6-methyl-5-hepten-2-one, and 6-methyl-5-hepten-2-ol, were associated with presymptomatic as well as scalded control fruit. Likewise, a large group of putative triterpenoids with mass spectral features similar to those of ursolic acid and beta-sitosterol were associated with control fruit and scald. Results demonstrate that extensive metabolomic changes associated with scald precede actual symptom development.

  2. Looking without Perceiving: Impaired Preattentive Perceptual Grouping in Autism Spectrum Disorder

    OpenAIRE

    Tiffany A Carther-Krone; Sarah Shomstein; Marotta, Jonathan J.

    2016-01-01

    Before becoming aware of a visual scene, our perceptual system has organized and selected elements in our environment to which attention should be allocated. Part of this process involves grouping perceptual features into a global whole. Individuals with autism spectrum disorders (ASD) rely on a more local processing strategy, which may be driven by difficulties perceptually grouping stimuli. We tested this notion using a line discrimination task in which two horizontal lines were superimpose...

  3. Perceptualization of scientific data

    Science.gov (United States)

    Grinstein, Georges G.; Smith, Stuart

    1990-08-01

    In this paper we discuss data exploration as a particularly difficult case within the general problem of data visualization. We describe (1) a novel graphic technique for displaying multidimensional data visually and (2) an auditory display integrated with the visual display that allows us to represent multidimensional data in sound. The visual/auditory display employs an "iconographic" technique that seeks to exploit the spontaneous perceptual capacity to sense and discriminate texture. Structures in data to be analyzed can appear, both visually and aurally, as distinct textural regions and contours when the data are represented iconographically. Sound can be used to reinforce the visual presentation or to augment the dimensionality of the visual display. The immediate focus of the work reported here is to investigate how best to transform data into perceptible visual and auditory textures, that is, how best to "perceptualize" the data. A key problem we discuss is deciding which fields of a multidimensional data set should be represented in the visual domain and which in the auditory domain. This activity is part of the University of Lowell's Exploratory Visualization (Exvis) project, a multidisciplinary effort to develop new paradigms for the exploration and analysis of data with high dimensionality.

  4. Perceptual Repetition Blindness Effects

    Science.gov (United States)

    Hochhaus, Larry; Johnston, James C.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    The phenomenon of repetition blindness (RB) may reveal a new limitation on human perceptual processing. Recently, however, researchers have attributed RB to post-perceptual processes such as memory retrieval and/or reporting biases. The standard rapid serial visual presentation (RSVP) paradigm used in most RB studies is, indeed, open to such objections. Here we investigate RB using a "single-frame" paradigm introduced by Johnston and Hale (1984) in which memory demands are minimal. Subjects made only a single judgement about whether one masked target word was the same or different than a post-target probe. Confidence ratings permitted use of signal detection methods to assess sensitivity and bias effects. In the critical condition for RB a precue of the post-target word was provided prior to the target stimulus (identity precue), so that the required judgement amounted to whether the target did or did not repeat the precue word. In control treatments, the precue was either an unrelated word or a dummy.

  5. Perceptual Constraints in Phonotactic Learning

    Science.gov (United States)

    Endress, Ansgar D.; Mehler, Jacques

    2010-01-01

    Structural regularities in language have often been attributed to symbolic or statistical general purpose computations, whereas perceptual factors influencing such generalizations have received less interest. Here, we use phonotactic-like constraints as a case study to ask whether the structural properties of specific perceptual and memory…

  6. Perceptual basis for reactive teleoperation.

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y. S.; Ewing, T. F.; Boyle, J. M.; Yule, T. J.

    2001-08-28

    To enhance task performance in partially structured environment, enhancement of teleoperation was proposed by introducing autonomous behaviors. Such autonomy is implemented based on reactive robotic architecture, where reactive motor agents that directly couples sensory inputs and motor actions become the building blocks. To this end, presented in this paper is a perceptual basis for the motor agents. The perceptual basis consists of perceptual agents that extracts environmental information from a structured light vision system and provide action oriented perception for the corresponding motor agents. Rather than performing general scene reconstruction, a perceptual agent directly provides the motion reference for the motor behavior. Various sensory mechanisms--sensor fission, fusion, and fashion--becomes basic building blocks of the perception process. Since perception is a process deeply intertwined with the motor actions, active perception may also incorporate motor behaviors as an integral perceptual process.

  7. Integrated approaches to perceptual learning.

    Science.gov (United States)

    Jacobs, Robert A

    2010-04-01

    New technologies and new ways of thinking have recently led to rapid expansions in the study of perceptual learning. We describe three themes shared by many of the nine articles included in this topic on Integrated Approaches to Perceptual Learning. First, perceptual learning cannot be studied on its own because it is closely linked to other aspects of cognition, such as attention, working memory, decision making, and conceptual knowledge. Second, perceptual learning is sensitive to both the stimulus properties of the environment in which an observer exists and to the properties of the tasks that the observer needs to perform. Moreover, the environmental and task properties can be characterized through their statistical regularities. Finally, the study of perceptual learning has important implications for society, including implications for science education and medical rehabilitation. Contributed articles relevant to each theme are summarized.

  8. Effects of musicianship and experimental task on perceptual segmentation

    DEFF Research Database (Denmark)

    Hartmann, Martin; Lartillot, Olivier; Toiviainen, Petri

    2015-01-01

    The perceptual structure of music is a fundamental issue in music psychology that can be systematically addressed via computational models. This study estimated the contribution of spectral, rhythmic and tonal descriptors for prediction of perceptual segmentation across stimuli. In a real-time task...... important to predict segmentation by listeners. Our results suggest that musicians pay attention to more features than non-musicians, including more high-level structure interactions. Prediction of non-real-time annotations involved more features, particularly interactions thereof, suggesting high context...

  9. A Novel Block-DCT and PCA Based Image Perceptual Hashing Algorithm

    Directory of Open Access Journals (Sweden)

    Zeng Jie

    2013-01-01

    Full Text Available Image perceptual hashing finds applications in content indexing, large-scale image database management, certification and authentication and digital watermarking. We propose a Block-DCT and PCA based image perceptual hash in this article and explore the algorithm in the application of tamper detection. The main idea of the algorithm is to integrate color histogram and DCT coefficients of image blocks as perceptual feature, then to compress perceptual features as inter-feature with PCA, and to threshold to create a robust hash. The robustness and discrimination properties of the proposed algorithm are evaluated in detail. Experimental results show that the proposed image perceptual hash algorithm can effectively address the tamper detection problem with advantageous robustness and discrimination.

  10. Perceptual Object Extraction Based on Saliency and Clustering

    Directory of Open Access Journals (Sweden)

    Qiaorong Zhang

    2010-08-01

    Full Text Available Object-based visual attention has received an increasing interest in recent years. Perceptual object is the basic attention unit of object-based visual attention. The definition and extraction of perceptual objects is one of the key technologies in object-based visual attention computation model. A novel perceptual object definition and extraction method is proposed in this paper. Based on Gestalt theory and visual feature integration theory, perceptual object is defined using homogeneity region, salient region and edges. An improved saliency map generating algorithm is employed first. Based on the saliency map, salient edges are extracted. Then graph-based clustering algorithm is introduced to get homogeneity regions in the image. Finally an integration strategy is adopted to combine salient edges and homogeneity regions to extract perceptual objects. The proposed perceptual object extraction method has been tested on lots of natural images. Experiment results and analysis are presented in this paper also. Experiment results show that the proposed method is reasonable and valid.

  11. Perceptual qualities and material classes.

    Science.gov (United States)

    Fleming, Roland W; Wiebel, Christiane; Gegenfurtner, Karl

    2013-07-11

    Under typical viewing conditions, we can easily group materials into distinct classes (e.g., woods, plastics, textiles). Additionally, we can also make many other judgments about material properties (e.g., hardness, rigidity, colorfulness). Although these two types of judgment (classification and inferring material properties) have different requirements, they likely facilitate one another. We conducted two experiments to investigate the interactions between material classification and judgments of material qualities in both the visual and semantic domains. In Experiment 1, nine students viewed 130 images of materials from 10 different classes. For each image, they rated nine subjective properties (glossiness, transparency, colorfulness, roughness, hardness, coldness, fragility, naturalness, prettiness). In Experiment 2, 65 subjects were given the verbal names of six material classes, which they rated in terms of 42 adjectives describing material qualities. In both experiments, there was notable agreement between subjects, and a relatively small number of factors (weighted combinations of different qualities) were substantially independent of one another. Despite the difficulty of classifying materials from images (Liu, Sharan, Adelson, & Rosenholtz, 2010), the different classes were well clustered in the feature space defined by the subjective ratings. K-means clustering could correctly identify class membership for over 90% of the samples, based on the average ratings across subjects. We also found a high degree of consistency between the two tasks, suggesting subjects access similar information about materials whether judging their qualities visually or from memory. Together, these findings show that perceptual qualities are well defined, distinct, and systematically related to material class membership.

  12. 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.

  13. Perceptual learning in sensorimotor adaptation.

    Science.gov (United States)

    Darainy, Mohammad; Vahdat, Shahabeddin; Ostry, David J

    2013-11-01

    Motor learning often involves situations in which the somatosensory targets of movement are, at least initially, poorly defined, as for example, in learning to speak or learning the feel of a proper tennis serve. Under these conditions, motor skill acquisition presumably requires perceptual as well as motor learning. That is, it engages both the progressive shaping of sensory targets and associated changes in motor performance. In the present study, we test the idea that perceptual learning alters somatosensory function and in so doing produces changes to human motor performance and sensorimotor adaptation. Subjects in these experiments undergo perceptual training in which a robotic device passively moves the subject's arm on one of a set of fan-shaped trajectories. Subjects are required to indicate whether the robot moved the limb to the right or the left and feedback is provided. Over the course of training both the perceptual boundary and acuity are altered. The perceptual learning is observed to improve both the rate and extent of learning in a subsequent sensorimotor adaptation task and the benefits persist for at least 24 h. The improvement in the present studies varies systematically with changes in perceptual acuity and is obtained regardless of whether the perceptual boundary shift serves to systematically increase or decrease error on subsequent movements. The beneficial effects of perceptual training are found to be substantially dependent on reinforced decision-making in the sensory domain. Passive-movement training on its own is less able to alter subsequent learning in the motor system. Overall, this study suggests perceptual learning plays an integral role in motor learning.

  14. Perceptual inference and autistic traits

    DEFF Research Database (Denmark)

    Skewes, Joshua; Jegindø, Else-Marie Elmholdt; Gebauer, Line

    2015-01-01

    Autistic people are better at perceiving details. Major theories explain this in terms of bottom-up sensory mechanisms, or in terms of top-down cognitive biases. Recently, it has become possible to link these theories within a common framework. This framework assumes that perception is implicit...... neural inference, combining sensory evidence with prior perceptual knowledge. Within this framework, perceptual differences may occur because of enhanced precision in how sensory evidence is represented, or because sensory evidence is weighted much higher than prior perceptual knowledge...

  15. Anterior urethral recurrence of superficial bladder cancer: its clinical significance.

    Directory of Open Access Journals (Sweden)

    Saika T

    2003-12-01

    Full Text Available The aim of this study was to reveal the clinical features of anterior urethral recurrence in patients with superficial bladder cancer, and to determine the appropriate treatment. Three hundred and three patients with superficial bladder cancer, who were newly diagnosed and initially treated conservatively in our hospital between 1965 and 1990, were followed for at least 5 years and their clinical outcomes were analyzed. Clinical factors, including anterior urethral recurrence, were evaluated statistically regarding tumor progression. Eight patients (2.6% had anterior urethral recurrence following superficial bladder cancer. Twenty-four patients (7.9% had tumor progression and 149 (49.2% had tumor recurrence. In a multivariate analysis using a logistic model, anterior urethral recurrence was the most important factor, followed by histological grade. Four of 5 patients who were treated for anterior urethral recurrent tumors by transurethral resection showed progression and died of the cancer within one year. Two of the remaining three patients who underwent radical cysto-urethrectomy at the time of anterior urethral recurrence survived. Anterior urethral recurrence following superficial bladder cancer is a predictor for rapid subsequent malignant progression. Once there is anterior urethral recurrence, radical intensive therapy, including radical cysto-urethrectomy, should be carried out immediately.

  16. Perceptual Load Modulates Object-Based Attention

    Science.gov (United States)

    Ho, Ming-Chou; Atchley, Paul

    2009-01-01

    Two experimental series are reported using both reaction time (RT) and a data-limited perceptual report to examine the effects of perceptual load on object-based attention. Perceptual load was manipulated across 3 levels by increasing the complexity of perceptual judgments. Data from the RT-based experiments showed object-based effects when the…

  17. Facial expression recognition in perceptual color space.

    Science.gov (United States)

    Lajevardi, Seyed Mehdi; Wu, Hong Ren

    2012-08-01

    This paper introduces a tensor perceptual color framework (TPCF) for facial expression recognition (FER), which is based on information contained in color facial images. The TPCF enables multi-linear image analysis in different color spaces and demonstrates that color components provide additional information for robust FER. Using this framework, the components (in either RGB, YCbCr, CIELab or CIELuv space) of color images are unfolded to two-dimensional (2- D) tensors based on multi-linear algebra and tensor concepts, from which the features are extracted by Log-Gabor filters. The mutual information quotient (MIQ) method is employed for feature selection. These features are classified using a multi-class linear discriminant analysis (LDA) classifier. The effectiveness of color information on FER using low-resolution and facial expression images with illumination variations is assessed for performance evaluation. Experimental results demonstrate that color information has significant potential to improve emotion recognition performance due to the complementary characteristics of image textures. Furthermore, the perceptual color spaces (CIELab and CIELuv) are better overall for facial expression recognition than other color spaces by providing more efficient and robust performance for facial expression recognition using facial images with illumination variation.

  18. Late sequelae of superficial irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hood, I.C.; Young, J.E.

    1984-10-01

    Superficial irradiation results in well recognized late sequelae including not only sclerosis and atrophy of skin and subcutaneous tissue, but also the development of benign and malignant tumors of skin and adjacent structures. The long latency between irradiation and its late effects allowed the early uncontrolled use of radiation treatment for benign conditions. The subsequent recognition of the causal relationship between tumors and previous irradiation has restricted its use to more appropriate purposes, although it is possible that it is still overused in some areas of dermatologic practice. Clinicians need to be aware of the time interval between irradiation and the development of its late sequelae, and the incidence of these sequelae. Appropriate irradiation exposure history should be a part of the evaluation of every patient.

  19. Perceptually Lossless Wavelet Compression

    Science.gov (United States)

    Watson, Andrew B.; Yang, Gloria Y.; Solomon, Joshua A.; Villasenor, John

    1996-01-01

    The Discrete Wavelet Transform (DWT) decomposes an image into bands that vary in spatial frequency and orientation. It is widely used for image compression. Measures of the visibility of DWT quantization errors are required to achieve optimal compression. Uniform quantization of a single band of coefficients results in an artifact that is the sum of a lattice of random amplitude basis functions of the corresponding DWT synthesis filter, which we call DWT uniform quantization noise. We measured visual detection thresholds for samples of DWT uniform quantization noise in Y, Cb, and Cr color channels. The spatial frequency of a wavelet is r 2(exp -1), where r is display visual resolution in pixels/degree, and L is the wavelet level. Amplitude thresholds increase rapidly with spatial frequency. Thresholds also increase from Y to Cr to Cb, and with orientation from low-pass to horizontal/vertical to diagonal. We propose a mathematical model for DWT noise detection thresholds that is a function of level, orientation, and display visual resolution. This allows calculation of a 'perceptually lossless' quantization matrix for which all errors are in theory below the visual threshold. The model may also be used as the basis for adaptive quantization schemes.

  20. 服装感性类型风格形象特征及文化元素构成分析%Analysis of image features and cultural elements for clothing perceptual type style

    Institute of Scientific and Technical Information of China (English)

    冯旭敏

    2012-01-01

    Grasping consumer' s style image accurately, designing products which consisted with the aesthetic demand of consumers, and transferring cultural information and brand connotation to consumers with the costume products, which were the brand way of business. Analyzing diversified beauty consciousness comprehensively from the perceptual angle, classifying the complex and varied styles, and then summarizing the very general perceptual categories the costume style image, which was an effective point to capture the aesthetic image of the target consumption group. The style types of costume should be identified based on the design elements and embodied cultural elements, and the costume culture as well as the connotation of the brand culture should express perfectly through the style image consisted of design elements and various cultural elements, etc.%准确把握消费者风格形象,策划设计开发与定位消费者审美需求相一致的产品,通过服装产品向消费者传递文化信息和品牌内涵,是品牌经营之道。从感性层面综合分析多样化美意识,将繁多的风格整理分类,归纳出概括性的感性类型——服装风格形象,是捕捉目标消费群体审美形象的有效切入点。服装风格类型要以设计要素及所融入的各类文化元素等为依据进行甄别,服装文化信息与品牌文化内涵则需要通过设计要素和各种文化元素等构成的风格形象才能完美表达。

  1. Superficial siderosis in the central nervous system

    Energy Technology Data Exchange (ETDEWEB)

    Pythinen, J. [Oulu Univ. (Finland). Dept. of Diagnostic Radiology; Paeaekkoe, E. [Oulu Univ. (Finland). Dept. of Diagnostic Radiology; Ilkko, E. [Oulu Univ. (Finland). Dept. of Diagnostic Radiology

    1995-02-01

    We describe a rare entity, superficial siderosis of the central nervous system, due to multiple small episodes of subarachnoid haemorrhage from any source. Non-specific neurological findings are associated with deposition of iron-containing pigments in the leptomeninges and superficial layers of the cortex. T2-weighted magnetic resonance imaging demonstrates characteristic low signal in the meninges. (orig.)

  2. Cochlear implantation in superficial siderosis.

    Science.gov (United States)

    Kim, Chong-Sun; Song, Jae-Jun; Park, Min-Hyun; Kim, Young Ho; Koo, Ja-Won

    2006-08-01

    Superficial siderosis (SS) of the central nervous system has been thought to be a rare condition that generates progressive hearing loss, ataxia, pyramidal signs, and dementia. The main cause of hearing loss by SS is thought to be neuronal. Because there is no histopathologic report of the human temporal bone in SS, there is a debate about the possibility of cochlear involvement. We present a 25-year-old man who was investigated for bilateral progressive sensorineural hearing loss and vestibular failure after head trauma. On brain MRI, SS of the central nervous system was detected. Distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) showed no response on both sides. However, integrity of the eighth nerve was proved by the electrical ABR test on the right side and the patient benefited significantly from cochlear implantation. The sensorineural hearing loss in SS seems to be related to cochlear damage as well as neuronal damage. So, cochlear implantation would be a hearing rehabilitation modality for the sensorineural hearing loss caused by SS.

  3. Silicon superficial texturing bypulsed laser

    Directory of Open Access Journals (Sweden)

    Ponce, L.

    1998-04-01

    Full Text Available Texturing of silicon surfaces with pulsed laser is made. The method is based on the formation of laser- induced periodic surface structure (LIPSS. The process is temporary characterized through the dynamic reflectance, thus determining the formation threshold of the structure. Relation between the different textures and the spectral reflectance of the samples before and after the treatment is also characterized. The mean value of spectral reflectance decreases up to a 6 %.

    Se realiza el texturado de superficies de silicio con un láser pulsado mediante la formación de una estructura periódica inducida por láser (LIPSS. Se caracteriza el proceso mediante reflectancia dinámica, determinándose el umbral de formación de la estructura. Se caracteriza el nivel de texturado midiendo la reflectancia espectral de las muestras antes y después del tratamiento. El valor medio de la reflectancia espectral disminuye hasta el 6 %.

  4. Exploring Tactile Perceptual Dimensions Using Materials Associated with Sensory Vocabulary.

    Science.gov (United States)

    Sakamoto, Maki; Watanabe, Junji

    2017-01-01

    Considering tactile sensation when designing products is important because the decision to purchase often depends on how products feel. Numerous psychophysical studies have attempted to identify important factors that describe tactile perceptions. However, the numbers and types of major tactile dimensions reported in previous studies have varied because of differences in materials used across experiments. To obtain a more complete picture of perceptual space with regard to touch, our study focuses on using vocabulary that expresses tactile sensations as a guiding principle for collecting material samples because these types of words are expected to cover all the basic categories within tactile perceptual space. We collected 120 materials based on a variety of Japanese sound-symbolic words for tactile sensations, and used the materials to examine tactile perceptual dimensions and their associations with affective evaluations. Analysis revealed six major dimensions: "Affective evaluation and Friction," "Compliance," "Surface," "Volume," "Temperature," and "Naturalness." These dimensions include four factors that previous studies have regarded as fundamental, as well as two new factors: "Volume" and "Naturalness." Additionally, we showed that "Affective evaluation" is more closely related to the "Friction" component (slipperiness and dryness) than to other tactile perceptual features. Our study demonstrates that using vocabulary could be an effective method for selecting material samples to explore tactile perceptual space.

  5. Perceptual averaging in individuals with Autism Spectrum Disorder

    Directory of Open Access Journals (Sweden)

    Jennifer Elise Corbett

    2016-11-01

    Full Text Available There is mounting evidence that observers rely on statistical summaries of visual information to maintain stable and coherent perception. Sensitivity to the mean (or other prototypical value of a visual feature (e.g., mean size appears to be a pervasive process in human visual perception. Previous studies in individuals diagnosed with Autism Spectrum Disorder (ASD have uncovered characteristic patterns of visual processing that suggest they may rely more on enhanced local representations of individual objects instead of computing such perceptual averages. To further explore the fundamental nature of abstract statistical representation in visual perception, we investigated perceptual averaging of mean size in a group of 12 high-functioning individuals diagnosed with ASD using simplified versions of two identification and adaptation tasks that elicited characteristic perceptual averaging effects in a control group of neurotypical participants. In Experiment 1, participants performed with above chance accuracy in recalling the mean size of a set of circles (mean task despite poor accuracy in recalling individual circle sizes (member task. In Experiment 2, their judgments of single circle size were biased by mean size adaptation. Overall, these results suggest that individuals with ASD perceptually average information about sets of objects in the surrounding environment. Our results underscore the fundamental nature of perceptual averaging in vision, and further our understanding of how autistic individuals make sense of the external environment.

  6. Perceptual learning: top to bottom.

    Science.gov (United States)

    Amitay, Sygal; Zhang, Yu-Xuan; Jones, Pete R; Moore, David R

    2014-06-01

    Perceptual learning has traditionally been portrayed as a bottom-up phenomenon that improves encoding or decoding of the trained stimulus. Cognitive skills such as attention and memory are thought to drive, guide and modulate learning but are, with notable exceptions, not generally considered to undergo changes themselves as a result of training with simple perceptual tasks. Moreover, shifts in threshold are interpreted as shifts in perceptual sensitivity, with no consideration for non-sensory factors (such as response bias) that may contribute to these changes. Accumulating evidence from our own research and others shows that perceptual learning is a conglomeration of effects, with training-induced changes ranging from the lowest (noise reduction in the phase locking of auditory signals) to the highest (working memory capacity) level of processing, and includes contributions from non-sensory factors that affect decision making even on a "simple" auditory task such as frequency discrimination. We discuss our emerging view of learning as a process that increases the signal-to-noise ratio associated with perceptual tasks by tackling noise sources and inefficiencies that cause performance bottlenecks, and present some implications for training populations other than young, smart, attentive and highly-motivated college students.

  7. Perceptual dimensions of style in paintings

    Directory of Open Access Journals (Sweden)

    Marković Slobodan

    2007-01-01

    Full Text Available The main purpose of this study is to specify the basic perceptual dimensions underlying the judgments of the physical features which define the style in paintings (e.g. salient form, colorful surface, oval contours etc.. The other aim of the study is to correlate these dimensions with the subjective (affective dimensions of the experience of paintings. In the preliminary study a set of 25 pairs of elementary perceptual descriptors were empirically specified, and a set of 25 bipolar scales were made (e.g. uncolored-multicolored. In the experiment 30 subjects judged 24 paintings (paintings were taken from the study of Radonjić and Marković, 2004 on 25 scales. Factor analysis revealed the four factors: form (scales: precise, neat, salient form etc., color (color contrast, lightness contrast, vivid colors, space (voluminosity, depth and oval contours and complexity (multicolored, ornate, detailed. Obtained factors reflected the nature of the phenomenological and neural segregation of form, color, depth processing, and partially of complexity processing (e.g. spatial frequency processing within both the form and color subsystem. The aim of the next step of analysis was to specify the correlations between two groups of judgments: (a mean judgments of 24 paintings on perceptual factors and (b mean judgments of the same set of 24 paintings on subjective (affective experience factors, i.e. regularity, attraction, arousal and relaxation (judgments taken from Radonjić and Marković, 2005. The following significant correlations were obtained: regularity-form, regularity-space, attraction-form and arousal-complexity (negative correlation. The reasons for the unexpected negative correlation between arousal and complexity should be specified in further studies.

  8. Auditory perceptual load: A review.

    Science.gov (United States)

    Murphy, Sandra; Spence, Charles; Dalton, Polly

    2017-02-08

    Selective attention is a crucial mechanism in everyday life, allowing us to focus on a portion of incoming sensory information at the expense of other less relevant stimuli. The circumstances under which irrelevant stimuli are successfully ignored have been a topic of scientific interest for several decades now. Over the last 20 years, the perceptual load theory (e.g. Lavie, 1995) has provided one robust framework for understanding these effects within the visual modality. The suggestion is that successful selection depends on the perceptual demands imposed by the task-relevant information. However, less research has addressed the question of whether the same principles hold in audition and, to date, the existing literature provides a mixed picture. Here, we review the evidence for and against the applicability of perceptual load theory in hearing, concluding that this question still awaits resolution.

  9. Finding phonological features in perception

    NARCIS (Netherlands)

    Chládková, K.

    2014-01-01

    This thesis investigated whether phonological features have perceptual bases. The search for features in perception was approached from several angles: from that of an adult listener who has a fully acquired language system in place, from that of a linguist who aims to uncover feature structures in

  10. Perceptual incongruence influences bistability and cortical activation

    NARCIS (Netherlands)

    Brouwer, G.J.; Tong, F.; Hagoort, P.; van Ee, R.

    2009-01-01

    We employed a parametric psychophysical design in combination with functional imaging to examine the influence of metric changes in perceptual incongruence on perceptual alternation rates and cortical responses. Subjects viewed a bistable stimulus defined by incongruent depth cues; bistability

  11. Scanning electron microscopy of superficial white onychomycosis*

    Science.gov (United States)

    de Almeida Jr., Hiram Larangeira; Boabaid, Roberta Oliveira; Timm, Vitor; Silva, Ricardo Marques e; de Castro, Luis Antonio Suita

    2015-01-01

    Superficial white onychomycosis is characterized by opaque, friable, whitish superficial spots on the nail plate. We examined an affected halux nail of a 20-year-old male patient with scanning electron microscopy. The mycological examination isolated Trichophyton mentagrophytes. Abundant hyphae with the formation of arthrospores were found on the nail's surface, forming small fungal colonies. These findings showed the great capacity for dissemination of this form of onychomycosis. PMID:26560225

  12. Treatment of superficial mycoses: review - part II

    OpenAIRE

    2013-01-01

    Superficial fungal infections of the hair, skin and nails are a major cause of morbidity in the world. Choosing the right treatment is not always simple because of the possibility of drug interactions and side effects. The first part of the article discusses the main treatments for superficial mycoses - keratophytoses, dermatophytosis, candidiasis, with a practical approach to the most commonly-used topical and systemic drugs , referring also to their dosage and duration of use. Promising new...

  13. Treatment of superficial mycoses: review - part II*

    OpenAIRE

    2013-01-01

    Superficial fungal infections of the hair, skin and nails are a major cause of morbidity in the world. Choosing the right treatment is not always simple because of the possibility of drug interactions and side effects. The first part of the article discusses the main treatments for superficial mycoses - keratophytoses, dermatophytosis, candidiasis, with a practical approach to the most commonly-used topical and systemic drugs , referring also to their dosage and duration of use. Promising new...

  14. Glans-preserving surgery for superficial penile cancer.

    Science.gov (United States)

    Li, Pengchao; Song, Ninghong; Yin, Changjun; Zhang, Wei; Li, Jie; Hua, Lixin; Wang, Zengjun; Cheng, Gong

    2012-01-01

    In this study, we investigated the safety and feasibility of glans-preserving surgery for superficial penile squamous cell carcinoma. Young patients with penile primary tumors exhibiting favorable histologic features were best suited for organ-sparing procedures, enabling them to avoid sexual disturbances. The study included 12 patients, 38-53 years of age (median age 46 years), with superficial lesions involving the glans penis, coronary sulcus, or shaft skin. After clinical staging and grading, those patients were offered a glans-preserving procedure to preserve the normal appearance and functional integrity of the glans penis. Of the 12 patients referred, the tumors were TaG1 in 4 patients, TaG2 in 3, TisG1 in 1, TisG2 in 1, T1G1 in 2, and T1G2 in 1. All patients returned to normal sexual activity 1 month postoperatively. Sexual function and sexual satisfaction were well maintained after surgery. The cosmetic results were considered satisfying/very satisfying by 83% (10 of 12 patients). Follow-up data were available on 12 patients at a mean follow-up of 62.5 months. Only 1 patient had recurrence 6 months after surgery, which was managed by a second glans-preserving surgery without recurrence. With careful patient selection and vigilant follow-up, anatomically suitable superficial penile cancer can be offered this glans-preserving surgery, while preserving function of the penis wherever possible.

  15. Mutual information, perceptual independence, and holistic face perception.

    Science.gov (United States)

    Fitousi, Daniel

    2013-07-01

    The concept of perceptual independence is ubiquitous in psychology. It addresses the question of whether two (or more) dimensions are perceived independently. Several authors have proposed perceptual independence (or its lack thereof) as a viable measure of holistic face perception (Loftus, Oberg, & Dillon, Psychological Review 111:835-863, 2004; Wenger & Ingvalson, Learning, Memory, and Cognition 28:872-892, 2002). According to this notion, the processing of facial features occurs in an interactive manner. Here, I examine this idea from the perspective of two theories of perceptual independence: the multivariate uncertainty analysis (MUA; Garner & Morton, Definitions, models, and experimental paradigms. Psychological Bulletin 72:233-259, 1969), and the general recognition theory (GRT; Ashby & Townsend, Psychological Review 93:154-179, 1986). The goals of the study were to (1) introduce the MUA, (2) examine various possible relations between MUA and GRT using numerical simulations, and (3) apply the MUA to two consensual markers of holistic face perception(-)recognition of facial features (Farah, Wilson, Drain, & Tanaka, Psychological Review 105:482-498, 1998) and the composite face effect (Young, Hellawell, & Hay, Perception 16:747-759, 1987). The results suggest that facial holism is generated by violations of several types of perceptual independence. They highlight the important theoretical role played by converging operations in the study of holistic face perception.

  16. Perceptual Fading without Retinal Adaptation

    Science.gov (United States)

    Hsieh, Po-Jang; Colas, Jaron T.

    2012-01-01

    A retinally stabilized object readily undergoes perceptual fading and disappears from consciousness. This startling phenomenon is commonly believed to arise from local bottom-up sensory adaptation to edge information that occurs early in the visual pathway, such as in the lateral geniculate nucleus of the thalamus or retinal ganglion cells. Here…

  17. Perceptual transparency from image deformation.

    Science.gov (United States)

    Kawabe, Takahiro; Maruya, Kazushi; Nishida, Shin'ya

    2015-08-18

    Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid's surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of "invisible" transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation.

  18. Perceptual basis of evolving Western musical styles.

    Science.gov (United States)

    Rodriguez Zivic, Pablo H; Shifres, Favio; Cecchi, Guillermo A

    2013-06-11

    The brain processes temporal statistics to predict future events and to categorize perceptual objects. These statistics, called expectancies, are found in music perception, and they span a variety of different features and time scales. Specifically, there is evidence that music perception involves strong expectancies regarding the distribution of a melodic interval, namely, the distance between two consecutive notes within the context of another. The recent availability of a large Western music dataset, consisting of the historical record condensed as melodic interval counts, has opened new possibilities for data-driven analysis of musical perception. In this context, we present an analytical approach that, based on cognitive theories of music expectation and machine learning techniques, recovers a set of factors that accurately identifies historical trends and stylistic transitions between the Baroque, Classical, Romantic, and Post-Romantic periods. We also offer a plausible musicological and cognitive interpretation of these factors, allowing us to propose them as data-driven principles of melodic expectation.

  19. Perceptual learning of acoustic noise generates memory-evoked potentials.

    Science.gov (United States)

    Andrillon, Thomas; Kouider, Sid; Agus, Trevor; Pressnitzer, Daniel

    2015-11-01

    Experience continuously imprints on the brain at all stages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show that the perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever a memory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics.

  20. Pattern classification of EEG signals reveals perceptual and attentional states.

    Science.gov (United States)

    List, Alexandra; Rosenberg, Monica D; Sherman, Aleksandra; Esterman, Michael

    2017-01-01

    Pattern classification techniques have been widely used to differentiate neural activity associated with different perceptual, attentional, or other cognitive states, often using fMRI, but more recently with EEG as well. Although these methods have identified EEG patterns (i.e., scalp topographies of EEG signals occurring at certain latencies) that decode perceptual and attentional states on a trial-by-trial basis, they have yet to be applied to the spatial scope of attention toward global or local features of the display. Here, we initially used pattern classification to replicate and extend the findings that perceptual states could be reliably decoded from EEG. We found that visual perceptual states, including stimulus location and object category, could be decoded with high accuracy peaking between 125-250 ms, and that the discriminative spatiotemporal patterns mirrored and extended our (and other well-established) ERP results. Next, we used pattern classification to investigate whether spatiotemporal EEG signals could reliably predict attentional states, and particularly, the scope of attention. The EEG data were reliably differentiated for local versus global attention on a trial-by-trial basis, emerging as a specific spatiotemporal activation pattern over posterior electrode sites during the 250-750 ms interval after stimulus onset. In sum, we demonstrate that multivariate pattern analysis of EEG, which reveals unique spatiotemporal patterns of neural activity distinguishing between behavioral states, is a sensitive tool for characterizing the neural correlates of perception and attention.

  1. Atypical Prosody in Asperger Syndrome: Perceptual and Acoustic Measurements

    OpenAIRE

    Marisa G. Filipe; Frota, Sónia; Castro, São Luís; Vicente, Selene G.

    2014-01-01

    It is known that individuals with Asperger syndrome (AS) may show no problems with regard to what is said (e.g., lexical content) but tend to have difficulties in how utterances are produced, i.e., they may show prosodic impairments. In the present study, we focus on the use of prosodic features to express grammatical meaning. Specifically, we explored the sentence type difference between statements and questions that is conveyed by intonation, using perceptual and acoustic measurements. Chil...

  2. Perceptual and cognitive spatial learning.

    Science.gov (United States)

    Bedford, F L

    1993-06-01

    Ss were taught novel mappings between visual space and motor space with either a variant on a prism adaptation paradigm (Experiments 1 and 2) or a nonperceptual cognitive task (Experiments 3 and 4). First, discrimination training specified that 1 visual location required a new pointing response but another location did not. This led to unusual generalization unlike typical generalization decrement. Second, training at 9 locations specified that 1 location required a new response but that the remaining 8 did not. This simple isolation mapping was unlearnable and instead a flat function fit through all of space. In contrast, for the cognitive paradigm, not only was isolation of one region of space easily learned, it was the preferred pattern of generalization. Implications for perceptual learning, as well as the qualitative distinctions between perceptual and cognitive learning, are discussed.

  3. Perceptual Color Characterization of Cameras

    Directory of Open Access Journals (Sweden)

    Javier Vazquez-Corral

    2014-12-01

    Full Text Available Color camera characterization, mapping outputs from the camera sensors to an independent color space, such as \\(XYZ\\, is an important step in the camera processing pipeline. Until now, this procedure has been primarily solved by using a \\(3 \\times 3\\ matrix obtained via a least-squares optimization. In this paper, we propose to use the spherical sampling method, recently published by Finlayson al., to perform a perceptual color characterization. In particular, we search for the \\(3 \\times 3\\ matrix that minimizes three different perceptual errors, one pixel based and two spatially based. For the pixel-based case, we minimize the CIE \\(\\Delta E\\ error, while for the spatial-based case, we minimize both the S-CIELAB error and the CID error measure. Our results demonstrate an improvement of approximately 3for the \\(\\Delta E\\ error, 7& for the S-CIELAB error and 13% for the CID error measures.

  4. Superficial Temporal Artery Pseudoaneurysm: A Case Report

    Science.gov (United States)

    Younus, Syed Muneeb; Imran, Muhammad; Qazi, Rabia

    2015-01-01

    Pseudoaneurysms of the superficial temporal artery are an uncommon vascular lesion of the external carotid system and most often the result of blunt head trauma. The frequency of pseudoaneurysms of the superficial temporal artery developing after craniotomy is exceedingly low and only a few cases have been reported. We present a case of pseudoaneurysm of this type in a 45-year-old male who underwent craniotomy for excision of meningioma. One month postoperatively, the craniotomy flap exhibited an enormous diffuse pulsate swelling. The suspected diagnosis of pseudoaneurysm arising from superficial temporal artery was confirmed on angiography. Surgical excision was done and no recurrences of the tumor or aneurysm were noted on subsequent follow up. PMID:26501064

  5. Generalization of multisensory perceptual learning

    Science.gov (United States)

    Powers III, Albert R.; Hillock-Dunn, Andrea; Wallace, Mark T.

    2016-01-01

    Life in a multisensory world requires the rapid and accurate integration of stimuli across the different senses. In this process, the temporal relationship between stimuli is critical in determining which stimuli share a common origin. Numerous studies have described a multisensory temporal binding window—the time window within which audiovisual stimuli are likely to be perceptually bound. In addition to characterizing this window’s size, recent work has shown it to be malleable, with the capacity for substantial narrowing following perceptual training. However, the generalization of these effects to other measures of perception is not known. This question was examined by characterizing the ability of training on a simultaneity judgment task to influence perception of the temporally-dependent sound-induced flash illusion (SIFI). Results do not demonstrate a change in performance on the SIFI itself following training. However, data do show an improved ability to discriminate rapidly-presented two-flash control conditions following training. Effects were specific to training and scaled with the degree of temporal window narrowing exhibited. Results do not support generalization of multisensory perceptual learning to other multisensory tasks. However, results do show that training results in improvements in visual temporal acuity, suggesting a generalization effect of multisensory training on unisensory abilities. PMID:27000988

  6. Treatment of superficial mycoses: review - part II*

    Science.gov (United States)

    Dias, Maria Fernanda Reis Gavazzoni; Bernardes-Filho, Fred; Quaresma-Santos, Maria Victória Pinto; Amorim, Adriana Gutstein da Fonseca; Schechtman, Regina Casz; Azulay, David Rubem

    2013-01-01

    Superficial fungal infections of the hair, skin and nails are a major cause of morbidity in the world. Choosing the right treatment is not always simple because of the possibility of drug interactions and side effects. The first part of the article discusses the main treatments for superficial mycoses - keratophytoses, dermatophytosis, candidiasis, with a practical approach to the most commonly-used topical and systemic drugs , referring also to their dosage and duration of use. Promising new, antifungal therapeutic alternatives are also highlighted, as well as available options on the Brazilian and world markets. PMID:24474103

  7. Treatment of superficial mycoses: review. Part II.

    Science.gov (United States)

    Dias, Maria Fernanda Reis Gavazzoni; Bernardes-Filho, Fred; Quaresma-Santos, Maria Victória Pinto; Amorim, Adriana Gutstein da Fonseca; Schechtman, Regina Casz; Azulay, David Rubem

    2013-01-01

    Superficial fungal infections of the hair, skin and nails are a major cause of morbidity in the world. Choosing the right treatment is not always simple because of the possibility of drug interactions and side effects. The first part of the article discusses the main treatments for superficial mycoses - keratophytoses, dermatophytosis, candidiasis, with a practical approach to the most commonly-used topical and systemic drugs , referring also to their dosage and duration of use. Promising new, antifungal therapeutic alternatives are also highlighted, as well as available options on the Brazilian and world markets.

  8. Acquisition versus consolidation of auditory perceptual learning using mixed-training regimens.

    Science.gov (United States)

    Maidment, David W; Kang, HiJee; Gill, Emma C; Amitay, Sygal

    2015-01-01

    Learning is considered to consist of two distinct phases-acquisition and consolidation. Acquisition can be disrupted when short periods of training on more than one task are interleaved, whereas consolidation can be disrupted when a second task is trained after the first has been initiated. Here we investigated the conditions governing the disruption to acquisition and consolidation during mixed-training regimens in which primary and secondary amplitude modulation tasks were either interleaved or presented consecutively. The secondary task differed from the primary task in either task-irrelevant (carrier frequency) or task-relevant (modulation rate) stimulus features while requiring the same perceptual judgment (amplitude modulation depth discrimination), or shared both irrelevant and relevant features but required a different judgment (amplitude modulation rate discrimination). Based on previous literature we predicted that acquisition would be disrupted by varying the task-relevant stimulus feature during training (stimulus interference), and that consolidation would be disrupted by varying the perceptual judgment required (task interference). We found that varying the task-relevant or -irrelevant stimulus features failed to disrupt acquisition but did disrupt consolidation, whereas mixing two tasks requiring a different perceptual judgment but sharing the same stimulus features disrupted both acquisition and consolidation. Thus, a distinction between acquisition and consolidation phases of perceptual learning cannot simply be attributed to (task-relevant) stimulus versus task interference. We propose instead that disruption occurs during acquisition when mixing two tasks requiring a perceptual judgment based on different cues, whereas consolidation is always disrupted regardless of whether different stimulus features or tasks are mixed. The current study not only provides a novel insight into the underlying mechanisms of perceptual learning, but also has

  9. Quick linguistic representations and precise perceptual representations : Language statistics and perceptual simulations under time constraints

    NARCIS (Netherlands)

    Hutchinson, S; Tillman, R.N.; Louwerse, M.M.

    2014-01-01

    Many studies have argued that language comprehension requires perceptual simulation. In previous work we have demonstrated that because language encodes perceptual relations, comprehenders can also rely on language statistics to bootstrap meaning through limited grounding. The extent comprehenders

  10. Quick linguistic representations and precise perceptual representations : Language statistics and perceptual simulations under time constraints

    NARCIS (Netherlands)

    Hutchinson, S; Tillman, R.N.; Louwerse, M.M.

    2014-01-01

    Many studies have argued that language comprehension requires perceptual simulation. In previous work we have demonstrated that because language encodes perceptual relations, comprehenders can also rely on language statistics to bootstrap meaning through limited grounding. The extent comprehenders d

  11. Perceptual-binding and persistent surface segregation

    OpenAIRE

    2004-01-01

    Visual input is segregated in the brain into subsystems that process different attributes such as motion and color. At the same time, visual information is perceptually segregated into objects and surfaces. Here we demonstrate that perceptual segregation of visual entities based on a transparency cue precedes and affects perceptual binding of attributes. Adding an irrelevant transparency cue paradoxically improved the pairing of color and motion for rapidly alternating surfaces. Subsequent ex...

  12. Optimizing Linked Perceptual Class Formation and Transfer of Function

    Science.gov (United States)

    Fields, Lanny; Garruto, Michelle

    2009-01-01

    A linked perceptual class consists of two distinct perceptual classes, A' and B', the members of which have become related to each other. For example, a linked perceptual class might be composed of many pictures of a woman (one perceptual class) and the sounds of that woman's voice (the other perceptual class). In this case, any sound of the…

  13. Superficial Urothelial Cancer in the Prostatic Urethra

    Directory of Open Access Journals (Sweden)

    Ziya Kirkali

    2006-01-01

    Full Text Available Transitional cell carcinoma (TCC is a multifocal disease of the urinary tract that can also involve the prostatic urethra (PU. The exact incidence of superficial involvement of the PU in patients with bladder TCC is not well known. Bladder TCC may involve the prostate in 12—40% of the patients and the degree of involvement can include urethral mucosa, ducts, acini, and stroma of the gland, which has been shown to affect the outcome. Risk factors for superficial urothelial cancer in the PU are high-grade, multifocal bladder TCC and presence of carcinoma in situ (CIS in the bladder. While visible tumors are easy to detect and resect, controversy still exists regarding the optimal technique to identify prostatic involvement by TCC. Prostatic urethral sampling by a transurethral resection biopsy or a cold-cup biopsy, particularly in the high-risk group of bladder cancer patients, has been recommended for detecting prostatic urethral involvement. Management of superficial prostatic involvement by TCC is also unclear. Currently, there is increasing recognition of the value of conservative treatment options with intravesical agents when there is superficial involvement of the PU. Particularly, intravesical bacillus Calmette-Guèrin (BCG seems to be an effective treatment alternative in the management of superficial involvement of the PU by TCC. Close follow-up by cystoscopy and PU biopsy at 3-month intervals, particularly in intermediate and high-risk patients who respond to intravesical therapy and in whom cystectomy is appropriate, is recommended in order to detect persistent tumor, recurrences, or progression.

  14. Superficial urothelial cancer in the prostatic urethra.

    Science.gov (United States)

    Kirkali, Ziya; Canda, A Erdem

    2006-02-28

    Transitional cell carcinoma (TCC) is a multifocal disease of the urinary tract that can also involve the prostatic urethra (PU). The exact incidence of superficial involvement of the PU in patients with bladder TCC is not well known. Bladder TCC may involve the prostate in 12-40% of the patients and the degree of involvement can include urethral mucosa, ducts, acini, and stroma of the gland, which has been shown to affect the outcome. Risk factors for superficial urothelial cancer in the PU are high-grade, multifocal bladder TCC and presence of carcinoma in situ (CIS) in the bladder. While visible tumors are easy to detect and resect, controversy still exists regarding the optimal technique to identify prostatic involvement by TCC. Prostatic urethral sampling by a transurethral resection biopsy or a cold-cup biopsy, particularly in the high-risk group of bladder cancer patients, has been recommended for detecting prostatic urethral involvement. Management of superficial prostatic involvement by TCC is also unclear. Currently, there is increasing recognition of the value of conservative treatment options with intravesical agents when there is superficial involvement of the PU. Particularly, intravesical bacillus Calmette-Guèrin (BCG) seems to be an effective treatment alternative in the management of superficial involvement of the PU by TCC. Close follow-up by cystoscopy and PU biopsy at 3-month intervals, particularly in intermediate and high-risk patients who respond to intravesical therapy and in whom cystectomy is appropriate, is recommended in order to detect persistent tumor, recurrences, or progression.

  15. Perceptual-binding and persistent surface segregation.

    Science.gov (United States)

    Moradi, Farshad; Shimojo, Shinsuke

    2004-11-01

    Visual input is segregated in the brain into subsystems that process different attributes such as motion and color. At the same time, visual information is perceptually segregated into objects and surfaces. Here we demonstrate that perceptual segregation of visual entities based on a transparency cue precedes and affects perceptual binding of attributes. Adding an irrelevant transparency cue paradoxically improved the pairing of color and motion for rapidly alternating surfaces. Subsequent experiments show: (1) Attributes are registered over the temporal window defined by the perceptual persistence of segregation, resulting in asynchrony in binding, and (2) attention is necessary for correct registration of attributes in the presence of ambiguity.

  16. Cerebellar tDCS dissociates the timing of perceptual decisions from perceptual change in speech

    NARCIS (Netherlands)

    Lametti, D.R.; Oostwoud Wijdenes, L.; Bonaiuto, J.; Bestmann, S.; Rothwell, J.C.

    2016-01-01

    Neuroimaging studies suggest that the cerebellum might play a role in both speech perception and speech perceptual learning. However, it remains unclear what this role is: does the cerebellum directly contribute to the perceptual decision? Or does it contribute to the timing of perceptual decisions?

  17. Superficial Siderosis and Sudden Sensorineural Hearing Loss: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Kirsti S. V. Lee

    2013-01-01

    Full Text Available This case report highlights an unusual case of sudden sensorineural hearing loss related to superficial siderosis (SS. Our patient had a craniotomy for medulloblastoma 23 years earlier, and this may represent a delayed complication related to this procedure. Magnetic resonance imaging (MRI remains the key diagnostic investigation to illustrate the imaging features of superficial siderosis and exclude other pathologies. Increased awareness of progressive and sudden hearing complications caused by SS is important in the otolaryngologic community to expedite management and better counsel patients during the consent process.

  18. Superficial siderosis and sudden sensorineural hearing loss: a case report and review of the literature.

    Science.gov (United States)

    Lee, Kirsti S V; Sritharan, Niranjan; Forrest, Allan

    2013-01-01

    This case report highlights an unusual case of sudden sensorineural hearing loss related to superficial siderosis (SS). Our patient had a craniotomy for medulloblastoma 23 years earlier, and this may represent a delayed complication related to this procedure. Magnetic resonance imaging (MRI) remains the key diagnostic investigation to illustrate the imaging features of superficial siderosis and exclude other pathologies. Increased awareness of progressive and sudden hearing complications caused by SS is important in the otolaryngologic community to expedite management and better counsel patients during the consent process.

  19. Perceptual hashing algorithms benchmark suite

    Institute of Scientific and Technical Information of China (English)

    Zhang Hui; Schmucker Martin; Niu Xiamu

    2007-01-01

    Numerous perceptual hashing algorithms have been developed for identification and verification of multimedia objects in recent years. Many application schemes have been adopted for various commercial objects. Developers and users are looking for a benchmark tool to compare and evaluate their current algorithms or technologies. In this paper, a novel benchmark platform is presented. PHABS provides an open framework and lets its users define their own test strategy, perform tests, collect and analyze test data. With PHABS, various performance parameters of algorithms can be tested, and different algorithms or algorithms with different parameters can be evaluated and compared easily.

  20. Reliable Adaptive Video Streaming Driven by Perceptual Semantics for Situational Awareness.

    Science.gov (United States)

    Pimentel-Niño, M A; Saxena, Paresh; Vazquez-Castro, M A

    2015-01-01

    A novel cross-layer optimized video adaptation driven by perceptual semantics is presented. The design target is streamed live video to enhance situational awareness in challenging communications conditions. Conventional solutions for recreational applications are inadequate and novel quality of experience (QoE) framework is proposed which allows fully controlled adaptation and enables perceptual semantic feedback. The framework relies on temporal/spatial abstraction for video applications serving beyond recreational purposes. An underlying cross-layer optimization technique takes into account feedback on network congestion (time) and erasures (space) to best distribute available (scarce) bandwidth. Systematic random linear network coding (SRNC) adds reliability while preserving perceptual semantics. Objective metrics of the perceptual features in QoE show homogeneous high performance when using the proposed scheme. Finally, the proposed scheme is in line with content-aware trends, by complying with information-centric-networking philosophy and architecture.

  1. Perceptual grouping effects on cursor movement expectations.

    Science.gov (United States)

    Dorneich, Michael C; Hamblin, Christopher J; Lancaster, Jeff A; Olofinboba, Olu

    2014-05-01

    Two studies were conducted to develop an understanding of factors that drive user expectations when navigating between discrete elements on a display via a limited degree-of-freedom cursor control device. For the Orion Crew Exploration Vehicle spacecraft, a free-floating cursor with a graphical user interface (GUI) would require an unachievable level of accuracy due to expected acceleration and vibration conditions during dynamic phases of flight. Therefore, Orion program proposed using a "caged" cursor to "jump" from one controllable element (node) on the GUI to another. However, nodes are not likely to be arranged on a rectilinear grid, and so movements between nodes are not obvious. Proximity between nodes, direction of nodes relative to each other, and context features may all contribute to user cursor movement expectations. In an initial study, we examined user expectations based on the nodes themselves. In a second study, we examined the effect of context features on user expectations. The studies established that perceptual grouping effects influence expectations to varying degrees. Based on these results, a simple rule set was developed to support users in building a straightforward mental model that closely matches their natural expectations for cursor movement. The results will help designers of display formats take advantage of the natural context-driven cursor movement expectations of users to reduce navigation errors, increase usability, and decrease access time. The rules set and guidelines tie theory to practice and can be applied in environments where vibration or acceleration are significant, including spacecraft, aircraft, and automobiles.

  2. Disambiguating Multi–Modal Scene Representations Using Perceptual Grouping Constraints

    Science.gov (United States)

    Pugeault, Nicolas; Wörgötter, Florentin; Krüger, Norbert

    2010-01-01

    In its early stages, the visual system suffers from a lot of ambiguity and noise that severely limits the performance of early vision algorithms. This article presents feedback mechanisms between early visual processes, such as perceptual grouping, stereopsis and depth reconstruction, that allow the system to reduce this ambiguity and improve early representation of visual information. In the first part, the article proposes a local perceptual grouping algorithm that — in addition to commonly used geometric information — makes use of a novel multi–modal measure between local edge/line features. The grouping information is then used to: 1) disambiguate stereopsis by enforcing that stereo matches preserve groups; and 2) correct the reconstruction error due to the image pixel sampling using a linear interpolation over the groups. The integration of mutual feedback between early vision processes is shown to reduce considerably ambiguity and noise without the need for global constraints. PMID:20544006

  3. Perceptual image hashing based on virtual watermark detection.

    Science.gov (United States)

    Khelifi, Fouad; Jiang, Jianmin

    2010-04-01

    This paper proposes a new robust and secure perceptual image hashing technique based on virtual watermark detection. The idea is justified by the fact that the watermark detector responds similarly to perceptually close images using a non embedded watermark. The hash values are extracted in binary form with a perfect control over the probability distribution of the hash bits. Moreover, a key is used to generate pseudo-random noise whose real values contribute to the randomness of the feature vector with a significantly increased uncertainty of the adversary, measured by mutual information, in comparison with linear correlation. Experimentally, the proposed technique has been shown to outperform related state-of-the art techniques recently proposed in the literature in terms of robustness with respect to image processing manipulations and geometric attacks.

