WorldWideScience

Sample records for body transfer illusion

  1. Removal of proprioception by BCI raises a stronger body ownership illusion in control of a humanlike robot

    Science.gov (United States)

    Alimardani, Maryam; Nishio, Shuichi; Ishiguro, Hiroshi

    2016-01-01

    Body ownership illusions provide evidence that our sense of self is not coherent and can be extended to non-body objects. Studying about these illusions gives us practical tools to understand the brain mechanisms that underlie body recognition and the experience of self. We previously introduced an illusion of body ownership transfer (BOT) for operators of a very humanlike robot. This sensation of owning the robot’s body was confirmed when operators controlled the robot either by performing the desired motion with their body (motion-control) or by employing a brain-computer interface (BCI) that translated motor imagery commands to robot movement (BCI-control). The interesting observation during BCI-control was that the illusion could be induced even with a noticeable delay in the BCI system. Temporal discrepancy has always shown critical weakening effects on body ownership illusions. However the delay-robustness of BOT during BCI-control raised a question about the interaction between the proprioceptive inputs and delayed visual feedback in agency-driven illusions. In this work, we compared the intensity of BOT illusion for operators in two conditions; motion-control and BCI-control. Our results revealed a significantly stronger BOT illusion for the case of BCI-control. This finding highlights BCI’s potential in inducing stronger agency-driven illusions by building a direct communication between the brain and controlled body, and therefore removing awareness from the subject’s own body. PMID:27654174

  2. Removal of proprioception by BCI raises a stronger body ownership illusion in control of a humanlike robot.

    Science.gov (United States)

    Alimardani, Maryam; Nishio, Shuichi; Ishiguro, Hiroshi

    2016-09-22

    Body ownership illusions provide evidence that our sense of self is not coherent and can be extended to non-body objects. Studying about these illusions gives us practical tools to understand the brain mechanisms that underlie body recognition and the experience of self. We previously introduced an illusion of body ownership transfer (BOT) for operators of a very humanlike robot. This sensation of owning the robot's body was confirmed when operators controlled the robot either by performing the desired motion with their body (motion-control) or by employing a brain-computer interface (BCI) that translated motor imagery commands to robot movement (BCI-control). The interesting observation during BCI-control was that the illusion could be induced even with a noticeable delay in the BCI system. Temporal discrepancy has always shown critical weakening effects on body ownership illusions. However the delay-robustness of BOT during BCI-control raised a question about the interaction between the proprioceptive inputs and delayed visual feedback in agency-driven illusions. In this work, we compared the intensity of BOT illusion for operators in two conditions; motion-control and BCI-control. Our results revealed a significantly stronger BOT illusion for the case of BCI-control. This finding highlights BCI's potential in inducing stronger agency-driven illusions by building a direct communication between the brain and controlled body, and therefore removing awareness from the subject's own body.

  3. The building blocks of the full body ownership illusion

    Directory of Open Access Journals (Sweden)

    Antonella eMaselli

    2013-03-01

    Full Text Available Previous work has reported that it is not difficult to give people the illusion of ownership over an artificial body, providing a powerful tool for the investigation of the neural and cognitive mechanisms underlying body perception and self consciousness. We present an experimental study that uses immersive virtual reality focused on identifying the perceptual building blocks of this illusion. We systematically manipulated visuotactile and visual sensorimotor contingencies, visual perspective, and the appearance of the virtual body in order to assess their relative role and mutual interaction. Consistent results from subjective reports and physiological measures showed that a first person perspective over a fake humanoid body is essential for eliciting a body ownership illusion. We found that the level of realism of the virtual body, in particular the realism of skin tone, plays a critical role: when high enough, the illusion can be triggered by the sole effect of the spatial overlap between the real and virtual bodies, providing congruent visuoproprioceptive information, with no need for the additional contribution of congruent visuotactile and/or visual sensorimotor cues. Additionally, we found that the processing of incongruent perceptual cues can be modulated by the level of the illusion: when the illusion is strong, incongruent cues are not experienced as incorrect. Participants exposed to asynchronous visuotactile stimulation can experience the ownership illusion and perceive touch as originating from an object seen to contact the virtual body. Analogously, when the level of realism of the virtual body and/or the spatial overlap of the two bodies is not high enough, the contribution of congruent multisensory and/or sensorimotor cues is required for evoking the illusion. On the basis of these results and inspired by findings from neurophysiological recordings in the monkey, we propose a model that accounts for many of the results reported