  4. Neurothekeoma palpebrae in association with multiple superficial angiomyxomas: Tegumental Angiomyxoma- Neurothekeoma syndrome (TAN syndrome

    Directory of Open Access Journals (Sweden)

    Tan Aik Kah

    2011-09-01

    Full Text Available We report a case of 10-year-old Indian girl with history of multiple superficial angiomyxoma, presented with three months history of painless right upper lid swelling. There were no visual dysfunctions. Previously, the patient had multiple superficial angiomyxoma (left pinna, left upper cheek, left upper limb, chest, right axilla, hard palate and epidermal cyst (chin. The histopathological specimens were negative to S-100 protein antibody. Systemic review and family history was unremarkable. Excision biopsy and upper lid reconstruction were performed. Intraoperatively the tumor was multilobulated, firm, well encapsulated and did not invade the underlying tarsal plate. Histopathological features of the upperlid tumor were consistent with nerves sheath myxoma (neurothekeoma. To the best of the authors’ knowledge, this is the first reported case of neurothekeoma in association with multiple superficial angiomyxoma.

  5. Establishment of a superficial skin infection model in mice by using Staphylococcus aureus and Streptococcus pyogenes.

    Science.gov (United States)

    Kugelberg, Elisabeth; Norström, Tobias; Petersen, Thomas K; Duvold, Tore; Andersson, Dan I; Hughes, Diarmaid

    2005-08-01

    A new animal model for the purpose of studying superficial infections is presented. In this model an infection is established by disruption of the skin barrier by partial removal of the epidermal layer by tape stripping and subsequent application of the pathogens Staphylococcus aureus and Streptococcus pyogenes. The infection and the infection route are purely topical, in contrast to those used in previously described animal models in mice, such as the skin suture-wound model, where the infection is introduced into the deeper layers of the skin. Thus, the present model is considered more biologically relevant for the study of superficial skin infections in mice and humans. Established topical antibiotic treatments are shown to be effective. The procedures involved in the model are simple, a feature that increases throughput and reproducibility. This new model should be applicable to the evaluation of novel antimicrobial treatments of superficial infections caused by S. aureus and S. pyogenes.

  6. Graphemes are perceptual reading units.

    Science.gov (United States)

    Rey, A; Ziegler, J C; Jacobs, A M

    2000-04-14

    Graphemes are commonly defined as the written representation of phonemes. For example, the word 'BREAD' is composed of the four phonemes /b/, /r/, /e/ and /d/, and consequently, of the four graphemes 'B', 'R', 'EA', and 'D'. Graphemes can thus be considered the minimal 'functional bridges' in the mapping between orthography and phonology. In the present study, we investigated the hypothesis that graphemes are processed as perceptual units by the reading system. If the reading system processes graphemes as units, then detecting a letter in a word should be harder when this letter is embedded in a multi-letter grapheme than when it corresponds to a single-letter grapheme. In Experiment 1A, done in English, participants were slower to detect a target letter in a word when the target letter was embedded in multi-letter grapheme (i.e. 'A' in 'BEACH') than when it corresponded to a single-letter grapheme (i.e. 'A' in 'PLACE'). In Experiment 1B, this effect was replicated in French. In Experiment 2, done in English, this grapheme effect remained when phonemic similarity between the target letter alone and the target letter inside the word was controlled. Together, the results are consistent with the assumption that graphemes are processed as perceptual reading units in alphabetic writing systems such as English or French.

  7. Task-irrelevant perceptual expertise.

    Science.gov (United States)

    Wong, Yetta K; Folstein, Jonathan R; Gauthier, Isabel

    2011-12-05

    Perceptual learning (PL) and perceptual expertise (PE) are two fields of visual training studies that investigate how practice improves visual performance. However, previous research suggests that PL can be acquired in a task-irrelevant manner while PE cannot and that PL is highly specific to the training objects and conditions while PE generalizes. These differences are difficult to interpret since PL and PE studies tend to differ on multiple dimensions. We designed a training study with novel objects to compare PL and PE while varying only the training task, such that the training objects, visual field, training duration, and type of learning assessment were kept constant. Manipulations of the training task sufficed to produce the standard effects obtained in PE and PL. In contrast to prior studies, we demonstrated that some degree of PE can be acquired in a task-irrelevant manner, similar to PL. Task-irrelevant PE resulted in similar shape matching ability compared to the directly trained PE. In addition, learning in both PE and PL generalizes to different untrained conditions, which does not support the idea that PE generalizes while PL is specific. Degrees of generalization can be explained by considering the psychological space of the stimuli used for training and the test of transfer.

  8. The perceptual balance of color

    Science.gov (United States)

    McDermott, Kyle C.; Webster, Michael A.

    2011-01-01

    The cone contrasts carrying different dimensions of color vision vary greatly in magnitude, yet the perceived contrast of color and luminance in the world appears similar. We examined how this perceptual balance is adjusted by adaptation to the contrast in images. Observers set the level of L vs. M and S vs. LM contrast in 1/f noise images to match the perceived strength of a fixed level of luminance contrast. The perceptual balance of color in the images was roughly consistent with the range of contrasts characteristic of natural images. Relative perceived contrast could be strongly biased by brief prior exposure to images with lower or higher levels of chromatic contrast. Similar adaptation effects were found for luminance contrast in images of natural scenes. For both, observers reliably chose the contrast balance that appeared correct, and these choices were rapidly recalibrated by adaptation. This recalibration of the norm for contrast could reflect both changes in sensitivity and shifts in criterion. Our results are consistent with the possibility that color mechanisms adjust the range of their responses to match the range of signals in the environment, and that contrast adaptation plays an important role in these adjustments. PMID:22330367

  9. Building online brand perceptual map.

    Science.gov (United States)

    Chiang, I-Ping; Lin, Chih-Ying; Wang, Kaisheng M

    2008-10-01

    Many companies have launched their products or services online as a new business focus, but only a few of them have survived the competition and made profits. The most important key to an online business's success is to create "brand value" for the customers. Although the concept of online brand has been discussed in previous studies, there is no empirical study on the measurement of online branding. As Web 2.0 emerges to be critical to online branding, the purpose of this study was to measure Taiwan's major Web sites with a number of personality traits to build a perceptual map for online brands. A pretest identified 10 most representative online brand perceptions. The results of the correspondence analysis showed five groups in the perceptual map. This study provided a practical view of the associations and similarities among online brands for potential alliance or branding strategies. The findings also suggested that brand perceptions can be used with identified consumer needs and behaviors to better position online services. The brand perception map in the study also contributed to a better understanding of the online brands in Taiwan.

  10. Efficacy and safety of endoscopic submucosal dissection for superficial cancer of the cervical esophagus.

    Science.gov (United States)

    Iizuka, Toshiro; Kikuchi, Daisuke; Hoteya, Shu; Kajiyama, Yoshiaki; Kaise, Mitsuru

    2017-08-01

    Cervical esophageal cancer (CEC) is a less common form of cancer and often locally advanced at the time of diagnosis; thus, survival rates for patients with CEC remain poor. However, no reports exist on results of endoscopic submucosal dissection (ESD) for superficial cancer at the cervical esophagus. The aim of this retrospective study was to elucidate the clinicopathological features and clinical outcomes of ESD for superficial CEC.  ESD was performed on 891 lesions (in 662 patients) for superficial esophageal cancer from January 2008 to December 2015. Of these, 45 lesions (45 patients) were enrolled in the case group (CEC), and 405 lesions (375 patients) were enrolled in the control group (superficial cancer in the middle thoracic esophagus). The safety of ESD, including R0 resection rate and adverse events, and the efficacy, such as the local recurrence rate and overall survival rate, were evaluated.  The R0 resection rate was 91.1 % in the case group and 96 % in the control group. The rate of esophageal stricture was significantly higher in the case group (20 %) than in the control group (6.6 %). There was no local recurrence, and the 3-year survival rate was 88.4 % in the case group and 96.7 % in the control group. ESD for superficial cancer in the cervical esophagus was achieved safely, and successful local control was also confirmed. However, the esophageal stricture after ESD was more frequent.

  11. Continuity and Discontinuity of Perceptual Development.

    Science.gov (United States)

    Fischer, Hardi

    Despite external changes such as those of magnitudes, the functional properties of the visual system also improve with increased age. According to Jean Piaget's centration/decentration theory, the process of perceptual development might continue until adulthood and even after. However, perceptual development should not be understood in all of its…

  12. Semantic Representations in 3D Perceptual Space

    Directory of Open Access Journals (Sweden)

    Suncica Zdravkovic

    2011-05-01

    Full Text Available Barsalou's (1999 perceptual theory of knowledge echoes the pre-20th century tradition of conceptualizing all knowledge as inherently perceptual. Hence conceptual space has an infinite number of dimensions and heavily relies on perceptual experience. Osgood's (1952 semantic differential technique was developed as a bridge between perception and semantics. We updated Osgood's methodology in order to investigate current issues in visual cognition by: (1 using a 2D rather than a 1D space to place the concepts, (2 having dimensions that were perceptual while the targets were conceptual, (3 coupling visual experience with another two perceptual domains (audition and touch, (4 analyzing the data using MDS (not factor analysis. In three experiments, subjects (N = 57 judged five concrete and five abstract words on seven bipolar scales in three perceptual modalities. The 2D space led to different patterns of response compared to the classic 1D space. MDS revealed that perceptual modalities are not equally informative for mapping word-meaning distances (Mantel min = −.23; Mantel max = .88. There was no reliable differences due to test administration modality (paper vs. computer, nor scale orientation. The present findings are consistent with multidimensionality of conceptual space, a perceptual basis for knowledge, and dynamic characteristics of concepts discussed in contemporary theories.

  13. Perceptual Fusion in Humans and Machines

    NARCIS (Netherlands)

    Salah, A.A.; Tanrı dağ , O.

    2008-01-01

    Humans perceive the world through different perceptual modalities, which are processed in the brain by modality-specific areas and structures. However, there also exist multimodal neurons and areas, specialized in integrating perceptual information to enhance or suppress brain response. The particu

  14. What factors control superficial lava dome explosivity?

    Science.gov (United States)

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoît; Morgan, Daniel J.

    2015-09-01

    Dome-forming eruption is a frequent eruptive style and a major hazard on numerous volcanoes worldwide. Lava domes are built by slow extrusion of degassed, viscous magma and may be destroyed by gravitational collapse or explosion. The triggering of lava dome explosions is poorly understood: here we propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite precipitation. Both processes generate an impermeable and rigid carapace allowing overpressurisation of the inner parts of the lava dome by the rapid input of vesiculated magma batches. The relative thickness of the cristobalite-rich carapace is an inverse function of the external lava dome surface area. Explosive activity is thus more likely to occur at the onset of lava dome extrusion, in agreement with observations, as the likelihood of superficial lava dome explosions depends inversely on lava dome volume. This new result is of interest for the whole volcanological community and for risk management.

  15. HISTOPATHOLOGY OF MARGINAL SUPERFICIAL PERIODONTIUM AT MENOPAUSE

    Directory of Open Access Journals (Sweden)

    A. Georgescu

    2012-03-01

    Full Text Available Premises: Sexual hormones may affect the general health condition of women, as early as puberty, continuing during pregnancy and also after menopause. Variations of the hormonal levels may cause different – either local or general – pathological modifications. Sexual hormones may also affect periodontal status, favourizing gingival inflammations and reducing periodontal resistance to the action of the bacterial plaque. Scope: Establishment of the correlations between the debut or the manifestation of menopause and the modifications produced in the superficial periodontium. Materials and method: Clinical and paraclinical investigations were performed on female patients with ages between 45 and 66 years, involving macroscopic, microscopic and radiological recording of the aspect of the superificial periodontium (gingiva. Results: Analysis of the histological sections evidenced atrophic and involutive modifications in the marginal superficial periodontium of female patients at menopause. Conclusions: Sexual hormones intervene in the histological equilibrium of the marginal superficial periodontium, influencing the periodontal health status, which explains the correlation between the subjective symptomatology specific to menopause and the histopatological aspect at epithelial level.

  16. Superficial Granulomatous Pyoderma Gangrenosum of the Penis: A Case Report

    Directory of Open Access Journals (Sweden)

    Shyamala S. Gopi

    2006-01-01

    Full Text Available Classic type of pyoderma gangrenosum (PG is an uncommon ulceronecrotic cutaneous disease of uncertain aetiology characterised by broad zones of confluent ulceration with violaceous undermined margins. Some 50% of cases are associated with systemic diseases. The superficial granulomatous variant of pyoderma gangrenosum (SGPG of the external genitalia is extremely rare Patients with this condition develop single or multiple ulcerated skin lesions often with sinus tract formation. The majority of these lesions were found on the trunk and limbs. SGPG is less likely to be associated with underlying disease processes than classic PG. We present a 58 year-old with recalcitrant penile ulceration demonstrated to be SGPG on biopsy. Although rare and poorly recognised, the histological features are sufficiently typical to allow the correct diagnosis to be established.

  17. Interdisciplinary Adventures in Perceptual Ecology

    Science.gov (United States)

    Bocast, Christopher S.

    A portfolio dissertation that began as acoustic ecology and matured into perceptual ecology, centered on ecomusicology, bioacoustics, and translational audio-based media works with environmental perspectives. The place of music in Western eco-cosmology through time provides a basis for structuring an environmental history of human sound perception. That history suggests that music may stabilize human mental activity, and that an increased musical practice may be essential for the human project. An overview of recent antecedents preceding the emergence of acoustic ecology reveals structural foundations from 20th century culture that underpin modern sound studies. The contextual role that Aldo Leopold, Jacob von Uexkull, John Cage, Marshall McLuhan, and others played in anticipating the development of acoustic ecology as an interdiscipline is detailed. This interdisciplinary aspect of acoustic ecology is defined and defended, while new developments like soundscape ecology are addressed, though ultimately sound studies will need to embrace a broader concept of full-spectrum "sensory" or "perceptual" ecology. The bioacoustic fieldwork done on spawning sturgeon emphasized this necessity. That study yielded scientific recordings and spectrographic analyses of spawning sounds produced by lake sturgeon, Acipenser fulvescens, during reproduction in natural habitats in the Lake Winnebago watershed in Wisconsin. Recordings were made on the Wolf and Embarrass River during the 2011-2013 spawning seasons. Several specimens were dissected to investigate possible sound production mechanisms; no sonic musculature was found. Drumming sounds, ranging from 5 to 7 Hz fundamental frequency, verified the infrasonic nature of previously undocumented "sturgeon thunder". Other characteristic noises of sturgeon spawning including low-frequency rumbles and hydrodynamic sounds were identified. Intriguingly, high-frequency signals resembling electric organ discharges were discovered. These

  18. Looking without Perceiving: Impaired Preattentive Perceptual Grouping in Autism Spectrum Disorder.

    Directory of Open Access Journals (Sweden)

    Tiffany A Carther-Krone

    Full Text Available Before becoming aware of a visual scene, our perceptual system has organized and selected elements in our environment to which attention should be allocated. Part of this process involves grouping perceptual features into a global whole. Individuals with autism spectrum disorders (ASD rely on a more local processing strategy, which may be driven by difficulties perceptually grouping stimuli. We tested this notion using a line discrimination task in which two horizontal lines were superimposed on a background of black and white dots organized so that, on occasion, the dots induced the Ponzo illusion if perceptually grouped together. Results showed that even though neither group was aware of the illusion, the ASD group was significantly less likely than typically developing group to make perceptual judgments influenced by the illusion, revealing difficulties in preattentive grouping of visual stimuli. This may explain why individuals with ASD rely on local processing strategies, and offers new insight into the mechanism driving perceptual grouping in the typically developing human brain.

  19. Depth image enhancement using perceptual texture priors

    Science.gov (United States)

    Bang, Duhyeon; Shim, Hyunjung

    2015-03-01

    A depth camera is widely used in various applications because it provides a depth image of the scene in real time. However, due to the limited power consumption, the depth camera presents severe noises, incapable of providing the high quality 3D data. Although the smoothness prior is often employed to subside the depth noise, it discards the geometric details so to degrade the distance resolution and hinder achieving the realism in 3D contents. In this paper, we propose a perceptual-based depth image enhancement technique that automatically recovers the depth details of various textures, using a statistical framework inspired by human mechanism of perceiving surface details by texture priors. We construct the database composed of the high quality normals. Based on the recent studies in human visual perception (HVP), we select the pattern density as a primary feature to classify textures. Upon the classification results, we match and substitute the noisy input normals with high quality normals in the database. As a result, our method provides the high quality depth image preserving the surface details. We expect that our work is effective to enhance the details of depth image from 3D sensors and to provide a high-fidelity virtual reality experience.

  20. Perceptual reasoning in adaptive fusion processing

    Science.gov (United States)

    Kadar, Ivan

    2002-07-01

    The author previously published a unified perceptual reasoning system framework for adaptive sensor fusion and situation assessment. Ths framework is re-examined to highlight the role of human perceptual reasoning and to establish the relationship between human perceptual reasoning and the Joint Director of Laboratories (JDL) fusion levels. Mappings between the fusion levels and the elements of perceptual reasoning are defined. Methods to populate the knowledge bases associated with each component of the perceptual reasoning system are highlighted. The concept and application of perception, the resultant system architecture and its candidate renditions using distributed interacting software agents (ISA) are discussed. The perceptual reasoning system is shown to be a natural governing mechanism for extracting, associating and fusing information from multiple sources while adaptively controlling the fusion level processes for optimum fusion performance. The unified modular system construct is shown to provide a formal framework to accommodate various implementation alternatives. The application of this architectural concept is illustrated for distributed fusion systems architectures and is sued to illustrate the benefits of the adaptive perceptual reasoning system concept.

  1. Perceptual centering of body segment orientation.

    Science.gov (United States)

    Hanes, Douglas A

    2007-01-01

    It has been shown experimentally that under certain combinations of sensory stimuli, human subjects can perceive one of several distinct illusions about their overall orientation in or movement through space. In at least some cases, the structure of such multistable illusory perceptions of orientation can be efficiently described by perceptual transformations that act on a current orientation estimate to yield an updated perceptual construct. Repeated application of identified generating transformations yields a limited set of predicted illusions for a given sensory environment. This approach is especially valuable for perceptual data that exhibits discretely differing classes of illusions between subjects or trials. In a previous study, application of a semigroup of perceptual centering transformations has succeeded in reproducing and simplifying data from an experiment in which subjects experiencing visual vection reported a range of illusions about the orientations of their gaze, head, and torso to gravity. After reviewing previously obtained results on perceptual centering, this article generalizes the approach, presenting the mathematics required to characterize perceptual transformations. The developed framework should be widely applicable in the understanding of perceptual illusions, particularly when these are guided by alignment with preferred constructs. Secondly, the article reveals the nontrivial mathematical process of perceptual semigroup formation and evaluation, deducing the complete description of the semigroup constructed in the previous study. Perceptual centering transformations identified in terrestrial experiments may predict illusions to be expected in spaceflight. For example, our results indicate that under certain conditions, many astronauts will misperceive a visual rotation axis to be centered in front of the head or even the torso.

  2. Estructura electrónica de superficies: estados de superficie y estados resonantes del calcio

    OpenAIRE

    H. Herrera; César Mora

    2006-01-01

    En este artículo presentamos un estudio detallado de la estructura electrónica de bandas de superficies orientadas (001) y (110) de cristales cúbicos centrados en la cara del Ca. Para nuestro estudio utilizamos la aproximación de enlace fuerte y el método de acoplamiento de la función de Green de superficie. Primero, construimos hamiltonianos de enlace fuerte en el formalismo de Slater Koster (SK). Utilizamos una base ortogonal de nueve orbitales atómicos (spd) por átomo en la celda unitaria....

  3. A unique variation of superficial palmar arch

    Directory of Open Access Journals (Sweden)

    Jiji PJ

    2009-09-01

    Full Text Available We present a unique variation in the arterial pattern of superficial palmar arch in which it was completed by one of the large terminal branches of radial artery. The origin of the arteria radialis indicis was also peculiar that it was arising from the communicating branch of the radial artery and further reinforced by the first dorsal metacarpal artery that joined it after reaching the volar aspect. Pertinent anatomical knowledge regarding the variations of the palmar arch is significant for the purposes of microvascular repairs and re-implantations.

  4. Perceptual Training Strongly Improves Visual Motion Perception in Schizophrenia

    Science.gov (United States)

    Norton, Daniel J.; McBain, Ryan K.; Ongur, Dost; Chen, Yue

    2011-01-01

    Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients' perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it…

  5. Perceptual Training Strongly Improves Visual Motion Perception in Schizophrenia

    Science.gov (United States)

    Norton, Daniel J.; McBain, Ryan K.; Ongur, Dost; Chen, Yue

    2011-01-01

    Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients' perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it…

  6. Perceptual fusion of polyphonic pitch in cochlear implant users.

    Science.gov (United States)

    Donnelly, Patrick J; Guo, Benjamin Z; Limb, Charles J

    2009-11-01

    In music, multiple pitches often occur simultaneously, an essential feature of harmony. In the present study, the authors assessed the ability of cochlear implant (CI) users to perceive polyphonic pitch. Acoustically presented stimuli consisted of one, two, or three superposed tones with different fundamental frequencies (f(0)). The normal hearing control group obtained significantly higher mean scores than the CI group. CI users performed near chance levels in recognizing two- and three-pitch stimuli, and demonstrated perceptual fusion of multiple pitches as single-pitch units. These results suggest that limitations in polyphonic pitch perception may significantly impair music perception in CI users.

  7. Perceptual incongruence influences bistability and cortical activation.

    Directory of Open Access Journals (Sweden)

    Gijs Joost Brouwer

    Full Text Available We employed a parametric psychophysical design in combination with functional imaging to examine the influence of metric changes in perceptual incongruence on perceptual alternation rates and cortical responses. Subjects viewed a bistable stimulus defined by incongruent depth cues; bistability resulted from incongruence between binocular disparity and monocular perspective cues that specify different slants (slant rivalry. Psychophysical results revealed that perceptual alternation rates were positively correlated with the degree of perceived incongruence. Functional imaging revealed systematic increases in activity that paralleled the psychophysical results within anterior intraparietal sulcus, prior to the onset of perceptual alternations. We suggest that this cortical activity predicts the frequency of subsequent alternations, implying a putative causal role for these areas in initiating bistable perception. In contrast, areas implicated in form and depth processing (LOC and V3A were sensitive to the degree of slant, but failed to show increases in activity when these cues were in conflict.

  8. Studying real-world perceptual expertise.

    Science.gov (United States)

    Shen, Jianhong; Mack, Michael L; Palmeri, Thomas J

    2014-01-01

    Significant insights into visual cognition have come from studying real-world perceptual expertise. Many have previously reviewed empirical findings and theoretical developments from this work. Here we instead provide a brief perspective on approaches, considerations, and challenges to studying real-world perceptual expertise. We discuss factors like choosing to use real-world versus artificial object domains of expertise, selecting a target domain of real-world perceptual expertise, recruiting experts, evaluating their level of expertise, and experimentally testing experts in the lab and online. Throughout our perspective, we highlight expert birding (also called birdwatching) as an example, as it has been used as a target domain for over two decades in the perceptual expertise literature.

  9. Fostering perceptual skills in medical diagnosis

    NARCIS (Netherlands)

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

    2011-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2011, April). Fostering perceptual skills in medical diagnosis. Meeting of the American Educational Research Association, New Orleans, USA.

  10. Fostering Perceptual Skills in Medical Diagnosis

    NARCIS (Netherlands)

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

    2010-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2010, August). Fostering perceptual skills in medical diagnosis. Meeting of the EARLI SIG2 Text and Graphics Comprehension. Tübingen.

  11. Motion transparency promotes synchronous perceptual binding.

    Science.gov (United States)

    Clifford, Colin W G; Spehar, Branka; Pearson, Joel

    2004-12-01

    While identified regions of human extrastriate visual cortex are functionally specialized for processing different attributes of an object, the cognitive and neural mechanisms by which these attributes are dynamically bound into integrated percepts are still largely mysterious. Here, we report that perceptual organization influences the dynamics of binding. Specifically, the perception of motion transparency promotes the synchronous perceptual binding of colour and motion, which otherwise exhibits considerable asynchronies. In addition, we demonstrate that perceptual asynchrony can be reinstated by manipulating stereoscopic disparity or speed within the stimulus. Our findings suggest that the phenomenology of colour-motion binding parallels the known physiology of motion processing in area MT of primate visual cortex, supporting the view that the dynamics of perceptual binding is a direct reflection of the time course of the underlying neural processing.

  12. Fostering Perceptual Skills in Medical Diagnosis

    NARCIS (Netherlands)

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

    2010-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2010, August). Fostering perceptual skills in medical diagnosis. Meeting of the EARLI SIG2 Text and Graphics Comprehension. Tübingen.

  13. Fostering perceptual skills in medical diagnosis

    NARCIS (Netherlands)

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

    2011-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2011, April). Fostering perceptual skills in medical diagnosis. Meeting of the American Educational Research Association, New Orleans, USA.

  14. Superficial microcirculation flow measurement using polarized light

    Science.gov (United States)

    Wu, Jiwei; Morgan, S. P.; Xiao, Yunshi

    2008-12-01

    Depth discrimination of polarized light is used in investigating laser Doppler measurement of the superficial microcirculation in tissue. Using polarization Monte Carlo simulation, temporal point spread function and power spectral distribution of backscattered polarization remaining light firstly are used to prove polarized light to be valid in measuring moving blood cell perfusion and mean flow velocity. Then simulation of layered medium model demonstrate that relationships between blood flow perfusion and mean frequency shift are linear to medium flowing velocity, and the Doppler shift information in polarization remaining light mainly comes from lower layer medium up to about 14 times of mean free path (MFP) of medium investigated and can be considered that Doppler effects come only from lower layer of the medium. Simulations in three-layer tissue model show that moving blood cell perfusion and mean blood cell moving velocity calculated from polarization remaining are much more sensitive to lower layer flow velocity variation, and more irrelevant to deeper layer flow rate fluctuations, that further confirms Doppler measurement from polarization remaining light to be effective for superficial microcirculation in tissue. Factors affecting Laser Doppler measurement like medium absorption, percentage of moving particles in blood detector size are discussed.

  15. Perceptual and performance biases in action selection

    OpenAIRE

    2008-01-01

    When we see an object in the world, there may be a large number of different ways to interact with that object. This large 'visuomotor space' can be constrained through affordances (perceptually available object properties defining potential uses), task demands and the actor's intentions. The effects of perceptual biases can be modified by performance factors, such as a limb's end-state-comfort (ESC; Rosenbaum et al. 1990). We investigated how two other potential performance biases affected i...

  16. Effect of practice on perceptual load

    OpenAIRE

    Mejia-Ramirez, Manuel

    2013-01-01

    Within attention studies, Lavie's load theory (Lavie & Tsal, 1994; Lavie, Hirst, de Fockert, & Viding, 2004) presented an account that could settle the question whether attention selects stimuli to be processed at an early or late stage of cognitive processing. This theory relied on the concepts of "perceptual load" and "attentional capacity", proposing that attentional resources are automatically allocated to stimuli, but when the perceptual load of the stimuli exceeds person's capacity, tas...

  17. Stereotype threat prevents perceptual learning.

    Science.gov (United States)

    Rydell, Robert J; Shiffrin, Richard M; Boucher, Kathryn L; Van Loo, Katie; Rydell, Michael T

    2010-08-10

    Stereotype threat (ST) refers to a situation in which a member of a group fears that her or his performance will validate an existing negative performance stereotype, causing a decrease in performance. For example, reminding women of the stereotype "women are bad at math" causes them to perform more poorly on math questions from the SAT and GRE. Performance deficits can be of several types and be produced by several mechanisms. We show that ST prevents perceptual learning, defined in our task as an increasing rate of search for a target Chinese character in a display of such characters. Displays contained two or four characters and half of these contained a target. Search rate increased across a session of training for a control group of women, but not women under ST. Speeding of search is typically explained in terms of learned "popout" (automatic attraction of attention to a target). Did women under ST learn popout but fail to express it? Following training, the women were shown two colored squares and asked to choose the one with the greater color saturation. Superimposed on the squares were task-irrelevant Chinese characters. For women not trained under ST, the presence of a trained target on one square slowed responding, indicating that training had caused the learning of an attention response to targets. Women trained under ST showed no slowing, indicating that they had not learned such an attention response.

  18. The development of race‐based perceptual categorization: skin color dominates early category judgments

    NARCIS (Netherlands)

    Dunham, Yarrow; Stepanova, Elena V.; Dotsch, Ron; Todorov, Alexander

    2014-01-01

    Prior research on the development of race‐based categorization has concluded that children understand the perceptual basis of race categories from as early as age 4 (e.g. Aboud, ). However, such work has rarely separated the influence of skin color from other physiognomic features considered by adul

  19. Contributions of Procedure and Stimulus Learning to Early, Rapid Perceptual Improvements

    Science.gov (United States)

    Ortiz, Jeanette A.; Wright, Beverly A.

    2009-01-01

    Improvements in performance on many perceptual skills can occur with only a single training session. Of interest here is what aspects of the training experience are being learned during this brief exposure. Although there is considerable evidence that learning associated with specific feature values of the stimulus used in training ("stimulus…

  20. Zooming in on the cause of the perceptual load effect in the go/no-go paradigm.

    Science.gov (United States)

    Chen, Zhe; Cave, Kyle R

    2016-08-01

    Perceptual load theory (Lavie, 2005) claims that attentional capacity that is not used for the current task is allocated to irrelevant distractors. It predicts that if the attentional demands of the current task are high, distractor interference will be low. One particularly powerful demonstration of perceptual load effects on distractor processing relies on a go/no-go cue that is interpreted by either simple feature detection or feature conjunction (Lavie, 1995). However, a possible alternative interpretation of these effects is that the differential degree of distractor processing is caused by how broadly attention is allocated (attentional zoom) rather than to perceptual load. In 4 experiments, we show that when stimuli are arranged to equalize the extent of spatial attention across conditions, distractor interference varies little whether cues are defined by a simple feature or a conjunction, and that the typical perceptual load effect emerges only when attentional zoom can covary with perceptual load. These results suggest that attentional zoom can account for the differential degree of distractor processing traditionally attributed to perceptual load in the go/no-go paradigm. They also provide new insight into how different factors interact to control distractor interference. (PsycINFO Database Record

  1. Cue Summation Enables Perceptual Grouping

    Science.gov (United States)

    Persike, Malte; Meinhardt, Gunter

    2008-01-01

    In order to study how basic features interact in shape perception, subjects detected target figure presence and identified target figure shape in a combined 2-alternative forced-choice task. Target figures were embedded in Gabor random fields and were defined by feature contrast in spatial frequency, orientation, or both. Two figure classes were…

  2. Generation and Perceptual Implicit Memory: Different Generation Tasks Produce Different Effects on Perceptual Priming

    Science.gov (United States)

    Mulligan, Neil W.; Dew, Ilana T. Z.

    2009-01-01

    The generation manipulation has been critical in delineating differences between implicit and explicit memory. In contrast to past research, the present experiments indicate that generating from a rhyme cue produces as much perceptual priming as does reading. This is demonstrated for 3 visual priming tasks: perceptual identification, word-fragment…

  3. Condiciones de la superficie deslizamiento con falla

    Directory of Open Access Journals (Sweden)

    María Cecilia Sierra B.

    2011-06-01

    Full Text Available Se modelan seis (6 taludes can diferentes ángulos de inclinación y peso unitario de 1.8 ton/m3, módulo de Young de 500 ton/m2 y relación de Poisson de 0.45. En cada uno de estos taludes se calculan los esfuerzos a través del talud y se determinan los puntos que están sometidos a mayores esfuerzos cortantes, correspondiendo estos a los estados de esfuerzos mas críticos, La ubicación de estos puntos es por donde comenzará y terminará la superficie de falla. Se obtiene un gráfico de diseño que permite obtener la pendiente máxima que debe tener un talud para que no se presente falla local en ningún punto.

  4. Perceptual learning of interrupted speech.

    Directory of Open Access Journals (Sweden)

    Michel Ruben Benard

    Full Text Available The intelligibility of periodically interrupted speech improves once the silent gaps are filled with noise bursts. This improvement has been attributed to phonemic restoration, a top-down repair mechanism that helps intelligibility of degraded speech in daily life. Two hypotheses were investigated using perceptual learning of interrupted speech. If different cognitive processes played a role in restoring interrupted speech with and without filler noise, the two forms of speech would be learned at different rates and with different perceived mental effort. If the restoration benefit were an artificial outcome of using the ecologically invalid stimulus of speech with silent gaps, this benefit would diminish with training. Two groups of normal-hearing listeners were trained, one with interrupted sentences with the filler noise, and the other without. Feedback was provided with the auditory playback of the unprocessed and processed sentences, as well as the visual display of the sentence text. Training increased the overall performance significantly, however restoration benefit did not diminish. The increase in intelligibility and the decrease in perceived mental effort were relatively similar between the groups, implying similar cognitive mechanisms for the restoration of the two types of interruptions. Training effects were generalizable, as both groups improved their performance also with the other form of speech than that they were trained with, and retainable. Due to null results and relatively small number of participants (10 per group, further research is needed to more confidently draw conclusions. Nevertheless, training with interrupted speech seems to be effective, stimulating participants to more actively and efficiently use the top-down restoration. This finding further implies the potential of this training approach as a rehabilitative tool for hearing-impaired/elderly populations.

  5. Perceptual and Acoustic Pecularities of Advertising Slogans (Melodic Aspect

    Directory of Open Access Journals (Sweden)

    Natalya Yuryevna Sorokoletova

    2015-12-01

    Full Text Available The article presents the results of a phonetic experiment on melodic features of public service advertising (PSA. The objective of PSA is to raise awareness, influence and change public attitudes and behavior towards a social issue. Being an integral part of modern society, PSA has its linguistic and extra-linguistic peculiarities. The goal of the investigation was to establish basic tones for an English-speaking public service advertising slogan, test their acoustic measures and describe the role they play in pragmatic function realization. The work is based on the material of 75English language public service advertising videos. The PSA slogans were selected, manipulated and tested. The perceptual analysis revealed the most productive (high fall, low fall, low rise and less productive (fall-rise and rise-fall nuclear tones of advertising slogans. The acoustic measures included: voice fundamental frequency maximal (F0 max, voice fundamental frequency minimal (F0 min, voice fundamental frequency mean (F0 and pitch range (F0 range. The analysis conducted with the help of Praat and Speech Analyzer computer software applications supported these observations. The comparative analysis of the results of the perceptual and acoustic experiments allowed to identify the basic melodic features involved in the implementation of the pragmatic effect of PSA slogans.

  6. Pupil size tracks perceptual content and surprise.

    Science.gov (United States)

    Kloosterman, Niels A; Meindertsma, Thomas; van Loon, Anouk M; Lamme, Victor A F; Bonneh, Yoram S; Donner, Tobias H

    2015-04-01

    Changes in pupil size at constant light levels reflect the activity of neuromodulatory brainstem centers that control global brain state. These endogenously driven pupil dynamics can be synchronized with cognitive acts. For example, the pupil dilates during the spontaneous switches of perception of a constant sensory input in bistable perceptual illusions. It is unknown whether this pupil dilation only indicates the occurrence of perceptual switches, or also their content. Here, we measured pupil diameter in human subjects reporting the subjective disappearance and re-appearance of a physically constant visual target surrounded by a moving pattern ('motion-induced blindness' illusion). We show that the pupil dilates during the perceptual switches in the illusion and a stimulus-evoked 'replay' of that illusion. Critically, the switch-related pupil dilation encodes perceptual content, with larger amplitude for disappearance than re-appearance. This difference in pupil response amplitude enables prediction of the type of report (disappearance vs. re-appearance) on individual switches (receiver-operating characteristic: 61%). The amplitude difference is independent of the relative durations of target-visible and target-invisible intervals and subjects' overt behavioral report of the perceptual switches. Further, we show that pupil dilation during the replay also scales with the level of surprise about the timing of switches, but there is no evidence for an interaction between the effects of surprise and perceptual content on the pupil response. Taken together, our results suggest that pupil-linked brain systems track both the content of, and surprise about, perceptual events.

  7. Frequent video game players resist perceptual interference.

    Directory of Open Access Journals (Sweden)

    Aaron V Berard

    Full Text Available Playing certain types of video games for a long time can improve a wide range of mental processes, from visual acuity to cognitive control. Frequent gamers have also displayed generalized improvements in perceptual learning. In the Texture Discrimination Task (TDT, a widely used perceptual learning paradigm, participants report the orientation of a target embedded in a field of lines and demonstrate robust over-night improvement. However, changing the orientation of the background lines midway through TDT training interferes with overnight improvements in overall performance on TDT. Interestingly, prior research has suggested that this effect will not occur if a one-hour break is allowed in between the changes. These results have suggested that after training is over, it may take some time for learning to become stabilized and resilient against interference. Here, we tested whether frequent gamers have faster stabilization of perceptual learning compared to non-gamers and examined the effect of daily video game playing on interference of training of TDT with one background orientation on perceptual learning of TDT with a different background orientation. As a result, we found that non-gamers showed overnight performance improvement only on one background orientation, replicating previous results with the interference in TDT. In contrast, frequent gamers demonstrated overnight improvements in performance with both background orientations, suggesting that they are better able to overcome interference in perceptual learning. This resistance to interference suggests that video game playing not only enhances the amplitude and speed of perceptual learning but also leads to faster and/or more robust stabilization of perceptual learning.

  8. Perceptual continuation and depth in visual phantoms can be explained by perceptual transparency.

    Science.gov (United States)

    Kitaoka, A; Gyoba, J; Kawabata, H; Sakurai, K

    2001-01-01

    We try to explain perceptual continuation and depth in the visual-phantom illusion in terms of perceptual transparency. Perceptual continuation of inducing gratings across the occluder in stationary phantoms could be explained with unique transparency, a notion proposed by Anderson (1997 Perception 26 419-453). This view is consistent with a number of previous reports including that of McCourt (1994 Vision Research 34 1609-1617) who criticized the stationary phantom illusion from the viewpoint of his counterphase lightness induction or grating induction, which might involve invalid transparency. Here we confirm that the photopic phantom illusion (Kitaoka et al, 1999 Perception 28 825-834) really gives in-phase lightness induction and involves bistable transparency. It is thus suggested that perceptual continuation and depth in the visual-phantom illusion depend on perceptual transparency.

  9. PERCEPTUAL CONSTANCY AND CONTEXTUAL ENHANCEMENT CONSTANCIA PERCEPTUAL Y MEJORAMIENTO CONTEXTUAL

    Directory of Open Access Journals (Sweden)

    HERIBERTO AVELINO

    2010-01-01

    Full Text Available The perception of the acoustic world surrounding us very often is different from its physical properties. Our mental representation of the sounds that we are exposed to are not in a one to one correspondence with the sounds we sense. Auditory objects and their environments are categorized and loaded in memory so that recognition of complex dynamic scenes are perceived optimally. Precise identification of voices and linguistic objects are crucial for effective communication. However, the normal context of hearing contains multiple, competing and noisy sources. In such disadvantageous conditions the identity of the percepts is more efficient if they are stored in memory. The results of the present study offer experimental evidence that high-level cognitive processes might constrain basic auditory mechanisms involved in identifying phonemic tone to guarantee perceptual constancy. The results showing a better identification of tones in contexts that are inveresely proportional to their frequency support the idea that peripheral auditory processing enhances the identification of the tones by a general function of contextual contrast.La percepción del mundo acústico que nos rodea es a menudo diferente de sus propiedades físicas. Nuestra representación mental de los sonidos a los que estamos expuestos no están en una correspondencia unívoca con los sonidos que sentimos. Los objetos auditivos y sus contextos son categorizados y acumulados en la memoria de forma tal que el reconocimiento de escenas dinámicas complejas son percibidas óptimamente. La identificación precisa de voces y objetos lingüísticos son cruciales para la comunicación efectiva. Sin embargo, el contexto normal de la escucha contiene fuentes múltiples, con ruido y en competencia. En estas condiciones de desventaja la identidad de los perceptos es más eficiente si son almacenados en la memoria. Los resultados del presente estudio ofrecen evidencia experimental de que

  10. Roles of attention in perceptual learning from perspectives of psychophysics and animal learning.

    Science.gov (United States)

    Tsushima, Yoshiaki; Watanabe, Takeo

    2009-05-01

    The role of attention in perceptual learning has been a topic of controversy. Sensory psychophysicists/physiologists and animal learning psychologists have conducted numerous studies to examine this role; but because these two types of researchers use two very different lines of approach, their findings have never been effectively integrated. In the present article, we review studies from both lines and use exposure-based learning experiments to discuss the role of attention in perceptual learning. In addition, we propose a model in which exposure-based learning occurs only when a task-irrelevant feature is weak. We hope that this article will provide new insight into the role of attention in perceptual learning to the benefit of both sensory psychophysicists/physiologists and animal learning psychologists.

  11. Reliable Adaptive Video Streaming Driven by Perceptual Semantics for Situational Awareness

    Directory of Open Access Journals (Sweden)

    M. A. Pimentel-Niño

    2015-01-01

    presented. The design target is streamed live video to enhance situational awareness in challenging communications conditions. Conventional solutions for recreational applications are inadequate and novel quality of experience (QoE framework is proposed which allows fully controlled adaptation and enables perceptual semantic feedback. The framework relies on temporal/spatial abstraction for video applications serving beyond recreational purposes. An underlying cross-layer optimization technique takes into account feedback on network congestion (time and erasures (space to best distribute available (scarce bandwidth. Systematic random linear network coding (SRNC adds reliability while preserving perceptual semantics. Objective metrics of the perceptual features in QoE show homogeneous high performance when using the proposed scheme. Finally, the proposed scheme is in line with content-aware trends, by complying with information-centric-networking philosophy and architecture.

  12. Volumetric and superficial characterization of carbon activated; Caracterizacion volumetrica y superficial de carbon activado

    Energy Technology Data Exchange (ETDEWEB)

    Carrera G, L.M.; Garcia S, I.; Jimenez B, J.; Solache R, M.; Lopez M, B.; Bulbulian G, S.; Olguin G, M.T. [Departamento de Quimica, Gerencia de Ciencias Basicas, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2000-07-01

    The activated carbon is the resultant material of the calcination process of natural carbonated materials as coconut shells or olive little bones. It is an excellent adsorbent of diluted substances, so much in colloidal form, as in particles form. Those substances are attracted and retained by the carbon surface. In this work is make the volumetric and superficial characterization of activated carbon treated thermically (300 Centigrade) in function of the grain size average. (Author)

  13. The perceptual saliency of fearful eyes and smiles: A signal detection study

    Science.gov (United States)

    Saban, Muhammet Ikbal; Rotshtein, Pia

    2017-01-01

    Facial features differ in the amount of expressive information they convey. Specifically, eyes are argued to be essential for fear recognition, while smiles are crucial for recognising happy expressions. In three experiments, we tested whether expression modulates the perceptual saliency of diagnostic facial features and whether the feature’s saliency depends on the face configuration. Participants were presented with masked facial features or noise at perceptual conscious threshold. The task was to indicate whether eyes (experiments 1-3A) or a mouth (experiment 3B) was present. The expression of the face and its configuration (i.e. spatial arrangement of the features) were manipulated. Experiment 1 compared fearful with neutral expressions, experiments 2 and 3 compared fearful versus happy expressions. The detection accuracy data was analysed using Signal Detection Theory (SDT), to examine the effects of expression and configuration on perceptual precision (d’) and response bias (c), separately. Across all three experiments, fearful eyes were detected better (higher d’) than neutral and happy eyes. Eyes were more precisely detected than mouths, whereas smiles were detected better than fearful mouths. The configuration of the features had no consistent effects across the experiments on the ability to detect expressive features. But facial configuration affected consistently the response bias. Participants used a more liberal criterion for detecting the eyes in canonical configuration and fearful expression. Finally, the power in low spatial frequency of a feature predicted its discriminability index. The results suggest that expressive features are perceptually more salient with a higher d’ due to changes at the low-level visual properties, with emotions and configuration affecting perception through top-down processes, as reflected by the response bias. PMID:28267761

  14. Perceptual processing of natural scenes at rapid rates: effects of complexity, content, and emotional arousal.

    Science.gov (United States)

    Löw, Andreas; Bradley, Margaret M; Lang, Peter J

    2013-12-01

    During rapid serial visual presentation (RSVP), the perceptual system is confronted with a rapidly changing array of sensory information demanding resolution. At rapid rates of presentation, previous studies have found an early (e.g., 150-280 ms) negativity over occipital sensors that is enhanced when emotional, as compared with neutral, pictures are viewed, suggesting facilitated perception. In the present study, we explored how picture composition and the presence of people in the image affect perceptual processing of pictures of natural scenes. Using RSVP, pictures that differed in perceptual composition (figure-ground or scenes), content (presence of people or not), and emotional content (emotionally arousing or neutral) were presented in a continuous stream for 330 ms each with no intertrial interval. In both subject and picture analyses, all three variables affected the amplitude of occipital negativity, with the greatest enhancement for figure-ground compositions (as compared with scenes), irrespective of content and emotional arousal, supporting an interpretation that ease of perceptual processing is associated with enhanced occipital negativity. Viewing emotional pictures prompted enhanced negativity only for pictures that depicted people, suggesting that specific features of emotionally arousing images are associated with facilitated perceptual processing, rather than all emotional content.

  15. Perceptual discrimination across contexts and contrasts in preschool-aged children

    Science.gov (United States)

    BYUN, Tara McALLISTER

    2015-01-01

    This paper investigates a proposed phonetically-based account of developmental phonological patterns that lack counterparts in adult typology. Adult listeners perceive some phonemic contrasts more accurately than others, and these differences in perceptual recoverability are posited to represent one influence on phonological typology. One hypothesis suggests that children and adults could differ in their patterns of relative perceptual sensitivity, and these differences could form the basis for some child-specific phonological patterns in production. However, there has been a lack of empirical evidence to support this claim. This study used a nonword discrimination task to investigate differences in perceptual recoverability across contrasts and contexts in typically-developing preschool children. Participants heard nonwords that were identical or differed by a single segment in initial or final position. Results revealed general agreement between child and adult listeners in the relative discriminability of different featural contrasts. For certain contrasts, discrimination accuracy was significantly greater in initial than final position, mirroring an asymmetry seen in adults. Overall, these results suggest that perceptual discrimination in preschool-aged children is broadly congruent with patterns of relative sensitivity observed in adult listeners. These findings suggest that factors other than perceptual recoverability should be explored to account for child-specific phonological patterns. PMID:26213418

  16. Retention of perceptual generalization of fear extinction.

    Science.gov (United States)

    Pappens, Meike; Schroijen, Mathias; Van den Bergh, Omer; Van Diest, Ilse

    2015-12-01

    Fear reduction obtained during a fear extinction procedure can generalize from the extinction stimulus to other perceptually similar stimuli. Perceptual generalization of fear extinction typically follows a perceptual gradient, with increasing levels of fear reduction the more a stimulus resembles the extinction stimulus. The current study aimed to investigate whether perceptual generalization of fear extinction can be observed also after a retention interval of 24h. Fear was acquired to three geometrical figures of different sizes (CS(+), CS1(+) and CS2(+)) by consistently pairing them with a short-lasting suffocation experience (US). Three other geometrical figures that were never followed by the US served as control stimuli (CS(-), CS1(-), CS2(-)). Next, only the CS(+) was extinguished by presenting it in the absence of the US. One day later, fear responses to all stimuli were assessed without any US-presentation. Outcome measures included startle blink EMG, skin conductance, US expectancy, respiratory rate and tidal volume. On day 2 spontaneous recovery of fear was observed in US expectancy and tidal volume, but not in the other outcomes. Evidence for the retention of fear extinction generalization was present in US expectancy and skin conductance, but a perceptual gradient in the retention of generalized fear extinction could not be observed.

  17. Perceptual Contrast Enhancement with Dynamic Range Adjustment

    Science.gov (United States)

    Zhang, Hong; Li, Yuecheng; Chen, Hao; Yuan, Ding; Sun, Mingui

    2013-01-01

    Recent years, although great efforts have been made to improve its performance, few Histogram equalization (HE) methods take human visual perception (HVP) into account explicitly. The human visual system (HVS) is more sensitive to edges than brightness. This paper proposes to take use of this nature intuitively and develops a perceptual contrast enhancement approach with dynamic range adjustment through histogram modification. The use of perceptual contrast connects the image enhancement problem with the HVS. To pre-condition the input image before the HE procedure is implemented, a perceptual contrast map (PCM) is constructed based on the modified Difference of Gaussian (DOG) algorithm. As a result, the contrast of the image is sharpened and high frequency noise is suppressed. A modified Clipped Histogram Equalization (CHE) is also developed which improves visual quality by automatically detecting the dynamic range of the image with improved perceptual contrast. Experimental results show that the new HE algorithm outperforms several state-of-the-art algorithms in improving perceptual contrast and enhancing details. In addition, the new algorithm is simple to implement, making it suitable for real-time applications. PMID:24339452

  18. Multisensory perceptual learning and sensory substitution.

    Science.gov (United States)

    Proulx, Michael J; Brown, David J; Pasqualotto, Achille; Meijer, Peter

    2014-04-01

    One of the most exciting recent findings in neuroscience has been the capacity for neural plasticity in adult humans and animals. Studies of perceptual learning have provided key insights into the mechanisms of neural plasticity and the changes in functional neuroanatomy that it affords. Key questions in this field of research concern how practice of a task leads to specific or general improvement. Although much of this work has been carried out with a focus on a single sensory modality, primarily visual, there is increasing interest in multisensory perceptual learning. Here we will examine how advances in perceptual learning research both inform and can be informed by the development and advancement of sensory substitution devices for blind persons. To allow 'sight' to occur in the absence of visual input through the eyes, visual information can be transformed by a sensory substitution device into a representation that can be processed as sound or touch, and thus give one the potential to 'see' through the ears or tongue. Investigations of auditory, visual and multisensory perceptual learning can have key benefits for the advancement of sensory substitution, and the study of sensory deprivation and sensory substitution likewise will further the understanding of perceptual learning in general and the reverse hierarchy theory in particular. It also has significant importance for the developing understanding of the brain in metamodal terms, where functional brain areas might be best defined by the computations they carry out rather than by their sensory-specific processing role.

  19. Traumatic aneurysm of superficial temporal artery. CT demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, A.; Tyagi, G.; Sahai, A.; Baijal, S.S. (G.B. Pant Hospital and M.A. Medical Coll., New Delhi (India). Dept. of Neurosurgery G.B. Pant Hospital and M.A. Medical Coll., New Delhi (India). Dept. of Radiology)

    1991-12-01

    A case of traumatic pseudo-aneurysm of the superficial temporal artery documented on Computed tomography (CT) and angiography is described in a 55-year-old female, who was treated by surgical excision. Computed tomographic appearance of this lesion is illustrated. This represents, to our knowledge, the first CT demonstration of traumatic aneurysm of superficial temporal artery within a large subgaleal haematoma. (orig.).

  20. Risk factors associated with acquiring superficial fungal infections in ...

    African Journals Online (AJOL)

    school children in South Western Nigeria: a comparative study. Olaide Oke Olutoyin1, Olaniyi ... Keywords: Risk factors, school children, skin, superficial fungal infections. ..... study with poor hygiene, malnutrition, overcrowding and poor general social ... cial determinants of health that influence the presence of superficial ...

  1. The Neural Circuitry of Expertise: Perceptual Learning and Social Cognition

    Directory of Open Access Journals (Sweden)

    Michael eHarre

    2013-12-01

    Full Text Available Amongst the most significant questions we are confronted with today include the integration of the brain's micro-circuitry, our ability to build the complex social networks that underpin society and how our society impacts on our ecological environment. In trying to unravel these issues one place to begin is at the level of the individual: to consider how we accumulate information about our environment, how this information leads to decisions and how our individual decisions in turn create our social environment. While this is an enormous task, we may already have at hand many of the tools we need. This article is intended to review some of the recent results in neuro-cognitive research and show how they can be extended to two very specific types of expertise: perceptual expertise and social cognition. These two cognitive skills span a vast range of our genetic heritage. Perceptual expertise developed very early in our evolutionary history and is likely a highly developed part of all mammals' cognitive ability. On the other hand social cognition is most highly developed in humans in that we are able to maintain larger and more stable long term social connections with more behaviourally diverse individuals than any other species. To illustrate these ideas I will discuss board games as a toy model of social interactions as they include many of the relevant concepts: perceptual learning, decision-making, long term planning and understanding the mental states of other people. Using techniques that have been developed in mathematical psychology, I show that we can represent some of the key features of expertise using stochastic differential equations. Such models demonstrate how an expert's long exposure to a particular context influences the information they accumulate in order to make a decision.These processes are not confined to board games, we are all experts in our daily lives through long exposure to the many regularities of daily tasks and

  2. The neural circuitry of expertise: perceptual learning and social cognition.

    Science.gov (United States)

    Harré, Michael

    2013-12-17

    Amongst the most significant questions we are confronted with today include the integration of the brain's micro-circuitry, our ability to build the complex social networks that underpin society and how our society impacts on our ecological environment. In trying to unravel these issues one place to begin is at the level of the individual: to consider how we accumulate information about our environment, how this information leads to decisions and how our individual decisions in turn create our social environment. While this is an enormous task, we may already have at hand many of the tools we need. This article is intended to review some of the recent results in neuro-cognitive research and show how they can be extended to two very specific and interrelated types of expertise: perceptual expertise and social cognition. These two cognitive skills span a vast range of our genetic heritage. Perceptual expertise developed very early in our evolutionary history and is a highly developed part of all mammals' cognitive ability. On the other hand social cognition is most highly developed in humans in that we are able to maintain larger and more stable long term social connections with more behaviorally diverse individuals than any other species. To illustrate these ideas I will discuss board games as a toy model of social interactions as they include many of the relevant concepts: perceptual learning, decision-making, long term planning and understanding the mental states of other people. Using techniques that have been developed in mathematical psychology, I show that we can represent some of the key features of expertise using stochastic differential equations (SDEs). Such models demonstrate how an expert's long exposure to a particular context influences the information they accumulate in order to make a decision.These processes are not confined to board games, we are all experts in our daily lives through long exposure to the many regularities of daily tasks and social

  3. The neural circuitry of expertise: perceptual learning and social cognition

    Science.gov (United States)

    Harré, Michael

    2013-01-01

    Amongst the most significant questions we are confronted with today include the integration of the brain's micro-circuitry, our ability to build the complex social networks that underpin society and how our society impacts on our ecological environment. In trying to unravel these issues one place to begin is at the level of the individual: to consider how we accumulate information about our environment, how this information leads to decisions and how our individual decisions in turn create our social environment. While this is an enormous task, we may already have at hand many of the tools we need. This article is intended to review some of the recent results in neuro-cognitive research and show how they can be extended to two very specific and interrelated types of expertise: perceptual expertise and social cognition. These two cognitive skills span a vast range of our genetic heritage. Perceptual expertise developed very early in our evolutionary history and is a highly developed part of all mammals' cognitive ability. On the other hand social cognition is most highly developed in humans in that we are able to maintain larger and more stable long term social connections with more behaviorally diverse individuals than any other species. To illustrate these ideas I will discuss board games as a toy model of social interactions as they include many of the relevant concepts: perceptual learning, decision-making, long term planning and understanding the mental states of other people. Using techniques that have been developed in mathematical psychology, I show that we can represent some of the key features of expertise using stochastic differential equations (SDEs). Such models demonstrate how an expert's long exposure to a particular context influences the information they accumulate in order to make a decision.These processes are not confined to board games, we are all experts in our daily lives through long exposure to the many regularities of daily tasks and social

  4. Neural correlates of individual performance differences in resolving perceptual conflict.

    Directory of Open Access Journals (Sweden)

    Franziska Labrenz

    Full Text Available Attentional mechanisms are a crucial prerequisite to organize behavior. Most situations may be characterized by a 'competition' between salient, but irrelevant stimuli and less salient, relevant stimuli. In such situations top-down and bottom-up mechanisms interact with each other. In the present fMRI study, we examined how interindividual differences in resolving situations of perceptual conflict are reflected in brain networks mediating attentional selection. Doing so, we employed a change detection task in which subjects had to detect luminance changes in the presence and absence of competing distractors. The results show that good performers presented increased activation in the orbitofrontal cortex (BA 11, anterior cingulate (BA 25, inferior parietal lobule (BA 40 and visual areas V2 and V3 but decreased activation in BA 39. This suggests that areas mediating top-down attentional control are stronger activated in this group. Increased activity in visual areas reflects distinct neuronal enhancement relating to selective attentional mechanisms in order to solve the perceptual conflict. Opposed to good performers, brain areas activated by poor performers comprised the left inferior parietal lobule (BA 39 and fronto-parietal and visual regions were continuously deactivated, suggesting that poor performers perceive stronger conflict than good performers. Moreover, the suppression of neural activation in visual areas might indicate a strategy of poor performers to inhibit the processing of the irrelevant non-target feature. These results indicate that high sensitivity in perceptual areas and increased attentional control led to less conflict in stimulus processing and consequently to higher performance in competitive attentional selection.

  5. Neural correlates of individual performance differences in resolving perceptual conflict.

    Science.gov (United States)

    Labrenz, Franziska; Themann, Maria; Wascher, Edmund; Beste, Christian; Pfleiderer, Bettina

    2012-01-01

    Attentional mechanisms are a crucial prerequisite to organize behavior. Most situations may be characterized by a 'competition' between salient, but irrelevant stimuli and less salient, relevant stimuli. In such situations top-down and bottom-up mechanisms interact with each other. In the present fMRI study, we examined how interindividual differences in resolving situations of perceptual conflict are reflected in brain networks mediating attentional selection. Doing so, we employed a change detection task in which subjects had to detect luminance changes in the presence and absence of competing distractors. The results show that good performers presented increased activation in the orbitofrontal cortex (BA 11), anterior cingulate (BA 25), inferior parietal lobule (BA 40) and visual areas V2 and V3 but decreased activation in BA 39. This suggests that areas mediating top-down attentional control are stronger activated in this group. Increased activity in visual areas reflects distinct neuronal enhancement relating to selective attentional mechanisms in order to solve the perceptual conflict. Opposed to good performers, brain areas activated by poor performers comprised the left inferior parietal lobule (BA 39) and fronto-parietal and visual regions were continuously deactivated, suggesting that poor performers perceive stronger conflict than good performers. Moreover, the suppression of neural activation in visual areas might indicate a strategy of poor performers to inhibit the processing of the irrelevant non-target feature. These results indicate that high sensitivity in perceptual areas and increased attentional control led to less conflict in stimulus processing and consequently to higher performance in competitive attentional selection.

  6. Visible digital watermarking system using perceptual models

    Science.gov (United States)

    Cheng, Qiang; Huang, Thomas S.

    2001-03-01

    This paper presents a visible watermarking system using perceptual models. %how and why A watermark image is overlaid translucently onto a primary image, for the purposes of immediate claim of copyright, instantaneous recognition of owner or creator, or deterrence to piracy of digital images or video. %perceptual The watermark is modulated by exploiting combined DCT-domain and DWT-domain perceptual models. % so that the watermark is visually uniform. The resulting watermarked image is visually pleasing and unobtrusive. The location, size and strength of the watermark vary randomly with the underlying image. The randomization makes the automatic removal of the watermark difficult even though the algorithm is known publicly but the key to the random sequence generator. The experiments demonstrate that the watermarked images have pleasant visual effect and strong robustness. The watermarking system can be used in copyright notification and protection.

  7. On Macroscopic Complexity and Perceptual Coding

    CERN Document Server

    Scoville, John

    2010-01-01

    While Shannon information establishes limits to the universal data compression of binary data, no existing theory provides an equivalent characterization of the lossy data compression algorithms prevalent in audiovisual media. The current paper proposes a mathematical framework for perceptual coding and inference which quantifies the complexity of objects indistinguishable to a particular observer. A definition of the complexity is presented and related to a generalization of Boltzmann entropy for these equivalence classes. When the classes are partitions of phase space, corresponding to classical observations, this is the proper Boltzmann entropy and the macroscopic complexity agrees with the Algorithmic Entropy. For general classes, the macroscopic complexity measure determines the optimal lossy compression of the data. Conversely, perceptual coding algorithms may be used to construct upper bounds on certain macroscopic complexities. Knowledge of these complexities, in turn, allows perceptual inference whic...

  8. Perceptual Templates Improvement through Action Video Game Playing and Comparison to Perceptual Learning

    Directory of Open Access Journals (Sweden)

    Ruyuan Zhang

    2011-05-01

    Full Text Available Action video game playing substantially improves visual performance; however, the source of this improvement remains unclear. Here we use the equivalent external noise technique to characterize the mechanism by which action video games may facilitate performance (Lu & Dosher, 1998. In first study, Action Video Game Players (VGPs and Non-Action Video Game Players (NVGPs performed a foveal orientation identification task at different external noise levels. VGPs showed lower thresholds than NVGPs with a marked difference at different noise levels. Perceptual Template Model fitting indicated that there were an 11% additive noise reduction and a 25% external noise exclusion. The causal effect of action video game playing was confirmed in a following 50 hour training study, This work establishes that playing action video games leads to robust internal addictive and external noise exclusion, consistent with the use of better matched perceptual templates. To investigate the discrepancy between our results and previous fovea perceptual learning research (Lu et al, 2004, same stimuli in previous experiment were used in perceptual learning experiment and we find same perceptual template improvement pattern. This suggest both action video game playing and perceptual learning could lead to better perceptual template.

  9. Security analysis of robust perceptual hashing

    Science.gov (United States)

    Koval, Oleksiy; Voloshynovskiy, Sviatoslav; Beekhof, Fokko; Pun, Thierry

    2008-02-01

    In this paper we considered the problem of security analysis of robust perceptual hashing in authentication application. The main goal of our analysis was to estimate the amount of trial efforts of the attacker, who is acting within the Kerckhoffs security principle, to reveal a secret key. For this purpose, we proposed to use Shannon equivocation that provides an estimate of complexity of the key search performed based on all available prior information and presented its application to security evaluation of particular robust perceptual hashing algorithms.

  10. A perceptual account of symbolic reasoning

    Directory of Open Access Journals (Sweden)

    David eLandy

    2014-04-01

    Full Text Available People can be taught to manipulate symbols according to formal mathematical and logical rules. Cognitive scientists have traditionally viewed this capacity—the capacity for symbolic reasoning—as grounded in the ability to internally represent numbers, logical relationships, and mathematical rules in an abstract, amodal fashion. We present an alternative view, portraying symbolic reasoning as a special kind of embodied reasoning in which arithmetic and logical formulae, externally represented as notations, serve as targets for powerful perceptual and sensorimotor systems. Although symbolic reasoning often conforms to abstract mathematical principles, it is typically implemented by perceptual and sensorimotor engagement with concrete environmental structures.

  11. Perceptual transparency in neon color spreading displays.

    Science.gov (United States)

    Ekroll, Vebjørn; Faul, Franz

    2002-08-01

    In neon color spreading displays, both a color illusion and perceptual transparency can be seen. In this study, we investigated the color conditions for the perception of transparency in such displays. It was found that the data are very well accounted for by a generalization of Metelli's (1970) episcotister model of balanced perceptual transparency to tristimulus values. This additive model correctly predicted which combinations of colors would lead to optimal impressions of transparency. Color combinations deviating slightly from the additive model also looked transparent, but less convincingly so.

  12. A perceptual account of symbolic reasoning.

    Science.gov (United States)

    Landy, David; Allen, Colin; Zednik, Carlos

    2014-01-01

    People can be taught to manipulate symbols according to formal mathematical and logical rules. Cognitive scientists have traditionally viewed this capacity-the capacity for symbolic reasoning-as grounded in the ability to internally represent numbers, logical relationships, and mathematical rules in an abstract, amodal fashion. We present an alternative view, portraying symbolic reasoning as a special kind of embodied reasoning in which arithmetic and logical formulae, externally represented as notations, serve as targets for powerful perceptual and sensorimotor systems. Although symbolic reasoning often conforms to abstract mathematical principles, it is typically implemented by perceptual and sensorimotor engagement with concrete environmental structures.

  13. Superficial malignant peripheral nerve sheath tumor arising from diffuse neurofibroma in a neurofibromatosis type 1 patient.

    Science.gov (United States)

    Inoue, Takuya; Kuwashiro, Maki; Misago, Noriyuki; Narisawa, Yutaka

    2014-07-01

    Malignant peripheral nerve sheath tumors (MPNST) are regarded as sarcomas that arise from peripheral nerves or that display differentiation along the lines of the various elements of the nerve sheath. These tumors occur in deep soft tissues, but superficial primary MPNST with a cutaneous or subcutaneous origin have rarely been reported. A 70-year-old woman presented with a 3-4-year history of a slowly enlarging soft nodule on the left side of her neck. The histopathological diagnosis of the nodule was low-grade MPNST arising from diffuse neurofibroma. There was increased cellularity, but no necrosis or mitotic activity. These histopathological findings pose difficulties in differential diagnosis from a neurofibroma with atypical histological features. We report a rare case of superficial MPNST arising from diffuse neurofibroma associated with underlying occipital bone dysplasia in a neurofibromatosis type 1 patient.

  14. Shared Neural Substrates of Emotionally Enhanced Perceptual and Mnemonic Vividness

    Directory of Open Access Journals (Sweden)

    Rebecca M. Todd

    2013-05-01

    Full Text Available It is well known that emotionally salient events are remembered more vividly than mundane ones. Our recent research has demonstrated that such memory vividness is due in part to the subjective experience of emotional events as more perceptually vivid, an effect we call emotion-enhanced vividness, or EEV. The present study built on previously reported research in which fMRI data were collected while participants rated relative levels of visual noise overlaid on emotionally salient and neutral images. Ratings of greater EEV were associated with greater activation in the amygdala, visual cortex, and posterior insula. In the present study, we measured BOLD activation that predicted recognition memory vividness for these same images one week later. Results showed that, after controlling for differences between scenes in low-level objective features, hippocampus activation uniquely predicted subsequent memory vividness. In contrast, amygdala and visual cortex regions that were sensitive to EEV were also modulated by subsequent ratings of memory vividness. These findings suggest shared neural substrates for the influence of emotional salience on perceptual and mnemonic vividness, with amygdala and visual cortex activation at encoding contributing to the experience of both perception and subsequent memory.

  15. UNILATERAL INCOMPLETE SUPERFICIAL PALMAR ARCH: A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Subhankar Chakraborty

    2015-12-01

    Full Text Available The functional importance of hand is revealed by its rich vascularity contributed by superficial and deep palmar arches (SPA and DPA.Superficial palmar arch is located superficial to flexor tendons, and deep palmar arch deep to lumbrical muscles. Variations are found more often in SPA than DPA, later being more or less constant. During routine undergraduate dissection, we observed, unilateral incomplete SPA being formed by superficial palmar branches of ulnar and radial artery in the right hand of a male cadaver. These two arteries remained independent without anastomosis forming incomplete arch (SPA.The superficial branch of ulnar artery entered hand superficial to flexor retinaculum and supplied middle, ring and little finger by three branches. The superficial branch of radial artery via its two branches supplied index finger and thumb. Classical SPA formation was seen on left side. The presence of an incomplete SPA as in this case is a potential danger in RA harvesting for CABG.Variations in SPA play a pivotal role in microvascular surgical procedures of hand, RAinterventions and arterial graft applications.

  16. Prevalence of superficial siderosis following singular, acute aneurysmal subarachnoid hemorrhage

    Energy Technology Data Exchange (ETDEWEB)

    Lummel, N.; Bochmann, K. [Ludwig-Maximilian-University, Department of Neuroradiology, Klinikum Grosshadern, Munich (Germany); Bernau, C. [Leibniz-Rechenzentrum, Munich (Germany); Thon, N. [Ludwig-Maximilian-University, Department of Neurosurgery, Klinikum Grosshadern, Munich (Germany); Linn, J. [Technical University, Department of Neuroradiology, Klinikum Dresden, Dresden (Germany)

    2015-04-01

    Superficial siderosis is presumably a consequence of recurrent bleeding into the subarachnoid space. The objective of this study was to assess the prevalence of superficial siderosis after singular, aneurysmal subarachnoid hemorrhage (SAH) in the long term. We retrospectively identified all patients who presented with a singular, acute, aneurysmal SAH at our institution between 2010 and 2013 and in whom a magnetic resonance imaging (MRI) including T2*-weighted imaging was available at least 4 months after the acute bleeding event. MRI scans were judged concerning the presence and distribution of superficial siderosis. Influence of clinical data, Fisher grade, localization, and cause of SAH as well as the impact of neurosurgical interventions on the occurrence of superficial siderosis was tested. Seventy-two patients with a total of 117 MRIs were included. Mean delay between SAH and the last available MRI was 47.4 months (range 4-129). SAH was Fisher grade 1 in 2 cases, 2 in 4 cases, 3 in 10 cases, and 4 in 56 cases. Superficial siderosis was detected in 39 patients (54.2 %). In all patients with more than one MRI scan, localization and distribution of superficial siderosis did not change over time. Older age (p = 0.02) and higher degree of SAH (p = 0.03) were significantly associated with the development of superficial siderosis. Superficial siderosis develops in approximately half of patients after singular, aneurysmal SAH and might be more common in patients with an older age and a greater amount of blood. However, additional factors must play a role in whether a patient is prone to develop superficial siderosis or not. (orig.)

  17. Comportamiento hidráulico de los sistemas de riego por goteo superficial y sub superficial

    OpenAIRE

    2011-01-01

    Para su evaluación el sistema de riego fue montado con un diseño experimental completamente aleatorizado, con cuatro tratamientos, uno con el sistema de riego por goteo superficial y tres con sistemas de riego por goteo sub superficiales con emisores soterrados a 15, 30 y 45 centímetros de profundidad. Se realizaron evaluaciones de laboratorio y de campo de los principales parámetros hidráulicos del sistema, al inicio de la primera campaña de riego y al final de la tercera, obteniéndose en el...

  18. Fostering perceptual skills in medical diagnosis

    NARCIS (Netherlands)

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

    2010-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2010, August). Fostering perceptual skills in medical diagnosis. Meeting of the EARLI SIG6/7 Instructional Design and Learning and Instruction with Computers, Ulm, Germany.

  19. Prior expectations facilitate metacognition for perceptual decision.

    Science.gov (United States)

    Sherman, M T; Seth, A K; Barrett, A B; Kanai, R

    2015-09-01

    The influential framework of 'predictive processing' suggests that prior probabilistic expectations influence, or even constitute, perceptual contents. This notion is evidenced by the facilitation of low-level perceptual processing by expectations. However, whether expectations can facilitate high-level components of perception remains unclear. We addressed this question by considering the influence of expectations on perceptual metacognition. To isolate the effects of expectation from those of attention we used a novel factorial design: expectation was manipulated by changing the probability that a Gabor target would be presented; attention was manipulated by instructing participants to perform or ignore a concurrent visual search task. We found that, independently of attention, metacognition improved when yes/no responses were congruent with expectations of target presence/absence. Results were modeled under a novel Bayesian signal detection theoretic framework which integrates bottom-up signal propagation with top-down influences, to provide a unified description of the mechanisms underlying perceptual decision and metacognition. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Perceptual effects of overlapping curved glass

    NARCIS (Netherlands)

    Cruz, P.J.S.; Veer, F.A.; Carvalho, P.L.L.

    2010-01-01

    The application of glass in contemporary architecture explores perceptual phenomenon that intentionally change the way we experience space. SANAA'S recent work uses glass in a radical way, proposing a renewed approach to transparency. The Toledo Glass Pavilion, with most spaces defined by glass

  1. Perceptual effects of overlapping curved glass

    NARCIS (Netherlands)

    Cruz, P.J.S.; Veer, F.A.; Carvalho, P.L.L.

    2010-01-01

    The application of glass in contemporary architecture explores perceptual phenomenon that intentionally change the way we experience space. SANAA'S recent work uses glass in a radical way, proposing a renewed approach to transparency. The Toledo Glass Pavilion, with most spaces defined by glass wall

  2. Perceptual evaluation of different image fusion schemes

    NARCIS (Netherlands)

    Toet, A.; IJspeert, J.K.

    2001-01-01

    Human perceptual performance was tested with images of nighttime outdoor scenes. The scenes were registered both with a dual band (visual and near infrared) image intensified low-light CCD camera (DII) and with a thermal middle wavelength band (3-5 μm) infrared (IR) camera. Fused imagery was

  3. Modelling the Perceptual Components of Loudspeaker Distortion

    DEFF Research Database (Denmark)

    Olsen, Sune L.; Agerkvist, Finn T.; MacDonald, Ewen;

    2016-01-01

    While non-linear distortion in loudspeakers decreases audio quality, the perceptual consequences can vary substantially. This paper investigates the metric Rnonlin [1] which was developed to predict subjective measurements of sound quality in nonlinear systems. The generalisability of the metric...

  4. Sensorineural hearing loss and auditory perceptual organization

    Science.gov (United States)

    Hall, Joseph W.; Grose, John H.; Buss, Emily

    2004-05-01

    This talk will consider the implications of sensorineural hearing loss for auditory perceptual organization. In everyday environments, the listener is often faced with the difficulty of processing a target sound that intermingles acoustically with one or more extraneous sounds. Under such circumstances, several auditory processes enable the complex waveforms reaching the two ears to be interpreted in terms of putative auditory objects giving rise to the target and extraneous sounds. Such processes of perceptual organization depend upon the central analysis of cues that allow distributed spectral information to be either linked together or split apart on the basis of details related to such variables as synchrony of onset/modulation, harmonic relation, rhythm, and interaural differences. Efficient perceptual organization must depend not only upon such central auditory analyses but also upon the fidelity with which the peripheral auditory system encodes the spectral and temporal characteristics of sound. We will consider the implications of sensorineural hearing loss for perceptual organization in terms of both peripheral and central auditory processes.

  5. Adaptation and perceptual norms in color vision.

    Science.gov (United States)

    Webster, Michael A; Leonard, Deanne

    2008-11-01

    Many perceptual dimensions are thought to be represented relative to an average value or norm. Models of norm-based coding assume that the norm appears psychologically neutral because it reflects a neutral response in the underlying neural code. We tested this assumption in human color vision by asking how judgments of "white" are affected as neural responses are altered by adaptation. The adapting color was varied to determine the stimulus level that did not bias the observer's subjective white point. This level represents a response norm at the stages at which sensitivity is regulated by the adaptation, and we show that these response norms correspond to the perceptually neutral stimulus and that they can account for how the perception of white varies both across different observers and within the same observer at different locations in the visual field. We also show that individual differences in perceived white are reduced when observers are exposed to a common white adapting stimulus, suggesting that the perceptual differences are due in part to differences in how neural responses are normalized. These results suggest a close link between the norms for appearance and coding in color vision and illustrate a general paradigm for exploring this link in other perceptual domains.

  6. Perceptual analysis from confusions between vowels

    NARCIS (Netherlands)

    van der Kamp, L.J.T.; Pols, L.C.W.

    1971-01-01

    In an experiment on vowel identification confusions were obtained between 11 Dutch vowel sounds. To recover the perceptual configurations of the stimuli multidimensional scaling techniques were applied directly to the asymmetric confusion matrix, and to the symmetrized confusion matrix. In order to

  7. Well-Founded Belief and Perceptual Justification

    DEFF Research Database (Denmark)

    Broncano-Berrocal, Fernando

    2016-01-01

    According to Alan Millar, justified beliefs are well-founded beliefs. Millar cashes out the notion of well-foundedness in terms of having an adequate reason to believe something and believing it for that reason. To make his account of justified belief compatible with perceptual justification he a...

  8. Fusion of perceptions for perceptual robotics

    NARCIS (Netherlands)

    Ciftcioglu, O.; Bittermann, M.S.; Sariyildiz, I.S.

    2006-01-01

    Fusion of perception information for perceptual robotics is described. The visual perception is mathematically modelled as a probabilistic process obtaining and interpreting visual data from an environment. The visual data is processed in a multiresolutional form via wavelet transform and optimally

  9. Perceptual and performance biases in action selection

    NARCIS (Netherlands)

    Wilson, A.; van Bergen, E.; van Swieten, L.; Kent, S.; Mon-Williams, M.

    2008-01-01

    When we see an object in the world, there may be a large number of different ways to interact with that object. This large 'visuomotor space' can be constrained through affordances (perceptually available object properties defining potential uses), task demands and the actor's intentions. The effect

  10. Perceptual Load Influences Selective Attention across Development

    Science.gov (United States)

    Couperus, Jane W.

    2011-01-01

    Research suggests that visual selective attention develops across childhood. However, there is relatively little understanding of the neurological changes that accompany this development, particularly in the context of adult theories of selective attention, such as N. Lavie's (1995) perceptual load theory of attention. This study examined visual…

  11. Improving Perceptual Skills with 3-Dimensional Animations.

    Science.gov (United States)

    Johns, Janet Faye; Brander, Julianne Marie

    1998-01-01

    Describes three-dimensional computer aided design (CAD) models for every component in a representative mechanical system; the CAD models made it easy to generate 3-D animations that are ideal for teaching perceptual skills in multimedia computer-based technical training. Fifteen illustrations are provided. (AEF)

  12. Fostering perceptual skills in medical diagnosis

    NARCIS (Netherlands)

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

    2010-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2010, August). Fostering perceptual skills in medical diagnosis. Meeting of the EARLI SIG6/7 Instructional Design and Learning and Instruction with Computers, Ulm, Germany.

  13. Improving Perceptual Skills with 3-Dimensional Animations.

    Science.gov (United States)

    Johns, Janet Faye; Brander, Julianne Marie

    1998-01-01

    Describes three-dimensional computer aided design (CAD) models for every component in a representative mechanical system; the CAD models made it easy to generate 3-D animations that are ideal for teaching perceptual skills in multimedia computer-based technical training. Fifteen illustrations are provided. (AEF)

  14. Perceptual crossing: the simplest online paradigm

    Science.gov (United States)

    Auvray, Malika; Rohde, Marieke

    2012-01-01

    Researchers in social cognition increasingly realize that many phenomena cannot be understood by investigating offline situations only, focusing on individual mechanisms and an observer perspective. There are processes of dynamic emergence specific to online situations, when two or more persons are engaged in a real-time interaction that are more than just the sum of the individual capacities or behaviors, and these require the study of online social interaction. Auvray et al.'s (2009) perceptual crossing paradigm offers possibly the simplest paradigm for studying such online interactions: two persons, a one-dimensional space, one bit of information, and a yes/no answer. This study has provoked a lot of resonance in different areas of research, including experimental psychology, computer/robot modeling, philosophy, psychopathology, and even in the field of design. In this article, we review and critically assess this body of literature. We give an overview of both behavioral experimental research and simulated agent modeling done using the perceptual crossing paradigm. We discuss different contexts in which work on perceptual crossing has been cited. This includes the controversy about the possible constitutive role of perceptual crossing for social cognition. We conclude with an outlook on future research possibilities, in particular those that could elucidate the link between online interaction dynamics and individual social cognition. PMID:22723776

  15. Perceptual dimensions for a dynamic tactile display

    Science.gov (United States)

    Pappas, Thrasyvoulos N.; Tartter, Vivien C.; Seward, Andrew G.; Genzer, Boris; Gourgey, Karen; Kretzschmar, Ilona

    2009-02-01

    We propose a new approach for converting graphical and pictorial information into tactile patterns that can be displayed in a static or dynamic tactile device. The key components of the proposed approach are (1) an algorithm that segments a scene into perceptually uniform segments; (2) a procedure for generating perceptually distinct tactile patterns; and (3) a mapping of the visual textures of the segments into tactile textures that convey similar concepts. We used existing digital halftoning and other techniques to generate a wide variety of tactile textures. We then conducted formal and informal subjective tests with sighted (but visually blocked) and visually-impaired subjects to determine the ability of human tactile perception to perceive differences among them. In addition to generating perceptually distinguishable tactile patterns, our goal is to identify significant dimensions of tactile texture perception, which will make it possible to map different visual attributes into independent tactile attributes. Our experimental results indicate that it is poosible to generate a number of perceptually distinguishable tactile patterns, and that different dimensions of tactile texture perception can indeed be identified.

  16. Superficial Fibromatosis Mimicking Glomus Tumor of the Second Toe.

    Science.gov (United States)

    Jo, Hyang Jeong; Chae, Soo Uk; Kim, Gang Deuk; Kim, Yeung Jin; Choi, Deok Hwa; Park, Jae In

    2015-09-01

    Various types of tumor can occur in the subungual space, including glomus tumors, subungual exostosis, hemangioma, epidermal cysts, and malignant tumors. While fibromatosis can occur at various sites throughout the body, it is very rarely seen in the toe. Here, we are the first to report a case of superficial fibromatosis mimicking a glomus tumor in the subungual space of the second toe. The presentation of this condition shows the possibility of encountering uncommon superficial fibromatosis in the distal phalanx of the toe, and suggests that superficial fibromatosis should be included in the differential diagnosis of a glomus tumor in the toe.

  17. Revisión sobre modelado de superficies complejas

    Directory of Open Access Journals (Sweden)

    Juan D. Osorio

    2004-01-01

    Full Text Available Este artículo presenta una revisión de las técnicas más empleadas para la obtención de modelos computacionales de superficies complejas. Estas representaciones están siendo utilizadas en diversas áreas de la industria mediante procedimientos de ingeniería reversa. Las tres principales categorías son las superficies funcionales (implícitas, paramétricas y las superficies complejas simplicial (mallas triangulares. Se realiza un paralelo entre estos métodos y se exponen las ventajas y las desventajas de cada una de estas representaciones.

  18. Perceptual similarity of visual patterns predicts dynamic neural activation patterns measured with MEG.

    Science.gov (United States)

    Wardle, Susan G; Kriegeskorte, Nikolaus; Grootswagers, Tijl; Khaligh-Razavi, Seyed-Mahdi; Carlson, Thomas A

    2016-05-15

    Perceptual similarity is a cognitive judgment that represents the end-stage of a complex cascade of hierarchical processing throughout visual cortex. Previous studies have shown a correspondence between the similarity of coarse-scale fMRI activation patterns and the perceived similarity of visual stimuli, suggesting that visual objects that appear similar also share similar underlying patterns of neural activation. Here we explore the temporal relationship between the human brain's time-varying representation of visual patterns and behavioral judgments of perceptual similarity. The visual stimuli were abstract patterns constructed from identical perceptual units (oriented Gabor patches) so that each pattern had a unique global form or perceptual 'Gestalt'. The visual stimuli were decodable from evoked neural activation patterns measured with magnetoencephalography (MEG), however, stimuli differed in the similarity of their neural representation as estimated by differences in decodability. Early after stimulus onset (from 50ms), a model based on retinotopic organization predicted the representational similarity of the visual stimuli. Following the peak correlation between the retinotopic model and neural data at 80ms, the neural representations quickly evolved so that retinotopy no longer provided a sufficient account of the brain's time-varying representation of the stimuli. Overall the strongest predictor of the brain's representation was a model based on human judgments of perceptual similarity, which reached the limits of the maximum correlation with the neural data defined by the 'noise ceiling'. Our results show that large-scale brain activation patterns contain a neural signature for the perceptual Gestalt of composite visual features, and demonstrate a strong correspondence between perception and complex patterns of brain activity.

  19. Perceptual Discrimination In Static and Dynamic Noise: The Temporal Relation Between Perceptual Encoding and Decision-making

    Science.gov (United States)

    Ratcliff, Roger; Smith, Philip L.

    2010-01-01

    We report nine new experiments and reanalyze three published experiments that investigate factors affecting the time course of perceptual processing and its effects on subsequent decision making. Stimuli in letter discrimination and brightness discrimination tasks were degraded with static and dynamic noise. The onset and the time course of decision making were quantified by fitting the data with the diffusion model. Dynamic noise and, to a lesser extent, static noise, produced large shifts in the leading edge of the RT distribution in letter discrimination but had little effect in brightness discrimination. We interpret these shifts as changes in the onset of decision making. The different pattern of shifts in letter discrimination and brightness discrimination implies that decision making in the two tasks was affected differently by noise. The changes in RT distributions found with letter stimuli are inconsistent with the hypothesis that noise increases RTs to letter stimuli simply by reducing the rate at which evidence accumulates in the decision process. Instead, they imply that noise also delays the time at which evidence accumulation begins. The delay is shown not to be the result of strategic processes or the result of using different stimuli in different tasks. Our results imply, rather, that the onset of evidence accumulation in the decision process is time-locked to the perceptual encoding of the stimulus features needed to do the task. Two mechanisms that could produce this time-locking are described. PMID:20121313

  20. Antibody conjugate radioimmunotherapy of superficial bladder cancer

    Directory of Open Access Journals (Sweden)

    Alan Perkins

    2002-09-01

    Full Text Available The administration of antibody conjugates for cancer therapy is now proving to be of clinical value. We are currently undertaking a programme of clinical studies using the monoclonal antibody C595 (IgG3 which reacts with the MUC1 glycoprotein antigen that is aberrantly expressed in a high proportion of bladder tumours. Radioimmunoconjugates of the C595 antibody have been produced with high radiolabelling efficiency and immunoreactivity using Tc-99m and In-111 for diagnostic imaging, and disease staging and the cytotoxic radionuclides Cu-67 and Re-188 for therapy of superficial bladder cancer. A Phase I/II therapeutic trail involving the intravesical administration of antibody directly into the bladder has now begun.A administração de anticorpos conjugados para o tratamento do câncer está agora provando ser de valor clínico. Nós estamos atualmente realizando um programa de estudos clínicos usando o anticorpo monoclonal C595 (IgG3 que reage com a glicoproteína MUC1 que está aberrantemente expressa numa alta proporção de tumores de bexiga. Tem sido produzidos radioimunoconjugados do anticorpo C595, com alta eficiência de radiomarcação e a imunoreatividade, usando-se o Tc-99m e In-111, para o diagnóstico por imagem e estagiamento de doenças. Tem sido produzidos, também, radionuclídeos citotóxicos (Cu-67 e Re-188 para o tratamento de cânceres superficiais de bexiga. A fase terapêutica I/II já se iniciou, envolvendo a administração intravesical do anticorpo diretamente na bexiga.

  1. Hemipelvic irradiation for superficial bladder cancer

    Energy Technology Data Exchange (ETDEWEB)

    Tashiro, Kazuya; Machida, Toyohei; Ooishi, Yukihiko; Ueda, Masataka; Kido, Akira; Wada, Tetsuro; Yoshigoe, Fukuo; Yamashita, Takashi; Mochizuki, Sachio

    1985-02-01

    In 15 patients with superficial bladder cancer hemipelvic irradiation was performed for prevention of relapse of cancer and decrease in side effects with following results. All patients received TUR-Bt at our department during the six years period from 1978 to 1983. As to stages, one was classified as Ta, 11 as T 1 and 3 as T 2, and pathologic diagnosis was transitional epithelial carcinoma of grade 1 in 1 case, grade 2 in 8 cases and grade 3 in 6 cases. Irradiation was started from the 7 th to 14 th day after TUR-Bt. At first, hemipelvic anterior and posterior field including the field from the affected pelvis to 1 to 2 cm beyond the midline toward the contralateral side and from the aortic bifurcation to the prostatic urethra were irradiated at a dose of 45 Gy. Then, whole bladder field was given an additional rotation irradiation of 20 Gy. The mean observation period was 43 months (ranging from 12 to 79 months) and relapse of cancer was observed in 6 cases out of 15 cases (40%). The site of relapse was in the irradiated site in 2 cases, contralateral site in 3 cases and both side in 1 cases. However, in all of the relapsed cases no aggravation in differential degree or progression in stage was observed. As the side effects, radiation cystitis developed as a delayed damage in 1 case. Thus, although no efficacy for prevention of relapse which we had expected was not seen, this irradiation method effectively inhibited the progression of lesion and development of delayed damage. (author).

  2. The perceptual domain: a taxonomy for allied health educators.

    Science.gov (United States)

    Hooker, E Z

    1981-08-01

    A taxonomy of the perceptual domain was proposed over a decade ago. It is hierarchical, as are the taxonomies in the cognitive, affective, and psychomotor domains. Perception involves extraction of information from presenting stimuli, and there is progression of information extraction as the hierarchy is ascended. Perceptual performance at the higher levels of the taxonomy assumes perceptual abilities at the lower levels. A modified version of the perceptual taxonomy applicable to allied health education is presented. Methods concerning application of the taxonomy are suggested. Use of the taxonomy of the perceptual domain would help allied health educators plan instruction and evaluate teaching.

  3. Perceptual importance analysis for H.264/AVC bit allocation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The existing H.264/AVC rate control schemes rarely include the perceptual considerations. As a result, the improvements in visual quality are hardly comparable to those in peak signal-to-noise ratio (PSNR). In this paper, we propose a perceptual importance analysis scheme to accurately abstract the spatial and temporal perceptual characteristics of video contents. Then we perform bit allocation at macroblock (MB) level by adopting a perceptual mode decision scheme, which adaptively updates the Lagrangian multiplier for mode decision according to the perceptual importance of each MB. Simulation results show that the proposed scheme can efficiently reduce bit rates without visual quality degradation.

  4. Influence of Perceptual Saliency Hierarchy on Learning of Language Structures: An Artificial Language Learning Experiment.

    Science.gov (United States)

    Gong, Tao; Lam, Yau W; Shuai, Lan

    2016-01-01

    Psychological experiments have revealed that in normal visual perception of humans, color cues are more salient than shape cues, which are more salient than textural patterns. We carried out an artificial language learning experiment to study whether such perceptual saliency hierarchy (color > shape > texture) influences the learning of orders regulating adjectives of involved visual features in a manner either congruent (expressing a salient feature in a salient part of the form) or incongruent (expressing a salient feature in a less salient part of the form) with that hierarchy. Results showed that within a few rounds of learning participants could learn the compositional segments encoding the visual features and the order between them, generalize the learned knowledge to unseen instances with the same or different orders, and show learning biases for orders that are congruent with the perceptual saliency hierarchy. Although the learning performances for both the biased and unbiased orders became similar given more learning trials, our study confirms that this type of individual perceptual constraint could contribute to the structural configuration of language, and points out that such constraint, as well as other factors, could collectively affect the structural diversity in languages.

  5. Atypical prosody in Asperger syndrome: perceptual and acoustic measurements.

    Science.gov (United States)

    Filipe, Marisa G; Frota, Sónia; Castro, São Luís; Vicente, Selene G

    2014-08-01

    It is known that individuals with Asperger syndrome (AS) may show no problems with regard to what is said (e.g., lexical content) but tend to have difficulties in how utterances are produced, i.e., they may show prosodic impairments. In the present study, we focus on the use of prosodic features to express grammatical meaning. Specifically, we explored the sentence type difference between statements and questions that is conveyed by intonation, using perceptual and acoustic measurements. Children aged 8 and 9 years with AS (n = 12) were matched according to age and nonverbal intelligence with typically developing peers (n = 17). Although children with AS could produce categorically accurate prosodic patterns, their prosodic contours were perceived as odd by adult listeners, and acoustic measurements showed alterations in duration and pitch. Additionally, children with AS had greater variability in fundamental frequency contours compared to typically developing peers.

  6. Age-related declines of stability in visual perceptual learning.

    Science.gov (United States)

    Chang, Li-Hung; Shibata, Kazuhisa; Andersen, George J; Sasaki, Yuka; Watanabe, Takeo

    2014-12-15

    One of the biggest questions in learning is how a system can resolve the plasticity and stability dilemma. Specifically, the learning system needs to have not only a high capability of learning new items (plasticity) but also a high stability to retain important items or processing in the system by preventing unimportant or irrelevant information from being learned. This dilemma should hold true for visual perceptual learning (VPL), which is defined as a long-term increase in performance on a visual task as a result of visual experience. Although it is well known that aging influences learning, the effect of aging on the stability and plasticity of the visual system is unclear. To address the question, we asked older and younger adults to perform a task while a task-irrelevant feature was merely exposed. We found that older individuals learned the task-irrelevant features that younger individuals did not learn, both the features that were sufficiently strong for younger individuals to suppress and the features that were too weak for younger individuals to learn. At the same time, there was no plasticity reduction in older individuals within the task tested. These results suggest that the older visual system is less stable to unimportant information than the younger visual system. A learning problem with older individuals may be due to a decrease in stability rather than a decrease in plasticity, at least in VPL. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Superficial Radiation Therapy for the Treatment of Nonmelanoma Skin Cancers.

    Science.gov (United States)

    McGregor, Sean; Minni, John; Herold, David

    2015-12-01

    Superficial radiation therapy has become more widely available to dermatologists. With the advent of more portable machines, it has become more convenient for dermatology practices to employ in an office-based setting. The goal of this paper is to provide a deeper insight into the role of superficial radiation therapy in dermatology practice and to review the current literature surrounding its use in the treatment of both basal and squamous cell carcinomas.

  8. Functional Compartmentalization of the Human Superficial Masseter Muscle

    OpenAIRE

    Guzmán-Venegas, Rodrigo A.; Biotti Picand, Jorge L.; Francisco J Berral de la Rosa

    2015-01-01

    Some muscles have demonstrated a differential recruitment of their motor units in relation to their location and the nature of the motor task performed; this involves functional compartmentalization. There is little evidence that demonstrates the presence of a compartmentalization of the superficial masseter muscle during biting. The aim of this study was to describe the topographic distribution of the activity of the superficial masseter (SM) muscle's motor units using high-density surface e...

  9. Category and perceptual learning in subjects with treated Wilson's disease.

    Directory of Open Access Journals (Sweden)

    Pengjing Xu

    Full Text Available To explore the relationship between category and perceptual learning, we examined both category and perceptual learning in patients with treated Wilson's disease (WD, whose basal ganglia, known to be important in category learning, were damaged by the disease. We measured their learning rate and accuracy in rule-based and information-integration category learning, and magnitudes of perceptual learning in a wide range of external noise conditions, and compared the results with those of normal controls. The WD subjects exhibited deficits in both forms of category learning and in perceptual learning in high external noise. However, their perceptual learning in low external noise was relatively spared. There was no significant correlation between the two forms of category learning, nor between perceptual learning in low external noise and either form of category learning. Perceptual learning in high external noise was, however, significantly correlated with information-integration but not with rule-based category learning. The results suggest that there may be a strong link between information-integration category learning and perceptual learning in high external noise. Damage to brain structures that are important for information-integration category learning may lead to poor perceptual learning in high external noise, yet spare perceptual learning in low external noise. Perceptual learning in high and low external noise conditions may involve separate neural substrates.

  10. Category and Perceptual Learning in Subjects with Treated Wilson's Disease

    Science.gov (United States)

    Xu, Pengjing; Lu, Zhong-Lin; Wang, Xiaoping; Dosher, Barbara; Zhou, Jiangning; Zhang, Daren; Zhou, Yifeng

    2010-01-01

    To explore the relationship between category and perceptual learning, we examined both category and perceptual learning in patients with treated Wilson's disease (WD), whose basal ganglia, known to be important in category learning, were damaged by the disease. We measured their learning rate and accuracy in rule-based and information-integration category learning, and magnitudes of perceptual learning in a wide range of external noise conditions, and compared the results with those of normal controls. The WD subjects exhibited deficits in both forms of category learning and in perceptual learning in high external noise. However, their perceptual learning in low external noise was relatively spared. There was no significant correlation between the two forms of category learning, nor between perceptual learning in low external noise and either form of category learning. Perceptual learning in high external noise was, however, significantly correlated with information-integration but not with rule-based category learning. The results suggest that there may be a strong link between information-integration category learning and perceptual learning in high external noise. Damage to brain structures that are important for information-integration category learning may lead to poor perceptual learning in high external noise, yet spare perceptual learning in low external noise. Perceptual learning in high and low external noise conditions may involve separate neural substrates. PMID:20224790

  11. Outcome of superficial squamous cell carcinoma of the esophagus: a clinicopathological study

    Directory of Open Access Journals (Sweden)

    Maria Aparecida Coelho de Arruda Henry

    2013-05-01

    Full Text Available PURPOSE: To analyze the clinicopathological features and outcome of patients with pathologically proven superficial squamous cell carcinoma of the esophagus. METHODS: A total of 234 consecutive cases of esophageal carcinoma in a 15-year period were reviewed. RESULTS: Superficial esophageal cancer was found in five patients (2.1%. They were four men and one woman and the mean age was 52.5 years. Smoking and alcohol were the main risk factors. Achalasia due to Chagas disease occurred in one patient and a second primary tumor developed in the larynx in another patient. Four patients underwent esophagectomy and one patient received chemoradiotherapy. The histopathologic diagnosis was of squamous cell carcinoma in all cases. Intramucosal tumor (Tis was identified in three cases and superficially invasive carcinoma in two cases. Four patients are free of disease with survival times of two, four, six and nine years. The patient who developed laryngeal cancer died six years after esophagectomy. CONCLUSION: Long-term survival in patients with esophageal cancer is related to early diagnosis. Therefore, a less aggressive surgical approach, such as endoscopic resection, may be a good option for these patients, if depth of tumor invasion can be accurately predicted by the new imaging tools.

  12. Urodeles remove mesoderm from the superficial layer by subduction through a bilateral primitive streak.

    Science.gov (United States)

    Shook, David R; Majer, Christina; Keller, Ray

    2002-08-15

    Urodeles begin gastrulation with much of their presumptive mesoderm in the superficial cell layer, all of which must move into the deep layers during development. We studied the morphogenesis of superficial mesoderm in the urodeles Ambystoma maculatum, Ambystoma mexicanum, and Taricha granulosa. In all three species, somitic, lateral, and ventral mesoderm move into the deep layer during gastrulation, ingressing through a "bilateral primitive streak" just inside the blastopore. The mesodermal epithelium appears to slide under the endodermal epithelium by a mechanism we term "subduction." Subduction removes the large expanse of superficial presumptive somitic and lateral-ventral mesoderm that initially separates the sub-blastoporal endoderm from the notochord, leaving the endoderm bounding the still epithelial notochord along the gastrocoel roof. Subduction may be a common feature of urodele gastrulation, differing in this regard from anurans. Subducting cells constrict their apices and become bottle-shaped as they approach the junction of the mesodermal and endodermal epithelia. Subducting bottle cells endocytose apical membrane and withdraw the tight junctional component cingulin from the contracting circumferential tight junctions. Either in conjunction with or immediately after subducting, the mesodermal cells undergo an epithelial-to-mesenchymal transition. The mechanism by which epithelial cells release their apical junctions to become mesenchymal, without disrupting the integrity of the epithelium, remains mysterious, but this system should prove useful in understanding this process in a developmental context.

  13. Comparative histopathology of pemphigus foliaceus and superficial folliculitis in the dog.

    Science.gov (United States)

    Kuhl, K A; Shofer, F S; Goldschmidt, M H

    1994-01-01

    A comparative histopathologic study of 50 cases of pemphigus foliaceus and 47 cases of superficial folliculitis in the dog was undertaken to identify those histopathologic features important in differentiating these diseases. All cases were diagnosed by the Surgical Pathology Service of the Laboratory of Pathology of the University of Pennsylvania, School of Veterinary Medicine, between January 1986 and March 1991. These cases were followed clinically to determine the accuracy of the initial histopathologic diagnosis. Data were analyzed by Fisher's exact test for discrete data and the Mann-Whitney U-test for continuous data. A probability of Siberian Husky, Laborador Retriever, Miniature Schnauzer, Old English Sheepdog, Scottish Terrier, Chinese Shar Pei, Spitz, Shetland Sheep Dog, Weimeraner, and West Highland White Terrier. An increased risk of developing pemphigus foliaceus was noted in the Akita (OR = 37.8), English Springer Spaniel (OR = 20.7), Chow Chow (OR = 12.3), Chinese Shar Pei (OR = 7.9), and Collie (OR = 3.9). Pemphigus foliaceus had a higher average density of acantholytic cells (226 +/- 22.9) than superficial folliculitis (11.8 +/- 4.6), and acantholytic cells were 183 times more likely to be present in pemphigus foliaceus. The presence of rafts of acantholytic cells occurred in pemphigus foliaceus (23/50) more often than superficial folliculitis (1/47). Recornification and reformation of pustules were, respectively, 13.4 and 3.6 times more likely to occur in pemphigus foliaceus.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Time-course of perceptual processing of "hole" and "no-hole"figures: An ERP study

    Institute of Scientific and Technical Information of China (English)

    Weina Zhu; Junjun Zhang; Changle Zhou

    2013-01-01

    Closure or the presence of a "hole" is an emergent perceptual feature that can be extracted by the visual system early on.This feature has been shown to have perceptual advantages over openness or "no-hole".In this study,we investigated when and how the human brain differentiates between "hole" and "no-hole" figures.Event-related potentials (ERPs) were recorded during a passive observation paradigm.Two pairs of simple figures (Experiment 1) and two sets of Greek letters (Experiment 2) were used as stimuli.The ERPs of "hole" and "no-hole"figures differed ~90 ms after stimulus onset:"hole"figures elicited smaller P1 and N1 amplitudes than "no-hole" figures.These suggest that both P1 and N1 components are sensitive to the difference between "hole" and "no-hole" figures; perception of "hole" and "no-hole" figures might be differentiated early during visual processing.

  15. Superficial Fungal Infections in Patients with Hematologic Malignancies: A Case-Control Study

    Directory of Open Access Journals (Sweden)

    Berna Ülgen Altay

    2011-06-01

    Full Text Available Background and Design: Dermatophytes, yeasts and some moulds settle on the skin and mucosal surfaces in immunocompetent individuals as commensals. Patients with diabetes mellitus, HIV-positive patients, organ transplant recipients and the patients with malignancies are predisposed to develop superficial fungal infections. We aimed to determine the prevalence, clinical and mycological features of superficial fungal infections in patients with hematologic malignancies in this case-control study.Material and Method: Eighty patients with hematologic malignancies (49 men, 31 women and 50 healthy individuals (22 men, 28 women randomly selected at our clinical department as controls were included to this study between 2003 and 2004. The mean age was 52±1.85 years in patients and 41.56±2.04 years in controls. All patients were inspected for superficial fungal infections. Skin scrapings and mucosal swabs were obtained from the toe web, inguinal region, any suspicious lesion and oral mucosa. Nail samples were also collected. All samples were examined by direct microscopy and cultured in Sabouraud dextrose agar (SDA. The yeasts were established in germ-tube production. Results: Fifty-six (70% of 80 patients with hematologic malignancies had fungal colonization, whereas 21 (42% of 50 controls had. For both groups, oral mucosa was the predominant area that fungus was mostly isolated from. A rising number of non-dermatophyte moulds (26% was observed. Candida albicans was the predominant agent isolated from the culture.Conclusion: The prevalence of superficial fungal infection was higher in patients with hematologic malignancies (being immunosuppressed than in the normal population. Candida albicans was the predominant isolated agent that was found in our study. We observed oral mucosa candidal infection mostly. The rising number of non-dermatophyte moulds is attributed to long-term use of antibiotics, cytotoxic chemotherapies and antifungals.

  16. Drenaje suplementario del sistema venoso superficial en colgajos pediculados Supplementary drainage of superficial venous system in pedicled flaps

    Directory of Open Access Journals (Sweden)

    A. Fernández García

    2012-06-01

    Full Text Available Los colgajos pediculados pueden sufrir edema y congestión debido a que su drenaje a trevés del sistema venoso superfical es imposible y el flujo hacia el sistema profundo a nivel del pedículo es precario. Esta situación suele evolucionar hacia la necrosis parcial o la pérdida total del colgajo en pocas horas. La apertura del sistema venoso superficial permite el drenaje adecuado de los tejidos transferidos y evita estas complicaciones. Este artículo analiza el papel de las anastomosis microquirúrgicas en el sistema venoso superficial de los colgajos pediculados. Esta técnica permite comunicar el sistema venoso superfical de los tejidos transferidos con el sistema venoso superficial del territorio que rodea al defecto. Presentamos los resultados obtenidos con esta técnica en colgajos de perforante en hélice, colgajos miocutáneos, colgajos neurocutáneos y colgajos fasciograsos volteados.The pedicled flaps can suffer edema and congestion due to the impossibility of drainage toward the superficial venous system and the precarious flow via the deep system at the level of the pedicle. The evolution of this situation is usually partial necrosis or total loss of the flap in a few hours. The opening of the venous superficial system achieves an appropriate drainage of the transfered tissues and avoids these complications. In this article we analyze the role of the microsurgical anastomosis at the level of the superficial venous system of pedicled flaps. This technique allows to communicate the superficial venous system of the transfered tissues with the superficial venous system of the territory around the defect. We report the results with this method in propeller perforator flaps, miocutaneous flaps, neurocutaneous flaps and adipofascial turn over flaps.

  17. Lack of Methylene Blue Staining in Superficial Epithelia as a Possible Marker for Superficial Lateral Spread of Bile Duct Cancer

    Directory of Open Access Journals (Sweden)

    I. Maetani

    1996-01-01

    epithelia. The cancerous epithelia stained significantly less often than either the normal (p = 0.000005 or the metaplastic (p = 0.001 epithelia. Evaluation of methylene blue staining during PTCS revealed that this stain was absorbed by the cholangial epithelia, not superficially stuck to it. The difference in methylene blue staining properties between the cancerous and normal epithelia could be helpful to clarify the boundary of superficial lateral spread of bile duct cancer.