  4. A Virtual Reality Full Body Illusion Improves Body Image Disturbance in Anorexia Nervosa

    NARCIS (Netherlands)

    Keizer, Anouk; van Elburg, Annemarie; Helms, Rossa; Dijkerman, H Chris

    2016-01-01

    BACKGROUND: Patients with anorexia nervosa (AN) have a persistent distorted experience of the size of their body. Previously we found that the Rubber Hand Illusion improves hand size estimation in this group. Here we investigated whether a Full Body Illusion (FBI) affects body size estimation of bod

  5. Illusions.

    Science.gov (United States)

    Osterhaus, Kenneth

    An art activity introduces intermediate grade and middle school students to optical illusions. Students practice drawing geometric shapes such as cubes, cylinders, cones, and pyramids, then combine these shapes to create the illusion of their choice. Graphic outlines for each shape are provided. This document is one of a collection of materials…

  6. Towards a digital body: the virtual arm illusion

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available The integration of the human brain with computers is an interesting new area of applied neuroscience, where one application is replacement of a person’s real body by a virtual representation. Here we demonstrate that a virtual limb can be made to feel part of your body if appropriate multisensory correlations are provided. We report an illusion that is invoked through tactile stimulation on a person’s hidden real right hand with synchronous virtual visual stimulation on an aligned 3D stereo virtual arm projecting horizontally out of their shoulder. An experiment with 21 male participants showed displacement of ownership towards the virtual hand, as illustrated by questionnaire responses and proprioceptive drift. A control experiment with asynchronous tapping was carried out with a different set of 20 male participants who did not experience the illusion. After 5 minutes of stimulation the virtual arm rotated. Evidence suggests that the extent of the illusion was also correlated with the degree of muscle activity onset in the right arm as measured by EMG during this period that the arm was rotating, for the synchronous but not the asynchronous condition. A completely virtual object can therefore be experienced as part of one’s self, which opens up the possibility that an entire virtual body could be felt as one’s own in future virtual reality applications or online games, and be an invaluable tool for the understanding of the brain mechanisms underlying body ownership.

  7. Proprioceptive body illusions modulate the visual perception of reaching distance.

    Directory of Open Access Journals (Sweden)

    Agustin Petroni

    Full Text Available The neurobiology of reaching has been extensively studied in human and non-human primates. However, the mechanisms that allow a subject to decide-without engaging in explicit action-whether an object is reachable are not fully understood. Some studies conclude that decisions near the reach limit depend on motor simulations of the reaching movement. Others have shown that the body schema plays a role in explicit and implicit distance estimation, especially after motor practice with a tool. In this study we evaluate the causal role of multisensory body representations in the perception of reachable space. We reasoned that if body schema is used to estimate reach, an illusion of the finger size induced by proprioceptive stimulation should propagate to the perception of reaching distances. To test this hypothesis we induced a proprioceptive illusion of extension or shrinkage of the right index finger while participants judged a series of LEDs as reachable or non-reachable without actual movement. Our results show that reach distance estimation depends on the illusory perceived size of the finger: illusory elongation produced a shift of reaching distance away from the body whereas illusory shrinkage produced the opposite effect. Combining these results with previous findings, we suggest that deciding if a target is reachable requires an integration of body inputs in high order multisensory parietal areas that engage in movement simulations through connections with frontal premotor areas.

  8. Proprioceptive Body Illusions Modulate the Visual Perception of Reaching Distance

    Science.gov (United States)

    Petroni, Agustin; Carbajal, M. Julia; Sigman, Mariano

    2015-01-01

    The neurobiology of reaching has been extensively studied in human and non-human primates. However, the mechanisms that allow a subject to decide—without engaging in explicit action—whether an object is reachable are not fully understood. Some studies conclude that decisions near the reach limit depend on motor simulations of the reaching movement. Others have shown that the body schema plays a role in explicit and implicit distance estimation, especially after motor practice with a tool. In this study we evaluate the causal role of multisensory body representations in the perception of reachable space. We reasoned that if body schema is used to estimate reach, an illusion of the finger size induced by proprioceptive stimulation should propagate to the perception of reaching distances. To test this hypothesis we induced a proprioceptive illusion of extension or shrinkage of the right index finger while participants judged a series of LEDs as reachable or non-reachable without actual movement. Our results show that reach distance estimation depends on the illusory perceived size of the finger: illusory elongation produced a shift of reaching distance away from the body whereas illusory shrinkage produced the opposite effect. Combining these results with previous findings, we suggest that deciding if a target is reachable requires an integration of body inputs in high order multisensory parietal areas that engage in movement simulations through connections with frontal premotor areas. PMID:26110274