  18. Amniotic membrane transplant with superficial keratectomy in superficial corneal degenerations: Efficacy in a rural population of north India

    Directory of Open Access Journals (Sweden)

    Rao Aparna

    2008-01-01

    Full Text Available Aim: To evaluate the applicability and efficacy of superficial keratectomy with transplantation of preserved amniotic membrane in superficial corneal degenerations in a rural population of Northern India in terms of visual improvement and surface regularization. Settings: Peripheral referral center in rural north India. Materials and Methods: This was a prospective non-comparative interventional case series where 24 eyes of 20 farmers from peripheral rural areas (M:F = 19:1 with visually significant superficial degenerative disorders (15 eyes with climatic droplet keratopathy one of which was associated with Salzmann nodular degeneration and nine eyes with band-shaped keratopathy were subjected to amniotic membrane transplantation (single or multiple layer combined with superficial keratectomy. Subjective and objective outcomes after surgery were evaluated and analyzed and statistical significance of the outcomes in various disorders was evaluated. Results: Eighty-eight per cent (21 eyes had symptomatic relief from distressing preoperative symptoms while postoperative visual improvement by two or more lines was achieved in 23 eyes (96% over a mean follow-up period of 26.8 ± 10.2 months. The surface irregularity present preoperatively was relieved in 23 cases while postoperative decline of vision with visually significant scarring was seen in one case (4%, which was labeled as failure. Conclusions: Amniotic membrane transplant with superficial keratectomy helped achieve subjective comfort, visual rehabilitation and clinical regularization of the corneal surface in superficial corneal degenerations during the mean followup of 26.8 ± 10.2 months in rural setups.

  19. Functional consequences of experience-dependent plasticity on tactile perception following perceptual learning.

    Science.gov (United States)

    Trzcinski, Natalie K; Gomez-Ramirez, Manuel; Hsiao, Steven S

    2016-09-01

    Continuous training enhances perceptual discrimination and promotes neural changes in areas encoding the experienced stimuli. This type of experience-dependent plasticity has been demonstrated in several sensory and motor systems. Particularly, non-human primates trained to detect consecutive tactile bar indentations across multiple digits showed expanded excitatory receptive fields (RFs) in somatosensory cortex. However, the perceptual implications of these anatomical changes remain undetermined. Here, we trained human participants for 9 days on a tactile task that promoted expansion of multi-digit RFs. Participants were required to detect consecutive indentations of bar stimuli spanning multiple digits. Throughout the training regime we tracked participants' discrimination thresholds on spatial (grating orientation) and temporal tasks on the trained and untrained hands in separate sessions. We hypothesized that training on the multi-digit task would decrease perceptual thresholds on tasks that require stimulus processing across multiple digits, while also increasing thresholds on tasks requiring discrimination on single digits. We observed an increase in orientation thresholds on a single digit. Importantly, this effect was selective for the stimulus orientation and hand used during multi-digit training. We also found that temporal acuity between digits improved across trained digits, suggesting that discriminating the temporal order of multi-digit stimuli can transfer to temporal discrimination of other tactile stimuli. These results suggest that experience-dependent plasticity following perceptual learning improves and interferes with tactile abilities in manners predictive of the task and stimulus features used during training.

  20. Functional consequences of experience-dependent plasticity on tactile perception following perceptual learning

    Science.gov (United States)

    Trzcinski, Natalie K; Gomez-Ramirez, Manuel; Hsiao, Steven S.

    2016-01-01

    Continuous training enhances perceptual discrimination and promotes neural changes in areas encoding the experienced stimuli. This type of experience-dependent plasticity has been demonstrated in several sensory and motor systems. Particularly, non-human primates trained to detect consecutive tactile bar indentations across multiple digits showed expanded excitatory receptive fields (RFs) in somatosensory cortex. However, the perceptual implications of these anatomical changes remain undetermined. Here, we trained human participants for nine days on a tactile task that promoted expansion of multi-digit RFs. Participants were required to detect consecutive indentations of bar stimuli spanning multiple digits. Throughout the training regime we tracked participants’ discrimination thresholds on spatial (grating orientation) and temporal tasks on the trained and untrained hands in separate sessions. We hypothesized that training on the multi-digit task would decrease perceptual thresholds on tasks that require stimulus processing across multiple digits, while also increasing thresholds on tasks requiring discrimination on single digits. We observed an increase in orientation thresholds on a single-digit. Importantly, this effect was selective for the stimulus orientation and hand used during multi-digit training. We also found that temporal acuity between digits improved across trained digits, suggesting that discriminating the temporal order of multi-digit stimuli can transfer to temporal discrimination of other tactile stimuli. These results suggest that experience-dependent plasticity following perceptual learning improves and interferes with tactile abilities in manners predictive of the task and stimulus features used during training. PMID:27422224

  1. Surprise Leads to Noisier Perceptual Decisions

    Directory of Open Access Journals (Sweden)

    Marta I Garrido

    2011-02-01

    Full Text Available Surprising events in the environment can impair task performance. This might be due to complete distraction, leading to lapses during which performance is reduced to guessing. Alternatively, unpredictability might cause a graded withdrawal of perceptual resources from the task at hand and thereby reduce sensitivity. Here we attempt to distinguish between these two mechanisms. Listeners performed a novel auditory pitch—duration discrimination, where stimulus loudness changed occasionally and incidentally to the task. Responses were slower and less accurate in the surprising condition, where loudness changed unpredictably, than in the predictable condition, where the loudness was held constant. By explicitly modelling both lapses and changes in sensitivity, we found that unpredictable changes diminished sensitivity but did not increase the rate of lapses. These findings suggest that background environmental uncertainty can disrupt goal-directed behaviour. This graded processing strategy might be adaptive in potentially threatening contexts, and reflect a flexible system for automatic allocation of perceptual resources.

  2. Deception in plants: mimicry or perceptual exploitation?

    Science.gov (United States)

    Schaefer, H Martin; Ruxton, Graeme D

    2009-12-01

    Mimicry involves adaptive resemblance between a mimic and a model. However, despite much recent research, it remains contentious in plants. Here, we review recent progress on studying deception by flowers, distinguishing between plants relying on mimicry to achieve pollination and those relying on the exploitation of the perceptual biases of animals. We disclose fundamental differences between both mechanisms and explain why the evolution of exploitation is less constrained than that of mimicry. Exploitation of perceptual biases might thus be a precursor for the gradual evolution of mimicry. Increasing knowledge on the sensory and cognitive filters in animals, and on the selective pressures that maintain them, should aid researchers in tracing the evolutionary dynamics of deception in plants.

  3. Zen Mountains: An Illusion of Perceptual Transparency

    Directory of Open Access Journals (Sweden)

    Susan G. Wardle

    2015-04-01

    Full Text Available The human visual system is usually very successful in segmenting complex natural scenes. During a trip to the Nepalese Himalayas, we observed an impossible example of Nature's beauty: “transparent” mountains. The scene is captured in a photograph in which a pair of mountain peaks viewed in the far distance appear to be transparent. This illusion results from a fortuitous combination of lighting and scene conditions, which induce an erroneous integration of multiple segmentation cues. The illusion unites three classic principles of visual perception: Metelli's constraints for perceptual transparency, the Gestalt principle of good continuation, and depth from contrast and atmospheric scattering. This real-world “failure” of scene segmentation reinforces how ingeniously the human visual system typically integrates complex sources of perceptual information using heuristics based on likelihood as shortcuts to veridical perception.

  4. Neurophysiological mechanisms involved in auditory perceptual organization

    Directory of Open Access Journals (Sweden)

    Aurélie Bidet-Caulet

    2009-09-01

    Full Text Available In our complex acoustic environment, we are confronted with a mixture of sounds produced by several simultaneous sources. However, we rarely perceive these sounds as incomprehensible noise. Our brain uses perceptual organization processes to independently follow the emission of each sound source over time. If the acoustic properties exploited in these processes are well-established, the neurophysiological mechanisms involved in auditory scene analysis have raised interest only recently. Here, we review the studies investigating these mechanisms using electrophysiological recordings from the cochlear nucleus to the auditory cortex, in animals and humans. Their findings reveal that basic mechanisms such as frequency selectivity, forward suppression and multi-second habituation shape the automatic brain responses to sounds in a way that can account for several important characteristics of perceptual organization of both simultaneous and successive sounds. One challenging question remains unresolved: how are the resulting activity patterns integrated to yield the corresponding conscious perceptsµ

  5. Monocular depth effects on perceptual fading.

    Science.gov (United States)

    Hsu, Li-Chuan; Kramer, Peter; Yeh, Su-Ling

    2010-08-06

    After prolonged viewing, a static target among moving non-targets is perceived to repeatedly disappear and reappear. An uncrossed stereoscopic disparity of the target facilitates this Motion-Induced Blindness (MIB). Here we test whether monocular depth cues can affect MIB too, and whether they can also affect perceptual fading in static displays. Experiment 1 reveals an effect of interposition: more MIB when the target appears partially covered by, than when it appears to cover, its surroundings. Experiment 2 shows that the effect is indeed due to interposition and not to the target's contours. Experiment 3 induces depth with the watercolor illusion and replicates Experiment 1. Experiments 4 and 5 replicate Experiments 1 and 3 without the use of motion. Since almost any stimulus contains a monocular depth cue, we conclude that perceived depth affects perceptual fading in almost any stimulus, whether dynamic or static. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. From Perceptual Categories to Concepts: What Develops?

    Science.gov (United States)

    Sloutsky, Vladimir M

    2010-09-01

    People are remarkably smart: they use language, possess complex motor skills, make non-trivial inferences, develop and use scientific theories, make laws, and adapt to complex dynamic environments. Much of this knowledge requires concepts and this paper focuses on how people acquire concepts. It is argued that conceptual development progresses from simple perceptual grouping to highly abstract scientific concepts. This proposal of conceptual development has four parts. First, it is argued that categories in the world have different structure. Second, there might be different learning systems (sub-served by different brain mechanisms) that evolved to learn categories of differing structures. Third, these systems exhibit differential maturational course, which affects how categories of different structures are learned in the course of development. And finally, an interaction of these components may result in the developmental transition from perceptual groupings to more abstract concepts. This paper reviews a large body of empirical evidence supporting this proposal.

  7. Perceptual digital imaging methods and applications

    CERN Document Server

    Lukac, Rastislav

    2012-01-01

    Visual perception is a complex process requiring interaction between the receptors in the eye that sense the stimulus and the neural system and the brain that are responsible for communicating and interpreting the sensed visual information. This process involves several physical, neural, and cognitive phenomena whose understanding is essential to design effective and computationally efficient imaging solutions. Building on advances in computer vision, image and video processing, neuroscience, and information engineering, perceptual digital imaging greatly enhances the capabilities of tradition

  8. Fusion of perceptions for perceptual robotics

    OpenAIRE

    Ciftcioglu, O.; Bittermann, M.S.; Sariyildiz, I.S.

    2006-01-01

    Fusion of perception information for perceptual robotics is described. The visual perception is mathematically modelled as a probabilistic process obtaining and interpreting visual data from an environment. The visual data is processed in a multiresolutional form via wavelet transform and optimally estimated via extended Kalman filtering in each resolution level and the outcomes are fused for each data block. The measurement involves visual perception in the virtual reality which has direct i...

  9. Atypicalities in Perceptual Adaptation in Autism Do Not Extend to Perceptual Causality

    Science.gov (United States)

    Karaminis, Themelis; Turi, Marco; Neil, Louise; Badcock, Nicholas A.; Burr, David; Pellicano, Elizabeth

    2015-01-01

    A recent study showed that adaptation to causal events (collisions) in adults caused subsequent events to be less likely perceived as causal. In this study, we examined if a similar negative adaptation effect for perceptual causality occurs in children, both typically developing and with autism. Previous studies have reported diminished adaptation for face identity, facial configuration and gaze direction in children with autism. To test whether diminished adaptive coding extends beyond high-level social stimuli (such as faces) and could be a general property of autistic perception, we developed a child-friendly paradigm for adaptation of perceptual causality. We compared the performance of 22 children with autism with 22 typically developing children, individually matched on age and ability (IQ scores). We found significant and equally robust adaptation aftereffects for perceptual causality in both groups. There were also no differences between the two groups in their attention, as revealed by reaction times and accuracy in a change-detection task. These findings suggest that adaptation to perceptual causality in autism is largely similar to typical development and, further, that diminished adaptive coding might not be a general characteristic of autism at low levels of the perceptual hierarchy, constraining existing theories of adaptation in autism. PMID:25774507

  10. Atypicalities in perceptual adaptation in autism do not extend to perceptual causality.

    Directory of Open Access Journals (Sweden)

    Themelis Karaminis

    Full Text Available A recent study showed that adaptation to causal events (collisions in adults caused subsequent events to be less likely perceived as causal. In this study, we examined if a similar negative adaptation effect for perceptual causality occurs in children, both typically developing and with autism. Previous studies have reported diminished adaptation for face identity, facial configuration and gaze direction in children with autism. To test whether diminished adaptive coding extends beyond high-level social stimuli (such as faces and could be a general property of autistic perception, we developed a child-friendly paradigm for adaptation of perceptual causality. We compared the performance of 22 children with autism with 22 typically developing children, individually matched on age and ability (IQ scores. We found significant and equally robust adaptation aftereffects for perceptual causality in both groups. There were also no differences between the two groups in their attention, as revealed by reaction times and accuracy in a change-detection task. These findings suggest that adaptation to perceptual causality in autism is largely similar to typical development and, further, that diminished adaptive coding might not be a general characteristic of autism at low levels of the perceptual hierarchy, constraining existing theories of adaptation in autism.

  11. Perceptual consequences of "hidden" hearing loss.

    Science.gov (United States)

    Plack, Christopher J; Barker, Daphne; Prendergast, Garreth

    2014-09-09

    Dramatic results from recent animal experiments show that noise exposure can cause a selective loss of high-threshold auditory nerve fibers without affecting absolute sensitivity permanently. This cochlear neuropathy has been described as hidden hearing loss, as it is not thought to be detectable using standard measures of audiometric threshold. It is possible that hidden hearing loss is a common condition in humans and may underlie some of the perceptual deficits experienced by people with clinically normal hearing. There is some evidence that a history of noise exposure is associated with difficulties in speech discrimination and temporal processing, even in the absence of any audiometric loss. There is also evidence that the tinnitus experienced by listeners with clinically normal hearing is associated with cochlear neuropathy, as measured using Wave I of the auditory brainstem response. To date, however, there has been no direct link made between noise exposure, cochlear neuropathy, and perceptual difficulties. Animal experiments also reveal that the aging process itself, in the absence of significant noise exposure, is associated with loss of auditory nerve fibers. Evidence from human temporal bone studies and auditory brainstem response measures suggests that this form of hidden loss is common in humans and may have perceptual consequences, in particular, regarding the coding of the temporal aspects of sounds. Hidden hearing loss is potentially a major health issue, and investigations are ongoing to identify the causes and consequences of this troubling condition.

  12. Perceptual and neural olfactory similarity in honeybees.

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    Fernando Guerrieri

    2005-04-01

    Full Text Available The question of whether or not neural activity patterns recorded in the olfactory centres of the brain correspond to olfactory perceptual measures remains unanswered. To address this question, we studied olfaction in honeybees Apis mellifera using the olfactory conditioning of the proboscis extension response. We conditioned bees to odours and tested generalisation responses to different odours. Sixteen odours were used, which varied both in their functional group (primary and secondary alcohols, aldehydes and ketones and in their carbon-chain length (from six to nine carbons. The results obtained by presentation of a total of 16 x 16 odour pairs show that (i all odorants presented could be learned, although acquisition was lower for short-chain ketones; (ii generalisation varied depending both on the functional group and the carbon-chain length of odours trained; higher generalisation was found between long-chain than between short-chain molecules and between groups such as primary and secondary alcohols; (iii for some odour pairs, cross-generalisation between odorants was asymmetric; (iv a putative olfactory space could be defined for the honeybee with functional group and carbon-chain length as inner dimensions; (v perceptual distances in such a space correlate well with physiological distances determined from optophysiological recordings of antennal lobe activity. We conclude that functional group and carbon-chain length are inner dimensions of the honeybee olfactory space and that neural activity in the antennal lobe reflects the perceptual quality of odours.

  13. Perceptual and Neural Olfactory Similarity in Honeybees

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    Guerrieri Fernando

    2005-01-01

    Full Text Available The question of whether or not neural activity patterns recorded in the olfactory centres of the brain correspond to olfactory perceptual measures remains unanswered. To address this question, we studied olfaction in honeybees Apis mellifera using the olfactory conditioning of the proboscis extension response. We conditioned bees to odours and tested generalisation responses to different odours. Sixteen odours were used, which varied both in their functional group (primary and secondary alcohols, aldehydes and ketones and in their carbon-chain length (from six to nine carbons.The results obtained by presentation of a total of 16 x 16 odour pairs show that (i all odorants presented could be learned, although acquisition was lower for short-chain ketones; (ii generalisation varied depending both on the functional group and the carbon-chain length of odours trained; higher generalisation was found between long-chain than between short-chain molecules and between groups such as primary and secondary alcohols; (iii for some odour pairs, cross-generalisation between odorants was asymmetric; (iv a putative olfactory space could be defined for the honeybee with functional group and carbon-chain length as inner dimensions; (v perceptual distances in such a space correlate well with physiological distances determined from optophysiological recordings of antennal lobe activity. We conclude that functional group and carbon-chain length are inner dimensions of the honeybee olfactory space and that neural activity in the antennal lobe reflects the perceptual quality of odours.

  14. Perceptual centering effects in body orientation.

    Science.gov (United States)

    Hanes, D A

    2006-04-01

    This study mathematically characterizes the results of DiZio and Lackner (Percept Psychphys 39(1): 39-46) on the perception of self-orientation during circular vection induced by an optokinetic stimulus. Using the hypothesis of perceptual centering, it is shown that five basic centering transformations can logically account for the full range of illusions reported by the subjects. All five of these transformations center the perceived orientations of body components, the rotating disk, and gravity : two align the perceived visual and inertial rotation axes, one centers the perceived axis of visual rotation in front of the head, and two straighten the perceived neck angle. These transformations generate a mathematical semigroup. Application of the semigroup to an actual stimulus condition generates an orbit of predicted illusions. The semigroup analysis of perceptual centering predicts all of the illusions observed in the experiments of DiZio and Lackner (Percept Psychphys 39(1): 39-46). Moreover, the structure of perceptual centering (1) provides a logical explanation for the occurrence of those misperceptions; and (2) predicts the complete set of perceptions that are expected to occur in a larger sample. In addition, our analysis predicts illusions in experimental conditions not yet investigated.

  15. Brightness and darkness as perceptual dimensions.

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    Tony Vladusich

    2007-10-01

    Full Text Available A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D space varying from bright to dark. The results of many previous psychophysical studies suggest, by contrast, that achromatic colors are represented as points in a color space composed of two or more perceptual dimensions. The nature of these perceptual dimensions, however, presently remains unclear. Here we provide direct evidence that brightness and darkness form the dimensions of a two-dimensional (2-D achromatic color space. This color space may play a role in the representation of object surfaces viewed against natural backgrounds, which simultaneously induce both brightness and darkness signals. Our 2-D model generalizes to the chromatic dimensions of color perception, indicating that redness and greenness (blueness and yellowness also form perceptual dimensions. Collectively, these findings suggest that human color space is composed of six dimensions, rather than the conventional three.

  16. Perceptual asymmetries and handedness: A neglected link?

    Directory of Open Access Journals (Sweden)

    Daniele eMarzoli

    2014-02-01

    Full Text Available Healthy individuals tend to weigh in more the left than the right side of visual space in a variety of contexts, ranging from pseudoneglect to perceptual asymmetries for faces. Among the common explanations proposed for the attentional and perceptual advantages of the left visual field, a link with the prevalence of right-handedness in humans has never been suggested, although some evidence seems to converge in favor of a bias of spatial attention towards the region most likely coincident with another person’s right hand during a face-to-face interaction. Such a bias might imply an increased efficiency in monitoring both communicative and aggressive acts, the right limb being more used than the left in both types of behaviour. Although attentional and perceptual asymmetries could be linked to right-handedness at the level of phylogeny because of the evolutionarily advantage of directing attention towards the region where others’ dominant hand usually operates, it is also legitimate to question whether, at the ontogenetic level, frequent exposure to right-handed individuals may foster leftward biases. These views are discussed in the light of extant literature, and a number of tests are proposed in order to assess our hypotheses.

  17. Interocular transfer of perceptual skills after sleep.

    Science.gov (United States)

    Deliens, Gaétane; Schmitz, Rémy; Peigneux, Philippe

    2014-01-24

    Several studies suggest that sleep improves perceptual skills in the visual texture discrimination task (TDT). Here we report that besides consolidation, sleep also generalizes the learned perceptual abilities to the untrained eye. Healthy volunteers (n = 32) were trained on the TDT, in which they had to discriminate between horizontal and vertical target textures briefly presented in the periphery of the visual field (left upper quadrant). After a 10-hr interval filled with either sleep or wakefulness, they were retested first on the trained eye in the trained quadrant and then on the untrained eye and quadrant. In line with prior findings, visual discrimination was globally higher after sleep than after wakefulness, as compared to performance levels at the end of training. Furthermore, discrimination performance was significantly improved only in the sleep condition for the untrained eye in the same quadrant, but also showed a trend to generalize to the untrained eye and untrained quadrant. Our results suggest that sleep-dependent perceptual skills continue developing at a later visual-process stage than the V1 area, where learning is not monocular anymore.

  18. Perceptual crossing: The simplest online paradigm

    Directory of Open Access Journals (Sweden)

    Malika eAuvray

    2012-06-01

    Full Text Available Researchers in social cognition increasingly realize that many phenomena cannot be understood by investigating offline situations only, focusing on individual mechanisms and an observer perspective. There are processes of dynamic emergence specific to online situations, when two or more persons are engaged in a real-time interaction that are more than just the sum of the individual capacities or behaviours, and these require the study of online social interaction. Auvray et al.’s (2009 perceptual crossing paradigm offers possibly the simplest paradigm for studying such online interactions: two persons, a one-dimensional space, one bit of information, and a yes/no answer. Despite, or maybe because of its simplicity, this study has provoked a lot of resonance in different areas of research, including experimental psychology, computer/robot modelling, philosophy, more recently psychopathology, and even in the field of design. In this article, we review and critically assess this body of literature. We give an overview over work on the perceptual crossing paradigm, both concerning behavioural experiments and computational agent modelling, and review the different contexts in which it has been referred to. We discuss the controversy about the possible constitutive role of perceptual crossing for social cognition and other theoretical contexts in which the research has been cited, offering our own interpretation. We conclude with an outlook on future research possibilities, in particular those that could elucidate the link between online interaction dynamics and individual social cognition.

  19. Biochemical composition of the superficial layer of articular cartilage.

    Science.gov (United States)

    Crockett, R; Grubelnik, A; Roos, S; Dora, C; Born, W; Troxler, H

    2007-09-15

    To gain more information on the mechanism of lubrication in articular joints, the superficial layer of bovine articular cartilage was mechanically removed in a sheet of ice that formed on freezing the cartilage. Freeze-dried samples contained low concentrations of chondroitin sulphate and protein. Analysis of the protein by SDS PAGE showed that the composition of the sample was comparable to that of synovial fluid (SF). Attenuated total reflection infrared (ATR-IR) spectroscopy of the dried residue indicated that the sample contained mostly hyaluronan. Moreover, ATR-IR spectroscopy of the upper layer of the superficial layer, adsorbed onto silicon, showed the presence of phospholipids. A gel could be formed by mixing hyaluronan and phosphatidylcholine in water with mechanical properties similar to those of the superficial layer on cartilage. Much like the superficial layer of natural cartilage, the surface of this gel became hydrophobic on drying out. Thus, it is proposed that the superficial layer forms from hyaluronan and phospholipids, which associate by hydrophobic interactions between the alkyl chains of the phospholipids and the hydrophobic faces of the disaccharide units in hyaluronan. This layer is permeable to material from the SF and the cartilage, as shown by the presence of SF proteins and chondroitin sulphate. As the cartilage dries out after removal from the joint, the phospholipids migrate towards the surface of the superficial layer to reduce the surface tension. It is also proposed that the highly efficient lubrication in articular joints can, at least in part, be attributed to the ability of the superficial layer to adsorb and hold water on the cartilage surface, thus creating a highly viscous boundary protection.

  20. EEG-fMRI based information theoretic characterization of the human perceptual decision system.

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    Dirk Ostwald

    Full Text Available The modern metaphor of the brain is that of a dynamic information processing device. In the current study we investigate how a core cognitive network of the human brain, the perceptual decision system, can be characterized regarding its spatiotemporal representation of task-relevant information. We capitalize on a recently developed information theoretic framework for the analysis of simultaneously acquired electroencephalography (EEG and functional magnetic resonance imaging data (fMRI (Ostwald et al. (2010, NeuroImage 49: 498-516. We show how this framework naturally extends from previous validations in the sensory to the cognitive domain and how it enables the economic description of neural spatiotemporal information encoding. Specifically, based on simultaneous EEG-fMRI data features from n = 13 observers performing a visual perceptual decision task, we demonstrate how the information theoretic framework is able to reproduce earlier findings on the neurobiological underpinnings of perceptual decisions from the response signal features' marginal distributions. Furthermore, using the joint EEG-fMRI feature distribution, we provide novel evidence for a highly distributed and dynamic encoding of task-relevant information in the human brain.

  1. Superficial dose evaluation of four dose calculation algorithms

    Science.gov (United States)

    Cao, Ying; Yang, Xiaoyu; Yang, Zhen; Qiu, Xiaoping; Lv, Zhiping; Lei, Mingjun; Liu, Gui; Zhang, Zijian; Hu, Yongmei

    2017-08-01

    Accurate superficial dose calculation is of major importance because of the skin toxicity in radiotherapy, especially within the initial 2 mm depth being considered more clinically relevant. The aim of this study is to evaluate superficial dose calculation accuracy of four commonly used algorithms in commercially available treatment planning systems (TPS) by Monte Carlo (MC) simulation and film measurements. The superficial dose in a simple geometrical phantom with size of 30 cm×30 cm×30 cm was calculated by PBC (Pencil Beam Convolution), AAA (Analytical Anisotropic Algorithm), AXB (Acuros XB) in Eclipse system and CCC (Collapsed Cone Convolution) in Raystation system under the conditions of source to surface distance (SSD) of 100 cm and field size (FS) of 10×10 cm2. EGSnrc (BEAMnrc/DOSXYZnrc) program was performed to simulate the central axis dose distribution of Varian Trilogy accelerator, combined with measurements of superficial dose distribution by an extrapolation method of multilayer radiochromic films, to estimate the dose calculation accuracy of four algorithms in the superficial region which was recommended in detail by the ICRU (International Commission on Radiation Units and Measurement) and the ICRP (International Commission on Radiological Protection). In superficial region, good agreement was achieved between MC simulation and film extrapolation method, with the mean differences less than 1%, 2% and 5% for 0°, 30° and 60°, respectively. The relative skin dose errors were 0.84%, 1.88% and 3.90%; the mean dose discrepancies (0°, 30° and 60°) between each of four algorithms and MC simulation were (2.41±1.55%, 3.11±2.40%, and 1.53±1.05%), (3.09±3.00%, 3.10±3.01%, and 3.77±3.59%), (3.16±1.50%, 8.70±2.84%, and 18.20±4.10%) and (14.45±4.66%, 10.74±4.54%, and 3.34±3.26%) for AXB, CCC, AAA and PBC respectively. Monte Carlo simulation verified the feasibility of the superficial dose measurements by multilayer Gafchromic films. And the rank

  2. The relationship between visual working memory and attention: retention of precise colour information in the absence of effects on perceptual selection.

    Science.gov (United States)

    Hollingworth, Andrew; Hwang, Seongmin

    2013-10-19

    We examined the conditions under which a feature value in visual working memory (VWM) recruits visual attention to matching stimuli. Previous work has suggested that VWM supports two qualitatively different states of representation: an active state that interacts with perceptual selection and a passive (or accessory) state that does not. An alternative hypothesis is that VWM supports a single form of representation, with the precision of feature memory controlling whether or not the representation interacts with perceptual selection. The results of three experiments supported the dual-state hypothesis. We established conditions under which participants retained a relatively precise representation of a parcticular colour. If the colour was immediately task relevant, it reliably recruited attention to matching stimuli. However, if the colour was not immediately task relevant, it failed to interact with perceptual selection. Feature maintenance in VWM is not necessarily equivalent with feature-based attentional selection.

  3. Perceptual fluency, auditory generation, and metamemory: analyzing the perceptual fluency hypothesis in the auditory modality.

    Science.gov (United States)

    Besken, Miri; Mulligan, Neil W

    2014-03-01

    Judgments of learning (JOLs) are sometimes influenced by factors that do not impact actual memory performance. One recent proposal is that perceptual fluency during encoding affects metamemory and is a basis of metacognitive illusions. In the present experiments, participants identified aurally presented words that contained inter-spliced silences (the generate condition) or that were intact, a manipulation analogous to visual generation manipulations. The generate condition produced lower perceptual fluency as assessed by both accuracy and identification latency. Consistent with the perceptual fluency hypothesis, the less fluent, generate condition produced lower JOLs than the intact condition. However, actual memory performance was greater in the generation than intact condition in free recall (Experiment 1) and recognition (Experiment 3). The negative effect of generation on JOLs occurred for both aggregate and item-by-item JOLs, but in the latter case, the positive generation effect in actual memory performance was reduced or eliminated (as also occurs with visual generation tasks; Experiments 2 and 4). Furthermore, the decrease in perceptual fluency produced by the generation manipulation was correlated with the decrease in JOLs for this condition (Experiment 5). The negative effect of generation on JOLs persisted even when participants were warned that the generation condition produces equal or greater memory performance compared to the intact condition (Experiment 6). The results are in accord with the perceptual fluency hypothesis and show that this metamemory illusion is related to objective measures of perceptual difficulty. With regard to actual memory performance, this novel auditory generation manipulation produces results consistent with those produced in the visual modality.

  4. Perceptual learning: tactile letter recognition transfers across body surfaces.

    Science.gov (United States)

    Arnold, Gabriel; Auvray, Malika

    2014-01-01

    Visual-to-tactile sensory substitution devices are designed to assist visually impaired people by converting visual stimuli into tactile stimuli. The important claim has been made that, after training with these devices, the tactile stimuli can be moved from one body surface to another without any decrease in performance. This claim, although recurrent, has never been empirically investigated. Moreover, studies in the field of tactile perceptual learning suggest that performance improvement transfers only to body surfaces that are closely represented in the somatosensory cortex, i.e. adjacent or homologous contralateral body surfaces. These studies have however mainly used discrimination tasks of stimuli varying along only one feature (e.g., orientation of gratings) whereas, in sensory substitution, tactile information consists of more complex stimuli. The present study investigated the extent to which there is a transfer of tactile letter learning. Participants first underwent a baseline session in which the letters were presented on their belly, thigh, and shin. They were subsequently trained on only one of these body surfaces, and then re-tested on all of them, as a post-training session. The results revealed that performance improvement was the same for both the trained and the untrained surfaces. Moreover, this transfer of perceptual learning was equivalent for adjacent and non-adjacent body surfaces, suggesting that tactile learning transfer occurs independently of the distance on the body. A control study consisting of the same baseline and post-training sessions, without training in between, revealed weaker improvement between the two sessions. The obtained results support the claim that training with sensory substitution devices results in a relative independence from the stimulated body surface.

  5. Clinical, microscopic and microbial characterization of exfoliative superficial pyoderma-associated epidermal collarettes in dogs.

    Science.gov (United States)

    Banovic, Frane; Linder, Keith; Olivry, Thierry

    2017-02-01

    The microscopic and microbial features of the spreading epidermal collarettes of canine exfoliative superficial pyodermas are poorly characterized. To characterize the clinical, cytological, microbial and histopathological features of epidermal collarettes in five dogs. Cytology from the margins of collarettes identified neutrophils, extracellular and intracellular cocci within neutrophils but no acantholytic keratinocytes. Phenotypic and genotypic analyses identified all bacterial isolates from the centre and margin of five epidermal collarettes as Staphylococcus pseudintermedius. PCRs of collarette-associated Staphylococcus strains did not amplify genes encoding for the known exfoliative toxins expA and expB, whereas the predicted siet and speta amplification products were detected in all isolates. Microscopically, epidermal collarettes consisted of interfollicular, epidermal spongiotic pustules. Advancing edges of lesions consisted of peripheral intracorneal clefts in the deep stratum disjunctum above an intact stratum compactum; they contained lytic neutrophil debris, bacterial cocci and fluid, but no acantholytic keratinocytes. This intracorneal location of bacteria was confirmed using Gram stains and fluorescent in situ hybridization with eubacterial- and Staphylococcus-specific probes. The indirect immunofluorescence staining patterns of desmoglein-1, desmocollin-1, claudin-1, E-cadherin and corneodesmosin were discontinuous and patchy in areas of spongiotic pustules, whereas only that of corneodesmosin was weaker and patchy in advancing collarette edges. Epidermal collarettes represent unique clinical and histological lesions of exfoliative superficial pyodermas that are distinct from those of impetigo and superficial bacterial folliculitis. The characterization of possible causative staphylococcal exfoliatin proteases and the role of corneodesmosin in collarette pathogenesis deserve further investigation. © 2016 ESVD and ACVD.

  6. Clinical characteristics of patients with persistent postural-perceptual dizziness

    OpenAIRE

    Roseli Saraiva Moreira Bittar; Eliane Maria Dias von Söhsten Lins

    2015-01-01

    INTRODUCTION: Persistent postural-perceptual dizziness is the dizziness that lasts for over three months with no clinical explanation for its persistence. The patient's motor response pattern presents changes and most patients manifest significant anxiety. OBJECTIVE: To evaluate the clinical characteristics of patients with persistent postural and perceptual dizziness. METHODS: statistical analysis of clinical aspects of patients with persistent postural-perceptual dizziness. RESULTS: 81 pati...

  7. The role of perceptual load in object recognition

    OpenAIRE

    Lavie, Nilli; Lin, Zhicheng; Zokaei, Nahid; Thoma, Volker

    2009-01-01

    Predictions from perceptual load theory (Lavie, 1995, 2005) regarding object recognition across the same or different viewpoints were tested. Results showed that high perceptual load reduces distracter\\ud recognition levels despite always presenting distracter objects from the same view. They also showed that the levels of distracter recognition were unaffected by a change in the distracter object view under conditions of low perceptual load. These results were found both with repetition prim...

  8. Long-term evolution of superficial optic disc drusen

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; Lund-Andersen, Henrik; Hamann, Steffen

    2017-01-01

    with hereditary ODD were included. RESULTS: Mean age at initial and follow-up examination was, respectively, 16.8 and 73.3 years. The median follow-up time was 56 years. A minimal or non-existing change in superficial ODD anatomy (size and number) was seen in 10 of 12 eyes. There was a tendency towards more......PURPOSE: Optic disc drusen (ODD) is hyaline deposits in the optic nerve head seen in 1-2% of the population. Long-term evolution of ODD anatomy and visual field defects in ODD patients is a key factor for learning more about pathophysiology and prognosis of the condition. With a median follow......-up period of 56 years, this is the first study that evaluates superficial optic disc anatomy and visual fields in patients with ODD over a life span. METHODS: Observational case series investigating progression of superficial optic disc anatomy and visual fields in ODD patients. Eight patients...

  9. Física de superficies: métodos experimentales

    OpenAIRE

    2012-01-01

    Hace unos 30 años se empezó con el estudio de superficies sólidas y hoy son muchos los investigadores que en el mundo entero se dedican al estudio de las propiedades físicas y químicas de superficies e interfaces.La motivación radica en que en las interacciones entre los diversos sistemas que componen nuestro universo se hallan involucradas sus superficies, razón suficiente para captar la importancia de su estudio para la vida humana y su repercusión tecnológica y económica. A ella habría que...

  10. Case report: cochlear implantation in a patient with superficial siderosis.

    Science.gov (United States)

    Ryan, Michelle; Piplica, Doris; Zhang, Ming

    2014-12-01

    This is a retrospective case review study. Current understanding of cochlear implantation in patients with superficial siderosis is limited, with roughly 15 reported cases worldwide. The purpose of this study is to report an additional case of cochlear implantation in a patient with superficial siderosis and to contribute to the current literature available on outcomes of implantation in these individuals. One cochlear implant user with superficial siderosis in a tertiary referral center. Therapeutic and rehabilitative. Open set speech perception word scores increased from 0% preimplantation with bilateral hearing aids to 8% postimplantation in the bimodal condition (cochlear implant in the left ear and hearing aid in the right ear). Phoneme scores increased from 16% preimplantation to 36% postimplantation. The patient also demonstrated improvement from 38% preimplantation to 83% postimplantation on a closed set word test. Performance on open set recorded sentences did not improve; however, open set sentences administered live voice revealed an increase in performance from 4% preimplantation to 25% postimplantation in the auditory only condition and from 59% to 86% in the auditory-visual condition. For this patient with superficial siderosis, only marginal improvements in test scores at 11 months postimplantation were seen. Minimally, the use of a cochlear implant did prevent further deterioration of auditory performance. Therefore, patients with superficial siderosis who choose to proceed with cochlear implantation may still report perceived benefit from the maintenance of speech perception abilities even in the presence of minimal improvement. Rapid deterioration in hearing thresholds and speech discrimination before implantation may be an indicator of an actively progressing case of superficial siderosis, which may suggest possible limited benefit from cochlear implantation.

  11. Conceptual and Methodological Concerns in the Theory of Perceptual Load

    Directory of Open Access Journals (Sweden)

    Hanna eBenoni

    2013-08-01

    Full Text Available The present paper provides a short critical review of the theory of perceptual load. It closely examines the basic tenets and assumptions of the theory and identifies major conceptual and methodological problems that have been largely ignored in the literature. The discussion focuses on problems in the definition of the concept of perceptual load, on the circularity in the characterization and manipulation of perceptual load and the confusion between the concept of perceptual load and its operationalization. The paper also selectively reviews evidence supporting the theory as well as inconsistent evidence which proposed alternative dominant factors influencing the efficacy of attentional selection.

  12. UV radiation sensors with unitary and binary superficial barrier

    Science.gov (United States)

    Dorogan, Valerian; Vieru, Tatiana; Kosyak, V.; Damaskin, I.; Chirita, F.

    1998-07-01

    UV radiation sensors with unitary and binary superficial barrier, made on the basis of GaP - SnO2 and GaAs - AlGaAs - SnO2 heterostructures, are presented in the paper. Technological and constructive factors, which permit to realize a high conversion efficiency and to exclude the influence of visible spectrum upon the photoanswer, are analyzed. It was established that the presence of an isotypical superficial potential barrier permits to suppress the photoanswer component formed by absorption of visible and infrared radiation in semiconductor structure bulk.

  13. PHOTODYNAMIC DIAGNOSIS AND FLUORESCENCE SPECTROSCOPY IN SUPERFICIAL BLADDER CANCER

    Directory of Open Access Journals (Sweden)

    I. G. Rusakov

    2009-01-01

    Full Text Available A comprehensive fluorescence technique has been developed to study the urinary bladder mucosa in patients with superficial bladder cancer (BC, by using alasense, white light cystoscopy, fluorescence cytoscopy, and local fluorescence spectroscopy in vivo. Quantification of urothelium fluorescence in the red emission foci of 5-ALA-induced protophorphyrin, with the local autofluorescence intensity being borne in mind, has been shown to increase the specificity of photodynamic diagnosis of superficial BC from 70 to 85% (p ≤ 0.05 and the total accuracy of the technique from 80 to 86%.  

  14. Nicotine facilitates memory consolidation in perceptual learning.

    Science.gov (United States)

    Beer, Anton L; Vartak, Devavrat; Greenlee, Mark W

    2013-01-01

    Perceptual learning is a special type of non-declarative learning that involves experience-dependent plasticity in sensory cortices. The cholinergic system is known to modulate declarative learning. In particular, reduced levels or efficacy of the neurotransmitter acetylcholine were found to facilitate declarative memory consolidation. However, little is known about the role of the cholinergic system in memory consolidation of non-declarative learning. Here we compared two groups of non-smoking men who learned a visual texture discrimination task (TDT). One group received chewing tobacco containing nicotine for 1 h directly following the TDT training. The other group received a similar tasting control substance without nicotine. Electroencephalographic recordings during substance consumption showed reduced alpha activity and P300 latencies in the nicotine group compared to the control group. When re-tested on the TDT the following day, both groups responded more accurately and more rapidly than during training. These improvements were specific to the retinal location and orientation of the texture elements of the TDT suggesting that learning involved early visual cortex. A group comparison showed that learning effects were more pronounced in the nicotine group than in the control group. These findings suggest that oral consumption of nicotine enhances the efficacy of nicotinic acetylcholine receptors. Our findings further suggest that enhanced efficacy of the cholinergic system facilitates memory consolidation in perceptual learning (and possibly other types of non-declarative learning). In that regard acetylcholine seems to affect consolidation processes in perceptual learning in a different manner than in declarative learning. Alternatively, our findings might reflect dose-dependent cholinergic modulation of memory consolidation. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

  15. Perceptual consequences of disrupted auditory nerve activity.

    Science.gov (United States)

    Zeng, Fan-Gang; Kong, Ying-Yee; Michalewski, Henry J; Starr, Arnold

    2005-06-01

    Perceptual consequences of disrupted auditory nerve activity were systematically studied in 21 subjects who had been clinically diagnosed with auditory neuropathy (AN), a recently defined disorder characterized by normal outer hair cell function but disrupted auditory nerve function. Neurological and electrophysical evidence suggests that disrupted auditory nerve activity is due to desynchronized or reduced neural activity or both. Psychophysical measures showed that the disrupted neural activity has minimal effects on intensity-related perception, such as loudness discrimination, pitch discrimination at high frequencies, and sound localization using interaural level differences. In contrast, the disrupted neural activity significantly impairs timing related perception, such as pitch discrimination at low frequencies, temporal integration, gap detection, temporal modulation detection, backward and forward masking, signal detection in noise, binaural beats, and sound localization using interaural time differences. These perceptual consequences are the opposite of what is typically observed in cochlear-impaired subjects who have impaired intensity perception but relatively normal temporal processing after taking their impaired intensity perception into account. These differences in perceptual consequences between auditory neuropathy and cochlear damage suggest the use of different neural codes in auditory perception: a suboptimal spike count code for intensity processing, a synchronized spike code for temporal processing, and a duplex code for frequency processing. We also proposed two underlying physiological models based on desynchronized and reduced discharge in the auditory nerve to successfully account for the observed neurological and behavioral data. These methods and measures cannot differentiate between these two AN models, but future studies using electric stimulation of the auditory nerve via a cochlear implant might. These results not only show the unique

  16. Prolonged perceptual learning of positional acuity in adult amblyopia: perceptual template retuning dynamics.

    Science.gov (United States)

    Li, Roger W; Klein, Stanley A; Levi, Dennis M

    2008-12-24

    Amblyopia is a developmental abnormality that results in physiological alterations in the visual cortex and impairs form vision. It is often successfully treated by patching the sound eye in infants and young children, but is generally considered to be untreatable in adults. However, a number of recent studies suggest that repetitive practice of a visual task using the amblyopic eye results in improved performance in both children and adults with amblyopia. These perceptual learning studies have used relatively brief periods of practice; however, clinical studies have shown that the time-constant for successful patching is long. The time-constant for perceptual learning in amblyopia is still unknown. Here we show that the time-constant for perceptual learning depends on the degree of amblyopia. Severe amblyopia requires >50 h (approximately equal to 35,000 trials) to reach plateau, yielding as much as a five-fold improvement in performance at a rate of approximately equal to 1.5%/h. There is significant transfer of learning from the amblyopic to the dominant eye, suggesting that the learning reflects alterations in higher decision stages of processing. Using a reverse correlation technique, we document, for the first time, a dynamic retuning of the amblyopic perceptual decision template and a substantial reduction in internal spatial distortion. These results show that the mature amblyopic brain is surprisingly malleable, and point to more intensive treatment methods for amblyopia.

  17. Perceptual advantage for category-relevant perceptual dimensions: The case of shape and motion

    Directory of Open Access Journals (Sweden)

    Jonathan R Folstein

    2014-12-01

    Full Text Available Category learning facilitates perception along relevant stimulus dimensions, even when tested in a discrimination task that does not require categorization. While this general phenomenon has been demonstrated previously, perceptual facilitation along dimensions has been documented by measuring different specific phenomena in different studies using different kinds of objects. Across several object domains, there is support for acquired distinctiveness, the stretching of a perceptual dimension relevant to learned categories. Studies using faces and studies using simple separable visual dimensions have also found evidence of acquired equivalence, the shrinking of a perceptual dimension irrelevant to learned categories, and categorical perception, the local stretching across the category boundary. These later two effects are rarely observed with complex non-face objects. Failures to find these effects with complex non-face objects may have been because the dimensions tested previously were perceptually integrated. Here we tested effects of category learning with non-face objects categorized along dimensions that have been found to be processed by different areas of the brain, shape and motion. While we replicated acquired distinctiveness, we found no evidence for acquired equivalence or categorical perception.

  18. False Memories Lack Perceptual Detail: Evidence from Implicit Word-Stem Completion and Perceptual Identification Tests

    Science.gov (United States)

    Hicks, J.L.; Starns, J.J.

    2005-01-01

    We used implicit measures of memory to ascertain whether false memories for critical nonpresented items in the DRM paradigm (Deese, 1959; Roediger & McDermott, 1995) contain structural and perceptual detail. In Experiment 1, we manipulated presentation modality in a visual word-stem-completion task. Critical item priming was significant and…

  19. Exploring Perceptual Skills in Children with Autism Spectrum Disorders: From Target Detection to Dynamic Perceptual Discrimination

    Science.gov (United States)

    Miller, Louisa; McGonigle-Chalmers, Maggie

    2014-01-01

    Perceptual processing in autism is associated with both "strengths" and "weaknesses" but within a literature that varies widely in terms of the assessments used. We report data from 12 children with autism spectrum disorders (ASD) and 12 age and IQ matched neurotypical controls tested on a set of tasks using the same stimuli…

  20. Perceptual Plasticity for Auditory Object Recognition

    Directory of Open Access Journals (Sweden)

    Shannon L. M. Heald

    2017-05-01

    Full Text Available In our auditory environment, we rarely experience the exact acoustic waveform twice. This is especially true for communicative signals that have meaning for listeners. In speech and music, the acoustic signal changes as a function of the talker (or instrument, speaking (or playing rate, and room acoustics, to name a few factors. Yet, despite this acoustic variability, we are able to recognize a sentence or melody as the same across various kinds of acoustic inputs and determine meaning based on listening goals, expectations, context, and experience. The recognition process relates acoustic signals to prior experience despite variability in signal-relevant and signal-irrelevant acoustic properties, some of which could be considered as “noise” in service of a recognition goal. However, some acoustic variability, if systematic, is lawful and can be exploited by listeners to aid in recognition. Perceivable changes in systematic variability can herald a need for listeners to reorganize perception and reorient their attention to more immediately signal-relevant cues. This view is not incorporated currently in many extant theories of auditory perception, which traditionally reduce psychological or neural representations of perceptual objects and the processes that act on them to static entities. While this reduction is likely done for the sake of empirical tractability, such a reduction may seriously distort the perceptual process to be modeled. We argue that perceptual representations, as well as the processes underlying perception, are dynamically determined by an interaction between the uncertainty of the auditory signal and constraints of context. This suggests that the process of auditory recognition is highly context-dependent in that the identity of a given auditory object may be intrinsically tied to its preceding context. To argue for the flexible neural and psychological updating of sound-to-meaning mappings across speech and music, we

  1. A ratio model of perceptual transparency.

    Science.gov (United States)

    Tommasi, M

    1999-12-01

    A ratio model of the achromatic transparency of a phenomenal surface on a bipartite background is proposed. The model asserts that transparency corresponds to the evaluation of the ratio of the lightness difference inside the transparent surface to the difference in reference lightness inside the background. It applies to both balanced and unbalanced transparency. The ratio model was compared experimentally with the previous perceptual model of achromatic transparency proposed by Metelli. Each model was tested by comparing the rated with the predicted transparency. Analysis shows that the ratio model provides better predictions of transparency than those provided by Metelli's model.

  2. Perceptual Grouping via Untangling Gestalt Principles

    DEFF Research Database (Denmark)

    Qi, Yonggang; Guo, Jun; Li, Yi

    2013-01-01

    Gestalt principles, a set of conjoining rules derived from hu- man visual studies, have been known to play an important role in computer vision. Many applications such as image segmentation, contour grouping and scene understanding of- ten rely on such rules to work. However, the problem of Gestalt...... the importance of Gestalt rules by solving a learning to rank problem, and formulate a multi-label graph-cuts algo- rithm to group image primitives while taking into account the learned Gestalt confliction. Our experiment results confirm the existence of Gestalt confliction in perceptual grouping and demonstrate...

  3. Perceptual Grouping via Untangling Gestalt Principles

    DEFF Research Database (Denmark)

    Qi, Yonggang; Guo, Jun; Li, Yi

    2013-01-01

    Gestalt principles, a set of conjoining rules derived from hu- man visual studies, have been known to play an important role in computer vision. Many applications such as image segmentation, contour grouping and scene understanding of- ten rely on such rules to work. However, the problem of Gestalt...... the importance of Gestalt rules by solving a learning to rank problem, and formulate a multi-label graph-cuts algo- rithm to group image primitives while taking into account the learned Gestalt confliction. Our experiment results confirm the existence of Gestalt confliction in perceptual grouping and demonstrate...

  4. Perceptual hashing of sheet music based on graphical representation

    Science.gov (United States)

    Kremser, Gert; Schmucker, Martin

    2006-02-01

    For the protection of Intellectual Property Rights (IPR), different passive protection methods have been developed. These watermarking and fingerprinting technologies protect content beyond access control and thus tracing illegal distributions as well as the identification of people who are responsible for a illegal distribution is possible. The public's attention was attracted especially to the second application by the illegal distribution of the so called 'Hollywood screeners'. The focus of current research is on audio and video content and images. These are the common content types we are faced with every day, and which mostly have a huge commercial value. Especially the illegal distribution of content that has not been officially published shows the potential commercial impact of illegal distributions. Content types, however, are not limited to audio, video and images. There is a range of other content types, which also deserve the development of passive protection technologies. For sheet music for instance, different watermarking technologies have been developed, which up to this point only function within certain limitations. This is the reason why we wanted to find out how to develop a fingerprinting or perceptual hashing method for sheet music. In this article, we describe the development of our algorithm for sheet music, which is based on simple graphical features. We describe the selection of these features and the subsequent processing steps. The resulting compact representation is analyzed and the first performance results are reported.

  5. Who can you trust? Behavioral and neural differences between perceptual and memory-based influences

    Directory of Open Access Journals (Sweden)

    John D Rudoy

    2009-08-01

    Full Text Available Decisions about whether to trust someone can be influenced by competing sources of information, such as analysis of facial features versus remembering specific information about the person. We hypothesized that such sources can differentially influence trustworthiness judgments depending on the circumstances in which judgments are made. In our experiments, subjects first learned face-word associations. Stimuli were trustworthy and untrustworthy faces selected on the basis of consensus judgments and personality attributes that carried either the same valence (consistent with face or the opposite valence (inconsistent with face. Subsequently, subjects rated the trustworthiness of each face. Both learned and perceptual information influenced ratings, but learned information was less influential under speeded than under non-speeded conditions. EEG data further revealed neural evidence of the processing of these two competing sources. Perceptual influences were apparent earlier than memory influences, substantiating the conclusion that time pressure can selectively disrupt memory retrieval relevant to trustworthiness attributions.

  6. An Improved Speech Enhancement Method based on Teager Energy Operator and Perceptual Wavelet Packet Decomposition

    Directory of Open Access Journals (Sweden)

    Huan Zhao

    2011-06-01

    Full Text Available According to the distribution characteristic of noise and clean speech signal in the frequency domain, a new speech enhancement method based on teager energy operator (TEO and perceptual wavelet packet decomposition (PWPD is proposed. Firstly, a modified Mask construction method is made to protect the acoustic cues at the low frequencies. Then a level-dependent parameter is introduced to further adjust the thresholds in light of the noise distribution feature. At last the sub-bands which have very little influence are set directly 0 to improve the signal-to-noise ratio (SNR and reduce the computation load. Simulation results show that, under different kinds of noise environments, this new method not only enhances the signal-to-noise ratio (SNR and perceptual evaluation of speech quality (PESQ, but also reduces the computation load, which is very advantageous for real-time realizing.

  7. Perceptual evaluation of motor speech following treatment for childhood cerebellar tumour.

    Science.gov (United States)

    Cornwell, Petrea L; Murdoch, Bruce E; Ward, Elizabeth C; Kellie, Stewart

    2003-12-01

    The speech characteristics, oromotor function and speech intelligibility of a group of children treated for cerebellar tumour (CT) was investigated perceptually. Assessment of these areas was performed on 11 children treated for CT with dysarthric speech as well as 21 non-neurologically impaired controls matched for age and sex to obtain a comprehensive perceptual profile of their speech and oromotor mechanism. Contributing to the perception of dysarthria were a number of deviant speech dimensions including imprecision of consonants, hoarseness and decreased pitch variation, as well as a reduction in overall speech intelligibility for both sentences and connected speech. Oromotor assessment revealed deficits in lip, tongue and laryngeal function, particularly relating to deficits in timing and coordination of movements. The most salient features of the dysarthria seen in children treated for CT were the mild nature of the speech disorder and clustering of speech deficits in the prosodic, phonatory and articulatory aspects of speech production.

  8. Perceptual memory drives learning of retinotopic biases for bistable stimuli.

    Directory of Open Access Journals (Sweden)

    Aidan Peter Murphy

    2014-02-01

    Full Text Available The visual system exploits past experience at multiple timescales to resolve perceptual ambiguity in the retinal image. For example, perception of a bistable stimulus can be biased towards one interpretation over another when preceded by a brief presentation of a disambiguated version of the stimulus (positive priming or through intermittent presentations of the ambiguous stimulus (stabilization. Similarly, prior presentations of unambiguous stimuli can be used to explicitly train a long-lasting association between a percept and a retinal location (perceptual association. These phenonema have typically been regarded as independent processes, with short-term biases attributed to perceptual memory and longer-term biases described as associative learning. Here we tested for interactions between these two forms of experience-dependent perceptual bias and demonstrate that short-term processes strongly influence long-term outcomes. We first demonstrate that the establishment of long-term perceptual contingencies does not require explicit training by unambiguous stimuli, but can arise spontaneously during the periodic presentation of brief, ambiguous stimuli. Using rotating Necker cube stimuli, we observed enduring, retinotopically specific perceptual biases that were expressed from the outset and remained stable for up to forty minutes, consistent with the known phenomenon of perceptual stabilization. Further, bias was undiminished after a break period of five minutes, but was readily reset by interposed periods of continuous, as opposed to periodic, ambiguous presentation. Taken together, the results demonstrate that perceptual biases can arise naturally and may principally reflect the brain’s tendency to favor recent perceptual interpretation at a given retinal location. Further, they suggest that an association between retinal location and perceptual state, rather than a physical stimulus, is sufficient to generate long-term biases in perceptual

  9. Tromboflebite superficial: epidemiologia, fisiopatologia, diagnóstico e tratamento Superficial thrombophlebitis: epidemiology, physiopathology, diagnosis and treatment

    Directory of Open Access Journals (Sweden)

    Marcone Lima Sobreira

    2008-06-01

    Full Text Available A tromboflebite superficial de membros inferiores é doença de ocorrência comum, estando associada a diversas condições clínicas e cirúrgicas. Historicamente considerada doença benigna, devido à sua localização superficial e ao fácil diagnóstico, o tratamento foi conservador durante muito tempo, na maioria dos casos. Entretanto, relatos recentes de freqüências altas de complicações tromboembólicas associadas - 22 a 37% para trombose venosa profunda e até 33% para embolia pulmonar - alertaram para a necessidade de abordagens diagnósticas e terapêuticas mais amplas, visando diagnosticar e tratar essas possíveis complicações. A possibilidade da coexistência dessas e de outras desordens sistêmicas (colagenoses, neoplasias, trombofilias interfere na avaliação e influencia a conduta terapêutica, que pode ser clínica, cirúrgica ou combinada. No entanto, devido à falta de ensaios clínicos controlados e às incertezas quanto a sua história natural, o diagnóstico e o tratamento da tromboflebite superficial continuam indefinidos. Neste trabalho, foi feita uma revisão da literatura analisando-se a epidemiologia, fisiopatologia e estado atual do diagnóstico e tratamento da tromboflebite superficial.Superficial thrombophlebitis of the lower limbs is a commonly occurring disease, and it is associated with various clinical and surgical conditions. Historically considered to be a benign disease due to its superficial location and easy diagnosis, its treatment was, for a long time, conservative in most cases. Nevertheless, recent reports of high frequency and associated thromboembolic complications, which vary from 22 to 37% for deep venous thrombosis and up to 33% for pulmonary embolism, have indicated the need for broader diagnostic and therapeutic approaches in order to diagnose and treat such possible complications. The possibility of coexistence of these and other systemic disorders (collagenosis, neoplasia, thrombophilia

  10. Interpolación y ajuste de superficies en componentes mecánicos digitalizados empleando superficies B-Spline

    OpenAIRE

    2014-01-01

    Este documento de tesis tiene el propósito de describir una metodología para obtener nubes de puntos que representen a superficies (o parches de geometría compleja) de piezas mecánicas que pueden ser replicadas en la industria. Estos puntos se obtuvieron utilizando el método de interpolación superficial B-Spline que deben cumplir un margen de error conocido y controlado de acuerdo a las tolerancias de fabricación utilizados en estos procesos de fabricación. En primer lugar e...

  11. On the Use of Memory Models in Audio Features

    DEFF Research Database (Denmark)

    Jensen, Karl Kristoffer

    2011-01-01

    Audio feature estimation is potentially improved by including higher- level models. One such model is the Short Term Memory (STM) model. A new paradigm of audio feature estimation is obtained by adding the influence of notes in the STM. These notes are identified when the perceptual spectral flux...

  12. Auditory Perceptual Learning for Speech Perception Can be Enhanced by Audiovisual Training

    Science.gov (United States)

    Bernstein, Lynne E.; Auer, Edward T.; Eberhardt, Silvio P.; Jiang, Jintao

    2013-01-01

    Speech perception under audiovisual (AV) conditions is well known to confer benefits to perception such as increased speed and accuracy. Here, we investigated how AV training might benefit or impede auditory perceptual learning of speech degraded by vocoding. In Experiments 1 and 3, participants learned paired associations between vocoded spoken nonsense words and nonsense pictures. In Experiment 1, paired-associates (PA) AV training of one group of participants was compared with audio-only (AO) training of another group. When tested under AO conditions, the AV-trained group was significantly more accurate than the AO-trained group. In addition, pre- and post-training AO forced-choice consonant identification with untrained nonsense words showed that AV-trained participants had learned significantly more than AO participants. The pattern of results pointed to their having learned at the level of the auditory phonetic features of the vocoded stimuli. Experiment 2, a no-training control with testing and re-testing on the AO consonant identification, showed that the controls were as accurate as the AO-trained participants in Experiment 1 but less accurate than the AV-trained participants. In Experiment 3, PA training alternated AV and AO conditions on a list-by-list basis within participants, and training was to criterion (92% correct). PA training with AO stimuli was reliably more effective than training with AV stimuli. We explain these discrepant results in terms of the so-called “reverse hierarchy theory” of perceptual learning and in terms of the diverse multisensory and unisensory processing resources available to speech perception. We propose that early AV speech integration can potentially impede auditory perceptual learning; but visual top-down access to relevant auditory features can promote auditory perceptual learning. PMID:23515520

  13. Diagnostic and therapeutic challenges in superficial CNS siderosis

    DEFF Research Database (Denmark)

    Kondziella, Daniel; Lindelof, M.; Haziri, Donika

    2015-01-01

    that neurodegeneration due to haemosiderin-associated iron toxicity becomes irreversible with time. CONCLUSION: Surgical therapy in superficial CNS siderosis is rarely achieved. We suggest that prospective, large-scale multicentre studies are needed to search for non-surgical therapies that reverse (or prevent) ongoing...... neurotoxicity due to accumulating iron toxicity. FUNDING: not relevant. TRIAL REGISTRATION: not relevant....

  14. Superficies bioactivas en implantología: una nueva perspectiva

    Directory of Open Access Journals (Sweden)

    A. Cutando

    2007-02-01

    Full Text Available Actualmente, tras años de investigación en implantología, en los cuales se han realizado muchos trabajos, en donde se han estudiado diferentes tipos de superficies de implantes, lisas y rugosas, en un intento de mejorar, tanto en el tiempo como en la calidad , la osteointegración, se ha concluido que los implantes de superficie rugosa con un intervalo de rugosidad entre 1,0-2,0 nm, son los que parecen dar una mejor respuesta ósea y mejores resultados clínicos, pero desde un punto de vista exclusivamente mecánico. Hoy en día las investigaciones se centran en el desarrollo de superficies denominadas bioactivas, las cuales son capaces de interaccionar con el hueso que rodea al implante, como ocurre cuando el implante es revestido con carbonato cálcico o bien con flúor. Pero sabemos que dentro del metabolismo óseo, juegan importantes papeles, moléculas, como son la melatonina y la hormona del crecimiento entre otras, las cuales deben de ser tenidas en cuenta a la hora de hablar de osteointegración. Se realiza una breve descripción de la fisiología de ambas moléculas y se valora su aplicación al concepto de superficie bioactiva en implantología.

  15. Superficial Needling Therapy for Tennis Elbow in 40 Cases

    Institute of Scientific and Technical Information of China (English)

    GE Heng-bi; XIAO Yuan-chun

    2003-01-01

    Superficial needling therapy was employed to treat 40 cases of tennis elbow. For the cases of qi and blood stagnation, cupping therapy was added. Thirty-eight cases were cured after one treatment and 2 cases were cured after two treatments.

  16. Frey′s Syndrome as a Sequela of Superficial Parotidectomy

    Directory of Open Access Journals (Sweden)

    Rishi Kumar Bali

    2006-01-01

    The disorder is characterized by unilateral sweating and flushing of facial skin in the area of parotid gland occurring during meals. We present a case of a patient who developed symptoms of Frey Syndrome 4 months after undergoing superficial parotidectomy on left side.

  17. Atypical Presentation of Fibrolipomatous Hamartoma of Superficial Peroneal Nerve.

    Science.gov (United States)

    Dhinsa, Baljinder Singh; Lidder, Surjit; Abbasian, Ali

    2016-01-01

    Fibrolipomatous hamartoma is a rare presentation in the foot. An accurate diagnosis is key, with magnetic resonance imaging findings considered definitive. The management is dependent on the symptoms. We present an atypical presentation of fibrolipomatous hamartoma of the superficial peroneal nerve and discuss the current published data.

  18. Superficial dermatomycoses: a prospective clinico-mycological study

    Directory of Open Access Journals (Sweden)

    Surekha A

    2015-01-01

    Full Text Available Background: Dermatomycoses are more prevalent in India due to favourable climatic conditions, poverty, poor hygiene and overcrowding. Sparse published data are available regarding superficial dermatomycoses from India. Methods: In this prospective study, demographic characteristics, clinical spectrum and risk factors for the development were studied in 198 patients with superficial dermatomycoses. Results: Their mean age was 34.1 ± 15.3 years; there were 108 (54.5% males. Majority of the patients (50.5% belonged to upper-lower socio-economic status (Class IV as per modified Kuppuswamy’s classification. Most of the patients (69.7% had presented with dermatophytoses. Among superficial dermatomy-coses, tinea corporis was the most common (29.3% clinical type. Potassium hydroxide mount was positive in 77.7% and culture was positive in 30.8%. Trichophyton rubrum was the most common species isolated (64%. Multivariable analysis using logistic regression revealed older age (> 50 years to be an independent predictor for the development of tinea corporis (p<0.001. Conclusions: Our observations suggest that superficial dermatomycoses are an important cause of morbidity and should be carefully searched for especially in the elderly so that effective curative treatment can be instituted.

  19. Tattoo removal by superficial dermabrasion. Five-year experience.

    Science.gov (United States)

    Clabaugh, W A

    1975-04-01

    A 5-year clinical experience using superficial dermabrasion to remove tattoos is presented. This procedure can be done quickly in the office with low patient risk. Good pigment removal is obtained with little or no scar formation. Cases are presented which are typical of the 250 tattoos removed in the last 5 years.

  20. Implicit Recognition Based on Lateralized Perceptual Fluency

    Directory of Open Access Journals (Sweden)

    Iliana M. Vargas

    2012-02-01

    Full Text Available In some circumstances, accurate recognition of repeated images in an explicit memory test is driven by implicit memory. We propose that this “implicit recognition” results from perceptual fluency that influences responding without awareness of memory retrieval. Here we examined whether recognition would vary if images appeared in the same or different visual hemifield during learning and testing. Kaleidoscope images were briefly presented left or right of fixation during divided-attention encoding. Presentation in the same visual hemifield at test produced higher recognition accuracy than presentation in the opposite visual hemifield, but only for guess responses. These correct guesses likely reflect a contribution from implicit recognition, given that when the stimulated visual hemifield was the same at study and test, recognition accuracy was higher for guess responses than for responses with any level of confidence. The dramatic difference in guessing accuracy as a function of lateralized perceptual overlap between study and test suggests that implicit recognition arises from memory storage in visual cortical networks that mediate repetition-induced fluency increments.

  1. What is automatized during perceptual categorization?

    Science.gov (United States)

    Roeder, Jessica L; Ashby, F Gregory

    2016-09-01

    An experiment is described that tested whether stimulus-response associations or an abstract rule are automatized during extensive practice at perceptual categorization. Twenty-seven participants each completed 12,300 trials of perceptual categorization, either on rule-based (RB) categories that could be learned explicitly or information-integration (II) categories that required procedural learning. Each participant practiced predominantly on a primary category structure, but every third session they switched to a secondary structure that used the same stimuli and responses. Half the stimuli retained their same response on the primary and secondary categories (the congruent stimuli) and half switched responses (the incongruent stimuli). Several results stood out. First, performance on the primary categories met the standard criteria of automaticity by the end of training. Second, for the primary categories in the RB condition, accuracy and response time (RT) were identical on congruent and incongruent stimuli. In contrast, for the primary II categories, accuracy was higher and RT was lower for congruent than for incongruent stimuli. These results are consistent with the hypothesis that rules are automatized in RB tasks, whereas stimulus-response associations are automatized in II tasks. A cognitive neuroscience theory is proposed that accounts for these results.

  2. Motivation and intelligence drive auditory perceptual learning.

    Directory of Open Access Journals (Sweden)

    Sygal Amitay

    Full Text Available BACKGROUND: Although feedback on performance is generally thought to promote perceptual learning, the role and necessity of feedback remain unclear. We investigated the effect of providing varying amounts of positive feedback while listeners attempted to discriminate between three identical tones on learning frequency discrimination. METHODOLOGY/PRINCIPAL FINDINGS: Using this novel procedure, the feedback was meaningless and random in relation to the listeners' responses, but the amount of feedback provided (or lack thereof affected learning. We found that a group of listeners who received positive feedback on 10% of the trials improved their performance on the task (learned, while other groups provided either with excess (90% or with no feedback did not learn. Superimposed on these group data, however, individual listeners showed other systematic changes of performance. In particular, those with lower non-verbal IQ who trained in the no feedback condition performed more poorly after training. CONCLUSIONS/SIGNIFICANCE: This pattern of results cannot be accounted for by learning models that ascribe an external teacher role to feedback. We suggest, instead, that feedback is used to monitor performance on the task in relation to its perceived difficulty, and that listeners who learn without the benefit of feedback are adept at self-monitoring of performance, a trait that also supports better performance on non-verbal IQ tests. These results show that 'perceptual' learning is strongly influenced by top-down processes of motivation and intelligence.

  3. Perceptual organization at attended and unattended locations

    Institute of Scientific and Technical Information of China (English)

    HAN; Shihui; Glyn; W.; Humphreys

    2005-01-01

    This study examined the effects of attention on forming perceptual units by proximity grouping and by uniform connectedness (UC). In Experiment 1 a row of three global letters defined by either proximity or UC was presented at the center of the visual field. Participants were asked to identify the letter in the middle of stimulus arrays while ignoring the flankers. The stimulus onset asynchrony (SOA) between stimulus arrays and masks varied between 180 and 500 ms. We found that responses to targets defined by proximity grouping were slower than to those defined by UC at median SOAs but there were no differences at short or long SOAs. Incongruent flankers slowed responses to targets and this flanker compatibility effect was larger for UC than for proximity-defined flankers. Experiment 2 examined the effects of spatial precueing on discrimination responses to proximity- and UC-defined targets. The advantage for targets defined by UC over targets defined by proximity grouping was greater at uncued relative to cued locations. The results suggest that the advantage for UC over proximity grouping in forming perceptual units is contingent on the stimuli not being fully attended, and that paying attention to the stimuli differentially benefits proximity grouping.

  4. Motivation and intelligence drive auditory perceptual learning.

    Science.gov (United States)

    Amitay, Sygal; Halliday, Lorna; Taylor, Jenny; Sohoglu, Ediz; Moore, David R

    2010-03-23

    Although feedback on performance is generally thought to promote perceptual learning, the role and necessity of feedback remain unclear. We investigated the effect of providing varying amounts of positive feedback while listeners attempted to discriminate between three identical tones on learning frequency discrimination. Using this novel procedure, the feedback was meaningless and random in relation to the listeners' responses, but the amount of feedback provided (or lack thereof) affected learning. We found that a group of listeners who received positive feedback on 10% of the trials improved their performance on the task (learned), while other groups provided either with excess (90%) or with no feedback did not learn. Superimposed on these group data, however, individual listeners showed other systematic changes of performance. In particular, those with lower non-verbal IQ who trained in the no feedback condition performed more poorly after training. This pattern of results cannot be accounted for by learning models that ascribe an external teacher role to feedback. We suggest, instead, that feedback is used to monitor performance on the task in relation to its perceived difficulty, and that listeners who learn without the benefit of feedback are adept at self-monitoring of performance, a trait that also supports better performance on non-verbal IQ tests. These results show that 'perceptual' learning is strongly influenced by top-down processes of motivation and intelligence.

  5. Implicit recognition based on lateralized perceptual fluency.

    Science.gov (United States)

    Vargas, Iliana M; Voss, Joel L; Paller, Ken A

    2012-02-06

    In some circumstances, accurate recognition of repeated images in an explicit memory test is driven by implicit memory. We propose that this "implicit recognition" results from perceptual fluency that influences responding without awareness of memory retrieval. Here we examined whether recognition would vary if images appeared in the same or different visual hemifield during learning and testing. Kaleidoscope images were briefly presented left or right of fixation during divided-attention encoding. Presentation in the same visual hemifield at test produced higher recognition accuracy than presentation in the opposite visual hemifield, but only for guess responses. These correct guesses likely reflect a contribution from implicit recognition, given that when the stimulated visual hemifield was the same at study and test, recognition accuracy was higher for guess responses than for responses with any level of confidence. The dramatic difference in guessing accuracy as a function of lateralized perceptual overlap between study and test suggests that implicit recognition arises from memory storage in visual cortical networks that mediate repetition-induced fluency increments.

  6. On the filter approach to perceptual transparency.

    Science.gov (United States)

    Faul, Franz; Ekroll, Vebjørn

    2011-06-09

    In F. Faul and V. Ekroll (2002), we proposed a filter model of perceptual transparency that describes typical color changes caused by optical filters and accurately predicts perceived transparency. Here, we provide a more elaborate analysis of this model: (A) We address the question of how the model parameters can be estimated in a robust way. (B) We show that the parameters of the original model, which are closely related to physical properties, can be transformed into the alternative parameters hue H, saturation S, transmittance V, and clarity C that better reflect perceptual dimensions of perceived transparency. (C) We investigate the relation of H, S, V, and C to the physical parameters of optical filters and show that C is closely related to the refractive index of the filter, whereas V and S are closely related to its thickness. We also demonstrate that the latter relationship can be used to estimate relative filter thickness from S and V. (D) We investigate restrictions on S that result from properties of color space and determine its distribution under realistic choices of physical parameters. (E) We experimentally determine iso-saturation curves that yield nominal saturation values for filters of different hue such that they appear equally saturated.

  7. Revisiting the empirical case against perceptual modularity

    Science.gov (United States)

    Masrour, Farid; Nirshberg, Gregory; Schon, Michael; Leardi, Jason; Barrett, Emily

    2015-01-01

    Some theorists hold that the human perceptual system has a component that receives input only from units lower in the perceptual hierarchy. This thesis, that we shall here refer to as the encapsulation thesis, has been at the center of a continuing debate for the past few decades. Those who deny the encapsulation thesis often rely on the large body of psychological findings that allegedly suggest that perception is influenced by factors such as the beliefs, desires, goals, and the expectations of the perceiver. Proponents of the encapsulation thesis, however, often argue that, when correctly interpreted, these psychological findings are compatible with the thesis. In our view, the debate over the significance and the correct interpretation of these psychological findings has reached an impasse. We hold that this impasse is due to the methodological limitations over psychophysical experiments, and it is very unlikely that such experiments, on their own, could yield results that would settle the debate. After defending this claim, we argue that integrating data from cognitive neuroscience resolves the debate in favor of those who deny the encapsulation thesis. PMID:26583001

  8. Dysarthria in Friedreich's ataxia: a perceptual analysis.

    Science.gov (United States)

    Folker, Joanne; Murdoch, Bruce; Cahill, Louise; Delatycki, Martin; Corben, Louise; Vogel, Adam

    2010-01-01

    The aims of this study were to: (1) evaluate the perceptual speech dimensions, speech intelligibility and dysarthria severity of a group of individuals diagnosed with Friedreich's ataxia (FRDA); (2) determine the presence of subgroups within FRDA dysarthria; (3) investigate the relationship between the speech outcome and the clinical factors of disease progression. The study included 38 individuals (21 female, 17 male) with a confirmed diagnosis of FRDA. A group of 20 non-neurologically impaired individuals served as controls. Perceptual analysis, investigating 30 different dimensions of speech, was conducted on a speech sample obtained from each participant. In addition, the Assessment of Intelligibility of Dysarthria Speech was administered. All FRDA participants presented with dysarthria with severities ranging from mild to moderate. Cluster analysis revealed 3 subgroups, the first presenting with mild dysarthric symptoms, the second with increased velopharyngeal involvement and the third characterized by increased laryngeal dysfunction. Dysarthria severity showed a significant correlation to disease duration but to no other clinical measure. The findings support the notion of subgroups in FRDA dysarthria, representing distinct impairments of the speech mechanism and perhaps reflective of differing evolutions beyond the cerebellum.

  9. Perceptual learning during action video game playing.

    Science.gov (United States)

    Green, C Shawn; Li, Renjie; Bavelier, Daphne

    2010-04-01

    Action video games have been shown to enhance behavioral performance on a wide variety of perceptual tasks, from those that require effective allocation of attentional resources across the visual scene, to those that demand the successful identification of fleetingly presented stimuli. Importantly, these effects have not only been shown in expert action video game players, but a causative link has been established between action video game play and enhanced processing through training studies. Although an account based solely on attention fails to capture the variety of enhancements observed after action game playing, a number of models of perceptual learning are consistent with the observed results, with behavioral modeling favoring the hypothesis that avid video game players are better able to form templates for, or extract the relevant statistics of, the task at hand. This may suggest that the neural site of learning is in areas where information is integrated and actions are selected; yet changes in low-level sensory areas cannot be ruled out. Copyright © 2009 Cognitive Science Society, Inc.

  10. Perceptual quality estimation of H.264/AVC videos using reduced-reference and no-reference models

    Science.gov (United States)

    Shahid, Muhammad; Pandremmenou, Katerina; Kondi, Lisimachos P.; Rossholm, Andreas; Lövström, Benny

    2016-09-01

    Reduced-reference (RR) and no-reference (NR) models for video quality estimation, using features that account for the impact of coding artifacts, spatio-temporal complexity, and packet losses, are proposed. The purpose of this study is to analyze a number of potentially quality-relevant features in order to select the most suitable set of features for building the desired models. The proposed sets of features have not been used in the literature and some of the features are used for the first time in this study. The features are employed by the least absolute shrinkage and selection operator (LASSO), which selects only the most influential of them toward perceptual quality. For comparison, we apply feature selection in the complete feature sets and ridge regression on the reduced sets. The models are validated using a database of H.264/AVC encoded videos that were subjectively assessed for quality in an ITU-T compliant laboratory. We infer that just two features selected by RR LASSO and two bitstream-based features selected by NR LASSO are able to estimate perceptual quality with high accuracy, higher than that of ridge, which uses more features. The comparisons with competing works and two full-reference metrics also verify the superiority of our models.

  11. Development of the perceptual span in reading: A longitudinal study.

    Science.gov (United States)

    Sperlich, Anja; Meixner, Johannes; Laubrock, Jochen

    2016-06-01

    The perceptual span is a standard measure of parafoveal processing, which is considered highly important for efficient reading. Is the perceptual span a stable indicator of reading performance? What drives its development? Do initially slower and faster readers converge or diverge over development? Here we present the first longitudinal data on the development of the perceptual span in elementary school children. Using the moving window technique, eye movements of 127 German children in three age groups (Grades 1, 2, and 3 in Year 1) were recorded at two time points (T1 and T2) 1 year apart. Introducing a new measure of the perceptual span, nonlinear mixed-effects modeling was used to separate window size effects from asymptotic reading performance. Cross-sectional differences were well replicated longitudinally. Asymptotic reading rate increased monotonously with grade, but in a decelerating fashion. A significant change in the perceptual span was observed only between Grades 2 and 3. Together with results from a cross-lagged panel model, this suggests that the perceptual span increases as a consequence of relatively well-established word reading. Stabilities of observed and predicted reading rates were high after Grade 1, whereas the perceptual span was only moderately stable for all grades. Comparing faster and slower readers as assessed at T1, in general, a pattern of stable between-group differences emerged rather than a compensatory pattern; second and third graders even showed a Matthew effect in reading rate and the perceptual span, respectively.

  12. Auditory perceptual simulation: Simulating speech rates or accents?

    Science.gov (United States)

    Zhou, Peiyun; Christianson, Kiel

    2016-07-01

    When readers engage in Auditory Perceptual Simulation (APS) during silent reading, they mentally simulate characteristics of voices attributed to a particular speaker or a character depicted in the text. Previous research found that auditory perceptual simulation of a faster native English speaker during silent reading led to shorter reading times that auditory perceptual simulation of a slower non-native English speaker. Yet, it was uncertain whether this difference was triggered by the different speech rates of the speakers, or by the difficulty of simulating an unfamiliar accent. The current study investigates this question by comparing faster Indian-English speech and slower American-English speech in the auditory perceptual simulation paradigm. Analyses of reading times of individual words and the full sentence reveal that the auditory perceptual simulation effect again modulated reading rate, and auditory perceptual simulation of the faster Indian-English speech led to faster reading rates compared to auditory perceptual simulation of the slower American-English speech. The comparison between this experiment and the data from Zhou and Christianson (2016) demonstrate further that the "speakers'" speech rates, rather than the difficulty of simulating a non-native accent, is the primary mechanism underlying auditory perceptual simulation effects.

  13. Selective Attention to Perceptual Dimensions and Switching between Dimensions

    Science.gov (United States)

    Meiran, Nachshon; Dimov, Eduard; Ganel, Tzvi

    2013-01-01

    In the present experiments, the question being addressed was whether switching attention between perceptual dimensions and selective attention to dimensions are processes that compete over a common resource? Attention to perceptual dimensions is usually studied by requiring participants to ignore a never-relevant dimension. Selection failure…

  14. Perceptual biases in relation to paranormal and conspiracy beliefs

    NARCIS (Netherlands)

    van Elk, M.

    2015-01-01

    Previous studies have shown that one’s prior beliefs have a strong effect on perceptual decision-making and attentional processing. The present study extends these findings by investigating how individual differences in paranormal and conspiracy beliefs are related to perceptual and attentional bias

  15. Harnessing the Wandering Mind: The Role of Perceptual Load

    Science.gov (United States)

    Forster, Sophie; Lavie, Nilli

    2009-01-01

    Perceptual load is a key determinant of distraction by task-irrelevant stimuli (e.g., Lavie, N. (2005). "Distracted and confused?: Selective attention under load." "Trends in Cognitive Sciences," 9, 75-82). Here we establish the role of perceptual load in determining an internal form of distraction by task-unrelated thoughts (TUTs or…

  16. Free-classification of perceptually similar speakers with dysarthria.

    Science.gov (United States)

    Lansford, Kaitlin L; Liss, Julie M; Norton, Rebecca E

    2014-12-01

    In this investigation, the construct of perceptual similarity was explored in the dysarthrias. Specifically, we employed an auditory free-classification task to determine whether listeners could cluster speakers by perceptual similarity, whether the clusters mapped to acoustic metrics, and whether the clusters were constrained by dysarthria subtype diagnosis. Twenty-three listeners blinded to speakers' medical and dysarthria subtype diagnoses participated. The task was to group together (drag and drop) the icons corresponding to 33 speakers with dysarthria on the basis of how similar they sounded. Cluster analysis and multidimensional scaling (MDS) modeled the perceptual dimensions underlying similarity. Acoustic metrics and perceptual judgments were used in correlation analyses to facilitate interpretation of the derived dimensions. Six clusters of similar-sounding speakers and 3 perceptual dimensions underlying similarity were revealed. The clusters of similar-sounding speakers were not constrained by dysarthria subtype diagnosis. The 3 perceptual dimensions revealed by MDS were correlated with metrics for articulation rate, intelligibility, and vocal quality, respectively. This study shows (a) feasibility of a free-classification approach for studying perceptual similarity in dysarthria, (b) correspondence between acoustic and perceptual metrics to clusters of similar-sounding speakers, and (c) similarity judgments transcended dysarthria subtype diagnosis.

  17. Ambiguity Tolerance and Perceptual Learning Styles of Chinese EFL Learners

    Science.gov (United States)

    Li, Haishan; He, Qingshun

    2016-01-01

    Ambiguity tolerance and perceptual learning styles are the two influential elements showing individual differences in EFL learning. This research is intended to explore the relationship between Chinese EFL learners' ambiguity tolerance and their preferred perceptual learning styles. The findings include (1) the learners are sensitive to English…

  18. Perceptual Organization of Visual Structure Requires a Flexible Learning Mechanism

    Science.gov (United States)

    Aslin, Richard N.

    2011-01-01

    Bhatt and Quinn (2011) provide a compelling and comprehensive review of empirical evidence that supports the operation of principles of perceptual organization in young infants. They also have provided a comprehensive list of experiences that could serve to trigger the learning of at least some of these principles of perceptual organization, and…

  19. Perceptual maps: the good, the bad and the ugly

    NARCIS (Netherlands)

    J.C. Gower (John); P.J.F. Groenen (Patrick); M. van de Velden (Michel); K. Vines (Karen)

    2010-01-01

    textabstractPerceptual maps are often used in marketing to visually study relations between two or more attributes. However, in many perceptual maps published in the recent literature it remains unclear what is being shown and how the relations between the points in the map can be interpreted or eve

  20. Perceptual Learning: 12-Month-Olds' Discrimination of Monkey Faces

    Science.gov (United States)

    Fair, Joseph; Flom, Ross; Jones, Jacob; Martin, Justin

    2012-01-01

    Six-month-olds reliably discriminate different monkey and human faces whereas 9-month-olds only discriminate different human faces. It is often falsely assumed that perceptual narrowing reflects a permanent change in perceptual abilities. In 3 experiments, ninety-six 12-month-olds' discrimination of unfamiliar monkey faces was examined. Following…

  1. Perceptual Specificity Effects in Rereading: Evidence from Eye Movements

    Science.gov (United States)

    Sheridan, Heather; Reingold, Eyal M.

    2012-01-01

    The present experiments examined perceptual specificity effects using a rereading paradigm. Eye movements were monitored while participants read the same target word twice, in two different low-constraint sentence frames. The congruency of perceptual processing was manipulated by either presenting the target word in the same distortion typography…

  2. The Role of Perceptual Load in Object Recognition

    Science.gov (United States)

    Lavie, Nilli; Lin, Zhicheng; Zokaei, Nahid; Thoma, Volker

    2009-01-01

    Predictions from perceptual load theory (Lavie, 1995, 2005) regarding object recognition across the same or different viewpoints were tested. Results showed that high perceptual load reduces distracter recognition levels despite always presenting distracter objects from the same view. They also showed that the levels of distracter recognition were…

  3. The Role of Perceptual Load in Inattentional Blindness

    Science.gov (United States)

    Cartwright-Finch, Ula; Lavie, Nilli

    2007-01-01

    Perceptual load theory offers a resolution to the long-standing early vs. late selection debate over whether task-irrelevant stimuli are perceived, suggesting that irrelevant perception depends upon the perceptual load of task-relevant processing. However, previous evidence for this theory has relied on RTs and neuroimaging. Here we tested the…

  4. Perceptual Specificity Effects in Rereading: Evidence from Eye Movements

    Science.gov (United States)

    Sheridan, Heather; Reingold, Eyal M.

    2012-01-01

    The present experiments examined perceptual specificity effects using a rereading paradigm. Eye movements were monitored while participants read the same target word twice, in two different low-constraint sentence frames. The congruency of perceptual processing was manipulated by either presenting the target word in the same distortion typography…

  5. Bayesian Face Recognition and Perceptual Narrowing in Face-Space

    Science.gov (United States)

    Balas, Benjamin

    2012-01-01

    During the first year of life, infants' face recognition abilities are subject to "perceptual narrowing", the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in…

  6. Major Superficial White Matter Abnormalities in Huntington's Disease

    Science.gov (United States)

    Phillips, Owen R.; Joshi, Shantanu H.; Squitieri, Ferdinando; Sanchez-Castaneda, Cristina; Narr, Katherine; Shattuck, David W.; Caltagirone, Carlo; Sabatini, Umberto; Di Paola, Margherita

    2016-01-01

    Background: The late myelinating superficial white matter at the juncture of the cortical gray and white matter comprising the intracortical myelin and short-range association fibers has not received attention in Huntington's disease. It is an area of the brain that is late myelinating and is sensitive to both normal aging and neurodegenerative disease effects. Therefore, it may be sensitive to Huntington's disease processes. Methods: Structural MRI data from 25 Pre-symptomatic subjects, 24 Huntington's disease patients and 49 healthy controls was run through a cortical pattern-matching program. The surface corresponding to the white matter directly below the cortical gray matter was then extracted. Individual subject's Diffusion Tensor Imaging (DTI) data was aligned to their structural MRI data. Diffusivity values along the white matter surface were then sampled at each vertex point. DTI measures with high spatial resolution across the superficial white matter surface were then analyzed with the General Linear Model to test for the effects of disease. Results: There was an overall increase in the axial and radial diffusivity across much of the superficial white matter (p < 0.001) in Pre-symptomatic subjects compared to controls. In Huntington's disease patients increased diffusivity covered essentially the whole brain (p < 0.001). Changes are correlated with genotype (CAG repeat number) and disease burden (p < 0.001). Conclusions: This study showed broad abnormalities in superficial white matter even before symptoms are present in Huntington's disease. Since, the superficial white matter has a unique microstructure and function these abnormalities suggest it plays an important role in the disease. PMID:27242403

  7. Major Superficial White Matter Abnormalities in Huntington disease

    Directory of Open Access Journals (Sweden)

    Owen Robert Phillips

    2016-05-01

    Full Text Available BackgroundThe late myelinating superficial white matter at the juncture of the cortical gray and white matter comprising the intracortical myelin and short-range association fibers has not received attention in Huntington’s disease. It is an area of the brain that is late myelinating and is sensitive to both normal aging and neurodegenerative disease effects. Therefore, it may be sensitive to Huntington’s disease processes. MethodsStructural MRI data from 25 Pre-symptomatic subjects, 24 Huntington’s disease patients and 49 healthy controls was run through a cortical pattern-matching program. The surface corresponding to the white matter directly below the cortical gray matter was then extracted. Individual subject’s Diffusion Tensor Imaging (DTI data was aligned to their structural MRI data. Diffusivity values along the white matter surface were then sampled at each vertex point. DTI measures with high spatial resolution across the superficial white matter surface were then analyzed with the General Linear Model to test for the effects of disease. ResultsThere was an overall increase in the axial and radial diffusivity across much of the superficial white matter (p < 0.001 in Pre-symptomatic subjects compared to controls. In Huntington’s disease patients increased diffusivity covered essentially the whole brain (p < 0.001. Changes are correlated with genotype (CAG repeat number and disease burden (p < 0.001.ConclusionsThis study showed broad abnormalities in superficial white matter even before symptoms are present in Huntington’s disease. Since the superficial white matter has a unique microstructure and function these abnormalities suggest it plays an important role in the disease.

  8. Deep and superficial skin scrapings from a feline immunodeficiency virus-positive cat.

    Science.gov (United States)

    Neel, Jennifer A; Tarigo, Jaime; Tater, Kathy C; Grindem, Carol B

    2007-03-01

    An 8-year-old, neutered male, domestic shorthair cat housed at the North Carolina State University, College of Veterinary Medicine, Laboratory Animal Research facility as part of a research colony was examined because of mulifocal skin lesions. The lesions consisted of patchy alopecia with mild crusting of the periauricular region, neck, and dorsum; periauricular excoriations; marked dorsal seborrhea and scaling; and generalized erythematous papules. A moderate amount of ceruminous exudate was present in both ear canals. Results of testing for feline immunodeficiency virus (FIV) were positive. An ear swab specimen and superficial and deep skin scrapings were obtained, mounted with oil on glass slides, and coverslipped for microscopic examination. Two populations of mites were observed: a large population of slender, long (approximately 200 microm), adult mites with long, tapering abdomens that comprised two-thirds of the total body length; and a smaller population of more translucent and shorter mites (approximately 100 microm) with wide, blunt abdomens that had prominent transverse ridges. The interpretation was demodicosis, with Demodex cati and D gatoi co-infection. Histologic sections of biopsies from skin lesions on the neck, dorsum, and periauricular area contained a mild perivascular and perifollicular inflammatory infiltrate composed predominantly of histiocytes, lymphocytes, and plasma cells. Diffusely within the follicular lumina and occasionally within the superficial keratin, a myriad of Demodex organisms were observed. Intrafollicular mites were compatible in appearance with D cati whereas those in the corneal layer were suggestive of D gatoi. Demodicosis is an uncommon disease of cats, and rare cases of dual infection have been documented, occasionally in FIV-infected cats. The dual infection emphasizes the importance of doing both superficial and deep skin scrapings and of recognizing the unique microscopic features of different Demodex mites.

  9. Exogenous attention facilitates location transfer of perceptual learning.

    Science.gov (United States)

    Donovan, Ian; Szpiro, Sarit; Carrasco, Marisa

    2015-01-01

    Perceptual skills can be improved through practice on a perceptual task, even in adulthood. Visual perceptual learning is known to be mostly specific to the trained retinal location, which is considered as evidence of neural plasticity in retinotopic early visual cortex. Recent findings demonstrate that transfer of learning to untrained locations can occur under some specific training procedures. Here, we evaluated whether exogenous attention facilitates transfer of perceptual learning to untrained locations, both adjacent to the trained locations (Experiment 1) and distant from them (Experiment 2). The results reveal that attention facilitates transfer of perceptual learning to untrained locations in both experiments, and that this transfer occurs both within and across visual hemifields. These findings show that training with exogenous attention is a powerful regime that is able to overcome the major limitation of location specificity.

  10. Perceptual centres in speech - an acoustic analysis

    Science.gov (United States)

    Scott, Sophie Kerttu

    Perceptual centres, or P-centres, represent the perceptual moments of occurrence of acoustic signals - the 'beat' of a sound. P-centres underlie the perception and production of rhythm in perceptually regular speech sequences. P-centres have been modelled both in speech and non speech (music) domains. The three aims of this thesis were toatest out current P-centre models to determine which best accounted for the experimental data bto identify a candidate parameter to map P-centres onto (a local approach) as opposed to the previous global models which rely upon the whole signal to determine the P-centre the final aim was to develop a model of P-centre location which could be applied to speech and non speech signals. The first aim was investigated by a series of experiments in which a) speech from different speakers was investigated to determine whether different models could account for variation between speakers b) whether rendering the amplitude time plot of a speech signal affects the P-centre of the signal c) whether increasing the amplitude at the offset of a speech signal alters P-centres in the production and perception of speech. The second aim was carried out by a) manipulating the rise time of different speech signals to determine whether the P-centre was affected, and whether the type of speech sound ramped affected the P-centre shift b) manipulating the rise time and decay time of a synthetic vowel to determine whether the onset alteration was had more affect on P-centre than the offset manipulation c) and whether the duration of a vowel affected the P-centre, if other attributes (amplitude, spectral contents) were held constant. The third aim - modelling P-centres - was based on these results. The Frequency dependent Amplitude Increase Model of P-centre location (FAIM) was developed using a modelling protocol, the APU GammaTone Filterbank and the speech from different speakers. The P-centres of the stimuli corpus were highly predicted by attributes of

  11. Toward a perceptual theory of transparency.

    Science.gov (United States)

    Singh, Manish; Anderson, Barton L

    2002-07-01

    Theories of perceptual transparency have typically been developed within the context of a physical model that generates the percept of transparency (F. Metelli's episcotister model, 1974b). Here 2 fundamental questions are investigated: (a) When does the visual system initiate the percept of one surface seen through another? (b) How does it assign surface properties to a transparent layer? Results reveal systematic deviations from the predictions of Metelli's model, both for initiating image decomposition into multiple surfaces and for assigning surface attributes. Specifically, results demonstrate that the visual system uses Michelson contrast as a critical image variable to initiate percepts of transparency and to assign transmittance to transparent surfaces. Findings are discussed in relation to previous theories of transparency, lightness, brightness, and contrast-contrast.

  12. Confidence leak in perceptual decision-making

    Science.gov (United States)

    Rahnev, Dobromir; Koizumi, Ai; McCurdy, Li Yan; D’Esposito, Mark; Lau, Hakwan

    2015-01-01

    We live in a continuous environment in which the visual scene changes on a slow timescale. It has been shown that, to exploit such environmental stability, the brain creates a “continuity field” such that objects seen seconds ago influence the perception of current objects. What is unknown is whether a similar mechanism exists at the level of our metacognitive representations. In three experiments we demonstrate a robust inter-task “confidence leak” that cannot be explained by response priming or attentional fluctuations. Observers’ ability to modulate this confidence leak predicted higher capacity for metacognition as well as greater gray matter volume in the prefrontal cortex. A model based on normative principles from Bayesian inference explained the results by postulating that observers subjectively estimate the perceptual signal strength in a stable environment. These results point to the existence of a novel metacognitive mechanism mediated by regions in prefrontal cortex. PMID:26408037

  13. Perceptual effects in auralization of virtual rooms

    Science.gov (United States)

    Kleiner, Mendel; Larsson, Pontus; Vastfjall, Daniel; Torres, Rendell R.

    2002-05-01

    By using various types of binaural simulation (or ``auralization'') of physical environments, it is now possible to study basic perceptual issues relevant to room acoustics, as well to simulate the acoustic conditions found in concert halls and other auditoria. Binaural simulation of physical spaces in general is also important to virtual reality systems. This presentation will begin with an overview of the issues encountered in the auralization of room and other environments. We will then discuss the influence of various approximations in room modeling, in particular, edge- and surface scattering, on the perceived room response. Finally, we will discuss cross-modal effects, such as the influence of visual cues on the perception of auditory cues, and the influence of cross-modal effects on the judgement of ``perceived presence'' and the rating of room acoustic quality.

  14. Asymmetric transfer of auditory perceptual learning

    Directory of Open Access Journals (Sweden)

    Sygal eAmitay

    2012-11-01

    Full Text Available Perceptual skills can improve dramatically even with minimal practice. A major and practical benefit of learning, however, is in transferring the improvement on the trained task to untrained tasks or stimuli, yet the mechanisms underlying this process are still poorly understood. Reduction of internal noise has been proposed as a mechanism of perceptual learning, and while we have evidence that frequency discrimination (FD learning is due to a reduction of internal noise, the source of that noise was not determined. In this study, we examined whether reducing the noise associated with neural phase locking to tones can explain the observed improvement in behavioural thresholds. We compared FD training between two tone durations (15 and 100 ms that straddled the temporal integration window of auditory nerve fibers upon which computational modeling of phase locking noise was based. Training on short tones resulted in improved FD on probe tests of both the long and short tones. Training on long tones resulted in improvement only on the long tones. Simulations of FD learning, based on the computational model and on signal detection theory, were compared with the behavioral FD data. We found that improved fidelity of phase locking accurately predicted transfer of learning from short to long tones, but also predicted transfer from long to short tones. The observed lack of transfer from long to short tones suggests the involvement of a second mechanism. Training may have increased the temporal integration window which could not transfer because integration time for the short tone is limited by its duration. Current learning models assume complex relationships between neural populations that represent the trained stimuli. In contrast, we propose that training-induced enhancement of the signal-to-noise ratio offers a parsimonious explanation of learning and transfer that easily accounts for asymmetric transfer of learning.

  15. Perceptual grouping determines haptic contextual modulation.

    Science.gov (United States)

    Overvliet, K E; Sayim, B

    2016-09-01

    Since the early phenomenological demonstrations of Gestalt principles, one of the major challenges of Gestalt psychology has been to quantify these principles. Here, we show that contextual modulation, i.e. the influence of context on target perception, can be used as a tool to quantify perceptual grouping in the haptic domain, similar to the visual domain. We investigated the influence of target-flanker grouping on performance in haptic vernier offset discrimination. We hypothesized that when, despite the apparent differences between vision and haptics, similar grouping principles are operational, a similar pattern of flanker interference would be observed in the haptic as in the visual domain. Participants discriminated the offset of a haptic vernier. The vernier was flanked by different flanker configurations: no flankers, single flanking lines, 10 flanking lines, rectangles and single perpendicular lines, varying the degree to which the vernier grouped with the flankers. Additionally, we used two different flanker widths (same width as and narrower than the target), again to vary target-flanker grouping. Our results show a clear effect of flankers: performance was much better when the vernier was presented alone compared to when it was presented with flankers. In the majority of flanker configurations, grouping between the target and the flankers determined the strength of interference, similar to the visual domain. However, in the same width rectangular flanker condition we found aberrant results. We discuss the results of our study in light of similarities and differences between vision and haptics and the interaction between different grouping principles. We conclude that in haptics, similar organization principles apply as in visual perception and argue that grouping and Gestalt are key organization principles not only of vision, but of the perceptual system in general.

  16. Size-sensitive perceptual representations underlie visual and haptic object recognition.

    Directory of Open Access Journals (Sweden)

    Matt Craddock

    Full Text Available A variety of similarities between visual and haptic object recognition suggests that the two modalities may share common representations. However, it is unclear whether such common representations preserve low-level perceptual features or whether transfer between vision and haptics is mediated by high-level, abstract representations. Two experiments used a sequential shape-matching task to examine the effects of size changes on unimodal and crossmodal visual and haptic object recognition. Participants felt or saw 3D plastic models of familiar objects. The two objects presented on a trial were either the same size or different sizes and were the same shape or different but similar shapes. Participants were told to ignore size changes and to match on shape alone. In Experiment 1, size changes on same-shape trials impaired performance similarly for both visual-to-visual and haptic-to-haptic shape matching. In Experiment 2, size changes impaired performance on both visual-to-haptic and haptic-to-visual shape matching and there was no interaction between the cost of size changes and direction of transfer. Together the unimodal and crossmodal matching results suggest that the same, size-specific perceptual representations underlie both visual and haptic object recognition, and indicate that crossmodal memory for objects must be at least partly based on common perceptual representations.

  17. Associative (prosop)agnosia without (apparent) perceptual deficits: a case-study.

    Science.gov (United States)

    Anaki, David; Kaufman, Yakir; Freedman, Morris; Moscovitch, Morris

    2007-04-09

    In associative agnosia early perceptual processing of faces or objects are considered to be intact, while the ability to access stored semantic information about the individual face or object is impaired. Recent claims, however, have asserted that associative agnosia is also characterized by deficits at the perceptual level, which are too subtle to be detected by current neuropsychological tests. Thus, the impaired identification of famous faces or common objects in associative agnosia stems from difficulties in extracting the minute perceptual details required to identify a face or an object. In the present study, we report the case of a patient DBO with a left occipital infarct, who shows impaired object and famous face recognition. Despite his disability, he exhibits a face inversion effect, and is able to select a famous face from among non-famous distractors. In addition, his performance is normal in an immediate and delayed recognition memory for faces, whose external features were deleted. His deficits in face recognition are apparent only when he is required to name a famous face, or select two faces from among a triad of famous figures based on their semantic relationships (a task which does not require access to names). The nature of his deficits in object perception and recognition are similar to his impairments in the face domain. This pattern of behavior supports the notion that apperceptive and associative agnosia reflect distinct and dissociated deficits, which result from damage to different stages of the face and object recognition process.

  18. Cholinergic enhancement augments magnitude and specificity of visual perceptual learning in healthy humans.

    Science.gov (United States)

    Rokem, Ariel; Silver, Michael A

    2010-10-12

    Learning through experience underlies the ability to adapt to novel tasks and unfamiliar environments. However, learning must be regulated so that relevant aspects of the environment are selectively encoded. Acetylcholine (ACh) has been suggested to regulate learning by enhancing the responses of sensory cortical neurons to behaviorally relevant stimuli. In this study, we increased synaptic levels of ACh in the brains of healthy human subjects with the cholinesterase inhibitor donepezil (trade name: Aricept) and measured the effects of this cholinergic enhancement on visual perceptual learning. Each subject completed two 5 day courses of training on a motion direction discrimination task, once while ingesting 5 mg of donepezil before every training session and once while placebo was administered. We found that cholinergic enhancement augmented perceptual learning for stimuli having the same direction of motion and visual field location used during training. In addition, perceptual learning with donepezil was more selective to the trained direction of motion and visual field location. These results, combined with previous studies demonstrating an increase in neuronal selectivity following cholinergic enhancement, suggest a possible mechanism by which ACh augments neural plasticity by directing activity to populations of neurons that encode behaviorally relevant stimulus features.

  19. Visual-perceptual impairment in children with cerebral palsy: a systematic review.

    Science.gov (United States)

    Ego, Anne; Lidzba, Karen; Brovedani, Paola; Belmonti, Vittorio; Gonzalez-Monge, Sibylle; Boudia, Baya; Ritz, Annie; Cans, Christine

    2015-04-01

    Visual perception is one of the cognitive functions often impaired in children with cerebral palsy (CP). The aim of this systematic literature review was to assess the frequency of visual-perceptual impairment (VPI) and its relationship with patient characteristics. Eligible studies were relevant papers assessing visual perception with five common standardized assessment instruments in children with CP published from January 1990 to August 2011. Of the 84 studies selected, 15 were retained. In children with CP, the proportion of VPI ranged from 40% to 50% and the mean visual perception quotient from 70 to 90. None of the studies reported a significant influence of CP subtype, IQ level, side of motor impairment, neuro-ophthalmological outcomes, or seizures. The severity of neuroradiological lesions seemed associated with VPI. The influence of prematurity was controversial, but a lower gestational age was more often associated with lower visual motor skills than with decreased visual-perceptual abilities. The impairment of visual perception in children with CP should be considered a core disorder within the CP syndrome. Further research, including a more systematic approach to neuropsychological testing, is needed to explore the specific impact of CP subgroups and of neuroradiological features on visual-perceptual development. © 2015 The Authors. Developmental Medicine & Child Neurology © 2015 Mac Keith Press.

  20. Linking Ecological and Perceptual Assessments for Environmental Management: a Coral Reef Case Study

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Dinsdale

    2009-12-01

    Full Text Available Integrating information from a range of community members in environmental management provides a more complete assessment of the problem and a diversification of management options, but is difficult to achieve. To investigate the relationship between different environmental interpretations, I compared three distinct measures of anchor damage on coral reefs: ecological measures, perceptual meanings, and subjective health judgments. The ecological measures identified an increase in the number of overturned corals and a reduction in coral cover, the perceptual meanings identified a loss of visual quality, and the health judgments identified a reduction in the health of the coral reef sites associated with high levels of anchoring. Combining the perceptual meanings and health judgments identified that the judgment of environmental health was a key feature that both scientific and lay participants used to describe the environment. Some participants in the survey were familiar with the coral reef environment, and others were not. However, they provided consistent judgment of a healthy coral reef, suggesting that these judgments were not linked to present-day experiences. By combining subjective judgments and ecological measures, the point at which the environment is deemed to lose visual quality was identified; for these coral reefs, if the level of damage rose above 10.3% and the cover of branching corals dropped below 17.1%, the reefs were described as unhealthy. Therefore, by combining the information, a management agency can involve the community in identifying when remedial action is required or when management policies are effectively maintaining a healthy ecosystem.

  1. Spread spectrum image watermarking based on perceptual quality metric.

    Science.gov (United States)

    Zhang, Fan; Liu, Wenyu; Lin, Weisi; Ngan, King Ngi

    2011-11-01

    Efficient image watermarking calls for full exploitation of the perceptual distortion constraint. Second-order statistics of visual stimuli are regarded as critical features for perception. This paper proposes a second-order statistics (SOS)-based image quality metric, which considers the texture masking effect and the contrast sensitivity in Karhunen-Loève transform domain. Compared with the state-of-the-art metrics, the quality prediction by SOS better correlates with several subjectively rated image databases, in which the images are impaired by the typical coding and watermarking artifacts. With the explicit metric definition, spread spectrum watermarking is posed as an optimization problem: we search for a watermark to minimize the distortion of the watermarked image and to maximize the correlation between the watermark pattern and the spread spectrum carrier. The simple metric guarantees the optimal watermark a closed-form solution and a fast implementation. The experiments show that the proposed watermarking scheme can take full advantage of the distortion constraint and improve the robustness in return.