  9. Weber's Illusion and Body Shape: Anisotropy of Tactile Size Perception on the Hand

    Science.gov (United States)

    Longo, Matthew R.; Haggard, Patrick

    2011-01-01

    The perceived distance between touches on a single skin surface is larger on regions of high tactile sensitivity than those with lower acuity, an effect known as "Weber's illusion". This illusion suggests that tactile size perception involves a representation of the perceived size of body parts preserving characteristics of the somatosensory…

  10. Combined induction of rubber-hand illusion and out-of-body experiences

    Directory of Open Access Journals (Sweden)

    Isadora eOlivé

    2012-05-01

    Full Text Available The emergence of self-consciousness depends on several processes: those of body ownership, attributing self-identity to the body, and those of self-location, localizing our sense of self. Studies of phenomena like the rubber hand illusion (RHi and out-of-body experience (OBE investigate these processes, respectively for representations of a body-part and the full-body. It is supposed that RHi only target processes related to body-part representations, while OBE only relates to full-body representations. The fundamental question whether the body-part and the full-body illusions relate to each other is nevertheless insufficiently investigated. In search for a link between body-part and full-body illusions in the brain we developed a behavioural task combining adapted versions of the RHi and OBE. Furthermore, for the investigation of this putative link we investigated the role of sensory and motor cues. We established a spatial dissociation between visual and proprioceptive feedback of a hand perceived through virtual reality in rest or action. Two experimental measures were introduced: one for the body-part illusion, the proprioceptive drift of the perceived localisation of the hand, and one for the full-body illusion, the shift in subjective-straight-ahead. In the rest and action conditions it was observed that the proprioceptive drift of the left hand and the shift in subjective-straight-ahead towards the manipulation side are equivalent. The combined effect was dependent on the manipulation of the visual representation of body-parts, rejecting any main or even modulatory role for relevant motor programs. Our study demonstrates for the first time that there is a systematic relationship between the body-part illusion and the full-body illusion, as shown by our measures. This suggests a link between the representations in the brain of a body-part and the full-body, and consequently a common mechanism underpinning both forms of ownership and self-location.

  11. Brain process for perception of the "out of the body" tactile illusion for virtual object interaction.

    Science.gov (United States)

    Lee, Hye Jin; Lee, Jaedong; Kim, Chi Jung; Kim, Gerard J; Kim, Eun-Soo; Whang, Mincheol

    2015-04-01

    "Out of the body" tactile illusion refers to the phenomenon in which one can perceive tactility as if emanating from a location external to the body without any stimulator present there. Taking advantage of such a tactile illusion is one way to provide and realize richer interaction feedback without employing and placing actuators directly at all stimulation target points. However, to further explore its potential, it is important to better understand the underlying physiological and neural mechanism. As such, we measured the brain wave patterns during such tactile illusion and mapped out the corresponding brain activation areas. Participants were given stimulations at different levels with the intention to create veridical (i.e., non-illusory) and phantom sensations at different locations along an external hand-held virtual ruler. The experimental data and analysis indicate that both veridical and illusory sensations involve, among others, the parietal lobe, one of the most important components in the tactile information pathway. In addition, we found that as for the illusory sensation, there is an additional processing resulting in the delay for the ERP (event-related potential) and involvement by the limbic lobe. These point to regarding illusion as a memory and recognition task as a possible explanation. The present study demonstrated some basic understanding; how humans process "virtual" objects and the way associated tactile illusion is generated will be valuable for HCI (Human-Computer Interaction).

  12. Sliding Perspectives: dissociating ownership from self-location during full body illusions in virtual reality

    Directory of Open Access Journals (Sweden)