  2. Patterns of superficial fibre formation in the European pearlfish (Rutilus frisii meidingeri) provide a general template for slow muscle development in teleost fish.

    Science.gov (United States)

    Stoiber, W; Haslett, J R; Goldschmid, A; Sänger, A M

    1998-06-01

    The debate about the pattern of muscle formation in teleost fish has recently been heightened in the literature. Here we examine superficial muscle development in the pearlfish, a cyprinid endemic to a small area of Central Europe, and uninfluenced by economic interest and breeding. Using light and electron microscopy, histochemistry and immunohistochemistry techniques, we report that: (1) Superficial fibre precursors originate close to the notochord, are part of the same cell population as the so-called muscle pioneer cells, and are transferred laterally to end up at the surface of the myotome. (2) Superficial fibre maturation is exceptionally rapid. Structural and enzymatic functionality is attained at a time when prospective deep fibres have not passed beyond the early myotube state. This strong contrast weakens as the embryo develops. (3) Apart from the muscle pioneers, the superficial fibres appear to be capable of functioning before they receive any direct innervation, implying that signals are transferred to these fibres via cell-to-cell junctions. We suggest that the capability of rapid superficial fibre maturation is a rather general feature among teleosts and may aid pre-hatch survival under a variable environment. Our results indicate that muscle formation in teleost fish may follow a common basic pattern that is open to considerable ontogenetic and phylogenetic modification in response to habitat conditions.

  3. A combined chemo-mechanical approach for aesthetic management of superficial enamel defects

    NARCIS (Netherlands)

    Ardu, S.; Benbachir, N.; Stavridakis, M.; Dietschi, D.L.; Krejci, I.; Feilzer, A.J.

    2009-01-01

    Objective The aim of this article is to describe an easy technique for managing small superficial defects in light to medium fluorosis. Method and materials The proposed technique is based on a selective abrasion of the superficial enamel and a recreation of the superficial macro and micro morpholog

  4. A combined chemo-mechanical approach for aesthetic management of superficial enamel defects

    NARCIS (Netherlands)

    Ardu, S.; Benbachir, N.; Stavridakis, M.; Dietschi, D.L.; Krejci, I.; Feilzer, A.J.

    2009-01-01

    Objective The aim of this article is to describe an easy technique for managing small superficial defects in light to medium fluorosis. Method and materials The proposed technique is based on a selective abrasion of the superficial enamel and a recreation of the superficial macro and micro morpholog

  5. Auditory-perceptual learning improves speech motor adaptation in children.

    Science.gov (United States)

    Shiller, Douglas M; Rochon, Marie-Lyne

    2014-08-01

    Auditory feedback plays an important role in children's speech development by providing the child with information about speech outcomes that is used to learn and fine-tune speech motor plans. The use of auditory feedback in speech motor learning has been extensively studied in adults by examining oral motor responses to manipulations of auditory feedback during speech production. Children are also capable of adapting speech motor patterns to perceived changes in auditory feedback; however, it is not known whether their capacity for motor learning is limited by immature auditory-perceptual abilities. Here, the link between speech perceptual ability and the capacity for motor learning was explored in two groups of 5- to 7-year-old children who underwent a period of auditory perceptual training followed by tests of speech motor adaptation to altered auditory feedback. One group received perceptual training on a speech acoustic property relevant to the motor task while a control group received perceptual training on an irrelevant speech contrast. Learned perceptual improvements led to an enhancement in speech motor adaptation (proportional to the perceptual change) only for the experimental group. The results indicate that children's ability to perceive relevant speech acoustic properties has a direct influence on their capacity for sensory-based speech motor adaptation.

  6. The neural basis of implicit perceptual sequence learning

    Directory of Open Access Journals (Sweden)

    Freja eGheysen

    2011-11-01

    Full Text Available The present fMRI study investigated the neural areas involved in implicit perceptual sequence learning. To obtain more insight in the functional contributions of the brain areas, we tracked both the behavioral and neural time course of the learning process, using a perceptual serial color matching task. Next, to investigate whether the neural time course was specific for perceptual information, imaging results were compared to the results of implicit motor sequence learning, previously investigated using an identical serial color matching task. Results indicated that implicit sequences can be acquired by at least two neural systems: the caudate nucleus and the hippocampus, having different operating principles. The caudate nucleus contributed to the implicit sequence learning process for perceptual as well as motor information in a similar and gradual way. The hippocampus, on the other hand, was engaged in a much faster learning process which was more pronounced for the motor compared to the perceptual task. Interestingly, the perceptual and motor learning process occurred on a comparable implicit level, suggesting that consciousness is not the main determinant factor dissociating the hippocampal from the caudate learning system. This study is not only the first to successfully and unambiguously compare brain activation between perceptual and motor levels of implicit sequence learning, it also provides new insights into the specific hippocampal and caudate learning function.

  7. Rugosidad y textura de superficies: experimentos y simulaciones

    Directory of Open Access Journals (Sweden)

    Watson L. Vargas

    2006-01-01

    Full Text Available En este trabajo se aplican algunos elementos de la geometría fractal al estudio y caracterización de la rugosidad superficial. Los materiales bajo estudio consisten en agregados naturales, de amplia aplicación en la industria de la construcción. Se aplican tanto técnicas experimentales basadas en análisis de imágenes como modelos teóricos. En particular se explora el potencial de la lacunaridad –un método de análisis derivado de la geometría fractal, para describir patrones y dispersión espacial. Los resultados ilustran su aplicación en la caracterización de rugosidad superficial. Se discuten igualmente, limitaciones y ventajas de esta aproximación.

  8. Effects of superficial gas velocity on process dynamics in bioreactors

    Science.gov (United States)

    Devi, T. T.; Kumar, B.

    2014-06-01

    Present work analyzes the flow hydrodynamics and mass transfer mechanisms in double Rushton and CD-6 impeller on wide range (0.0075-0.25 m/s) of superficial gas velocity ( v g) in a gas-liquid phase bioreactor by employing computational fluid dynamics (CFD) technique. The volume averaged velocity magnitude and dissipation rate are found higher with increasing superficial gas velocity. Higher relative power draw ( P g/ P 0) is predicted in CD-6 than the Rushton impeller but no significant difference in volume averaged mass transfer coefficient ( k L a) observed between these two types of impeller. The ratio of power draw with mass transfer coefficient has been found higher in CD-6 impeller (25-50 %) than the Rushton impeller.

  9. Variation in the Branching Pattern of the Superficial Palmar Arch

    Directory of Open Access Journals (Sweden)

    Sumalatha S

    2016-05-01

    Full Text Available In this article we describe a rare variation in the superficial palmar arch (SPA encountered during routine cadaveric dissection. SPA was formed by the superficial branches of ulnar and radial arteries which provided a proper digital branch to the ulnar side of the little finger and three common palmar digital branches to the medial four digits. Additionally a first common digital artery was seen to emerge from the radial side of SPA which further divided into the arteria princeps pollicis and arteria radialis indicis. We also found a small communicating branch between the arteria princeps pollicis and the radial artery in the anatomical snuff box. Such arterial variations in the palm due to alteration in the developmental sequence remains a crucial issue in the reconstructive hand surgeries, especially while dealing with the innovative microsurgical procedures, where these varied patterns act as pivotal points around which successful results of various advanced surgical procedures revolve.

  10. Movimiento superficial del glaciar rocoso de las Argualas

    Directory of Open Access Journals (Sweden)

    Sanjosé, J. J.

    1995-12-01

    Full Text Available At present the Argualas rock glacier is active and it flows to a surface axial mean velocity of 22,3 cm/year. The flow velocities have been determinated by surveying techniques made between 1991 and 1994. This technic complements the geomorphological observations and deepens in the knov/ledge of the glacier surface dynamics.

    El glaciar rocoso de las Argualas es activo en la actualidad y fluye a una velocidad media axial en superficie de 22.3 cm/año. El flujo se ha determinado median te las técnicas de auscultación topográfica realizadas entre los años 1991 y 1994. Esta técnica ha permitido complementar el análisis geomorfológico, profundizado en el estudio de la dinámica superficial del glaciar.

  11. Endoscopic removal or ablation of oesophageal and gastric superficial tumours.

    Science.gov (United States)

    Deprez, P H; Aouattah, T; Piessevaux, H

    2006-01-01

    Endoscopic mucosal resection was developed in Eastern countries as a curative treatment for superficial carcinomas in the stomach and oesophagus. Experience in Western countries is more recent and limited due to less frequent diagnosis of early gastric cancers compared to the Japanese and Korean populations and to more frequent use of ablation techniques such as argon plasma coagulation and photodynamic therapy in pre-neoplastic lesions and superficial tumours. This review summarizes the respective indications, advantages, disadvantages, limitations and complications of the different ablative and resection techniques in the upper gastrointestinal tract. Several methods are described such as electrocoagulation, argon plasma coagulation, photodynamic therapy, lift and cut resection, cap assisted aspiration and band ligation mucosectomy, and endoscopic submucosal dissection. Local results in more than 170 patients managed with endoscopic resection of oesophageal high grade dysplasia or squamous cell carcinoma and gastric or Barrett's epithelium high grade dysplasia or adenocarcinoma furthermore demonstrate the safety and effectiveness of endoscopic resection practiced in experienced centres.

  12. Causative agents of superficial mycoses in Istanbul, Turkey: retrospective study.

    Science.gov (United States)

    Koksal, Fatma; Er, Emine; Samasti, Mustafa

    2009-09-01

    The aim of the present study was to determine the percentage of agents, which can give rise to superficial fungal infections in Istanbul, Turkey. Between 2000 and 2007, the clinical samples collected from 8,200 patients attending the outpatient Dermatology Clinic at Mihrimahsultan Medical Center were examined by direct microscopy and culture. Pathogen fungi were detected in 5,722 of the patients. Of the isolates were 4,218 (74%) dermatophytes, 1,196 (21%) Candida sp., 170 (3%) Malassezia furfur, and 138 (2%) Trichosporon sp. Among the dermatophytes, Trichophyton sp. was the most common isolate followed by Epidermophyton floccosum (243) and Microsporum sp. Among the Candida species, C. albicans (549) was also frequently found. Onychomycosis was the most prevalent type of infection, followed by tinea pedis, tinea cruris, tinea corporis, and tinea capitis. In conclusion, our study showed that the most common isolated agents from superficial infections were T. rubrum being Candida sp. the second most prevalent.

  13. Measurement of the angle of superficial tension by images

    Science.gov (United States)

    Yanez M., Javier; Alonso R., Sergio

    2006-02-01

    When a liquid is deposited on a surface, this one form a certain angle with respect to the surface, where depending on its value, it will conclude that so hard it is his adhesion with the surface. By means of the analysis of images we looked for to measure this angle of superficial tension. In order to make this measurement, we propose a technique by means of projective transformations and one method of regression to estimation parameters to conic fitting.

  14. Cervical Spinal Meningeal Melanocytoma Presenting as Intracranial Superficial Siderosis

    Directory of Open Access Journals (Sweden)

    Savitha Srirama Jayamma

    2015-01-01

    Full Text Available Meningeal melanocytoma is a rare pigmented tumor of the leptomeningeal melanocytes. This rare entity results in diagnostic difficulty in imaging unless clinical and histopathology correlation is performed. In this case report, we describe a case of meningeal melanocytoma of the cervical region presenting with superficial siderosis. Extensive neuroradiological examination is necessary to locate the source of the bleeding in such patients. Usually, the patient will be cured by the complete surgical excision of the lesion.

  15. Superficial urinary bladder tumors treatment results: A 10-year experience

    Directory of Open Access Journals (Sweden)

    Stanković Jablan

    2007-01-01

    Full Text Available Background/Aim. The most common urinary bladder tumors are superficial tumors. Due to their tension to relapse and progress towards deeper layers after surgical therapy, an adequate therapy significantly contributed to the improvement of the results of urinary bladder tumors treatment. Staging and gradus of the tumor, presence of the carcinoma in situ (CIS or relapses significantly influenced the choice of the therapy. The aim of this study was to ascertain the effectiveness of the intravesicelly applied BCG (Bacille Colmette - Guerin vaccine or chemiotherapy in the prevention of the relapses and further progression of superficial urinary bladder tumors. Methods. All of the diagnosed superficial tumors of bladder were removed by transurethral resection (TUR. After receiving the patohistological finding they were subjected to adjuvant therapy, immune BCG vaccine or chemiotherapy (epirubicin, doxorubicin, mitomycin-C. The third group did not accept adjuvant therapy, but had regularly scheduled cystoscopic controls. The appearance of relapses, progression of stage and grades of the tumor, as well as possible unwanted effects of adjuvant therapy were registered. Results. The applied immunotherapy (BCG influenced decreased tumor relapses (7% and statistically important difference between patients who had taken adjuvant chemotherapy (relapses 18.4% and those without this therapy was acknowledged. Grades of tumor did not show statistically significant difference on tumor relapse. A significantly longer period of time in the appearance of tumor relapse after BCG (29.33 months, had significant importance comparing to chemio (9.44 months or non-taken adjuvant therapy (9.84 months. Very small number of unwanted effects suggested an obligatory undertaking adjuvant therapy after TUR of superficial tumors. Conclusion. A significant decrease of relapses as well as avoidance of further progression of urinary bladder tumors, has introduced adjuvant therapy in

  16. Transient superficial peroneal nerve palsy after anterior cruciate ligament reconstruction

    OpenAIRE

    Majed Alrowaili

    2016-01-01

    A 19-year-old male subject was diagnosed with medial meniscal, lateral meniscal and anterior cruciate ligament (ACL) tear. The symptoms did not subside after 4 months of physical therapy, and he underwent arthroscopic partial medial and lateral meniscectomy and ACL reconstruction. Immediately after the patient woke up from general anesthesia, he started experience loss of sensation in the area of superficial peroneal nerve with inverted dorsiflexion of foot and ankle. Instantly, the bandage a...

  17. Attentional sets influence perceptual load effects, but not dilution effects.

    Science.gov (United States)

    Benoni, Hanna; Zivony, Alon; Tsal, Yehoshua

    2014-01-01

    Perceptual load theory [Lavie, N. (1995). Perceptual load as a necessary condition for selective attention. Journal of Experimental Psychology: Human Perception and Performance, 21, 451-468.; Lavie, N., & Tsal, Y. (1994) Perceptual load as a major determinant of the locus of selection in visual attention. Perception & Psychophysics, 56, 183-197.] proposes that interference from distractors can only be avoided in situations of high perceptual load. This theory has been supported by blocked design manipulations separating low load (when the target appears alone) and high load (when the target is embedded among neutral letters). Tsal and Benoni [(2010a). Diluting the burden of load: Perceptual load effects are simply dilution effects. Journal of Experimental Psychology: Human Perception and Performance, 36, 1645-1656.; Benoni, H., & Tsal, Y. (2010). Where have we gone wrong? Perceptual load does not affect selective attention. Vision Research, 50, 1292-1298.] have recently shown that these manipulations confound perceptual load with "dilution" (the mere presence of additional heterogeneous items in high-load situations). Theeuwes, Kramer, and Belopolsky [(2004). Attentional set interacts with perceptual load in visual search. Psychonomic Bulletin & Review, 11, 697-702.] independently questioned load theory by suggesting that attentional sets might also affect distractor interference. When high load and low load were intermixed, and participants could not prepare for the presentation that followed, both the low-load and high-load trials showed distractor interference. This result may also challenge the dilution account, which proposes a stimulus-driven mechanism. In the current study, we presented subjects with both fixed and mixed blocks, including a mix of dilution trials with low-load trials and with high-load trials. We thus separated the effect of dilution from load and tested the influence of attentional sets on each component. The results revealed that whereas

  18. Differences in excitability between median and superficial radial sensory axons.

    Science.gov (United States)

    Fujimaki, Yumi; Kanai, Kazuaki; Misawa, Sonoko; Shibuya, Kazumoto; Isose, Sagiri; Nasu, Saiko; Sekiguchi, Yukari; Ohmori, Shigeki; Noto, Yu-ichi; Kugio, Yumiko; Shimizu, Toshio; Matsubara, Shiro; Lin, Cindy S Y; Kuwabara, Satoshi

    2012-07-01

    The aim of this study was to investigate differences in excitability properties of human median and superficial radial sensory axons (e.g., axons innervating the glabrous and hairy skin in the hand). Previous studies have shown that excitability properties differ between motor and sensory axons, and even among sensory axons between median and sural sensory axons. In 21 healthy subjects, threshold tracking was used to examine excitability indices such as strength-duration time constant, threshold electrotonus, supernormality, and threshold change at the 0.2 ms inter-stimulus interval in latent addition. In addition, threshold changes induced by ischemia for 10 min were compared between median and superficial radial sensory axons. Compared with radial sensory axons, median axons showed shorter strength-duration time constant, greater threshold changes in threshold electrotonus (fanning-out), greater supernormality, and smaller threshold changes in latent addition. Threshold changes in both during and after ischemia were greater for median axons. These findings suggest that membrane potential in human median sensory axons is more negative than in superficial radial axons, possibly due to greater activity of electrogenic Na(+)/K(+) pump. These results may reflect adaptation to impulses load carried by median axons that would be far greater with a higher frequency. Biophysical properties are not identical in different human sensory axons, and therefore their responses to disease may differ. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  19. A Study of Superficial Mycosis in South Gujarat Region

    Directory of Open Access Journals (Sweden)

    Parul Patel, Summaiya Mulla, Disha Patel, Gaurishankar Shrimali

    2010-12-01

    Full Text Available Aim: To know the seroprevalence of clinical pattern of dermatophytosis and non – dermatophytic fungi (superficial mycosis with most common fungal pathogen in the South Gujarat region of the India. Methods: A clinical and mycological study of superficial mycosis was conducted on 198 cases (127 male and 71 female. Direct microscopy by KOH mount and culture was undertaken to isolate the fungal pathogen in each case. Results: 123 out of 198 cases (62.12% were positive by direct microscopy in which 58 (29.29% were positive by culture. The commonest age group involved was 21 – 30 years. Tinea corporis was the most common clinical presentation and Trichopyton rubrum was the most common fungal pathogen isolated. Non dermatophytic fungus like pityriasis versicolor and yeast like candida species were isolated in 17(22.67% cased and 8 (10.67% cases respectively. Conclusion: It was concluded that along with dermatophytes, nondermatophytic fungi are also emerging as important causes of superficial mycosis.

  20. Double Sided Watermark Embedding and Detection with Perceptual Analysis

    CERN Document Server

    Zhong, Jidong

    2007-01-01

    In our previous work, we introduced a double-sided technique that utilizes but not reject the host interference. Due to its nice property of utilizing but not rejecting the host interference, it has a big advantage over the host interference schemes in that the perceptual analysis can be easily implemented for our scheme to achieve the locally bounded maximum embedding strength. Thus, in this work, we detail how to implement the perceptual analysis in our double-sided schemes since the perceptual analysis is very important for improving the fidelity of watermarked contents. Through the extensive performance comparisons, we can further validate the performance advantage of our double-sided schemes.

  1. Caracterización físico-química de la superficie de 9 implantes dentales con 3 distintos tratamientos de superficie

    OpenAIRE

    Rodríguez Rius, Daniel; García Sabán, Francisco

    2005-01-01

    Existen diversos tratamientos de superficie aplicados a los implantes dentales. El objetivo del presente estudio es comparar las características físico-químicas de la superficie de implantes dentales de titanio sometidos a diversos tratamientos de superficie. 9 implantes dentales procedentes del mismo lote de fabricación fueron separados en 3 grupos y sometidos a 3 tipos de tratamiento de superficie diferentes: mecanizado, grabado ácido y un ataque químico denominado Avan...

  2. Diagnostic utility of narrow-band imaging endoscopy for pharyngeal superficial carcinoma

    Institute of Scientific and Technical Information of China (English)

    Noboru Yoshimura; Kenichi Goda; Hisao Tajiri; Yukinaga Yoshida; Takakuni Kato; Yoichi Seino; Masahiro Ikegami; Mitsuyoshi Urashima

    2011-01-01

    AIM: To investigate the endoscopic features of pha-ryngeal superficial carcinoma and evaluate the utility of narrow-band imaging (NBI) for this disease.METHODS: In the present prospective study, 335 patients underwent conventional white light (CWL) en-doscopy and non-magnified/magnified NBI endoscopy, followed by an endoscopic biopsy, for 445 superficial lesions in the oropharynx and hypopharynx. The macroscopic appearance of superficial lesions was categorized as either elevated (< 5 mm in height), flat, or depressed (not ulcerous). Superficial carcinoma (SC) was defined as a superficial lesion showing high-grade dysplasia or squamous cell carcinoma on histology. The color, delineation, and macroscopic appearances of the lesions were evaluated by CWL endoscopy. The ratio of the brownish area/intervascular brownish epithelium (IBE), as well as microvascular proliferation, dilation, and irregularities, was determined by non-magnified/ magnified NBI endoscopy. An experienced pathologist who was unaware of the endoscopic findings made the histological diagnoses. By comparing endoscopic findings with histology, we determined the endoscopic features of SC and evaluated the diagnostic utility of NBI.RESULTS: The 445 lesions were divided histologically into two groups: a non-SC group, including non-neo-plasia and low-grade dysplasia cases, and an SC group. Of the 445 lesions examined, 333 were classified as non-SC and 112 were classified as SC. There were no significant differences in age, gender, or the location of the lesions between the patients in the two groups. The mean diameter of the SC lesions was significantly greater than that of non-SC lesions (11.0 7.6 mm vs 4.6 3.6 mm, respectively, P < 0.001). Comparisons of CWL endoscopy findings for SC and non-SC lesions by univariate analysis revealed that the incidence of redness (72% vs 41%, respectively, P< 0.001) and a flat or depressed type of lesion (58% vs 44%, respectively, P = 0.013) was significantly higher in

  3. Spoken Language Identification Using Hybrid Feature Extraction Methods

    CERN Document Server

    Kumar, Pawan; Mishra, A N; Chandra, Mahesh

    2010-01-01

    This paper introduces and motivates the use of hybrid robust feature extraction technique for spoken language identification (LID) system. The speech recognizers use a parametric form of a signal to get the most important distinguishable features of speech signal for recognition task. In this paper Mel-frequency cepstral coefficients (MFCC), Perceptual linear prediction coefficients (PLP) along with two hybrid features are used for language Identification. Two hybrid features, Bark Frequency Cepstral Coefficients (BFCC) and Revised Perceptual Linear Prediction Coefficients (RPLP) were obtained from combination of MFCC and PLP. Two different classifiers, Vector Quantization (VQ) with Dynamic Time Warping (DTW) and Gaussian Mixture Model (GMM) were used for classification. The experiment shows better identification rate using hybrid feature extraction techniques compared to conventional feature extraction methods.BFCC has shown better performance than MFCC with both classifiers. RPLP along with GMM has shown be...

  4. BCG and the treatment of superficial bladder cancer.

    Science.gov (United States)

    Moss, J T; Kadmon, D

    1991-12-01

    In this report, we review the evolution of bacillus Calmette-Guérin (BCG) immunotherapy as a legitimate form of treatment in superficial, nonmuscle-invasive bladder cancer. In the US, an estimated 45,000 new cases of bladder cancer are diagnosed each year and the annual death rate approaches 11,000. Approximately 70 percent of these cancers are superficial at the time of initial presentation. The treatment of superficial bladder cancer has three objectives: (1) eradication of existing disease, (2) prophylaxis against tumor recurrence, and (3) prevention of tumor progression (either muscular invasion, metastatic spread, or both). Cystectomy generally is reserved for muscle-invasive disease. Transurethral resection of the bladder tumor is the preferred initial therapy. Intravesical instillations of various chemotherapeutic agents following transurethral resection have been extensively investigated. Some of the common agents used include thiotepa, mitomycin, and doxorubicin. Despite such treatment efforts, however, over 40 percent of patients with superficial bladder cancer experience a recurrence of their tumor within three years. Approximately half of these recurrences either present as less-well-differentiated tumors or have already penetrated into the bladder musculature, metastasized, or both. Since Morales et al. first introduced intravesical BCG vaccine for prophylaxis as well as for treatment of superficial bladder tumors in 1976, support has grown rapidly for its use as an alternative to chemotherapy. When used with prophylactic intent following transurethral resection, recurrence rates are lower than those achieved with other agents. In addition, BCG is emerging as the consensus drug of choice for treating carcinoma in situ of the bladder. The mechanisms by which BCG exerts its antitumor activity remain largely unknown. BCG is thought to stimulate a localized, nonspecific inflammatory response that leads to subsequent shedding of tumor cells. A large body

  5. Superficial perineal leiomyosarcoma in an adolescent female and a review of the literature including vulvar leiomyosarcomas

    DEFF Research Database (Denmark)

    Grove, A; Backman Nøhr, S

    1992-01-01

    differentiated and showed immunoreactivity for alpha-smooth muscle actin and desmin. A review of the literature on superficial leiomyosarcomas indicates that superficial perineal leiomyosarcomas may be more aggressive than superficial leiomyosarcomas in general. As the presented tumour occurred in a female......Superficial perineal leiomyosarcomas are rare, with only three previously reported examples. We encountered a superficial (deep subcutaneous) perineal leiomyosarcoma in a 17-year-old female. At follow-up two years after a wide excision, there were no signs of recurrence. The tumour was well...

  6. Neuroimaging Evidence for 2 Types of Plasticity in Association with Visual Perceptual Learning.

    Science.gov (United States)

    Shibata, Kazuhisa; Sasaki, Yuka; Kawato, Mitsuo; Watanabe, Takeo

    2016-09-01

    Visual perceptual learning (VPL) is long-term performance improvement as a result of perceptual experience. It is unclear whether VPL is associated with refinement in representations of the trained feature (feature-based plasticity), improvement in processing of the trained task (task-based plasticity), or both. Here, we provide empirical evidence that VPL of motion detection is associated with both types of plasticity which occur predominantly in different brain areas. Before and after training on a motion detection task, subjects' neural responses to the trained motion stimuli were measured using functional magnetic resonance imaging. In V3A, significant response changes after training were observed specifically to the trained motion stimulus but independently of whether subjects performed the trained task. This suggests that the response changes in V3A represent feature-based plasticity in VPL of motion detection. In V1 and the intraparietal sulcus, significant response changes were found only when subjects performed the trained task on the trained motion stimulus. This suggests that the response changes in these areas reflect task-based plasticity. These results collectively suggest that VPL of motion detection is associated with the 2 types of plasticity, which occur in different areas and therefore have separate mechanisms at least to some degree. © The Author 2016. Published by Oxford University Press.

  7. Role and Development of Perceptual Skills in Medical Education

    NARCIS (Netherlands)

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

    2011-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2010, May). Role and Development of Perceptual Skills in Medical Education. The Scandinavian Workshop on Applied Eye-Tracking (SWAET), Lund, Sweden.

  8. Cultural differences in perceptual reorganization in US and Piraha adults.

    Directory of Open Access Journals (Sweden)

    Jennifer M D Yoon

    Full Text Available Visual illusions and other perceptual phenomena can be used as tools to uncover the otherwise hidden constructive processes that give rise to perception. Although many perceptual processes are assumed to be universal, variable susceptibility to certain illusions and perceptual effects across populations suggests a role for factors that vary culturally. One striking phenomenon is seen with two-tone images-photos reduced to two tones: black and white. Deficient recognition is observed in young children under conditions that trigger automatic recognition in adults. Here we show a similar lack of cue-triggered perceptual reorganization in the Pirahã, a hunter-gatherer tribe with limited exposure to modern visual media, suggesting such recognition is experience- and culture-specific.

  9. Vowel normalization : a perceptual-acoustic study of Dutch vowels

    NARCIS (Netherlands)

    Adank, Patricia Martine

    2003-01-01

    In sociolinguistics, language variation in vowel sounds is typically studied using phonetic transcription. Phonetic transcription is carried out by expert listeners, who are capable of perceptually separating (socio-) linguistic variation from anatomical/physiological speaker-related

  10. Perceptual discrimination in fear generalization: Mechanistic and clinical implications.

    Science.gov (United States)

    Struyf, Dieter; Zaman, Jonas; Vervliet, Bram; Van Diest, Ilse

    2015-12-01

    For almost a century, Pavlovian conditioning is the imperative experimental paradigm to investigate the development and generalization of fear. However, despite the rich research tradition, the conceptualization of fear generalization has remained somewhat ambiguous. In this selective review, we focus explicitly on some challenges with the current operationalization of fear generalization and their impact on the ability to make inferences on its clinical potential and underlying processes. The main conclusion is that, despite the strong evidence that learning influences perception, current research has largely neglected the role of perceptual discriminability and its plasticity in fear generalization. We propose an alternative operationalization of generalization, where the essence is that Pavlovian conditioning itself influences the breadth of fear generalization via learning-related changes in perceptual discriminability. Hence a conceptualization of fear generalization is incomplete without an in-depth analysis of processes of perceptual discriminability. Furthermore, this highlights perceptual learning and discriminability as important future targets for pre-clinical and clinical research.

  11. Selective target processing: perceptual load or distractor salience?

    Science.gov (United States)

    Eltiti, Stacy; Wallace, Denise; Fox, Elaine

    2005-07-01

    Perceptual load theory (Lavie, 1995) states that participants cannot engage in focused attention when shown displays containing a low perceptual load, because attentional resources are not exhausted, whereas in high-load displays attention is always focused, because attentional resources are exhausted. An alternative "salience" hypothesis holds that the salience of distractors and not perceptual load per se determines selective attention. Three experiments were conducted to investigate the influence that target and distractor onsets and offsets have on selective processing in a standard interference task. Perceptual load theory predicts that, regardless of target or distractor presentation (onset or offset), interference from ignored distractors should occur in low-load displays only. In contrast, the salience hypothesis predicts that interference should occur when the distractor appears as an onset and would occur for distractor offsets only when the target was also an offset. Interference may even occur in highload displays if the distractor is more salient. The results supported the salience hypothesis.

  12. Role and Development of Perceptual Skills in Medical Education

    NARCIS (Netherlands)

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

    2011-01-01

    Jarodzka, H., Balslev, T., Holmqvist, K., Nyström, M., Scheiter, K., Gerjets, P., & Eika, B. (2010, May). Role and Development of Perceptual Skills in Medical Education. The Scandinavian Workshop on Applied Eye-Tracking (SWAET), Lund, Sweden.

  13. PERCEPTUAL MAPPING BASED ON IDIOSYNCRATIC SETS OF ATTRIBUTES

    NARCIS (Netherlands)

    STEENKAMP, JBEM; VANTRIJP, HCM; TENBERGE, JMF

    1994-01-01

    The authors describe a compositional perceptual mapping procedure, unrestricted attribute-elicitation mapping (UAM), which allows consumers to describe and rate the brands in their own terminology and thus relaxes the restrictive assumptions of traditional compositional mapping techniques regarding

  14. Acoustic and perceptual evaluation of category goodness of /t/ and /k/ in typical and misarticulated children's speech.

    Science.gov (United States)

    Strömbergsson, Sofia; Salvi, Giampiero; House, David

    2015-06-01

    This investigation explores perceptual and acoustic characteristics of children's successful and unsuccessful productions of /t/ and /k/, with a specific aim of exploring perceptual sensitivity to phonetic detail, and the extent to which this sensitivity is reflected in the acoustic domain. Recordings were collected from 4- to 8-year-old children with a speech sound disorder (SSD) who misarticulated one of the target plosives, and compared to productions recorded from peers with typical speech development (TD). Perceptual responses were registered with regards to a visual-analog scale, ranging from "clear [t]" to "clear [k]." Statistical models of prototypical productions were built, based on spectral moments and discrete cosine transform features, and used in the scoring of SSD productions. In the perceptual evaluation, "clear substitutions" were rated as less prototypical than correct productions. Moreover, target-appropriate productions of /t/ and /k/ produced by children with SSD were rated as less prototypical than those produced by TD peers. The acoustical modeling could to a large extent discriminate between the gross categories /t/ and /k/, and scored the SSD utterances on a continuous scale that was largely consistent with the category of production. However, none of the methods exhibited the same sensitivity to phonetic detail as the human listeners.

  15. Perceptual Grouping of Closed Contours Is Disrupted by the Interpretation of the Scene Layout

    Directory of Open Access Journals (Sweden)

    Junjun Zhang

    2017-09-01

    Full Text Available Closure is one of the grouping principles in perceptual organization. Studies have shown that closure can be affected by several factors, specifically by low-level image features. However, the effects of high-level non-image factors on grouping by closure are unknown. In two experiments we investigated how closure is affected when depth information is introduced to the 2D closed contours, whilst the other 2D features remain intact. The first experiment showed that the grouping of closed contours was disrupted by the manipulation in 3D layout. The second experiment showed that thus disruption resulted in the impairment of searching efficiency. These findings suggest that closure is not only determined by the image features, but also affected by the interpretation of the contextual scene layout.

  16. Effects of musicianship and experimental task on perceptual segmentation

    DEFF Research Database (Denmark)

    Hartmann, Martin; Lartillot, Olivier; Toiviainen, Petri

    2015-01-01

    The perceptual structure of music is a fundamental issue in music psychology that can be systematically addressed via computational models. This study estimated the contribution of spectral, rhythmic and tonal descriptors for prediction of perceptual segmentation across stimuli. In a real-time task...... dependency. The role of interactions on perception of musical change has an impact on the study of neural, kinetic and speech stream processing....

  17. Linguistic and perceptual processing of communicative cues in Asperger Syndrome

    OpenAIRE

    Saalasti, Satu

    2012-01-01

    Asperger Syndrome (AS) belongs to autism spectrum disorders where both verbal and non-verbal communication difficulties are at the core of the impairment. Social communication requires a complex use of affective, linguistic-cognitive and perceptual processes. In the four studies included in the current thesis, some of the linguistic and perceptual factors that are important for face-to-face communication were studied using behavioural methods. In all four studies the results obtained from ind...

  18. Perceptually-Driven Signal Analysis for Acoustic Event Classification

    Science.gov (United States)

    2007-09-26

    study of musical timbre . Defined as "the subjective attribute of sound which differentiates two or more sounds that have the same loudness, pitch and...therefore a better estimate of the likelihood function. 56 Bibliography [1] J. M. Grey, -AMultidimensional perceptual scaling of musical timbres ...Display, 2005. [10] J. M. Grey, "Perceptual effects of spectral modifications on musical timbres ," Journal of the Acoustical Society of America, vol. 63

  19. Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions

    Science.gov (United States)

    Murphy, Gillian; Greene, Ciara M.

    2016-01-01

    Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals. PMID:27625628

  20. Perceptual Load Affects Eyewitness Accuracy & Susceptibility to Leading Questions

    Directory of Open Access Journals (Sweden)

    Gillian Murphy

    2016-08-01

    Full Text Available Load Theory (Lavie, 1995; 2005 states that the level of perceptual load in a task (i.e. the amount of information involved in processing task-relevant stimuli determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator, the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals.

  1. Perceptual costs for motion transparency evaluated by two performance measures.

    Science.gov (United States)

    Suzuki, Naoto; Watanabe, Osamu

    2009-08-01

    Transparency perception is recognized as one of the important phenomena to understand the computational mechanism of early visual system. Transparency perception indicates that a simple theory reconstructing a single-valued field of a visual attribute, such as an optical-flow field, cannot model the neural mechanism for the human visual system and raises a fundamental issue of how visual attributes are represented and detected in the brain. It is considered that one of the important cues to reveal the neural encoding mechanism for overlapping surfaces is the perceptual cost in transparency perception. It has been known that the perceptual performance in motion transparency is worse than that expected from single motion perception. This perceptual "cost" would reflect the encoding strategy for transparent motions. Here we present a systematic study comparing the perceptual costs in motion transparency evaluated by two performance measures. The result showed that the properties of the perceptual costs varied with the performance measures. The perceptual cost evaluated by the motion detection threshold became smaller as a directional difference between overlapping motions increased, whereas the cost examined with the precision of directional judgments became worse. A computational analysis suggests that these contradictory results cannot be explained by a simple population coding model for motion directions.

  2. Automatic imitation? Imitative compatibility affects responses at high perceptual load.

    Science.gov (United States)

    Catmur, Caroline

    2016-04-01

    Imitation involves matching the visual representation of another's action onto the observer's own motor program for that action. However, there has been some debate regarding the extent to which imitation is "automatic"-that is, occurs without attention. Participants performed a perceptual load task in which images of finger movements were presented as distractors. Responses to target letter stimuli were performed via finger movements that could be imitatively compatible (requiring the same finger movement) or incompatible with the distractor movements: In this common stimulus-response compatibility manipulation, the stimulus set comprises images of the response movements, producing an imitative compatibility effect. Attention to the distractor movements was manipulated by altering perceptual load through increasing the number of nontarget letter stimuli. If imitation requires attention, then at high perceptual load, imitative compatibility should not affect response times. In contrast, imitative compatibility influenced response times at high perceptual load, demonstrating that distractor movements were processed. However, the compatibility effect was reversed, suggesting that longer response times at high perceptual load tap into an inhibitory stage of distractor movement processing. A follow-up experiment manipulating temporal delay between targets and distractor movements supported this explanation. Further experiments confirmed that nonmovement distractor stimuli in the same configuration produced standard perceptual load effects and that results were not solely due to effector compatibility. These data suggest that imitation can occur without attention. (PsycINFO Database Record

  3. Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions.

    Science.gov (United States)

    Murphy, Gillian; Greene, Ciara M

    2016-01-01

    Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals.

  4. Testing performance of CIECAM02 in predicting perceptual contrast

    Institute of Scientific and Technical Information of China (English)

    Weige Lü; Haisong Xu; M.Ronnier Luo

    2012-01-01

    A psychophysical experiment is performed on two large-size liquid crystal displays under three viewing conditions to assess perceptual contrast.Based on the visual data,the performance of CIECAM02 in predicting perceptual contrast under different viewing conditions is tested and compared with other models by F-test.Results show that the perceptual contrast models in the form of Weber contrast using CIECAM02 brightness Q agreed better with the contrast perception of human visual system compared to the models using luminance,CIELAB lightness L*,and CIECAM02 lightness J.%A psychophysical experiment is performed on two large-size liquid crystal displays under three viewing conditions to assess perceptual contrast. Based on the visual data, the performance of CIECAM02 in predicting perceptual contrast under different viewing conditions is tested and compared with other models by F-test. Results show that the perceptual contrast models in the form of Weber contrast using CIECAM02 brightness Q agreed better with the contrast perception of human visual system compared to the models using luminance, CIELAB lightness U, and CIECAM02 lightness J.

  5. A perceptual space of local image statistics.

    Science.gov (United States)

    Victor, Jonathan D; Thengone, Daniel J; Rizvi, Syed M; Conte, Mary M

    2015-12-01

    Local image statistics are important for visual analysis of textures, surfaces, and form. There are many kinds of local statistics, including those that capture luminance distributions, spatial contrast, oriented segments, and corners. While sensitivity to each of these kinds of statistics have been well-studied, much less is known about visual processing when multiple kinds of statistics are relevant, in large part because the dimensionality of the problem is high and different kinds of statistics interact. To approach this problem, we focused on binary images on a square lattice - a reduced set of stimuli which nevertheless taps many kinds of local statistics. In this 10-parameter space, we determined psychophysical thresholds to each kind of statistic (16 observers) and all of their pairwise combinations (4 observers). Sensitivities and isodiscrimination contours were consistent across observers. Isodiscrimination contours were elliptical, implying a quadratic interaction rule, which in turn determined ellipsoidal isodiscrimination surfaces in the full 10-dimensional space, and made predictions for sensitivities to complex combinations of statistics. These predictions, including the prediction of a combination of statistics that was metameric to random, were verified experimentally. Finally, check size had only a mild effect on sensitivities over the range from 2.8 to 14min, but sensitivities to second- and higher-order statistics was substantially lower at 1.4min. In sum, local image statistics form a perceptual space that is highly stereotyped across observers, in which different kinds of statistics interact according to simple rules.

  6. Perceptual learning improves stereoacuity in amblyopia.

    Science.gov (United States)

    Xi, Jie; Jia, Wu-Li; Feng, Li-Xia; Lu, Zhong-Lin; Huang, Chang-Bing

    2014-04-15

    Amblyopia is a developmental disorder that results in both monocular and binocular deficits. Although traditional treatment in clinical practice (i.e., refractive correction, or occlusion by patching and penalization of the fellow eye) is effective in restoring monocular visual acuity, there is little information on how binocular function, especially stereopsis, responds to traditional amblyopia treatment. We aim to evaluate the effects of perceptual learning on stereopsis in observers with amblyopia in the current study. Eleven observers (21.1 ± 5.1 years, six females) with anisometropic or ametropic amblyopia were trained to judge depth in 10 to 13 sessions. Red-green glasses were used to present three different texture anaglyphs with different disparities but a fixed exposure duration. Stereoacuity was assessed with the Fly Stereo Acuity Test and visual acuity was assessed with the Chinese Tumbling E Chart before and after training. Averaged across observers, training significantly reduced disparity threshold from 776.7″ to 490.4″ (P amblyopia. These results, together with previous evidence, suggest that structured monocular and binocular training might be necessary to fully recover degraded visual functions in amblyopia. Chinese Abstract.

  7. Perceptual Depth Quality in Distorted Stereoscopic Images.

    Science.gov (United States)

    Wang, Jiheng; Wang, Shiqi; Ma, Kede; Wang, Zhou

    2017-03-01

    Subjective and objective measurement of the perceptual quality of depth information in symmetrically and asymmetrically distorted stereoscopic images is a fundamentally important issue in stereoscopic 3D imaging that has not been deeply investigated. Here, we first carry out a subjective test following the traditional absolute category rating protocol widely used in general image quality assessment research. We find this approach problematic, because monocular cues and the spatial quality of images have strong impact on the depth quality scores given by subjects, making it difficult to single out the actual contributions of stereoscopic cues in depth perception. To overcome this problem, we carry out a novel subjective study where depth effect is synthesized at different depth levels before various types and levels of symmetric and asymmetric distortions are applied. Instead of following the traditional approach, we ask subjects to identify and label depth polarizations, and a depth perception difficulty index (DPDI) is developed based on the percentage of correct and incorrect subject judgements. We find this approach highly effective at quantifying depth perception induced by stereo cues and observe a number of interesting effects regarding image content dependency, distortion-type dependence, and the impact of symmetric versus asymmetric distortions. Furthermore, we propose a novel computational model for DPDI prediction. Our results show that the proposed model, without explicitly identifying image distortion types, leads to highly promising DPDI prediction performance. We believe that these are useful steps toward building a comprehensive understanding on 3D quality-of-experience of stereoscopic images.

  8. Adaptation to direction statistics modulates perceptual discrimination.

    Science.gov (United States)

    Price, Nicholas S C; Prescott, Danielle L

    2012-06-22

    Perception depends on the relative activity of populations of sensory neurons with a range of tunings and response gains. Each neuron's tuning and gain are malleable and can be modified by sustained exposure to an adapting stimulus. Here, we used a combination of human psychophysical testing and models of neuronal population decoding to assess how rapid adaptation to moving stimuli might change neuronal tuning and thereby modulate direction perception. Using a novel motion stimulus in which the direction changed every 10 ms, we demonstrated that 1,500 ms of adaptation to a distribution of directions was capable of modifying human psychophysical direction discrimination performance. Consistent with previous reports, we found perceptual repulsion following adaptation to a single direction. Notably, compared with a uniform adaptation condition in which all motion directions were equiprobable, discrimination was impaired after adaptation to a stimulus comprising only directions ± 30-60° from the discrimination boundary and enhanced after adaptation to the complementary range of directions. Thus, stimulus distributions can be selectively chosen to either impair or improve discrimination performance through adaptation. A neuronal population decoding model incorporating adaptation-induced repulsive shifts in direction tuning curves can account for most aspects of our psychophysical data; however, changes in neuronal gain are sufficient to account for all aspects of our psychophysical data.

  9. An Electrophysiological Index of Perceptual Goodness

    Science.gov (United States)

    Makin, Alexis D.J.; Wright, Damien; Rampone, Giulia; Palumbo, Letizia; Guest, Martin; Sheehan, Rhiannon; Cleaver, Helen; Bertamini, Marco

    2016-01-01

    A traditional line of work starting with the Gestalt school has shown that patterns vary in strength and salience; a difference in “Perceptual goodness.” The Holographic weight of evidence model quantifies goodness of visual regularities. The key formula states that W = E/N, where E is number of holographic identities in a pattern and N is number of elements. We tested whether W predicts the amplitude of the neural response to regularity in an extrastriate symmetry-sensitive network. We recorded an Event Related Potential (ERP) generated by symmetry called the Sustained Posterior Negativity (SPN). First, we reanalyzed the published work and found that W explained most variance in SPN amplitude. Then in four new studies, we confirmed specific predictions of the holographic model regarding 1) the differential effects of numerosity on reflection and repetition, 2) the similarity between reflection and Glass patterns, 3) multiple symmetries, and 4) symmetry and anti-symmetry. In all cases, the holographic approach predicted SPN amplitude remarkably well; particularly in an early window around 300–400 ms post stimulus onset. Although the holographic model was not conceived as a model of neural processing, it captures many details of the brain response to symmetry. PMID:27702812

  10. The Perceptual Basis of Vast Space.

    Science.gov (United States)

    Klatzky, Roberta L; Thompson, William B; Stefanucci, Jeanine K; Gill, Devin; McGee, D Kevin

    2017-03-20

    "Vast" is a word often applied to environmental terrain that is perceived to have large spatial extent. This judgment is made even at viewing distances where traditional metric depth cues are not useful. This paper explores the perceptual basis of vast experience, including reliability and visual precursors. Experiment 1 demonstrated strong agreement in ratings of the spatial extent of two-dimensional (2D) scene images by participants in two countries under very different viewing conditions. Image categories labeled "vast" often exemplified scene attributes of ruggedness and openness (Oliva & Torralba, 2001). Experiment 2 quantitatively assessed whether these properties predict vastness. High vastness ratings were associated with highly open, or moderately open but rugged, scenes. Experiment 3 provided evidence, consistent with theory, that metric distance perception does not directly mediate the observed vastness ratings. The question remains as to how people perceive vast space when information about environmental scale is unavailable from metric depth cues or associated scene properties. We consider possible answers, including contribution from strong cues to relative depth.

  11. Anger perceptually and conceptually narrows cognitive scope.

    Science.gov (United States)

    Gable, Philip A; Poole, Bryan D; Harmon-Jones, Eddie

    2015-07-01

    For the last 50 years, research investigating the effect of emotions on scope of cognitive processing was based on models proposing that affective valence determined cognitive scope. More recently, our motivational intensity model suggests that this past work had confounded valence with motivational intensity. Research derived from this model supports the idea that motivational intensity, rather than affective valence, explains much of the variance emotions have on cognitive scope. However, the motivational intensity model is limited in that the empirical work has examined only positive affects high in approach and negative affects high in avoidance motivation. Thus, perhaps only approach-positive and avoidance-negative states narrow cognitive scope. The present research was designed to clarify these conceptual issues by examining the effect of anger, a negatively valenced approach-motivated state, on cognitive scope. Results revealed that anger narrowed attentional scope relative to a neutral state and that attentional narrowing to anger was similar to the attentional narrowing caused by high approach-motivated positive affects (Study 1). This narrowing of attention was related to trait approach motivation (Studies 2 and Study 3). Anger also narrowed conceptual cognitive categorization (Study 4). Narrowing of categorization related to participants' approach motivation toward anger stimuli. Together, these results suggest that anger, an approach-motivated negative affect, narrows perceptual and conceptual cognitive scope. More broadly, these results support the conceptual model that motivational intensity per se, rather than approach-positive and avoidance-negative states, causes a narrowing of cognitive scope.

  12. Perceptual compensation for differences in speaking style

    Directory of Open Access Journals (Sweden)

    A. Davi eVitela

    2013-07-01

    Full Text Available It is well-established that listeners will shift their categorization of a target vowel as a function of acoustic characteristics of a preceding carrier phrase. These results have been interpreted as an example of perceptual normalization for variability resulting from differences in talker anatomy. The present study examined whether listeners would normalize for acoustic variability resulting from differences in speaking style within a single talker. Two vowel series were synthesized that varied between central and peripheral vowels (the vowels in beat‐bit and bod‐bud. Each member of the series was appended to one of four carrier phrases that were spoken in either a clear or reduced speech style. Participants categorized vowels in these eight contexts. A reliable shift in categorization as a function of speaking style was obtained for three of four phrase sets. This demonstrates that phrase context effects can be obtained with a single talker. However, the directions of the obtained shifts are not reliably predicted on the basis of the speaking style of the talker. Instead, it appears that the effect is determined by an interaction of the average spectrum of the phrase with the target vowel.

  13. Neuroticism as distancing: perceptual sources of evidence.

    Science.gov (United States)

    Liu, Tianwei; Ode, Scott; Moeller, Sara K; Robinson, Michael D

    2013-05-01

    Several theories and self-reported sources of data link individual differences in negative affectivity to avoidance motivation. Chronic avoidance motivation, through repeated practice, may result in a relatively cognitive distance-enhancing dynamic whereby events and stimuli are perceived as further away from the self, even when they are not threatening. Such predictions are novel but follow from cybernetic theories of self-regulation. In 5 studies (total N = 463), relations of this type were investigated. Study 1 presented participants with phrases that were ambiguous and found that trait negative affect predicted phrase interpretation in a distance-enhancing temporal direction. Study 2 replicated this effect across a systematic manipulation of event valence. Study 3 asked individuals to estimate the size of words and found that individuals higher in neuroticism generally perceived words to be smaller than did individuals lower in neuroticism. In Study 4, people high (but not low) in neuroticism perceived words to be shrinking faster than they were growing. In Study 5, greater perceptual distancing, in a font size estimation task, predicted more adverse reactions to negative events in daily life. Although normative effects varied across studies, consistent support for a chronic distancing perspective of individual differences in negative affectivity was found.

  14. Perceptual interaction of local motion signals.

    Science.gov (United States)

    Nitzany, Eyal I; Loe, Maren E; Palmer, Stephanie E; Victor, Jonathan D

    2016-11-01

    Motion signals are a rich source of information used in many everyday tasks, such as segregation of objects from background and navigation. Motion analysis by biological systems is generally considered to consist of two stages: extraction of local motion signals followed by spatial integration. Studies using synthetic stimuli show that there are many kinds and subtypes of local motion signals. When presented in isolation, these stimuli elicit behavioral and neurophysiological responses in a wide range of species, from insects to mammals. However, these mathematically-distinct varieties of local motion signals typically co-exist in natural scenes. This study focuses on interactions between two kinds of local motion signals: Fourier and glider. Fourier signals are typically associated with translation, while glider signals occur when an object approaches or recedes. Here, using a novel class of synthetic stimuli, we ask how distinct kinds of local motion signals interact and whether context influences sensitivity to Fourier motion. We report that local motion signals of different types interact at the perceptual level, and that this interaction can include subthreshold summation and, in some subjects, subtle context-dependent changes in sensitivity. We discuss the implications of these observations, and the factors that may underlie them.

  15. Neural Variability Quenching Predicts Individual Perceptual Abilities.

    Science.gov (United States)

    Arazi, Ayelet; Censor, Nitzan; Dinstein, Ilan

    2017-01-04

    Neural activity during repeated presentations of a sensory stimulus exhibits considerable trial-by-trial variability. Previous studies have reported that trial-by-trial neural variability is reduced (quenched) by the presentation of a stimulus. However, the functional significance and behavioral relevance of variability quenching and the potential physiological mechanisms that may drive it have been studied only rarely. Here, we recorded neural activity with EEG as subjects performed a two-interval forced-choice contrast discrimination task. Trial-by-trial neural variability was quenched by ∼40% after the presentation of the stimulus relative to the variability apparent before stimulus presentation, yet there were large differences in the magnitude of variability quenching across subjects. Individual magnitudes of quenching predicted individual discrimination capabilities such that subjects who exhibited larger quenching had smaller contrast discrimination thresholds and steeper psychometric function slopes. Furthermore, the magnitude of variability quenching was strongly correlated with a reduction in broadband EEG power after stimulus presentation. Our results suggest that neural variability quenching is achieved by reducing the amplitude of broadband neural oscillations after sensory input, which yields relatively more reproducible cortical activity across trials and enables superior perceptual abilities in individuals who quench more.

  16. Visual perceptual load induces inattentional deafness.

    Science.gov (United States)

    Macdonald, James S P; Lavie, Nilli

    2011-08-01

    In this article, we establish a new phenomenon of "inattentional deafness" and highlight the level of load on visual attention as a critical determinant of this phenomenon. In three experiments, we modified an inattentional blindness paradigm to assess inattentional deafness. Participants made either a low- or high-load visual discrimination concerning a cross shape (respectively, a discrimination of line color or of line length with a subtle length difference). A brief pure tone was presented simultaneously with the visual task display on a final trial. Failures to notice the presence of this tone (i.e., inattentional deafness) reached a rate of 79% in the high-visual-load condition, significantly more than in the low-load condition. These findings establish the phenomenon of inattentional deafness under visual load, thereby extending the load theory of attention (e.g., Lavie, Journal of Experimental Psychology. Human Perception and Performance, 25, 596-616, 1995) to address the cross-modal effects of visual perceptual load.

  17. Neural Correlates of Multisensory Perceptual Learning

    Science.gov (United States)

    Powers, Albert R.; Hevey, Matthew A.; Wallace, Mark T.

    2012-01-01

    The brain’s ability to bind incoming auditory and visual stimuli depends critically on the temporal structure of this information. Specifically, there exists a temporal window of audiovisual integration within which stimuli are highly likely to be perceived as part of the same environmental event. Several studies have described the temporal bounds of this window, but few have investigated its malleability. Recently, our laboratory has demonstrated that a perceptual training paradigm is capable of eliciting a 40% narrowing in the width of this window that is stable for at least one week after cessation of training. In the current study we sought to reveal the neural substrates of these changes. Eleven human subjects completed an audiovisual simultaneity judgment training paradigm, immediately before and after which they performed the same task during an event-related 3T fMRI session. The posterior superior temporal sulcus (pSTS) and areas of auditory and visual cortex exhibited robust BOLD decreases following training, and resting state and effective connectivity analyses revealed significant increases in coupling among these cortices after training. These results provide the first evidence of the neural correlates underlying changes in multisensory temporal binding and that likely represent the substrate for a multisensory temporal binding window. PMID:22553032

  18. New biological temporary skin cover Xe-Derma(®) in the treatment of superficial scald burns in children.

    Science.gov (United States)

    Zajicek, Robert; Matouskova, Eva; Broz, Ludomir; Kubok, Richard; Waldauf, Petr; Königova, Radana

    2011-03-01

    Xe-Derma® is a new dry sterile biological cover derived from acellular pig dermis. Hydrated Xe-Derma® displays bio-mechanical features similar to the normal skin. The aim of the present study was to compare the efficacy of Xe-Derma® with hydrocolloid dressing Askina THINSite® for treatment of superficial burns in children in a prospective study. In a prospective study, 86 patients (5 months to 7 years of age) with superficial scald burns on a surface area of 1-35% BSA were enrolled. In the course of the study, 43 patients were treated with Xe-Derma® and 43 patients with Askina THINSite®. We collected data including the percentage of BSA covered with biological or synthetic material, epithelization time, the number of complete conversions (deepening of 100% of covered area into deep dermal wound) under each cover, the number and extent of partial conversions (deepening of less then 100% of covered area into deep dermal wound), infectious complications, the number of reapplications of the temporary cover and the extent in square centimetres of dressing material needed for successful healing of 1% BSA. No significant difference in the epithelization time, percentage of conversion from superficial to deep dermal burns and percentage of infectious complication was detected between the two groups. However, patients in the Xe-Derma® group were burned on a more extensive burn surface area (p ≤ 0.028). Xe-Derma® showed adherence to the wound and therefore there has been no need to be changed The number of reapplications and therefore also the number of square centimetres needed for successful healing of 1% BSA were statistically higher in the Askina THINSite® group (p skin covers in the treatment of superficial scald burns in children. Copyright © 2010 Elsevier Ltd and ISBI. All rights reserved.

  19. Ingeniería de superficies y su impacto medioambiental

    Directory of Open Access Journals (Sweden)

    Agüero, A.

    2007-02-01

    Full Text Available Surface engineering addresses the modification of the microstructure and/or composition of the surface of components by mechanical, physical or chemical methods that may imply adding a material in order to change the surface properties of said component. One of its most important consequences is the significant increase of the useful life of a variety of components in a large number of industrial applications. Moreover, it contributes to energy savings by increasing efficiencies as it allows higher combustion temperatures, by allowing the use of lighter components and by significant friction reduction. In this paper, surface engineering is introduced, as well as its different modalities, examples of industrial applications and positive and negative environmental impacts.

    La ingeniería de superficies consiste en la modificación de la microestructura y/o la composición superficial de un componente mediante métodos mecánicos, físicos o químicos, que pueden implicar el aporte de otro material para cambiar las propiedades superficiales del mencionado componente. Una de sus consecuencias más importantes es que permite alargar significativamente, la vida útil de todo tipo de componentes empleados en un gran número de aplicaciones industriales. Por otra parte, contribuye al ahorro energético por permitir el aumento de las temperaturas de combustión consiguiendo una mayor eficiencia, por contribuir a la reducción de peso y por colaborar de forma significativa a disminuir la fricción entre componentes. En el presente trabajo se introduce la ingeniería de superficies, sus diferentes modalidades, algunos ejemplos de sus aplicaciones industriales y las interacciones, positivas y negativas, con el medio ambiente.

  20. Endoscopic mucosectomy: an alternative treatment for superficial esophageal cancer.

    Science.gov (United States)

    Lambert, R

    2000-01-01

    Recent trends in the management of superficial esophageal cancer consist of improved detection, pretherapeutic staging and reliable criteria for curative endoscopic therapy. The endoscopic treatment is legitimate when the cancer is at an early stage, intra-epithelial or microinvasive (m1 or m2) and N0. Submucosal cancer should not be treated with a curative intent by endotherapy. Concerning squamous cell cancer, the oriental and occidental pathologists include high-grade dysplasia in the same group as intramucosal cancer. The distinction is however maintained for adenocarcinoma in the Barrett's esophagus. Indications of endoscopic rather than surgical treatment rely on: (1) the small size of the tumor (not more than 2 cm in diameter); (2) the endoscopic morphology in the type 0 of the Japanese classification with the flat subtypes IIa and IIb rather than type IIc--there is high risk of submucosal invasion for the polypoid (type I) or ulcerated superficial cancer (type III); and (3) the endoscopic ultrasound staging, with confirmed integrity of the hyperechoic submucosal layer. The high-frequency (20 MHz) miniprobe is preferred to the standard (7.5 MHz) instrument. The elective procedure for tumor eradication is endoscopic mucosectomy. The technique is associated with a 6.8% risk of severe complications (hemorrhage or perforation) and a recurrence rate of 3%-7%. The 5-year survival rate is similar to that of surgery (over 80%). In the small group of patients with superficial esophageal cancer (less than 10% of the disease) endoscopic treatment may now be proposed in about 30% of cases, surgery is preferred for submucosal cancer and for neoplasia with a large surface. Areas of high-grade dysplasia in the Barrett's esophagus offer a new and increasing sector of indications. The concurrent endoscopic procedure of destruction--photodynamic therapy--is preferred for the destruction of lesions with poorly delineated limits.

  1. Functional compartmentalization of the human superficial masseter muscle.

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    Rodrigo A Guzmán-Venegas

    Full Text Available Some muscles have demonstrated a differential recruitment of their motor units in relation to their location and the nature of the motor task performed; this involves functional compartmentalization. There is little evidence that demonstrates the presence of a compartmentalization of the superficial masseter muscle during biting. The aim of this study was to describe the topographic distribution of the activity of the superficial masseter (SM muscle's motor units using high-density surface electromyography (EMGs at different bite force levels. Twenty healthy natural dentate participants (men: 4; women: 16; age 20±2 years; mass: 60±12 kg, height: 163±7 cm were selected from 316 volunteers and included in this study. Using a gnathodynamometer, bites from 20 to 100% maximum voluntary bite force (MVBF were randomly requested. Using a two-dimensional grid (four columns, six electrodes located on the dominant SM, EMGs in the anterior, middle-anterior, middle-posterior and posterior portions were simultaneously recorded. In bite ranges from 20 to 60% MVBF, the EMG activity was higher in the anterior than in the posterior portion (p-value = 0.001.The center of mass of the EMG activity was displaced towards the posterior part when bite force increased (p-value = 0.001. The topographic distribution of EMGs was more homogeneous at high levels of MVBF (p-value = 0.001. The results of this study show that the superficial masseter is organized into three functional compartments: an anterior, a middle and a posterior compartment. However, this compartmentalization is only seen at low levels of bite force (20-60% MVBF.

  2. Functional compartmentalization of the human superficial masseter muscle.

    Science.gov (United States)

    Guzmán-Venegas, Rodrigo A; Biotti Picand, Jorge L; de la Rosa, Francisco J Berral

    2015-01-01

    Some muscles have demonstrated a differential recruitment of their motor units in relation to their location and the nature of the motor task performed; this involves functional compartmentalization. There is little evidence that demonstrates the presence of a compartmentalization of the superficial masseter muscle during biting. The aim of this study was to describe the topographic distribution of the activity of the superficial masseter (SM) muscle's motor units using high-density surface electromyography (EMGs) at different bite force levels. Twenty healthy natural dentate participants (men: 4; women: 16; age 20±2 years; mass: 60±12 kg, height: 163±7 cm) were selected from 316 volunteers and included in this study. Using a gnathodynamometer, bites from 20 to 100% maximum voluntary bite force (MVBF) were randomly requested. Using a two-dimensional grid (four columns, six electrodes) located on the dominant SM, EMGs in the anterior, middle-anterior, middle-posterior and posterior portions were simultaneously recorded. In bite ranges from 20 to 60% MVBF, the EMG activity was higher in the anterior than in the posterior portion (p-value = 0.001).The center of mass of the EMG activity was displaced towards the posterior part when bite force increased (p-value = 0.001). The topographic distribution of EMGs was more homogeneous at high levels of MVBF (p-value = 0.001). The results of this study show that the superficial masseter is organized into three functional compartments: an anterior, a middle and a posterior compartment. However, this compartmentalization is only seen at low levels of bite force (20-60% MVBF).

  3. The distinctive features for standard Chinese (Putonghua)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jialu

    2006-01-01

    The distinctive features, which are one of the important research subjects in Phonetics and Phonology and in speech technology also, are the ultimate units of speech. Firstly a phoneme system of the standard Chinese-Putonghua was determined based on the results of cluster analysis of perceptual confusion of speech sounds of Putonghua. Then according to the principle of choice between the two opposites proposed by Jakobson, Fant and Halle, considering the characteristics of Putonghua the distinctive feature values for Initials, Finals and Tones were determined in this paper. And the features have been formulated at both acoustic level and genetic level. The distinctive feature trees of Chinese initials and finals were drawn in addition to the feature tables, in order to understand the distinctive features for individual phoneme easily.

  4. An improved MRI guided ultrasound system for superficial tumor hyperthermia

    Science.gov (United States)

    Zhu, Mengyuan; Shen, Guofeng; Su, Zhiqiang; Chen, Sheng; Wu, Hao

    2017-03-01

    Among many methods in tumor treatment, ultrasound hyperthermia is characterized by non-invasiveness, and it has been proven very effective for clinical treatment. But the problem of monitoring temperature limits its development. MRI-based temperature mapping techniques are safe compared with invasive methods and have been applied to detect temperature changes for a variety of applications. Among these techniques, the proton resonance frequency (PRF) method is relatively advanced. With a temperature measuring experiment and experiment conducted on tumors inside rabbit legs, the effectiveness of PRF method has been proved. This paper is to introduce an MRI guided ultrasound superficial tumor hyperthermia instrument based on PRF method.

  5. Composicion y deformacion de curvas, superficies y volumenes de bezier

    OpenAIRE

    Canchoa Quispe, Alessandri

    1998-01-01

    El presente trabajo enfoca el problema de la composición y deformación de cla¬vas, superficies y volúmenes de Bézier. Los algoritmos para encontrar los puntos de control de la composición (F=Fog) de simplejos o formas de producto tensorial de Bézier g:Rn -> RwyF:RN->Rd a partir de los puntos de control de g y F tienen aplicaciones práctica en el CAGD (Computer Aided Geometric Design). Estos algoritmos inicialmente fue presentado por DeRose [DeRo 88]: el algoritmo producto para la deformación ...

  6. Aneurysm of the superficial palmar arch: a case report.

    Science.gov (United States)

    Estrella, Emmanuel P; Lee, Ellen Y

    2008-01-01

    Aneurysms of the hand are uncommon lesions. The most common location is the ulnar artery. We present a case of a young female who consulted us for a hand mass with a history of trauma to the hand. Pre-operative arteriogram showed a superficial palmar arch aneurysm. The mass was excised and the arch was reconstructed using a reversed Y-shaped vein graft. Fourteen months after surgery, there was no recurrence of the aneurysm and the patient only reported occasional cold intolerance.

  7. Endoscopic and biopsy diagnoses of superficial, nonampullary, duodenal adenocarcinomas

    Science.gov (United States)

    Kakushima, Naomi; Kanemoto, Hideyuki; Sasaki, Keiko; Kawata, Noboru; Tanaka, Masaki; Takizawa, Kohei; Imai, Kenichiro; Hotta, Kinichi; Matsubayashi, Hiroyuki; Ono, Hiroyuki

    2015-01-01

    AIM: To investigate the accuracy of endoscopic or biopsy diagnoses of superficial nonampullary duodenal epithelial tumors (NADETs). METHODS: Clinicopathological data were reviewed for 84 superficial NADETs from 74 patients who underwent surgery or endoscopic resection between September 2002 and August 2014 at a single prefectural cancer center. Superficial NADETs were defined as lesions confined to the mucosa or submucosa. Demographic and clinicopathological data were retrieved from charts, endoscopic and pathologic reports. Endoscopic reports included endoscopic diagnosis, location, gross type, diameter, color, and presence or absence of biopsy. Endoscopic diagnoses were made by an endoscopist in charge of the examination before biopsy specimens were obtained. Endoscopic images were obtained using routine, front-view, high-resolution video endoscopy, and chromoendoscopy with indigocarmine was performed for all lesions. Endoscopic images were reviewed by at least two endoscopists to assess endoscopic findings indicative of carcinoma. Preoperative diagnoses based on endoscopy and biopsy findings were compared with histological diagnoses of resected specimens. Sensitivity, specificity, and accuracy were assessed for endoscopic diagnosis and biopsy diagnosis. RESULTS: The majority (81%) of the lesions were located in the second portion of the duodenum. The median lesion diameter was 14.5 mm according to final histology. Surgery was performed for 49 lesions from 39 patients, and 35 lesions from 35 patients were endoscopically resected. Final histology confirmed 65 carcinomas, 15 adenomas, and 3 hyperplasias. A final diagnosis of duodenal carcinoma was made for 91% (52/57) of the lesions diagnosed as carcinoma by endoscopy and 93% (42/45) of the lesions diagnosed as carcinoma by biopsy. The sensitivity, specificity, and accuracy of endoscopic diagnoses were 80%, 72%, and 78%, respectively, whereas those of biopsy diagnoses were 72%, 80%, and 74%, respectively

  8. Perceptually specific and perceptually non-specific influences on rereading benefits for spatially transformed text: evidence from eye movements.

    Science.gov (United States)

    Sheridan, Heather; Reingold, Eyal M

    2012-12-01

    The present study used eye tracking methodology to examine rereading benefits for spatially transformed text. Eye movements were monitored while participants read the same target word twice, in two different low-constraint sentence frames. The congruency of perceptual processing was manipulated by either applying the same type of transformation to the word during the first and second presentations (i.e., the congruent condition), or employing two different types of transformations across the two presentations of the word (i.e., the incongruent condition). Perceptual specificity effects were demonstrated such that fixation times for the second presentation of the target word were shorter for the congruent condition compared to the incongruent condition. Moreover, we demonstrated an additional perceptually non-specific effect such that second reading fixation times were shorter for the incongruent condition relative to a baseline condition that employed a normal typography (i.e., non-transformed) during the first presentation and a transformation during the second presentation. Both of these effects (i.e., perceptually specific and perceptually non-specific) were similar in magnitude for high and low frequency words, and both effects persisted across a 1 week lag between the first and second readings. We discuss the present findings in the context of the distinction between conscious and unconscious memory, and the distinction between perceptually versus conceptually driven processing. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Low level perceptual, not attentional, processes modulate distractor interference in high perceptual Load displays: evidence from neglect/extinction

    Directory of Open Access Journals (Sweden)

    Carmel eMevorach

    2014-01-01

    Full Text Available According to perceptual load theory (Lavie, 2005 distractor interference is determined by the availability of attentional resources. If target processing does not exhaust resources (with low perceptual load distractor processing will take place resulting in interference with a primary task; however when target processing uses-up attentional capacity (with high perceptual load interference can be avoided. An alternative account (Tsal & Benoni, 2010 suggests that perceptual load effects can be based on distractor dilution by the mere presence of additional neutral items in high load displays so that the effect is not driven by the amount of attention resources required for target processing. Here we tested whether patients with unilateral neglect or extinction would show dilution effects from neutral items in their contralesional (neglected/extinguished field, even though these items do not impose increased perceptual load on the target and at the same time attract reduced attentional resources compared to stimuli in the ipsilesional field. Thus, such items do not affect the amount of attention resources available for distractor processing. We found that contralesional neutral elements can eliminate distractor interference as strongly as centrally presented ones in neglect/extinction patients, despite contralesional items being less well attended. The data are consistent with an account in terms of perceptual dilution of distracters rather than available resources for distractor processing. We conclude that distractor dilution can underlie the elimination of distractor interference in visual displays.

  10. Low level perceptual, not attentional, processes modulate distractor interference in high perceptual load displays: evidence from neglect/extinction.

    Science.gov (United States)

    Mevorach, Carmel; Tsal, Yehoshua; Humphreys, Glyn W

    2014-01-10

    According to perceptual load theory (Lavie, 2005) distractor interference is determined by the availability of attentional resources. If target processing does not exhaust resources (with low perceptual load) distractor processing will take place resulting in interference with a primary task; however, when target processing uses-up attentional capacity (with high perceptual load) interference can be avoided. An alternative account (Tsal and Benoni, 2010a) suggests that perceptual load effects can be based on distractor dilution by the mere presence of additional neutral items in high-load displays so that the effect is not driven by the amount of attention resources required for target processing. Here we tested whether patients with unilateral neglect or extinction would show dilution effects from neutral items in their contralesional (neglected/extinguished) field, even though these items do not impose increased perceptual load on the target and at the same time attract reduced attentional resources compared to stimuli in the ipsilesional field. Thus, such items do not affect the amount of attention resources available for distractor processing. We found that contralesional neutral elements can eliminate distractor interference as strongly as centrally presented ones in neglect/extinction patients, despite contralesional items being less well attended. The data are consistent with an account in terms of perceptual dilution of distracters rather than available resources for distractor processing. We conclude that distractor dilution can underlie the elimination of distractor interference in visual displays.

  11. Superficially porous particles with 1000Å pores for large biomolecule high performance liquid chromatography and polymer size exclusion chromatography.

    Science.gov (United States)

    Wagner, Brian M; Schuster, Stephanie A; Boyes, Barry E; Shields, Taylor J; Miles, William L; Haynes, Mark J; Moran, Robert E; Kirkland, Joseph J; Schure, Mark R

    2017-03-17

    To facilitate mass transport and column efficiency, solutes must have free access to particle pores to facilitate interactions with the stationary phase. To ensure this feature, particles should be used for HPLC separations which have pores sufficiently large to accommodate the solute without restricted diffusion. This paper describes the design and properties of superficially porous (also called Fused-Core(®), core shell or porous shell) particles with very large (1000Å) pores specifically developed for separating very large biomolecules and polymers. Separations of DNA fragments, monoclonal antibodies, large proteins and large polystyrene standards are used to illustrate the utility of these particles for efficient, high-resolution applications.

  12. Sexual affordances, perceptual-motor invariance extraction and intentional nonlinear dynamics: sexually deviant and non-deviant patterns in male subjects.

    Science.gov (United States)

    Renaud, Patrice; Goyette, Mathieu; Chartier, Sylvain; Zhornitski, Simon; Trottier, Dominique; Rouleau, Joanne-L; Proulx, Jean; Fedoroff, Paul; Bradford, John-P; Dassylva, Benoit; Bouchard, Stephane

    2010-10-01

    Sexual arousal and gaze behavior dynamics are used to characterize deviant sexual interests in male subjects. Pedophile patients and non-deviant subjects are immersed with virtual characters depicting relevant sexual features. Gaze behavior dynamics as indexed from correlation dimensions (D2) appears to be fractal in nature and significantly different from colored noise (surrogate data tests and recurrence plot analyses were performed). This perceptual-motor fractal dynamics parallels sexual arousal and differs from pedophiles to non-deviant subjects when critical sexual information is processed. Results are interpreted in terms of sexual affordance, perceptual invariance extraction and intentional nonlinear dynamics.

  13. Newborns' Face Recognition: Role of Inner and Outer Facial Features

    Science.gov (United States)

    Turati, Chiara; Macchi Cassia, Viola; Simion, Francesca; Leo, Irene

    2006-01-01

    Existing data indicate that newborns are able to recognize individual faces, but little is known about what perceptual cues drive this ability. The current study showed that either the inner or outer features of the face can act as sufficient cues for newborns' face recognition (Experiment 1), but the outer part of the face enjoys an advantage…

  14. pGBbBShift - Perceptual Generalized Bitplane-by-Bitplane Shift

    Directory of Open Access Journals (Sweden)

    Jaime Moreno

    2013-12-01

    Full Text Available The paper we present pGBbBShift. This algorithm permits to code any Region of Interest (ROI in a perceptual way, i.e. the presented algorithm introduces some characteristics of the Human Visual System. Furthermore, it introduces features of chromatic induction to the GBbBShift method when bitplanes of ROI and background areas are coded. Thus, the included features balance visual importance of some pixels regardless their numerical importance, namely we avoid to use Information Theory criteria. Visual criteria are applied using the CIWaM, which is contrast band-pass ?lter that predicts color perception. pGBbBShift is compared against classical ROI algorithms, such as the MaxShift method of JPEG2000 and results show that there is no perceptual difference. pGBbBShift method is an open algorithm that can be applied in any wavelet based image coder such as JPEG2000, SPIHT or SPECK. Finally, we applied pGBbBShift to Hi-SET coder and we obtain the best results when the overall visual image quality is assessed

  15. Comparing lexically guided perceptual learning in younger and older listeners.

    Science.gov (United States)

    Scharenborg, Odette; Janse, Esther

    2013-04-01

    Numerous studies have shown that younger adults engage in lexically guided perceptual learning in speech perception. Here, we investigated whether older listeners are also able to retune their phonetic category boundaries. More specifically, in this research we tried to answer two questions. First, do older adults show perceptual-learning effects of similar size to those of younger adults? Second, do differences in lexical behavior predict the strength of the perceptual-learning effect? An age group comparison revealed that older listeners do engage in lexically guided perceptual learning, but there were two age-related differences: Younger listeners had a stronger learning effect right after exposure than did older listeners, but the effect was more stable for older than for younger listeners. Moreover, a clear link was shown to exist between individuals' lexical-decision performance during exposure and the magnitude of their perceptual-learning effects. A subsequent analysis on the results of the older participants revealed that, even within the older participant group, with increasing age the perceptual retuning effect became smaller but also more stable, mirroring the age group comparison results. These results could not be explained by differences in hearing loss. The age effect may be accounted for by decreased flexibility in the adjustment of phoneme categories or by age-related changes in the dynamics of spoken-word recognition, with older adults being more affected by competition from similar-sounding lexical competitors, resulting in less lexical guidance for perceptual retuning. In conclusion, our results clearly show that the speech perception system remains flexible over the life span.

  16. The superficial ulnar artery: development and clinical significance Artéria ulnar superficial: desenvolvimento e relevância clínica

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    Srinivasulu Reddy

    2007-09-01

    Full Text Available The principal arteries of the upper limb show a wide range of variation that is of considerable interest to orthopedic surgeons, plastic surgeons, radiologists and anatomists. We present here a case of superficial ulnar artery found during the routine dissection of right upper limb of a 50-year-old male cadaver. The superficial ulnar artery originated from the brachial artery, crossed the median nerve anteriorly and ran lateral to this nerve and the brachial artery. The superficial ulnar artery in the arm gave rise to a narrow muscular branch to the biceps brachii. At the elbow level the artery ran superficial to the bicipital aponeurosis where it was crossed by the median cubital vein. It then ran downward and medially superficial to the forearm flexor muscles, and then downward to enter the hand. At the palm, it formed the superficial and deep palmar arches together with the branches of the radial artery. The presence of a superficial ulnar artery is clinically important when raising forearm flaps in reconstructive surgery. The embryology and clinical significance of the variation are discussed.As principais artérias do membro superior apresentam uma ampla variação, que é relativamente importante a cirurgiões ortopédicos e plásticos, radiologistas e anatomistas.Apresentamosumcaso de artéria ulnar superficial encontrada durante dissecção de rotina de membro superior direito de um cadáver masculino de 50 anos de idade.Aartéria ulnar superficial originava-se da artéria braquial, cruzava o nervo mediano anteriormente e percorria lateralmente esse nervo e a artéria braquial. A artéria ulnar superficial no braço deu origem a um ramo muscular estreito do músculo bíceps braquial. Ao nível do cotovelo, a artéria percorria superficialmente a aponeurose bicipital, onde era cruzada pela veia cubital mediana. Percorria, então, em sentido descendente e medialmente superficial aos músculos flexores do antebraço, e então descendia para

  17. Drenaje suplementario del sistema venoso superficial en colgajos pediculados Supplementary drainage of superficial venous system in pedicled flaps

    OpenAIRE

    Fernández García,A.; C. Fernández Pascual; R.A. Moreno Villalba; Ll. Gerrero Navarro

    2012-01-01

    Los colgajos pediculados pueden sufrir edema y congestión debido a que su drenaje a trevés del sistema venoso superfical es imposible y el flujo hacia el sistema profundo a nivel del pedículo es precario. Esta situación suele evolucionar hacia la necrosis parcial o la pérdida total del colgajo en pocas horas. La apertura del sistema venoso superficial permite el drenaje adecuado de los tejidos transferidos y evita estas complicaciones. Este artículo analiza el papel de las anastomosis microqu...

  18. Clinical Evaluation of Superficial Fungal Infections in Children

    Directory of Open Access Journals (Sweden)

    Ragıp Ertaş

    2015-12-01

    Full Text Available Objective: This retrospective study was referred to evaluate 51 cases of superficial mycoses, referred to our Pediatric Dermatology outpatient clinic in one year. Methods: We reviewed following data for all patients: age, gender, accompanied diseases, clinical types, localization and treatment. Superficial mycotic infections were diagnosed on the basis of clinical picture, direct microscopy and some of them were confirmed by fungal cultures. Results: Our patients comprised 33 boys (64.7% and 18 girls (35.3%, with an average age of 6.2 years (range 4 months to 17 years. Eighteen patients (35.3% had dermatophytes on the scalp. Clinical forms, in the order of frequency, were: tinea capitis profunda in 10 patients (19.6%, tinea capitis superficialis in 8 patients (15.8%, tinea unguium in 8 patients (15.8%. Tinea capitis (35.3% was the most frequent form of dermatomycosis. The most common symptom was the pruritus. Thirty (58% patients were treated with local antimycotics and 21 (42% patients were treated with systemic terbinafine or itraconazole. Conclusion: In this study it was found that, tinea capitis was the most frequent form of dermatomycosis and onychomycosis in children are not uncommon as it is mentioned. The data also suggest that topical antifungal agents may be effective and well-tolerated in the treatment of onychomycosis and tinea capitis in children.

  19. Superficially located enlarged lymphoid follicles characterise nodular gastritis.

    Science.gov (United States)

    Okamura, Takuma; Sakai, Yasuhiro; Hoshino, Hitomi; Iwaya, Yugo; Tanaka, Eiji; Kobayashi, Motohiro

    2015-01-01

    Nodular gastritis is a form of chronic Helicobacter pylori gastritis affecting the gastric antrum and characterised endoscopically by the presence of small nodular lesions resembling gooseflesh. It is generally accepted that hyperplasia of lymphoid follicles histologically characterises nodular gastritis; however, quantitative analysis in support of this hypothesis has not been reported. Our goal was to determine whether nodular gastritis is characterised by lymphoid follicle hyperplasia.The number, size, and location of lymphoid follicles in nodular gastritis were determined and those properties compared to samples of atrophic gastritis. The percentages of high endothelial venule (HEV)-like vessels were also evaluated.The number of lymphoid follicles was comparable between nodular and atrophic gastritis; however, follicle size in nodular gastritis was significantly greater than that seen in atrophic gastritis. Moreover, lymphoid follicles in nodular gastritis were positioned more superficially than were those in atrophic gastritis. The percentage of MECA-79 HEV-like vessels was greater in areas with gooseflesh-like lesions in nodular versus atrophic gastritis.Superficially located hyperplastic lymphoid follicles characterise nodular gastritis, and these follicles correspond to gooseflesh-like nodular lesions observed endoscopically. These observations suggest that MECA-79 HEV-like vessels could play at least a partial role in the pathogenesis of nodular gastritis.

  20. Suction based mechanical characterization of superficial facial soft tissues.

    Science.gov (United States)

    Weickenmeier, J; Jabareen, M; Mazza, E

    2015-12-16

    The present study is aimed at a combined experimental and numerical investigation of the mechanical response of superficial facial tissues. Suction based experiments provide the location, time, and history dependent behavior of skin and SMAS (superficial musculoaponeurotic system) by means of Cutometer and Aspiration measurements. The suction method is particularly suitable for in vivo, multi-axial testing of soft biological tissue including a high repeatability in subsequent tests. The campaign comprises three measurement sites in the face, i.e. jaw, parotid, and forehead, using two different loading profiles (instantaneous loading and a linearly increasing and decreasing loading curve), multiple loading magnitudes, and cyclic loading cases to quantify history dependent behavior. In an inverse finite element analysis based on anatomically detailed models an optimized set of material parameters for the implementation of an elastic-viscoplastic material model was determined, yielding an initial shear modulus of 2.32kPa for skin and 0.05kPa for SMAS, respectively. Apex displacements at maximum instantaneous and linear loading showed significant location specificity with variations of up to 18% with respect to the facial average response while observing variations in repeated measurements in the same location of less than 12%. In summary, the proposed parameter sets for skin and SMAS are shown to provide remarkable agreement between the experimentally observed and numerically predicted tissue response under all loading conditions considered in the present study, including cyclic tests.

  1. A study of uniaxial tension on the superficial dermal microvasculature.

    Science.gov (United States)

    Barnhill, R L; Bader, D L; Ryan, T J

    1984-05-01

    A spring-loaded apparatus was designed to apply uniaxial tension to forearm skin in 17 human subjects--10 normals, 6 psoriatics, and 1 patient with scleroderma. Simultaneously, the effects of stretching on the upper dermal vasculature were observed stereomicroscopically. Progressive changes (collapse) in the superficial microvasculature--vertical capillary loops and horizontal subpapillary plexus--with increasing tension were photographed. Force and strains were recorded at the points of disappearance of virtually all vessels. An average force of 11.9 newtons (N), accompanied by a mean strain of 10.3%, resulted in occlusion of all vessels. A much higher force (18.5 N) was necessary to occlude blood flow in the 1 patient with scleroderma. In summary, we have described a new technique for the study of mechanical forces on the blood supply of the epidermis. The data have shown that uniaxial tension has important effects on the superficial dermal microvasculature, resulting in impedance and obliteration of blood flow at relatively low magnitudes.

  2. Aneurysms of the superficial venous system: classification and treatment

    Directory of Open Access Journals (Sweden)

    Ronald G. Bush

    2014-11-01

    Full Text Available Superficial venous aneurysms are rarely described and they may remain indolent or become the source for pulmonary emboli. A system of classification and treatment protocol according to size and location is proposed. Three hundred thirty patients were evaluated for symptomatic venous disease (C2-C6 over a 2-year period. A proposed designation for venous aneurysm is described. Patients fulfilling this criterion are described in reference to site of involvement, histologic findings, and method of treatment. Five percent of patients met the criteria for venous aneurysm. Nine aneurysms of the greater saphenous vein were identified. Three aneurysms were proximal to the subterminal valve and the rest were distal. Six aneurysms of the anterior accessory greater saphenous vein (AAGSV were identified. Three aneurysms of the AAGSV spontaneously thrombosed. Two patients presented with aneurysms of the small saphenous vein. Histology revealed thickened intima, smooth muscle and adventitia. Aneurysm designation relates to diameter of normal and contiguous vein. All superficial venous aneurysms in close proximity to the junction of the femoral or popliteal vein should be ligated. Classification of venous aneurysms should include the AAGSV, which may present with spontaneous thrombosis.

  3. Hemispheric asymmetries in the perceptual representations of words.

    Science.gov (United States)

    Lincoln, Amy E; Long, Debra L; Swick, Diane; Larsen, Jary; Baynes, Kathleen

    2008-01-10

    The representation of words in sentences can involve the activation and integration of perceptual information. For example, readers who are asked to view pictures of objects relating to a word in a sentence are influenced by perceptual information in the sentence context-readers are faster to respond to a picture of a whole apple after reading, "There is an apple in the bag," than after reading, "There is an apple in the salad." The purpose of this study was to examine how the two cerebral hemispheres use perceptual information about words as a function of sentence context. Patients who had damage to the left or right hemisphere and age-matched control participants read sentences that described, but did not entail, the shape or state of an object. They then made recognition judgments to pictures that either matched or mismatched the perceptual form implied by the sentence. Responses and latencies were examined for a match effect -- faster and more accurate responses to pictures in the match than mismatch condition -- controlling for comprehension ability and lesion size. When comprehension ability and lesion size are properly controlled, left-hemisphere-damaged patients and control participants exhibited the expected match effect, whereas right-hemisphere-damaged participants showed no effect of match condition. These results are consistent with research implicating the right hemisphere in the representation of contextually relevant perceptual information.

  4. Neural mechanisms underlying the induction and relief of perceptual curiosity

    Directory of Open Access Journals (Sweden)

    Marieke eJepma

    2012-02-01

    Full Text Available Curiosity is one of the most basic biological drives in both animals and humans, and has been identified as a key motive for learning and discovery. Despite the importance of curiosity and related behaviors, the topic has been largely neglected in human neuroscience; hence little is known about the neurobiological mechanisms underlying curiosity. We used functional magnetic resonance imaging (fMRI to investigate what happens in our brain during the induction and subsequent relief of perceptual curiosity. Our core findings were that (i the induction of perceptual curiosity, through the presentation of ambiguous visual input, activated the anterior insula and anterior cingulate cortex, brain regions sensitive to conflict and arousal; (ii the relief of perceptual curiosity, through visual disambiguation, activated regions of the striatum that have been related to reward processing; and (iii the relief of perceptual curiosity was associated with hippocampal activation and enhanced incidental memory. These findings provide the first demonstration of the neural basis of human perceptual curiosity. Our results provide neurobiological support for a classic psychological theory of curiosity, which holds that curiosity is an aversive condition of increased arousal whose termination is rewarding and facilitates memory.

  5. Perceptual Biases in Relation to Paranormal and Conspiracy Beliefs.

    Directory of Open Access Journals (Sweden)

    Michiel van Elk

    Full Text Available Previous studies have shown that one's prior beliefs have a strong effect on perceptual decision-making and attentional processing. The present study extends these findings by investigating how individual differences in paranormal and conspiracy beliefs are related to perceptual and attentional biases. Two field studies were conducted in which visitors of a paranormal conducted a perceptual decision making task (i.e. the face/house categorization task; Experiment 1 or a visual attention task (i.e. the global/local processing task; Experiment 2. In the first experiment it was found that skeptics compared to believers more often incorrectly categorized ambiguous face stimuli as representing a house, indicating that disbelief rather than belief in the paranormal is driving the bias observed for the categorization of ambiguous stimuli. In the second experiment, it was found that skeptics showed a classical 'global-to-local' interference effect, whereas believers in conspiracy theories were characterized by a stronger 'local-to-global interference effect'. The present study shows that individual differences in paranormal and conspiracy beliefs are associated with perceptual and attentional biases, thereby extending the growing body of work in this field indicating effects of cultural learning on basic perceptual processes.

  6. Perceptual learning reconfigures the effects of visual adaptation.

    Science.gov (United States)

    McGovern, David P; Roach, Neil W; Webb, Ben S

    2012-09-26

    Our sensory experiences over a range of different timescales shape our perception of the environment. Two particularly striking short-term forms of plasticity with manifestly different time courses and perceptual consequences are those caused by visual adaptation and perceptual learning. Although conventionally treated as distinct forms of experience-dependent plasticity, their neural mechanisms and perceptual consequences have become increasingly blurred, raising the possibility that they might interact. To optimize our chances of finding a functionally meaningful interaction between learning and adaptation, we examined in humans the perceptual consequences of learning a fine discrimination task while adapting the neurons that carry most information for performing this task. Learning improved discriminative accuracy to a level that ultimately surpassed that in an unadapted state. This remarkable improvement came at a price: adapting directions that before learning had little effect elevated discrimination thresholds afterward. The improvements in discriminative accuracy grew quickly and surpassed unadapted levels within the first few training sessions, whereas the deterioration in discriminative accuracy had a different time course. This learned reconfiguration of adapted discriminative accuracy occurred without a concomitant change to the characteristic perceptual biases induced by adaptation, suggesting that the system was still in an adapted state. Our results point to a functionally meaningful push-pull interaction between learning and adaptation in which a gain in sensitivity in one adapted state is balanced by a loss of sensitivity in other adapted states.

  7. Neural mechanisms underlying the induction and relief of perceptual curiosity.

    Science.gov (United States)

    Jepma, Marieke; Verdonschot, Rinus G; van Steenbergen, Henk; Rombouts, Serge A R B; Nieuwenhuis, Sander

    2012-01-01

    Curiosity is one of the most basic biological drives in both animals and humans, and has been identified as a key motive for learning and discovery. Despite the importance of curiosity and related behaviors, the topic has been largely neglected in human neuroscience; hence little is known about the neurobiological mechanisms underlying curiosity. We used functional magnetic resonance imaging (fMRI) to investigate what happens in our brain during the induction and subsequent relief of perceptual curiosity. Our core findings were that (1) the induction of perceptual curiosity, through the presentation of ambiguous visual input, activated the anterior insula and anterior cingulate cortex (ACC), brain regions sensitive to conflict and arousal; (2) the relief of perceptual curiosity, through visual disambiguation, activated regions of the striatum that have been related to reward processing; and (3) the relief of perceptual curiosity was associated with hippocampal activation and enhanced incidental memory. These findings provide the first demonstration of the neural basis of human perceptual curiosity. Our results provide neurobiological support for a classic psychological theory of curiosity, which holds that curiosity is an aversive condition of increased arousal whose termination is rewarding and facilitates memory.

  8. Neural mechanisms underlying the induction and relief of perceptual curiosity

    Science.gov (United States)

    Jepma, Marieke; Verdonschot, Rinus G.; van Steenbergen, Henk; Rombouts, Serge A. R. B.; Nieuwenhuis, Sander

    2012-01-01

    Curiosity is one of the most basic biological drives in both animals and humans, and has been identified as a key motive for learning and discovery. Despite the importance of curiosity and related behaviors, the topic has been largely neglected in human neuroscience; hence little is known about the neurobiological mechanisms underlying curiosity. We used functional magnetic resonance imaging (fMRI) to investigate what happens in our brain during the induction and subsequent relief of perceptual curiosity. Our core findings were that (1) the induction of perceptual curiosity, through the presentation of ambiguous visual input, activated the anterior insula and anterior cingulate cortex (ACC), brain regions sensitive to conflict and arousal; (2) the relief of perceptual curiosity, through visual disambiguation, activated regions of the striatum that have been related to reward processing; and (3) the relief of perceptual curiosity was associated with hippocampal activation and enhanced incidental memory. These findings provide the first demonstration of the neural basis of human perceptual curiosity. Our results provide neurobiological support for a classic psychological theory of curiosity, which holds that curiosity is an aversive condition of increased arousal whose termination is rewarding and facilitates memory. PMID:22347853

  9. Acoustic and perceptual similarity of Japanese and American English vowels.

    Science.gov (United States)

    Nishi, Kanae; Strange, Winifred; Akahane-Yamada, Reiko; Kubo, Rieko; Trent-Brown, Sonja A

    2008-07-01

    Acoustic and perceptual similarities between Japanese and American English (AE) vowels were investigated in two studies. In study 1, a series of discriminant analyses were performed to determine acoustic similarities between Japanese and AE vowels, each spoken by four native male speakers using F1, F2, and vocalic duration as input parameters. In study 2, the Japanese vowels were presented to native AE listeners in a perceptual assimilation task, in which the listeners categorized each Japanese vowel token as most similar to an AE category and rated its goodness as an exemplar of the chosen AE category. Results showed that the majority of AE listeners assimilated all Japanese vowels into long AE categories, apparently ignoring temporal differences between 1- and 2-mora Japanese vowels. In addition, not all perceptual assimilation patterns reflected context-specific spectral similarity patterns established by discriminant analysis. It was hypothesized that this incongruity between acoustic and perceptual similarity may be due to differences in distributional characteristics of native and non-native vowel categories that affect the listeners' perceptual judgments.

  10. Exogenous attention during perceptual group formation and dissolution.

    Science.gov (United States)

    Gonen, Fahrettin F; Ogmen, Haluk

    2017-02-01

    Under natural viewing conditions, a large amount of information reaches our senses, and the visual system uses attention and perceptual grouping to reduce the complexity of stimuli in order to make real-time perception possible. Prior studies have shown that attention and perceptual grouping operate in synergy; exogenous attention is deployed not only to the cued item, but also to the entire group. Here, we investigated how attention and perceptual grouping operate during the formation and dissolution of groups. Our results showed that reaction times are higher in the presence of perceptual groups than they are for ungrouped stimuli. On the other hand, attentional benefits of perceptual grouping were observed during both the formation and the dissolution of groups. The dynamics were similar during group formation and dissolution, showing a gradual effect that takes approximately half a second to reach its maximum level. In the case of group dissolution, the attentional benefits persisted for about a quarter of a second after dissolution of the group. Taken together, our results reveal the dynamics of how attention and grouping work in synergy during the transient period when groups form or dissolve.

  11. Perceptual and acoustic parameters of vocal nodules in children.

    Science.gov (United States)

    Gramuglia, Andréa Cristina Joia; Tavares, Elaine L M; Rodrigues, Sérgio Augusto; Martins, Regina H G

    2014-02-01

    Vocal nodules constitute the major cause of dysphonia during childhood. Auditory-perceptual and acoustic vocal analyses have been used to differentiate vocal nodules from normal voice in children. To study the value of auditory-perceptual and acoustic vocal analyses in assessments of children with nodules. Diagnostic test study. A comparative study was carried out including 100 children with videolaryngoscopic diagnosis of vocal nodules (nodule group-NG); and 100 children without vocal symptoms and with normal videolaryngoscopic exams (control group-CG). The age range of both groups was between 4 and 11 years. All children underwent auditory-perceptual vocal analyses (GRBASI scale); maximum phonation time and s/z ratio were calculated, and acoustic vocal analysis (MDVP software) were carried out. There was no difference in the values of maximum phonation time and s/z ratio between groups. Auditory-perceptual analysis indicated greater compromising of voice parameters for NG, compared to CG: G (79 versus 24), R (53 versus 3), B (67 versus 23) and S (35 versus 1). The values of acoustic parameters jitter, PPQ, shimmer, APQ, NHR and SPI were higher for NG for CG. The parameter f0 did not differ between groups. Compromising of auditory-perceptual (G, R, B and S) and acoustic vocal parameters (jitter, PPQ, shimmer, APQ, NHR and SPI) was greater for children with nodules than for those of the control group, which makes them important methods for assessing child dysphonia. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  12. Perceptual Biases in Relation to Paranormal and Conspiracy Beliefs.

    Science.gov (United States)

    van Elk, Michiel

    2015-01-01

    Previous studies have shown that one's prior beliefs have a strong effect on perceptual decision-making and attentional processing. The present study extends these findings by investigating how individual differences in paranormal and conspiracy beliefs are related to perceptual and attentional biases. Two field studies were conducted in which visitors of a paranormal conducted a perceptual decision making task (i.e. the face/house categorization task; Experiment 1) or a visual attention task (i.e. the global/local processing task; Experiment 2). In the first experiment it was found that skeptics compared to believers more often incorrectly categorized ambiguous face stimuli as representing a house, indicating that disbelief rather than belief in the paranormal is driving the bias observed for the categorization of ambiguous stimuli. In the second experiment, it was found that skeptics showed a classical 'global-to-local' interference effect, whereas believers in conspiracy theories were characterized by a stronger 'local-to-global interference effect'. The present study shows that individual differences in paranormal and conspiracy beliefs are associated with perceptual and attentional biases, thereby extending the growing body of work in this field indicating effects of cultural learning on basic perceptual processes.

  13. Clinical characteristics of patients with persistent postural-perceptual dizziness

    Directory of Open Access Journals (Sweden)

    Roseli Saraiva Moreira Bittar

    2015-06-01

    Full Text Available INTRODUCTION: Persistent postural-perceptual dizziness is the dizziness that lasts for over three months with no clinical explanation for its persistence. The patient's motor response pattern presents changes and most patients manifest significant anxiety. OBJECTIVE: To evaluate the clinical characteristics of patients with persistent postural and perceptual dizziness. METHODS: statistical analysis of clinical aspects of patients with persistent postural-perceptual dizziness. RESULTS: 81 patients, average age: 50.06 ± 12.16 years; female/male ratio: 5.7/1; main reasons for dizziness: visual stimuli (74%, body movements (52%, and sleep deprivation (38%. The most prevalent comorbidities were hypercholesterolemia (31%, migraine headaches (26%, carbohydrate metabolism disorders (22% and cervical syndrome (21%. DHI, State-Trait Anxiety Inventory - Trait, Beck Depression Inventory, and Hospital Anxiety and Depression Scale questionnaires were statistically different (p < 0.05 when compared to controls. 68% demonstrated clinical improvement after treatment with serotonin reuptake inhibitors. CONCLUSION: Persistent postural-perceptual dizziness affects more women than men, with a high associated prevalence of metabolic disorders and migraine. Questionnaires help to identify the predisposition to persistent postural-perceptual dizziness. The prognosis is good with adequate treatment.

  14. Antipsychotic treatment and the Rorschach Perceptual Thinking Index (PTI) in psychotic disorder patients: Effects of treatment.

    Science.gov (United States)

    Biagiarelli, Mario; Curto, Martina; Di Pomponio, Ileana; Comparelli, Anna; Baldessarini, Ross J; Ferracuti, Stefano

    2017-02-16

    The Rorschach-based Perceptual Thinking Index (PTI) is used to identify and rate features of psychotic disorders, but effects of antipsychotic treatment on such ratings is not clear. Accordingly, we examined potential effects of antipsychotic drugs on PTI measures in 114 patients with a psychotic or bipolar-I disorder. Use and doses of antipsychotic drugs (as chlorpromazine-equivalent [CPZ-eq] mg/day) were unrelated to PTI total or subscale scores in any diagnostic group. PTI scores were independently and significantly associated with psychotic symptomatic severity (PANSS score) and less with female sex. These findings support the validity and value of the PTI in identifying features of psychosis even in the presence of antipsychotic treatment.

  15. Superficie regladas y desarrollables a lo largo de curvas Bézier.

    OpenAIRE

    Londoño Arboleda, Mauricio Alejando

    2010-01-01

    Se estudian superficies regladas y se abordan sus elementos básicos como la línea de estricción y el parámetro de distribución. Se estudian algoritmos para el diseño de superficies desarrollables, a saber el algoritmo de Aumann y el algoritmo proyectivo de Pottmann, en este ´ ultimo las superficies desarrollables racionales de Bezier se interpretan como curvas en el espacio proyectivo dual (P3).Se estudia de manera exhaustiva el problema de diseño de superficies desarrollables de grado polino...

  16. Superficial aponeurosis of human gastrocnemius is elongated during contraction: implications for modeling muscle-tendon unit.

    Science.gov (United States)

    Muramatsu, Tadashi; Muraoka, Tetsuro; Kawakami, Yasuo; Fukunaga, Tetsuo

    2002-02-01

    Two questions were addressed in this study: (1) how much strain of the superficial aponeurosis of the human medial gastrocnemius muscle (MG) was obtained during voluntary isometric contractions in vivo, (2) whether there existed inhomogeneity of the strain along the superficial aponeurosis. Seven male subjects, whose knees were extended and ankles were flexed at right angle, performed isometric plantar flexion while elongation of superficial aponeurosis of MG was determined from the movements of the intersections made by the superficial aponeurosis and fascicles using ultrasonography. The strain of the superficial aponeurosis at the maximum voluntary contraction, estimated from the elongation and length data, was 5.6+/-1.2%. There was no significant difference in strain between the proximal and distal parts of the superficial aponeurosis. Based on the present result and that of our previous study for the same subjects (J. Appl. Physiol 90 (2001) 1671), a model was formulated for a contracting uni-pennate muscle-tendon unit. This model, which could be applied to isometric contractions at other angles and therefore of wide use, showed that similar strain between superficial and deep aponeuroses of MG contributed to homogeneous fascicle length change within MG during contractions. These findings would contribute to clarifying the functions of the superficial aponeurosis and the effects of the superficial aponeurosis elongation on the whole muscle behavior.

  17. A rare variant of the superficial ulnar artery, and its clinical implications: a case report

    Directory of Open Access Journals (Sweden)

    Senanayake Kithsiri J

    2007-11-01

    Full Text Available Abstract The superficial ulnar artery is a rare variation of the upper limb arterial system that arises from the brachial or axillary artery and runs superficial to the muscles arising from the medial epicondyle 123. The incidence is about 0.7 to 7% 145. In our routine dissections we found a superficial ulnar artery, which crossed the cubital fossa superficial to the bicipital aponeurosis making it highly vulnerable to intra-arterial injection. This is a rare variation that every medical and nursing staff member should know about.

  18. Direct Relationship Between Perceptual and Motor Variability

    Science.gov (United States)

    Liston, Dorion B.; Stone, Leland S.

    2010-01-01

    The time that elapses between stimulus onset and the onset of a saccadic eye movement is longer and more variable than can be explained by neural transmission times and synaptic delays (Carpenter, 1981, in: Eye Movements: Cognition & Visual Perception, Earlbaum). In theory, noise underlying response-time (RT) variability could arise at any point along the sensorimotor cascade, from sensory noise arising Vvithin the early visual processing shared Vvith perception to noise in the motor criterion or commands necessary to trigger movements. These two loci for internal noise can be distinguished empirically; sensory internal noise predicts that response time Vvill correlate Vvith perceived stimulus magnitude whereas motor internal noise predicts no such correlation. Methods. We used the data described by Liston and Stone (2008, JNS 28:13866-13875), in which subjects performed a 2AFC saccadic brightness discrimination task and the perceived brightness of the chosen stimulus was then quantified in a second 21FC perceptual task. Results. We binned each subject's data into quartiles for both signal strength (from dimmest to brightest) and RT (from slowest to fastest) and analyzed the trends in perceived brightness. We found significant effects of both signal strength (as expected) and RT on normalized perceived brightness (both p less than 0.0001, 2-way ANOVA), without significant interaction (p = 0.95, 2-way ANOVA). A plot of normalized perceived brightness versus normalized RT show's that more than half of the variance was shared (r2 = 0.56, P less than 0.0001). To rule out any possibility that some signal-strength related artifact was generating this effect, we ran a control analysis on pairs of trials with repeated presentations of identical stimuli and found that stimuli are perceived to be brighter on trials with faster saccades (p less than 0.001, paired t-test across subjects). Conclusion. These data show that shared early visual internal noise jitters perceived

  19. Vaginal superficial myofibroblastoma: a rare mesenchymal tumor of the lower female genital tract and a study of its association with viral infection.

    Science.gov (United States)

    Liu, Jing-Lan; Su, Tzu-Cheng; Shen, Ko-Hung; Lin, Shu-Hui; Wang, Hsin-Kai; Hsu, Jui-Chang; Chen, Chih-Jung

    2012-06-01

    Superficial myofibroblastoma is a rare mesenchymal tumor in the lower female genital tract. The exact etiology of superficial myofibroblastoma remains unclear. The association of viral infection and mesenchymal tumors has been well established in some particular types of soft tissue tumors. In the lower female genital tract, the intimate correlation of viral infection and tumor pathogenesis has been also proposed. We present a 59-year-old woman with postcoital bleeding for 1 month. The pelvic examination revealed a 2-cm polypoid mass mimicking leiomyoma at the vaginal fornix. Local excision was performed, and the pathological examination revealed a superficial myofibroblastoma. No tumor recurrence was noted during the 12-month follow-up. Pathological differential diagnosis of this tumor from other mesenchymal tumors is essential because of its distinct clinicopathological features. Furthermore, fluorescence in situ hybridization of human papilloma virus (HPV) and Epstein-Barr virus (EBV), as well as immunohistochemical staining of human herpesvirus 8 (HHV8), was negative in tumor cells. To the best of our knowledge, we are the first group to study the possible relationship of viral infection and the occurrence of this mesenchymal tumor. Our results suggested no association of vaginal superficial myofibroblastoma and infection with HPV, EBV, or HHV8.

  20. What factors control the superficial lava dome explosivity?

    Science.gov (United States)

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoit; Morgan, Daniel J.