    Antonella eMaselli

    2014-09-01

    Full Text Available Bodily illusions have been used to study bodily self-consciousness and disentangle its various components, among other the sense of ownership and self-location. Congruent multimodal correlations between the real body and a fake humanoid body can in fact trigger the illusion that the fake body is one’s own and/or disrupt the unity between the perceived self-location and the position of the physical body. However, the extent to which changes in self-location entail changes in ownership is still matter of debate. Here we address this problem with the support of immersive virtual reality. Congruent visuotactile stimulation was delivered on healthy participants to trigger full body illusions from different visual perspectives, each resulting in a different degree of overlap between real and virtual body. Changes in ownership and self-location were measured with novel self posture assessment tasks and with an adapted version of the cross-modal congruency task. We found that, despite their strong coupling, self-location and ownership can be selectively altered: self-location was affected when having a third person perspective over the virtual body, while ownership toward the virtual body was experienced only in the conditions with total or partial overlap. Thus, when the virtual body is seen in the far extra-personal space, changes in self-location were not coupled with changes in ownership. If a partial spatial overlap is present, ownership was instead typically experienced with a boosted change in the perceived self-location. We discussed results in the context of the current knowledge of the multisensory integration mechanisms contributing to self-body perception. We argue that changes in the perceived self-location are associated to the dynamical representation of peripersonal space encoded by visuotactile neurons. On the other hand, our results speak in favor of visuo-proprioceptive neuronal populations being a driving trigger in full body

  13. Transcending the Self – the Illusion of Body Ownership in Immersive Virtual Reality and its Impact on Behaviour

    Directory of Open Access Journals (Sweden)

    Mel Slater

    2011-10-01

    Full Text Available Virtual reality in various forms has been around for about 40 years. It has been considered mainly as a technology that can be used to generate the illusion of a transformation of place. However, it has recently been shown that it can successfully be used to transcend the self, through illusions of body ownership and transformation. Several papers have shown that it is possible to generate in people the illusory sense of ownership of a fake body using virtual reality techniques [1-5]. This can be achieved through synchronous multisensory stimulation with respect to the real and virtual body. For example, the participant sees his or her virtual body touched, while feeling the touch synchronously and in the same place on the real body. This can also lead to illusions of body transformation, such as a thin person having the illusion of being fat [6]. Our research suggests the prime importance of a first person perspective for the illusion of ownership, however, in [7] we also found that a representation of a person in a virtual mirror with synchronous visual-motor effects also results in a body ownership illusion. Although virtual body ownership has been established, what is also of interest are the consequences of this in terms of the attitudes and behaviour of the participant who experiences the transformed body. Our very recent work suggests that the illusion of ownership of a virtual body may also result in at least short-term transformations of behaviour and attitudes of the participant towards those that are appropriate to the virtual body. This talk will describe several experiments illustrating both the illusion of body ownership and its transformative effect on attitudes and behaviour.

  14. Susceptibility to the rubber hand illusion does not tell the whole body-awareness story.

    Science.gov (United States)

    David, Nicole; Fiori, Francesca; Aglioti, Salvatore M

    2014-03-01

    The rubber hand illusion (RHI) is an enigmatic illusion that creates a feeling of owning an artificial limb. Enthusiasts of this paradigm assert that it operationalizes bodily self-awareness, but there are reasons to doubt such a clear link. Because little is known about other functional contributions to the RHI, including effects of context-dependent visual processing and cognitive control or the ability to resolve intermodal conflict, we carried out two complementary experiments. In the first, we examined the relationships between the RHI and (1) body awareness, as assessed by the Body Perception Questionnaire (BPQ); (2) context-dependent visual processing, as assessed by the rod-and-frame test (RFT); and (3) conflict resolution, as assessed by the Stroop test. We found a significant positive correlation between the RHI-associated proprioceptive drift and context-dependent visual processing on the RFT, but not between the RHI and body awareness on the BPQ. In the second experiment, we examined the RHI in advanced yoga practitioners with an embodied lifestyle and a heightened sense of their own body in space. They succumbed to the illusion just as much as did yoga-naïve control participants, despite significantly greater body awareness on the BPQ. These findings suggest that susceptibility to the RHI and awareness of one's own body are at least partially independent processes.

  15. First Person Experience of Body Transfer in Virtual Reality

    Science.gov (United States)

    Slater, Mel; Spanlang, Bernhard; Sanchez-Vives, Maria V.; Blanke, Olaf

    2010-01-01

    Background Altering the normal association between touch and its visual correlate can result in the illusory perception of a fake limb as part of our own body. Thus, when touch is seen to be applied to a rubber hand while felt synchronously on the corresponding hidden real hand, an illusion of ownership of the rubber hand usually occurs. The illusion has also been demonstrated using visuomotor correlation between the movements of the hidden real hand and the seen fake hand. This type of paradigm has been used with respect to the whole body generating out-of-the-body and body substitution illusions. However, such studies have only ever manipulated a single factor and although they used a form of virtual reality have not exploited the power of immersive virtual reality (IVR) to produce radical transformations in body ownership. Principal Findings Here we show that a first person perspective of a life-sized virtual human female body that appears to substitute the male subjects' own bodies was sufficient to generate a body transfer illusion. This was demonstrated subjectively by questionnaire and physiologically through heart-rate deceleration in response to a threat to the virtual body. This finding is in contrast to earlier experimental studies that assume visuotactile synchrony to be the critical contributory factor in ownership illusions. Our finding was possible because IVR allowed us to use a novel experimental design for this type of problem with three independent binary factors: (i) perspective position (first or third), (ii) synchronous or asynchronous mirror reflections and (iii) synchrony or asynchrony between felt and seen touch. Conclusions The results support the notion that bottom-up perceptual mechanisms can temporarily override top down knowledge resulting in a radical illusion of transfer of body ownership. The research also illustrates immersive virtual reality as a powerful tool in the study of body representation and experience, since it supports

  16. Body ownership and experiential ownership in the self-touching illusion

    Directory of Open Access Journals (Sweden)

    Caleb eLiang

    2015-01-01

    Full Text Available We investigate two issues about the subjective experience of one’s body: first, is the experience of owning a full-body fundamentally different from the experience of owning a body-part? Second, when I experience a bodily sensation, does it guarantee that I cannot be wrong about whether it is me who feels it? To address these issues, we conducted a series of experiments that combined the rubber hand illusion (RHI and the body swap illusion. The subject wore a head mounted display (HMD connected with a stereo camera set on the experimenter’s head. Sitting face to face, they used their right hand holding a paintbrush to brush each other’s left hand. Through the HMD, the subject adopted the experimenter’s first-person perspective (1PP as if it was his/her own 1PP: the subject watched either the experimenter’s hand from the adopted 1PP, and/or the subject’s own hand from the adopted third-person perspective (3PP in the opposite direction (180°, or the subject’s full body from the adopted 3PP (180°, with or without face. The synchronous full-body conditions generate a self-touching illusion: many participants felt that I was brushing my own hand! We found that (1 the sense of body-part ownership and the sense of full-body ownership are not fundamentally different from each other; and (2 our data present a strong case against the mainstream philosophical view called the immunity principle (IEM. We argue that it is possible for misrepresentation to occur in the subject’s sense of experiential ownership (the sense that I am the one who is having this bodily experience. We discuss these findings and conclude that not only the sense of body ownership but also the sense of experiential ownership call for further interdisciplinary studies.

  17. Explaining away the body: experiences of supernaturally caused touch and touch on non-hand objects within the rubber hand illusion.

    Directory of Open Access Journals (Sweden)

    Jakob Hohwy

    Full Text Available BACKGROUND: In rubber hand illusions and full body illusions, touch sensations are projected to non-body objects such as rubber hands, dolls or virtual bodies. The robustness, limits and further perceptual consequences of such illusions are not yet fully explored or understood. A number of experiments are reported that test the limits of a variant of the rubber hand illusion. METHODOLOGY/PRINCIPAL FINDINGS: A variant of the rubber hand illusion is explored, in which the real and foreign hands are aligned in personal space. The presence of the illusion is ascertained with participants' scores and temperature changes of the real arm. This generates a basic illusion of touch projected to a foreign arm. Participants are presented with further, unusual visuotactile stimuli subsequent to onset of the basic illusion. Such further visuotactile stimulation is found to generate very unusual experiences of supernatural touch and touch on a non-hand object. The finding of touch on a non-hand object conflicts with prior findings, and to resolve this conflict a further hypothesis is successfully tested: that without prior onset of the basic illusion this unusual experience does not occur. CONCLUSIONS/SIGNIFICANCE: A rubber hand illusion is found that can arise when the real and the foreign arm are aligned in personal space. This illusion persists through periods of no tactile stimulation and is strong enough to allow very unusual experiences of touch felt on a cardboard box and experiences of touch produced at a distance, as if by supernatural causation. These findings suggest that one's visual body image is explained away during experience of the illusion and they may be of further importance to understanding the role of experience in delusion formation. The findings of touch on non-hand objects may help reconcile conflicting results in this area of research. In addition, new evidence is provided that relates to the recently discovered psychologically

  18. Experimental induction of a perceived telescoped limb using a full-body illusion

    Directory of Open Access Journals (Sweden)