    2015-04-01

    Dome-forming eruption is a frequent eruptive style; lava domes result from intermittent, slow extrusion of viscous lava. Most dome-forming eruptions produce highly microcrystallized and highly- to almost totally-degassed magmas which have a low explosive potential. During lava dome growth, recurrent collapses of unstable parts are the main destructive process of the lava dome, generating concentrated pyroclastic density currents (C-PDC) channelized in valleys. These C-PDC have a high, but localized, damage potential that largely depends on the collapsed volume. Sometimes, a dilute ash cloud surge develops at the top of the concentrated flow with an increased destructive effect because it may overflow ridges and affect larger areas. In some cases, large lava dome collapses can induce a depressurization of the magma within the conduit, leading to vulcanian explosions. By contrast, violent, laterally directed, explosions may occur at the base of a growing lava dome: this activity generates dilute and turbulent, highly-destructive, pyroclastic density currents (D-PDC), with a high velocity and propagation poorly dependent on the topography. Numerous studies on lava dome behaviors exist, but the triggering of lava dome explosions is poorly understood. Here, seven dome-forming eruptions are investigated: in the Lesser Antilles arc: Montagne Pelée, Martinique (1902-1905, 1929-1932 and 650 y. BP eruptions), Soufrière Hills, Montserrat; in Guatemala, Santiaguito (1929 eruption); in La Chaîne des Puys, France (Puy de Dome and Puy Chopine eruptions). We propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by these key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite

  1. Lower body lift with superficial fascial system suspension.

    Science.gov (United States)

    Lockwood, T

    1993-11-01

    Multiple body contour deformities of the trunk and thighs are commonly treated in separate stages to limit postoperative complications and disability. Recent advances in the surgical design of the medial thigh lift and the lateral thigh/buttock lift along with an understanding of the functional anatomy of the superficial fascial system have significantly improved results and decreased complications of trunk/thigh lifts. The enhanced safety of current trunk/thigh lifts has allowed new combinations to treat multiple body contour deformities in a single stage. Laxity of the entire lower trunk and thigh regions can be treated in one stage in selected patients. The lower body lift combines the transverse flank/thigh/buttock lift and the fascial anchoring medial thigh lift in one operation. In addition to the expected tightening of the flank, buttocks, and total thighs, this procedure results in a surprising degree of epigastric and hypogastric tightening of mild to moderate abdominal laxity without direct surgical undermining or umbilical transposition. Ten patients having the lower body lift alone or in combination with liposuction and other body contouring procedures were followed for 6 to 24 months. The primary indication for surgery is moderate to severe soft-tissue laxity of the lower trunk and thighs with minimal or mild residual fat deposits. Skin contour irregularities due to skin laxity (cellulite of laxity) or to postliposuction adhesions are frequently present and may be severe. Patients with significant fat deposits may be treated initially with liposuction 3 to 4 months earlier to become candidates for this procedure. Key technical elements of this procedure include (1) both supine and lateral decubitus positioning with the hip flexed and abducted to allow overcorrection, (2) appropriate direct surgical undermining through superficial fascial system zones of adherence in the superior thigh while avoiding the lymphatics of the femoral triangle, (3) more

  2. Cognitive structure of occupational risks represented by a perceptual map.

    Science.gov (United States)

    Cardoso-Junior, M M; Scarpel, R A

    2012-01-01

    The main focus of risk management is technical and rational analysis about the operational risks and by those imposed by the occupational environment. In this work one seeks to contribute to the risk perception study and to better comprehend how a group of occupational safety students assesses a set of activities and environmental agents. In this way it was used theory sustained by psychometric paradigm and multivariate analysis tools, mainly multidimensional scaling, generalized Procrustes analysis and facets theory, in order to construct the perceptual map of occupational risks. The results obtained showed that the essential characteristics of risks, which were initially splited in 4 facets were detected and maintained in the perceptual map. It was not possible to reveal the cognitive structure of the group, because the variability of the students was too high. Differences among the risks analyzed could not be detected as well in the perceptual map of the group.

  3. A critical evaluation of two approaches to defining perceptual salience

    Directory of Open Access Journals (Sweden)

    Bethany MacLeod

    2015-01-01

    Full Text Available The notion of perceptual salience is frequently invoked as an explanatory factor in discussions of various linguistic phenomena, but the way salience is defined varies between studies. This paper provides a critical evaluation of two approaches to operationalizing perceptual salience that have been applied to studies of phonetic accommodation: the criteria-list approach and the experimental approach. The purpose is to provide a starting point for researchers interested in exploring the role of perceptual salience in linguistic patterns, such as phonetic accommodation. In addition, the paper aims to consider the nature of the information captured by the different approaches, to explore how these approaches might be best used, and to examine how they reflect changes in theorizing on linguistic variables more generally.

  4. Probability shapes perceptual precision: A study in orientation estimation.

    Science.gov (United States)

    Jabar, Syaheed B; Anderson, Britt

    2015-12-01

    Probability is known to affect perceptual estimations, but an understanding of mechanisms is lacking. Moving beyond binary classification tasks, we had naive participants report the orientation of briefly viewed gratings where we systematically manipulated contingent probability. Participants rapidly developed faster and more precise estimations for high-probability tilts. The shapes of their error distributions, as indexed by a kurtosis measure, also showed a distortion from Gaussian. This kurtosis metric was robust, capturing probability effects that were graded, contextual, and varying as a function of stimulus orientation. Our data can be understood as a probability-induced reduction in the variability or "shape" of estimation errors, as would be expected if probability affects the perceptual representations. As probability manipulations are an implicit component of many endogenous cuing paradigms, changes at the perceptual level could account for changes in performance that might have traditionally been ascribed to "attention." (c) 2015 APA, all rights reserved).

  5. Perceptual reasoning managed situation assessment and adaptive fusion processing

    Science.gov (United States)

    Kadar, Ivan

    2001-08-01

    A unified perceptual reasoning system framework for adaptive sensor fusion and situation assessment is presented. The concept and application of perception, the resultant system architecture and its candidate renditions using knowledge- based systems and associative memory are discussed. The perceptual reasoning system is shown to be a natural governing mechanism for extracting, associating and fusing information from multiple sources while adaptively controlling the Joint Director of Laboratories (JDL) Fusion Model processes for optimum fusion system performance. The unified modular system construct is shown to provide a formal framework to accommodate various implementation alternatives. The application of this architectural concept is illustrated for representative network centric surveillance system architecture. A target identification system using Dempster-Shafer declarations level fusion is used to demonstrate the benefits of the adaptive perceptual reasoning system and the iterative evidential reasoning method.

  6. Constructing knowledge through perceptual processes in making craft-art

    Directory of Open Access Journals (Sweden)

    Milla Ojala

    2013-10-01

    Full Text Available The focus of the study is on the knowledge that is constructed through perceptual processes during craft making in the context of the Finnish Basic Education in the Arts (BEA system. Craft studies in the BEA are defined as craft-art. The research method used is the grounded theory. The data consists of seven interviews and participant observations. Participants in the study are adolescents who study craft-art in the BEA system in Visual Art School, Aimo in Hämeenlinna. The aim of the article is to present, define and reflect on the concepts, properties and dimensions concerning perceptual processes that are discovered in this stage of the study following grounded theory procedures. The perceptual processes are an essential means of constructing knowledge in craft-art. Consequently, one aim of the study is to discuss how these processes are connected to various types of knowledge. The perceptual processes are described by seven concepts: imitative, anticipative, evaluative, experimental, emotional, temporal and bodily perceptions. They indicate on a conceptual level the characteristic of knowledge constructed through perceptual processes in craft-art. Further, theconcepts have several properties that can vary dimensionally between two qualities. The properties are activity, function and position. The dimensions of the properties vary from active to passive, formal to informal and internal to external. In conclusion, the concepts can describe a large range of incidents in different situations. They also seem to describe well the practice of  craft-art and there are several connections with pre-existing concepts of knowledge.Keywords: Craft, Knowledge, Perceptual process, Basic Education in the Arts, Grounded Theory 

  7. Perceptual learning modifies the functional specializations of visual cortical areas.

    Science.gov (United States)

    Chen, Nihong; Cai, Peng; Zhou, Tiangang; Thompson, Benjamin; Fang, Fang

    2016-05-17

    Training can improve performance of perceptual tasks. This phenomenon, known as perceptual learning, is strongest for the trained task and stimulus, leading to a widely accepted assumption that the associated neuronal plasticity is restricted to brain circuits that mediate performance of the trained task. Nevertheless, learning does transfer to other tasks and stimuli, implying the presence of more widespread plasticity. Here, we trained human subjects to discriminate the direction of coherent motion stimuli. The behavioral learning effect substantially transferred to noisy motion stimuli. We used transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying the transfer of learning. The TMS experiment revealed dissociable, causal contributions of V3A (one of the visual areas in the extrastriate visual cortex) and MT+ (middle temporal/medial superior temporal cortex) to coherent and noisy motion processing. Surprisingly, the contribution of MT+ to noisy motion processing was replaced by V3A after perceptual training. The fMRI experiment complemented and corroborated the TMS finding. Multivariate pattern analysis showed that, before training, among visual cortical areas, coherent and noisy motion was decoded most accurately in V3A and MT+, respectively. After training, both kinds of motion were decoded most accurately in V3A. Our findings demonstrate that the effects of perceptual learning extend far beyond the retuning of specific neural populations for the trained stimuli. Learning could dramatically modify the inherent functional specializations of visual cortical areas and dynamically reweight their contributions to perceptual decisions based on their representational qualities. These neural changes might serve as the neural substrate for the transfer of perceptual learning.

  8. Perceptual learning of degraded speech by minimizing prediction error.

    Science.gov (United States)

    Sohoglu, Ediz; Davis, Matthew H

    2016-03-22

    Human perception is shaped by past experience on multiple timescales. Sudden and dramatic changes in perception occur when prior knowledge or expectations match stimulus content. These immediate effects contrast with the longer-term, more gradual improvements that are characteristic of perceptual learning. Despite extensive investigation of these two experience-dependent phenomena, there is considerable debate about whether they result from common or dissociable neural mechanisms. Here we test single- and dual-mechanism accounts of experience-dependent changes in perception using concurrent magnetoencephalographic and EEG recordings of neural responses evoked by degraded speech. When speech clarity was enhanced by prior knowledge obtained from matching text, we observed reduced neural activity in a peri-auditory region of the superior temporal gyrus (STG). Critically, longer-term improvements in the accuracy of speech recognition following perceptual learning resulted in reduced activity in a nearly identical STG region. Moreover, short-term neural changes caused by prior knowledge and longer-term neural changes arising from perceptual learning were correlated across subjects with the magnitude of learning-induced changes in recognition accuracy. These experience-dependent effects on neural processing could be dissociated from the neural effect of hearing physically clearer speech, which similarly enhanced perception but increased rather than decreased STG responses. Hence, the observed neural effects of prior knowledge and perceptual learning cannot be attributed to epiphenomenal changes in listening effort that accompany enhanced perception. Instead, our results support a predictive coding account of speech perception; computational simulations show how a single mechanism, minimization of prediction error, can drive immediate perceptual effects of prior knowledge and longer-term perceptual learning of degraded speech.

  9. Transient Superficial Peroneal Nerve Palsy After Anterior Cruciate Ligament Reconstruction.

    Science.gov (United States)

    Alrowaili, Majed

    2016-04-26

    A 19-year-old male subject was diagnosed with medial meniscal, lateral meniscal and anterior cruciate ligament (ACL) tear. The symptoms did not subside after 4 months of physical therapy, and he underwent arthroscopic partial medial and lateral meniscectomy and ACL reconstruction. Immediately after the patient woke up from general anesthesia, he started experience loss of sensation in the area of superficial peroneal nerve with inverted dorsiflexion of foot and ankle. Instantly, the bandage and knee brace was removed and a diagnosis of compartment syndrome was ruled out. After eight hours, post-operatively, the patient started receiving physiotherapy. He complained of numbness and tingling in the same area. After 24 h, post-operatively, the patient started to regain dorsiflexion and eversion gradually. Two days after the surgery, the patient exhibited complete recovery of neurological status.

  10. Superficial Circumflex Iliac Artery Perforator Flap for Dorsalis Pedis Reconstruction.

    Science.gov (United States)

    Tashiro, Kensuke; Yamashita, Shuji

    2017-04-01

    Reconstruction of dorsalis pedis with soft tissue is challenging because it needs to preserve thin structure to ensure that the patient will be able to wear shoes. Here, we report the use of a thin superficial circumflex iliac artery perforator (SCIP) flap in dorsalis pedis reconstruction. A 67-year-old man presented with a third-degree burn, which exposed his extensor tendons. A thin SCIP flap from the left inguinal region measuring 15 × 4 cm was transferred to the dorsalis pedis region. Postoperatively, no major cosmetic or functional problems were observed. Because the invasiveness of the donor site is nearly same between SCIP flap and skin graft from inguinal region, SCIP flap is better solution in point of textural qualities for dorsalis pedis reconstruction.

  11. MRI evaluation of superficial soft tissue lesions in children

    Energy Technology Data Exchange (ETDEWEB)

    Jabra, A.A. (Russel H. Morgan Dept. of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, MD (United States)); Taylor, G.A. (Russel H. Morgan Dept. of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, MD (United States))

    1993-10-01

    The role of MRI in the evaluation of superficial soft tissue lesions in children has not been well established. We present our experience with MRI in the evaluation of nineteen children with a variety of cutaneous and subcutaneous lesions. We find MRI to have a definite role in the evaluation of these lesions particularly when determining extent or depth of involvement would affect medical or surgical management. MRI has a less well defined role in tissue determination. Spin echo T1 and T2 weighted images were sufficient for evaluation in most cases. Fat suppression images added additional information in fatty tumors. The MRI appearance of juvenile hyaline fibromatosis and lipoblastomatosis has not been previously described and is included in this study. (orig.)

  12. Multiple superficial basal cell carcinomas (basalomatosis) following cobalt irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wollenberg, A.; Przybilla, B. [Muenchen Univ. (Germany). Dermatologische Klinik und Poliklinik; Peter, R.U. [Federal Armed Forces Medical Academy, Munich (Germany). Inst. of Radiobiology

    1995-10-01

    Basalomatosis is an uncommon skin condition characterized by the occurrence of multiple basal cell carcinomas. Many cases reported in the literature have been attributed to arsenic treatment in psoriasis patients. We report a patient with basalomatosis caused by cobalt-60 ({sup 60}Co) irradiation. A 55-year-old farmer developed 43 basal cell carcinomas 20 years after treatment of an immuno-blastoma with {sup 60}Co irradiation. All the tumours were located within the radiation fields. Other possible causes of basalomatosis, such as arsenic intoxication and basal cell naevus syndrome, were excluded. The patient`s multiple superficial basal cell carcinomas probably represent a late adverse effect of the {sup 60}Co irradiation. (Author).

  13. Superficial stellate cells of the dorsal cochlear nucleus

    Directory of Open Access Journals (Sweden)

    Pierre F. Apostolides

    2014-06-01

    Full Text Available The dorsal cochlear nucleus (DCN integrates auditory and multisensory signals at the earliest levels of auditory processing. Proposed roles for this region include sound localization in the vertical plane, head orientation to sounds of interest, and suppression of sensitivity to expected sounds. Auditory and non-auditory information streams to the DCN are refined by a remarkably complex array of inhibitory and excitatory interneurons, and the role of each cell type is gaining increasing attention. One inhibitory neuron that has been poorly appreciated to date is the superficial stellate cell. Here we review previous studies and describe new results that reveal the surprisingly rich interactions that this tiny interneuron has with its neighbors, interactions which enable it to respond to both multisensory and auditory afferents.

  14. Tratamento superficial dos agregados reciclados de RCD com hidrofugantes.

    OpenAIRE

    Winnie Franco Santos

    2016-01-01

    A proposta busca reduzir a absorção de água dos agregados reciclados de Resíduos de Construção e Demolição (RCD), através do tratamento de sua superfície com hidrofugante, de maneira que estes não aumentem o consumo de água tampouco reduzam a resistência mecânica. Os agregados reciclados de RCD foram caracterizados quanto à granulometria, morfologia, porosidade, ângulo de contato aparente, absorção de água, análise de imagem e rugosidade superficial. Em seguida, os mesmos foram tratados super...

  15. Transient superficial peroneal nerve palsy after anterior cruciate ligament reconstruction

    Directory of Open Access Journals (Sweden)

    Majed Alrowaili

    2016-06-01

    Full Text Available A 19-year-old male subject was diagnosed with medial meniscal, lateral meniscal and anterior cruciate ligament (ACL tear. The symptoms did not subside after 4 months of physical therapy, and he underwent arthroscopic partial medial and lateral meniscectomy and ACL reconstruction. Immediately after the patient woke up from general anesthesia, he started experience loss of sensation in the area of superficial peroneal nerve with inverted dorsiflexion of foot and ankle. Instantly, the bandage and knee brace was removed and a diagnosis of compartment syndrome was ruled out. After eight hours, post-operatively, the patient started receiving physiotherapy. He complained of numbness and tingling in the same area. After 24 h, post-operatively, the patient started to regain dorsiflexion and eversion gradually. Two days after the surgery, the patient exhibited complete recovery of neurological status.

  16. Biosensores: Un Acercamiento a La Resonancia del Plasmon Superficial.

    Directory of Open Access Journals (Sweden)

    Nardo Ramírez Frómeta

    2005-01-01

    Full Text Available Los biosensores, o los sensores basados sobre materiales biológicos, son utilizados en la actualidad en una amplia variedad de disciplinas, incluyendo la industria alimenticia, la medicina, y la ciencia ambiental. Está llegando a ser cada vez más importante para los investigadores y los científicos en éstos y otros campos tener una comprensión de los diversos tipos de biosensores que puedan ser utilizados, los principios detrás de ellos, así como sus ventajas y limitaciones. El énfasis especial se ha dedicado a los biosensores de resonancia del plasmon superficial (SPR. El biosensor óptico basado en la técnica SPR ha ganado atención debido a su velocidad de detección, alta especificidad, alta sensibilidad y posibilidad de análisis en tiempo real. El dispositivo SPR detecta cambios mínimos en el índice de refracción de la superficie de detección y de su vecindad inmediata. Esta detección altamente sensible se basa en una excitación colectiva de los electrones (los plasmons superficiales en una película metálica sobre un substrato (Ej. cristal, conduciendo a la absorción total de la luz en un ángulo particular de incidencia el cual es dependiente de los índices de refracción de cualquiera de los lados de la película metálica.

  17. Recent improvements to Thor with emphasis on perceptual coding tools

    Science.gov (United States)

    Davies, Thomas; Bjøntegaard, Gisle; Fuldseth, Arild; Midtskogen, Steinar

    2016-09-01

    Thor supports a number of coding tools that have the potential to improve perceptual as well as objective quality. Synthetic reference frames may be used to support high frame rate applications in circumstances where encoders might typically transmit reduced frame rate content. Quantization matrices can be used to give improved visual quality by allocating bits more closely according to perceptual significance. Thor's Constrained Low Pass Loop Filter provides significant subjective benefit in removing coding artefacts such as ringing. Improved colour fidelity can also be obtained by leveraging luma information. This paper discusses developments in these tools and their objective and subjective performance.

  18. An Improved Scalar Costa Scheme Based on Watson Perceptual Model

    Institute of Scientific and Technical Information of China (English)

    QI Kai-yue; CHEN Jian-bo; ZHOU Yi

    2008-01-01

    An improved scalar Costa scheme (SCS) was proposed by using improved Watson perceptual model to adaptively decide quantization step size and scaling factor. The improved scheme equals to embed hiding data based on an actual image. In order to withstand amplitude scaling attack, the Watson perceptual model was redefined, and the improved scheme using the new definition can insure quantization step size in decoder that is proportional to amplitude scaling attack factor. The performance of the improved scheme outperforms that of SCS with fixed quantization step size. The improved scheme combines information theory and visual model.

  19. Perceptual distortions and deceptions: what computers can teach us

    Science.gov (United States)

    Nour, Matthew M.; Nour, Joseph M.

    2017-01-01

    The nature of perception has fascinated philosophers for centuries, and has more recently been the focus of research in psychology and neuroscience. Many psychiatric disorders are characterised by perceptual abnormalities, ranging from sensory distortions to illusions and hallucinations. The distinction between normal and abnormal perception is, however, hard to articulate. In this article we argue that the distinction between normal perception and abnormal perception is best seen as a quantitative one, resting on the degree to which the observer's prior expectations influence perceptual inference. We illustrate this point with an example taken from researchers at Google working on computer vision. PMID:28184316

  20. Understanding Legacy Features with Featureous

    DEFF Research Database (Denmark)

    Olszak, Andrzej; Jørgensen, Bo Nørregaard

    2011-01-01

    Feature-centric comprehension of source code is essential during software evolution. However, such comprehension is oftentimes difficult to achieve due the discrepancies between structural and functional units of object-oriented programs. We present a tool for feature-centric analysis of legacy...

  1. Effect Size Matters : The Role of Language Statistics and Perceptual Simulation in Conceptual Processing

    NARCIS (Netherlands)

    Louwerse, M.M.; Hutchinson, S; Tillman, R.N.

    2014-01-01

    The cognitive science literature increasingly demonstrates that perceptual representations are activated during conceptual processing. Such findings suggest that the debate on whether conceptual processing is predominantly symbolic or perceptual has been resolved. However, studies too frequently pro

  2. Geometric Form Drawing: A Perceptual-Motor Approach to Preventive Remediation (The Steiner Approach)

    Science.gov (United States)

    Ogletree, Earl J.

    1975-01-01

    Provided is a rationale for geometric form drawing developed by Rudolf Steiner as a tool to develop motor coordination, perceptual skills, and cognition for mentally retarded and perceptually handicapped children. (Author/CL)

  3. Site Features

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset consists of various site features from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times...

  4. Feature Extraction

    CERN Document Server

    CERN. Geneva

    2015-01-01

    Feature selection and reduction are key to robust multivariate analyses. In this talk I will focus on pros and cons of various variable selection methods and focus on those that are most relevant in the context of HEP.

  5. Solar Features

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of solar feature datasets contributed by a number of national and private solar observatories located worldwide.

  6. Cross-modal selective attention and perceptual load in autism spectrum disorder

    OpenAIRE

    Tillmann, J. E.

    2016-01-01

    This thesis investigated cross-modal selective attention in children and adolescents with Autism Spectrum Disorder (ASD) and typically developing (TD) individuals using the Load Theory of Selective Attention and Cognitive Control (Lavie, 1995). Perceptual load theory states that perception of irrelevant stimuli depends on the perceptual load of the task (the amount of task relevant information). At low levels of perceptual load, when finite perceptual capacity is not reached, remaining resour...

  7. 周边视觉的知觉学习%Perceptual Learning of Peripheral Vision

    Institute of Scientific and Technical Information of China (English)

    徐笑含; 谢新秀; 邵志芳

    2012-01-01

    知觉学习是指知觉能力随着知觉训练或经验逐渐改变的现象。它具有特异性-迁移性,可以根据时程划分为快速学习和慢速学习。知觉学习意味着与知觉直接对应的脑区神经元激活方式的变化,并且与注意有着一定的联系。目前周边视觉的知觉学习研究已有一些成果:对于非语词刺激,随着练习,判断目标刺激(例如刺激朝向、游标视敏度)的能力,有很大的提升;对于语词刺激,周边视觉的知觉学习可以帮助提高阅读速度。可以通过提高视觉广度来提高周边视觉的阅读速度。周边视觉的知觉学习还有着重大应用价值,可以帮助中央凹视觉缺损的人们提高周边视觉能力,帮助恢复阅读能力。%Perceptual learning is defined as the improvement of the performance on perceptual tasks after training. Perceptual learning of human visual system has been widely investigated. Previous studies on perceptual learning were focused on its specificity and generalization. In some visual tasks, such as retinal location, spatial frequency or orientation, the learned performance is limited to the specific stimulus. In other visual tasks, the improved performance can be transferred to different stimuli or tasks. Specificity and generalization can be viewed as two the ends of a transferability continuum, on which each task may have a specific position (or value). Neurophysiological findings suggest that perceptual learning of different complexities may involve different levels of visual cortical processing, and the neural mechanism involved may depend on the feature ( e. g. , the complexity) of the stimulus in the task. Perceptual learning can be divided into fast learning and slow learning. A number of studies have used ERP and other brain imaging techniques to investigate the neural mechanism of visual perceptual learning under different time scales. Age-related macular degeneration (AMD) afflicts

  8. Can human eyes prevent perceptual narrowing for monkey faces in human infants?

    Science.gov (United States)

    Damon, Fabrice; Bayet, Laurie; Quinn, Paul C; Hillairet de Boisferon, Anne; Méary, David; Dupierrix, Eve; Lee, Kang; Pascalis, Olivier

    2015-07-01

    Perceptual narrowing has been observed in human infants for monkey faces: 6-month-olds can discriminate between them, whereas older infants from 9 months of age display difficulty discriminating between them. The difficulty infants from 9 months have processing monkey faces has not been clearly identified. It could be due to the structural characteristics of monkey faces, particularly the key facial features that differ from human faces. The current study aimed to investigate whether the information conveyed by the eyes is of importance. We examined whether the presence of Caucasian human eyes in monkey faces allows recognition to be maintained in 6-month-olds and facilitates recognition in 9- and 12-month-olds. Our results revealed that the presence of human eyes in monkey faces maintains recognition for those faces at 6 months of age and partially facilitates recognition of those faces at 9 months of age, but not at 12 months of age. The findings are interpreted in the context of perceptual narrowing and suggest that the attenuation of processing of other-species faces is not reversed by the presence of human eyes.

  9. Perceptual full-reference quality assessment of stereoscopic images by considering binocular visual characteristics.

    Science.gov (United States)

    Shao, Feng; Lin, Weisi; Gu, Shanbo; Jiang, Gangyi; Srikanthan, Thambipillai

    2013-05-01

    Perceptual quality assessment is a challenging issue in 3D signal processing research. It is important to study 3D signal directly instead of studying simple extension of the 2D metrics directly to the 3D case as in some previous studies. In this paper, we propose a new perceptual full-reference quality assessment metric of stereoscopic images by considering the binocular visual characteristics. The major technical contribution of this paper is that the binocular perception and combination properties are considered in quality assessment. To be more specific, we first perform left-right consistency checks and compare matching error between the corresponding pixels in binocular disparity calculation, and classify the stereoscopic images into non-corresponding, binocular fusion, and binocular suppression regions. Also, local phase and local amplitude maps are extracted from the original and distorted stereoscopic images as features in quality assessment. Then, each region is evaluated independently by considering its binocular perception property, and all evaluation results are integrated into an overall score. Besides, a binocular just noticeable difference model is used to reflect the visual sensitivity for the binocular fusion and suppression regions. Experimental results show that compared with the relevant existing metrics, the proposed metric can achieve higher consistency with subjective assessment of stereoscopic images.

  10. SCALABLE PERCEPTUAL AUDIO REPRESENTATION WITH AN ADAPTIVE THREE TIME-SCALE SINUSOIDAL SIGNAL MODEL

    Institute of Scientific and Technical Information of China (English)

    Al-Moussawy Raed; Yin Junxun; Song Shaopeng

    2004-01-01

    This work is concerned with the development and optimization of a signal model for scalable perceptual audio coding at low bit rates. A complementary two-part signal model consisting of Sines plus Noise (SN) is described. The paper presents essentially a fundamental enhancement to the sinusoidal modeling component. The enhancement involves an audio signal scheme based on carrying out overlap-add sinusoidal modeling at three successive time scales,large, medium, and small. The sinusoidal modeling is done in an analysis-by-synthesis overlapadd manner across the three scales by using a psychoacoustically weighted matching pursuits.The sinusoidal modeling residual at the first scale is passed to the smaller scales to allow for the modeling of various signal features at appropriate resolutions. This approach greatly helps to correct the pre-echo inherent in the sinusoidal model. This improves the perceptual audio quality upon our previous work of sinusoidal modeling while using the same number of sinusoids. The most obvious application for the SN model is in scalable, high fidelity audio coding and signal modification.

  11. Acoustic and perceptual characteristics of voicing in fricatives and fricative clusters.

    Science.gov (United States)

    Stevens, K N; Blumstein, S E; Glicksman, L; Burton, M; Kurowski, K

    1992-05-01

    Several types of measurements were made to determine the acoustic characteristics that distinguish between voiced and voiceless fricatives in various phonetic environments. The selection of measurements was based on a theoretical analysis that indicated the acoustic and aerodynamic attributes at the boundaries between fricatives and vowels. As expected, glottal vibration extended over a longer time in the obstruent interval for voiced fricatives than for voiceless fricatives, and there were more extensive transitions of the first formant adjacent to voiced fricatives than for the voiceless cognates. When two fricatives with different voicing were adjacent, there were substantial modifications of these acoustic attributes, particularly for the syllable-final fricative. In some cases, these modifications leads to complete assimilation of the voicing feature. Several perceptual studies with synthetic vowel-consonant-vowel stimuli and with edited natural stimuli examined the role of consonant duration, extent and location of glottal vibration, and extent of formant transitions on the identification of the voicing characteristics of fricatives. The perceptual results were in general consistent with the acoustic observations and with expectations based on the theoretical model. The results suggest that listeners base their voicing judgments of intervocalic fricatives on an assessment of the time interval in the fricative during which there is no glottal vibration. This time interval must exceed about 60 ms if the fricative is to be judged as voiceless, except that a small correction to this threshold is applied depending on the extent to which the first-formant transitions are truncated at the consonant boundaries.

  12. Automatic perceptual simulation of first language meanings during second language sentence processing in bilinguals.

    Science.gov (United States)

    Vukovic, Nikola; Williams, John N

    2014-01-01

    Research supports the claim that, when understanding language, people perform mental simulation using those parts of the brain which support sensation, action, and emotion. A major criticism of the findings quoted as evidence for embodied simulation, however, is that they could be a result of conscious image generation strategies. Here we exploit the well-known fact that bilinguals routinely and automatically activate both their languages during comprehension to test whether this automatic process is, in turn, modulated by embodied simulatory processes. Dutch participants heard English sentences containing interlingual homophones and implying specific distance relations, and had to subsequently respond to pictures of objects matching or mismatching this implied distance. Participants were significantly slower to reject critical items when their perceptual features matched said distance relationship. These results suggest that bilinguals not only activate task-irrelevant meanings of interlingual homophones, but also automatically simulate these meanings in a detailed perceptual fashion. Our study supports the claim that embodied simulation is not due to participants' conscious strategies, but is an automatic component of meaning construction. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. A Bayesian Reformulation of the Extended Drift-Diffusion Model in Perceptual Decision Making

    Science.gov (United States)

    Fard, Pouyan R.; Park, Hame; Warkentin, Andrej; Kiebel, Stefan J.; Bitzer, Sebastian

    2017-01-01

    Perceptual decision making can be described as a process of accumulating evidence to a bound which has been formalized within drift-diffusion models (DDMs). Recently, an equivalent Bayesian model has been proposed. In contrast to standard DDMs, this Bayesian model directly links information in the stimulus to the decision process. Here, we extend this Bayesian model further and allow inter-trial variability of two parameters following the extended version of the DDM. We derive parameter distributions for the Bayesian model and show that they lead to predictions that are qualitatively equivalent to those made by the extended drift-diffusion model (eDDM). Further, we demonstrate the usefulness of the extended Bayesian model (eBM) for the analysis of concrete behavioral data. Specifically, using Bayesian model selection, we find evidence that including additional inter-trial parameter variability provides for a better model, when the model is constrained by trial-wise stimulus features. This result is remarkable because it was derived using just 200 trials per condition, which is typically thought to be insufficient for identifying variability parameters in DDMs. In sum, we present a Bayesian analysis, which provides for a novel and promising analysis of perceptual decision making experiments. PMID:28553219

  14. A Bayesian Reformulation of the Extended Drift-Diffusion Model in Perceptual Decision Making

    Directory of Open Access Journals (Sweden)

    Pouyan R. Fard

    2017-05-01

    Full Text Available Perceptual decision making can be described as a process of accumulating evidence to a bound which has been formalized within drift-diffusion models (DDMs. Recently, an equivalent Bayesian model has been proposed. In contrast to standard DDMs, this Bayesian model directly links information in the stimulus to the decision process. Here, we extend this Bayesian model further and allow inter-trial variability of two parameters following the extended version of the DDM. We derive parameter distributions for the Bayesian model and show that they lead to predictions that are qualitatively equivalent to those made by the extended drift-diffusion model (eDDM. Further, we demonstrate the usefulness of the extended Bayesian model (eBM for the analysis of concrete behavioral data. Specifically, using Bayesian model selection, we find evidence that including additional inter-trial parameter variability provides for a better model, when the model is constrained by trial-wise stimulus features. This result is remarkable because it was derived using just 200 trials per condition, which is typically thought to be insufficient for identifying variability parameters in DDMs. In sum, we present a Bayesian analysis, which provides for a novel and promising analysis of perceptual decision making experiments.

  15. Einstein's jacket: evidence for long-term perceptual specificity in mental imagery.

    Science.gov (United States)

    Pearson, David G; Hollings, James

    2013-03-01

    To what extent are visual fantasies constrained by our perceptual experience of the real world? Our study exploits the fact that people's knowledge of the appearance of individuals from the early 20th Century (e.g., Albert Einstein, Winston Churchill) derives predominantly from viewing black-and-white media images. An initial experiment shows that mental imagery for individuals from this period are experienced as significantly less colourful than imagery for individuals from the era of colour media. A second experiment manipulated whether participants were instructed to explicitly imagine using colour or not (i.e., "imagine Albert Einstein wearing a green jacket" vs. "imagine Albert Einstein wearing a jacket"). Results show that colour manipulation only influences imagery for black-and-white era individuals, with no comparable effect on imagery for colour era individuals. This finding is replicated in a third experiment that includes an additional control condition of imagining generic characters (i.e., "Imagine a knight wearing a cloak" vs. "imagine a knight wearing a red cloak"). Again, only imagery for black-and-white era individuals is affected by the colour manipulation. Overall these results provide evidence for long-term perceptual specificity effects in mental imagery. We argue that visual fantasies can be constrained by surface features of underlying representations in memory, even when imagining something we have never directly perceived.

  16. Wave-atoms-based multipurpose scheme via perceptual image hashing and watermarking.

    Science.gov (United States)

    Liu, Fang; Fu, Qi-Kai; Cheng, Lee-Ming

    2012-09-20

    This paper presents a novel multipurpose scheme for content-based image authentication and copyright protection using a perceptual image hashing and watermarking strategy based on a wave atom transform. The wave atom transform is expected to outperform other transforms because it gains sparser expansion and better representation for texture than other traditional transforms, such as wavelet and curvelet transforms. Images are decomposed into multiscale bands with a number of tilings using the wave atom transform. Perceptual hashes are then extracted from the features of tiling in the third scale band for the purpose of content-based authentication; simultaneously, part of the selected hashes are designed as watermarks, which are embedded into the original images for the purpose of copyright protection. The experimental results demonstrate that the proposed scheme shows great performance in content-based authentication by distinguishing the maliciously attacked images from the nonmaliciously attacked images. Moreover, watermarks extracted from the proposed scheme also achieve high robustness against common malicious and nonmalicious image-processing attacks, which provides excellent copyright protection for images.

  17. Reducing crowding by weakening inhibitory lateral interactions in the periphery with perceptual learning.

    Directory of Open Access Journals (Sweden)

    Marcello Maniglia

    Full Text Available We investigated whether lateral masking in the near-periphery, due to inhibitory lateral interactions at an early level of central visual processing, could be weakened by perceptual learning and whether learning transferred to an untrained, higher-level lateral masking known as crowding. The trained task was contrast detection of a Gabor target presented in the near periphery (4° in the presence of co-oriented and co-aligned high contrast Gabor flankers, which featured different target-to-flankers separations along the vertical axis that varied from 2λ to 8λ. We found both suppressive and facilitatory lateral interactions at target-to-flankers distances (2λ - 4λ and 8λ, respectively that were larger than those found in the fovea. Training reduces suppression but does not increase facilitation. Most importantly, we found that learning reduces crowding and improves contrast sensitivity, but has no effect on visual acuity (VA. These results suggest a different pattern of connectivity in the periphery with respect to the fovea as well as a different modulation of this connectivity via perceptual learning that not only reduces low-level lateral masking but also reduces crowding. These results have important implications for the rehabilitation of low-vision patients who must use peripheral vision to perform tasks, such as reading and refined figure-ground segmentation, which normal sighted subjects perform in the fovea.

  18. Decoding of single-trial auditory mismatch responses for online perceptual monitoring and neurofeedback

    Directory of Open Access Journals (Sweden)

    Alex eBrandmeyer

    2013-12-01

    Full Text Available Multivariate pattern classification methods are increasingly applied to neuroimaging data in the context of both fundamental research and in brain-computer interfacing approaches. Such methods provide a framework for interpreting measurements made at the single-trial level with respect to a set of two or more distinct mental states. Here, we define an approach in which the output of a binary classifier trained on data from an auditory mismatch paradigm can be used for online tracking of perception and as a neurofeedback signal. The auditory mismatch paradigm is known to induce distinct perceptual states related to the presentation of high- and low-probability stimuli, which are reflected in event-related potential (ERP components such as the mismatch negativity (MMN. In the first part of the paper, we illustrate how pattern classification methods can be applied to data collected in an MMN paradigm, including discussion of the optimization of preprocessing steps, the interpretation of features and how the performance of these methods generalizes across individual participants and measurement sessions. We then go on to show that the output of these decoding methods can be used in online settings as a continuous index of single-trial brain activation underlying perceptual discrimination. We conclude by discussing several potential domains of application, including neurofeedback, cognitive monitoring and passive brain-computer interfaces.

  19. Perceptual grouping over time within and across auditory and tactile modalities.

    Directory of Open Access Journals (Sweden)

    I-Fan Lin

    Full Text Available In auditory scene analysis, population separation and temporal coherence have been proposed to explain how auditory features are grouped together and streamed over time. The present study investigated whether these two theories can be applied to tactile streaming and whether temporal coherence theory can be applied to crossmodal streaming. The results show that synchrony detection between two tones/taps at different frequencies/locations became difficult when one of the tones/taps was embedded in a perceptual stream. While the taps applied to the same location were streamed over time, the taps applied to different locations were not. This observation suggests that tactile stream formation can be explained by population-separation theory. On the other hand, temporally coherent auditory stimuli at different frequencies were streamed over time, but temporally coherent tactile stimuli applied to different locations were not. When there was within-modality streaming, temporally coherent auditory stimuli and tactile stimuli were not streamed over time, either. This observation suggests the limitation of temporal coherence theory when it is applied to perceptual grouping over time.

  20. Feature saliency and feedback information interactively impact visual category learning.

    Science.gov (United States)

    Hammer, Rubi; Sloutsky, Vladimir; Grill-Spector, Kalanit

    2015-01-01

    Visual category learning (VCL) involves detecting which features are most relevant for categorization. VCL relies on attentional learning, which enables effectively redirecting attention to object's features most relevant for categorization, while 'filtering out' irrelevant features. When features relevant for categorization are not salient, VCL relies also on perceptual learning, which enables becoming more sensitive to subtle yet important differences between objects. Little is known about how attentional learning and perceptual learning interact when VCL relies on both processes at the same time. Here we tested this interaction. Participants performed VCL tasks in which they learned to categorize novel stimuli by detecting the feature dimension relevant for categorization. Tasks varied both in feature saliency (low-saliency tasks that required perceptual learning vs. high-saliency tasks), and in feedback information (tasks with mid-information, moderately ambiguous feedback that increased attentional load, vs. tasks with high-information non-ambiguous feedback). We found that mid-information and high-information feedback were similarly effective for VCL in high-saliency tasks. This suggests that an increased attentional load, associated with the processing of moderately ambiguous feedback, has little effect on VCL when features are salient. In low-saliency tasks, VCL relied on slower perceptual learning; but when the feedback was highly informative participants were able to ultimately attain the same performance as during the high-saliency VCL tasks. However, VCL was significantly compromised in the low-saliency mid-information feedback task. We suggest that such low-saliency mid-information learning scenarios are characterized by a 'cognitive loop paradox' where two interdependent learning processes have to take place simultaneously.

  1. Extraction of auditory features and elicitation of attributes for the assessment of multichannel reproduced sound

    DEFF Research Database (Denmark)

    Choisel, Sylvain; Wickelmaier, Florian Maria

    2006-01-01

    ), subjects were asked to directly assign verbal labels to the features when encountering them, and to subsequently rate the sounds on the scales thus obtained. The second method required the subjects to consistently use the perceptually relevant features in triadic comparisons, without having to assign them...

  2. Feature Types and Object Categories: Is Sensorimotoric Knowledge Different for Living and Nonliving Things?

    Science.gov (United States)

    Ankerstein, Carrie A.; Varley, Rosemary A.; Cowell, Patricia E.

    2012-01-01

    Some models of semantic memory claim that items from living and nonliving domains have different feature-type profiles. Data from feature generation and perceptual modality rating tasks were compared to evaluate this claim. Results from two living (animals, fruits/vegetables) and two nonliving (tools, vehicles) categories showed that…

  3. A Computational Model of Perceptual and Mnemonic Deficits in Medial Temporal Lobe Amnesia.

    Science.gov (United States)

    Sadil, Patrick S; Cowell, Rosemary A

    2017-02-14

    Damage to the medial temporal lobe (MTL) has long been known to impair declarative memory, and recent evidence suggests that it also impairs visual perception. A theory termed the representational-hierarchical account explains such impairments by assuming that MTL stores conjunctive representations of items and events, and that individuals with MTL damage must rely upon representations of simple visual features in posterior visual cortex, which are inadequate to support memory and perception under certain circumstances. One recent study of visual discrimination behavior revealed a surprising antiperceptual learning effect in MTL-damaged individuals: With exposure to a set of visual stimuli, discrimination performance worsened rather than improved [Barense, M. D., Groen, I. I. A., Lee, A. C. H., Yeung, L. K., Brady, S. M., Gregori, M., et al. Intact memory for irrelevant information impairs perception in amnesia. Neuron, 75, 157-167, 2012]. We extend the representational-hierarchical account to explain this paradox by assuming that difficult visual discriminations are performed by comparing the relative "representational tunedness"-or familiarity-of the to-be-discriminated items. Exposure to a set of highly similar stimuli entails repeated presentation of simple visual features, eventually rendering all feature representations maximally and, thus, equally familiar; hence, they are inutile for solving the task. Discrimination performance in patients with MTL lesions is therefore impaired by stimulus exposure. Because the unique conjunctions represented in MTL do not occur repeatedly, healthy individuals are shielded from this perceptual interference. We simulate this mechanism with a neural network previously used to explain recognition memory, thereby providing a model that accounts for both mnemonic and perceptual deficits caused by MTL damage with a unified architecture and mechanism.

  4. Trifurcation of superficial brachial artery: a rare case with its clinico-embryological implications.

    Science.gov (United States)

    Gupta, N; Anshu, A; Dada, R

    2014-01-01

    Literatures on vasculature of upper limbs are crammed with reports of distinctly deviant version of normally prevalent vessels having modified origins, altered branching and odd courses. A unique anatomical variation in vascular pattern was observed during routine dissection of right upper limb in gross anatomy laboratory, AIIMS, New Delhi, India. The brachial artery was placed superficial to median nerve in the arm and therefore it was called superficial brachial artery. In the cubital fossa, 2.8 cm distal to intercondylar line of elbow joint, this superficial brachial artery terminated by trifurcation into radial, common interosseous and ulnar branches. Strikingly the ulnar branch, after its origin ran superficially over the median nerve and epitrochlear superficial flexor group of muscles of forearm in succession for the initial third of its course in the forearm, consequently it was addressed as superficial ulnar artery. The existence of superficial brachial artery in place of normal brachial artery, its termination by trifurcation into radial, common interosseous and superficial ulnar arteries with remarkably different courses, leads to confusing disposition of structures in the arm, cubital fossa and in the forearm and collectively makes this myriad of anatomical variations even rarer. The clinico-embryological revelations for combination of these unconventional observations, apprises and guides the specialized medical personnel attempting blind and invasive procedures in brachium and ante-brachium. This case report depicts the anatomical perspective and clinical implications on confronting a rare variant vasculature architecture pattern of upper limb.

  5. Chronic exertional compartment syndrome of the superficial posterior compartment: Soleus syndrome.

    Science.gov (United States)

    Gross, Christopher E; Parekh, Bela J; Adams, Samuel B; Parekh, Selene G

    2015-01-01

    Chronic exertional compartment syndrome (CECS) represents the second most-common cause of exertional leg pain with incidence of 27-33%. CECS of the superficial posterior compartment, or soleus syndrome, is rare and has only been discussed briefly in the literature. We discuss the management of two patients with bilateral soleus syndrome or CECS of the superficial posterior compartment.

  6. First-Hand Accounts of Sensory Perceptual Experiences in Autism: A Qualitative Analysis.

    Science.gov (United States)

    Jones, Robert S. P.; Quigney, Ciara; Huws, Jaci C.

    2003-01-01

    Five first-hand Web page accounts of unusual sensory perceptual experiences written by persons with high-functioning autism were selected for qualitative analysis. Four core categories emerged: turbulent sensory perceptual experiences; coping mechanisms; enjoyable sensory perceptual experiences; and awareness of being different, suggesting they…

  7. On Perceptual Distortion Minimization and Nonlinear Least-Squares Frequency Estimation

    DEFF Research Database (Denmark)

    Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2006-01-01

    In this paper, we present a framework for perceptual error minimization and sinusoidal frequency estimation based on a new perceptual distortion measure, and we state its optimal solution. Using this framework, we relate a number of well-known practical methods for perceptual sinusoidal parameter...

  8. Mississippi Perceptual Motor Symposium Proceedings (Jackson, April 20-21, 1973).

    Science.gov (United States)

    Carlson, Robert; And Others

    Presented are the proceedings of the Mississippi Perceptual-Motor Symposium, April 20-21, 1973. Included are papers on motor development, models for perceptual motor programming, children with minimal brain damage, effects of learning games or academic abilities, research on perceptual motor measures, and programs for motor development. (JB)

  9. The relationship between perceptual decision variables and confidence in the human brain

    NARCIS (Netherlands)

    Hebart, M.N.; Schriever, Y.; Donner, T.H.; Haynes, J.D.

    2015-01-01

    Perceptual confidence refers to the degree to which we believe in the accuracy of our percepts. Signal detection theory suggests that perceptual confidence is computed from an internal "decision variable," which reflects the amount of available information in favor of one or another perceptual

  10. The Development of Perceptual Grouping Biases in Infancy: A Japanese-English Cross-Linguistic Study

    Science.gov (United States)

    Yoshida, Katherine A.; Iversen, John R.; Patel, Aniruddh D.; Mazuka, Reiko; Nito, Hiromi; Gervain, Judit; Werker, Janet F.

    2010-01-01

    Perceptual grouping has traditionally been thought to be governed by innate, universal principles. However, recent work has found differences in Japanese and English speakers' non-linguistic perceptual grouping, implicating language in non-linguistic perceptual processes (Iversen, Patel, & Ohgushi, 2008). Two experiments test Japanese- and…

  11. Estudio del estado físico-mecánico de superficies tratadas por deformación plástica superficial. // Study of the mechanical and physical behavior of surfaces treated by superficial plastic deformation.

    Directory of Open Access Journals (Sweden)

    O. Boada Carrazana

    2003-05-01

    Full Text Available El presente trabajo aborda lo referente al estado del arte de la modelación y el comportamiento de las superficies tratadapor deformación plástica superficial (DPS. Se hace una breve descripción de la modelación elástica y plástica, de la teoríade la plasticidad y de las dislocaciones y se dan algunos resultados sobre la modelación del rodilado usando las técnicasde simulación y modelación, como el método de los elementos finitos, a partir del cual se obtienen los modelosmatemáticos para calcular las tensiones y deformaciones máximas.Palabras claves: deformación plástica superficial, rodilado, bruñido por rodillo, elementos finitos,modelación.____________________________________________________________________________Abstract.This paper deals with the state of the art of modelation and the behaviour of surfaces treated by superficial plasticdeformation. It is given a brief description of the elastic and plastic modelation, theory of plasticity and dislocations, andshowed some results about modelation of roller burnishing using simulation techniques like finite elements method toobtain the mathematics models in order to calculate the maximum stresses and strains.Key words: Superficial plastic deformation, roller burnishing, finite elements method, modelation.

  12. Multiattribute perceptual mapping with idiosyncratic brand and attribute sets

    NARCIS (Netherlands)

    Bijmolt, Tammo H. A.; van de Velden, Michel

    2012-01-01

    This article proposes an extremely flexible procedure for perceptual mapping based on multiattribute ratings, such that the respondent freely generates sets of both brands and attributes. Therefore, the brands and attributes are known and relevant to each participant. Collecting and analyzing such i

  13. Modelling perceptual characteristics of loudspeaker reproduction in a stereo setup

    DEFF Research Database (Denmark)

    Volk, Christer Peter; Bech, Søren; Pedersen, Torben Holm

    2017-01-01

    of the perceptual evaluation, four of the descriptors were found suited for modelling, with the purpose of developing metrics for prediction of Bass depth, Punch, Brilliance, and Dark-Bright. Bass depth and Punch were modelled as one due to high correlation between them. The experimental setup included loudspeaker...

  14. Attentional Modulation in Visual Cortex Is Modified during Perceptual Learning

    Science.gov (United States)

    Bartolucci, Marco; Smith, Andrew T.

    2011-01-01

    Practicing a visual task commonly results in improved performance. Often the improvement does not transfer well to a new retinal location, suggesting that it is mediated by changes occurring in early visual cortex, and indeed neuroimaging and neurophysiological studies both demonstrate that perceptual learning is associated with altered activity…

  15. Perceptual Wholes Can Reduce the Conscious Accessibility of Their Parts

    Science.gov (United States)

    Poljac, Ervin; de-Wit, Lee; Wagemans, Johan

    2012-01-01

    Humans can rapidly extract object and category information from an image despite surprising limitations in detecting changes to the individual parts of that image. In this article we provide evidence that the construction of a perceptual whole, or Gestalt, reduces awareness of changes to the parts of this object. This result suggests that the…

  16. Tongue-Palate Contact of Perceptually Acceptable Alveolar Stops

    Science.gov (United States)

    Lee, Alice; Gibbon, Fiona E.; O'Donovan, Cliona

    2013-01-01

    Increased tongue-palate contact for perceptually acceptable alveolar stops has been observed in children with speech sound disorders (SSD). This is a retrospective study that further investigated this issue by using quantitative measures to compare the target alveolar stops /t/, /d/ and /n/ produced in words by nine children with SSD (20 tokens of…

  17. Effects of Perceptual Variations on Number Comparison Tasks.

    Science.gov (United States)

    Kingma, Johannes; Loth, Franciska L.

    1984-01-01

    Investigates the performance of 502 children ranging in age from four years to six years, ten months, on two-choice and multiple-choice number comparison tasks, and explores the effects of perceptual manipulations of elements in the multiple-choice tasks. (RH)

  18. Lexically-guided perceptual learning in speech processing

    NARCIS (Netherlands)

    Eisner, F.

    2006-01-01

    During listening to spoken language, the perceptual system needs to adapt frequently to changes in talkers, and thus to considerable interindividual variability in the articulation of a given speech sound. This thesis investigated a learning process which allows listeners to use stored lexical repre

  19. Dichotomy and perceptual distortions in absolute pitch ability.

    Science.gov (United States)

    Athos, E Alexandra; Levinson, Barbara; Kistler, Amy; Zemansky, Jason; Bostrom, Alan; Freimer, Nelson; Gitschier, Jane

    2007-09-11

    Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a "perceptual magnet" centered at the note "A." In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the "sharp" direction. These findings speak both to the process of acquisition of AP and to its stability.

  20. Perceptual Anomalies in Schizophrenia: Integrating Phenomenology and Cognitive Neuroscience

    Science.gov (United States)

    Uhlhaas, Peter J.; Mishara, Aaron L.

    2007-01-01

    From phenomenological and experimental perspectives, research in schizophrenia has emphasized deficits in “higher” cognitive functions, including attention, executive function, as well as memory. In contrast, general consensus has viewed dysfunctions in basic perceptual processes to be relatively unimportant in the explanation of more complex aspects of the disorder, including changes in self-experience and the development of symptoms such as delusions. We present evidence from phenomenology and cognitive neuroscience that changes in the perceptual field in schizophrenia may represent a core impairment. After introducing the phenomenological approach to perception (Husserl, the Gestalt School), we discuss the views of Paul Matussek, Klaus Conrad, Ludwig Binswanger, and Wolfgang Blankenburg on perception in schizophrenia. These 4 psychiatrists describe changes in perception and automatic processes that are related to the altered experience of self. The altered self-experience, in turn, may be responsible for the emergence of delusions. The phenomenological data are compatible with current research that conceptualizes dysfunctions in perceptual processing as a deficit in the ability to combine stimulus elements into coherent object representations. Relationships of deficits in perceptual organization to cognitive and social dysfunction as well as the possible neurobiological mechanisms are discussed. PMID:17118973