    Laura eSchmalzl

    2011-04-01

    Full Text Available Phantom limbs refer to the sensation that an amputated or missing limb is still attached to the body. Phantom limbs may be perceived as continuous with the stump so as to resemble a normal limb, or as telescoped with the more distal portion of the phantom being perceived as having withdrawn within the stump. Telescoping tends to be related to increased levels of phantom pain, making it a clinically relevant phenomenon to investigate. In the current study we show that a full-body illusion can be used to induce the sensation of a telescoped limb in healthy individuals. For the induction of the full-body illusion, participants saw the body of a mannequin from a first person perspective while being subjected to synchronized visuo-tactile stimulation through stroking. Crucially, the mannequin was missing its left hand so as to resemble an amputee. By manipulating the positioning of the strokes applied to the mannequin’s stump with respect to the participants’ hand we were able to evoke the sensation of the participants’ hand being located either below the stump or, more crucially, inside the stump, i.e. telescoped. In three separate experiments these effects were supported by complementary subjective data from questionnaires, verbally reported perceived location of the hand, and manual pointing movements indicating hand position (proprioceptive drift. Taken together our results show that healthy individuals can experience the body of an upper limb amputee as their own, and that this can be associated with telescoping sensations. This is a theoretically important observation as it shows that ownership of an entire body can be evoked in the context of gross anatomical incongruence for a single limb, and that telescoping sensations occur as a consequence of the body representation system trying to reduce this incongruence. Furthermore, the present study might provide a new platform for future studies of the relationship between telescoping and

  19. Observational Learning from Animated Models: Effects of Studying-Practicing Alternation and Illusion of Control on Transfer

    NARCIS (Netherlands)

    Wouters, Pieter; Paas, Fred; Van Merriënboer, Jeroen

    2008-01-01

    Wouters, P. J. M., Paas, F., & Van Merriënboer, J. J. G. (2010). Observational learning from animated models: effects of studying-practicing alternation and illusion of control on transfer. Instructional Science, 38(1), 89-104. doi:10.1007/s11251-008-9079-0

  20. How to Build an Embodiment Lab: Achieving Body Representation Illusions in Virtual Reality

    Directory of Open Access Journals (Sweden)

    Bernhard eSpanlang

    2014-11-01

    Full Text Available Advances in computer graphics algorithms and virtual reality (VR systems, together with the reduction in cost of associated equipment, have led scientists to consider VR as a useful tool for conducting experimental studies in fields such as neuroscience and experimental psychology. In particular virtual body ownership, where the feeling of ownership over a virtual body is elicited in the participant, has become a useful tool in the study of body representation, in cognitive neuroscience and psychology, concerned with how the brain represents the body. Although VR has been shown to be a useful tool for exploring body ownership illusions, integrating the various technologies necessary for such a system can be daunting. In this paper we discuss the technical infrastructure necessary to achieve virtual embodiment. We describe a basic VR system and how it may be used for this purpose, and then extend this system with the introduction of real-time motion capture, a simple haptics system and the integration of physiological and brain electrical activity recordings.

  1. Visuospatial viewpoint manipulation during full-body illusion modulates subjective first-person perspective.

    Science.gov (United States)

    Pfeiffer, Christian; Schmutz, Valentin; Blanke, Olaf

    2014-12-01

    Self-consciousness is based on multisensory signals from the body. In full-body illusion (FBI) experiments, multisensory conflict was used to induce changes in three key aspects of bodily self-consciousness (BSC): self-identification (which body 'I' identify with), self-location (where 'I' am located), and first-person perspective (from where 'I' experience the world; 1PP). Here, we adapted a previous FBI protocol in which visuotactile stroking was administered by a robotic device (tactile stroking) and simultaneously rendered on the back of a virtual body (visual stroking) that participants viewed on a head-mounted display as if filmed from a posterior viewpoint of a camera. We compared the effects of two different visuospatial viewpoints on the FBI and thereby on these key aspects of BSC. During control manipulations, participants saw a no-body object instead of a virtual body (first experiment) or received asynchronous versus synchronous visuotactile stroking (second experiment). Results showed that within-subjects visuospatial viewpoint manipulations affected the subjective 1PP ratings if a virtual body was seen but had no effect for viewing a non-body object. However, visuospatial viewpoint had no effect on self-identification, but depended on the viewed object and visuotactile synchrony. Self-location depended on visuospatial viewpoint (first experiment) and visuotactile synchrony (second experiment). Our results show that the visuospatial viewpoint from which the virtual body is seen during FBIs modulates the subjective 1PP and that such viewpoint manipulations contribute to spatial aspects of BSC. We compare the present data with recent data revealing vestibular contributions to the subjective 1PP and discuss the multisensory nature of BSC and the subjective 1PP.

  2. Salivary Oxytocin Concentration Associates with the Subjective Feeling of Body Ownership during the Rubber Hand Illusion.

    Science.gov (United States)

    Ide, Masakazu; Wada, Makoto

    2017-01-01

    Oxytocin is a hormone of the posterior pituitary that promotes lactation, maternal bonding, and birth. Recent studies have shown that oxytocin may modulate social recognition in both sexes, and thus it may be related to empathy. Brain regions that are associated with social recognition and empathy (e.g., the insular cortex) are activated in the rubber hand illusion (RHI), which involves illusory ownership of a rubber hand caused by brush strokes applied synchronously to both a rubber hand and one of the participant's hand, which is hidden from view. It is intriguing to examine whether oxytocin modulates plastic changes in body representation, such as the changes occurring in the RHI. In the present study, we investigated the relationship between salivary oxytocin concentration and the feeling of rubber hand ownership. Brush strokes were applied synchronously or asynchronously to the participant's hand and a rubber hand on different days. Salivary oxytocin was measured before and after the behavioral tasks. We found that participants who had high concentrations of salivary oxytocin tended to feel strong ownership of the rubber hand. We also found that the participants with a high autism spectrum quotient (AQ) score who particularly felt difficulties in social skills and communications tended to feel weak rubber hand ownership. We observed that illusory body ownership was closely linked to social communications and a related neuroendocrine basis. The results of the present study suggest that an individual's salivary oxytocin concentration can predict the extent to which the individual experiences the RHI; furthermore, oxytocin might modulate the sensation of body ownership.

  3. Are movements necessary for the sense of body ownership? Evidence from the rubber hand illusion in pure hemiplegic patients.

    Directory of Open Access Journals (Sweden)

    Dalila Burin

    Full Text Available A question still debated within cognitive neuroscience is whether signals present during actions significantly contribute to the emergence of human's body ownership. In the present study, we aimed at answer this question by means of a neuropsychological approach. We administered the classical rubber hand illusion paradigm to a group of healthy participants and to a group of neurological patients affected by a complete left upper limb hemiplegia, but without any propriceptive/tactile deficits. The illusion strength was measured both subjectively (i.e., by a self-report questionnaire and behaviorally (i.e., the location of one's own hand is shifted towards the rubber hand. We aimed at examining whether, and to which extent, an enduring absence of movements related signals affects body ownership. Our results showed that patients displayed, respect to healthy participants, stronger illusory effects when the left (affected hand was stimulated and no effects when the right (unaffected hand was stimulated. In other words, hemiplegics had a weaker/more flexible sense of body ownership for the affected hand, but an enhanced/more rigid one for the healthy hand. Possible interpretations of such asymmetrical distribution of body ownership, as well as limits of our results, are discussed. Broadly speaking, our findings suggest that the alteration of the normal flow of signals present during movements impacts on human's body ownership. This in turn, means that movements have a role per se in developing and maintaining a coherent body ownership.

  4. Are movements necessary for the sense of body ownership? Evidence from the rubber hand illusion in pure hemiplegic patients.

    Science.gov (United States)

    Burin, Dalila; Livelli, Alessandro; Garbarini, Francesca; Fossataro, Carlotta; Folegatti, Alessia; Gindri, Patrizia; Pia, Lorenzo

    2015-01-01

    A question still debated within cognitive neuroscience is whether signals present during actions significantly contribute to the emergence of human's body ownership. In the present study, we aimed at answer this question by means of a neuropsychological approach. We administered the classical rubber hand illusion paradigm to a group of healthy participants and to a group of neurological patients affected by a complete left upper limb hemiplegia, but without any propriceptive/tactile deficits. The illusion strength was measured both subjectively (i.e., by a self-report questionnaire) and behaviorally (i.e., the location of one's own hand is shifted towards the rubber hand). We aimed at examining whether, and to which extent, an enduring absence of movements related signals affects body ownership. Our results showed that patients displayed, respect to healthy participants, stronger illusory effects when the left (affected) hand was stimulated and no effects when the right (unaffected) hand was stimulated. In other words, hemiplegics had a weaker/more flexible sense of body ownership for the affected hand, but an enhanced/more rigid one for the healthy hand. Possible interpretations of such asymmetrical distribution of body ownership, as well as limits of our results, are discussed. Broadly speaking, our findings suggest that the alteration of the normal flow of signals present during movements impacts on human's body ownership. This in turn, means that movements have a role per se in developing and maintaining a coherent body ownership.

  5. Pulling telescoped phantoms out of the stump: Manipulating the perceived position of phantom limbs using a full-body illusion

    Directory of Open Access Journals (Sweden)

    Laura eSchmalzl

    2011-11-01

    Full Text Available Most amputees experience phantom limbs, or the sensation that their amputated limb is still attached to the body. Phantom limbs can be perceived in the location previously occupied by the intact limb, or they can gradually retract inside the stump, a phenomenon referred to as telescoping. Telescoping is relevant from a clinical point of view, as it tends to be related to increased levels of phantom pain. In the current study we demonstrate how a full-body illusion can be used to temporarily revoke telescoping sensations in upper limb amputees. During this illusion participants view the body of a mannequin from a first person perspective while being subjected to synchronized visuo-tactile stimulation through stroking, which makes them experience the mannequin’s body as their own. In Experiment 1 we used an intact mannequin, and showed that amputees can experience ownership of an intact body as well as referral of touch from both hands of the mannequin. In Experiment 2 and 3 we used an amputated mannequin, and demonstrated that depending on the spatial location of the strokes applied to the mannequin, participants experienced their phantom hand to either remain telescoped, or to actually be located below the stump. The effects were supported by subjective data from questionnaires, as well as verbal reports of the perceived location of the phantom hand in a visual judgment task. These findings are of particular interest, as they show that the temporary revoking of telescoping sensations does not necessarily have to involve the visualization of an intact hand or illusory movement of the phantom (as in the rubber hand illusion or mirror visual feedback therapy, but that it can also be obtained through mere referral of touch from the stump to the spatial location corresponding to that previously occupied by the intact hand. Moreover, our study also provides preliminary evidence for the fact that these manipulations can have an effect on phantom pain

  6. Body representations in the human brain revealed by kinesthetic illusions and their essential contributions to motor control and corporeal awareness.

    Science.gov (United States)

    Naito, Eiichi; Morita, Tomoyo; Amemiya, Kaoru

    2016-03-01

    The human brain can generate a continuously changing postural model of our body. Somatic (proprioceptive) signals from skeletal muscles and joints contribute to the formation of the body representation. Recent neuroimaging studies of proprioceptive bodily illusions have elucidated the importance of three brain systems (motor network, specialized parietal systems, right inferior fronto-parietal network) in the formation of the human body representation. The motor network, especially the primary motor cortex, processes afferent input from skeletal muscles. Such information may contribute to the formation of kinematic/dynamic postural models of limbs, thereby enabling fast online feedback control. Distinct parietal regions appear to play specialized roles in the transformation/integration of information across different coordinate systems, which may subserve the adaptability and flexibility of the body representation. Finally, the right inferior fronto-parietal network, connected by the inferior branch of the superior longitudinal fasciculus, is consistently recruited when an individual experiences various types of bodily illusions and its possible roles relate to corporeal awareness, which is likely elicited through a series of neuronal processes of monitoring and accumulating bodily information and updating the body representation. Because this network is also recruited when identifying one's own features, the network activity could be a neuronal basis for self-consciousness.

  7. Is body dysmorphic disorder associated with abnormal bodily self-awareness? A study using the rubber hand illusion.

    Science.gov (United States)

    Kaplan, Ryan A; Enticott, Peter G; Hohwy, Jakob; Castle, David J; Rossell, Susan L

    2014-01-01

    Evidence from past research suggests that behaviours and characteristics related to body dissatisfaction may be associated with greater instability of perceptual body image, possibly due to problems in the integration of body-related multisensory information. We investigated whether people with body dysmorphic disorder (BDD), a condition characterised by body image disturbances, demonstrated enhanced susceptibility to the rubber hand illusion (RHI), which arises as a result of multisensory integration processes when a rubber hand and the participant's hidden real hand are stimulated in synchrony. Overall, differences in RHI experience between the BDD group and healthy and schizophrenia control groups (n = 17 in each) were not significant. RHI strength, however, was positively associated with body dissatisfaction and related tendencies. For the healthy control group, proprioceptive drift towards the rubber hand was observed following synchronous but not asynchronous stimulation, a typical pattern when inducing the RHI. Similar drifts in proprioceptive awareness occurred for the BDD group irrespective of whether stimulation was synchronous or not. These results are discussed in terms of possible abnormalities in visual processing and multisensory integration among people with BDD.

  8. Disturbances in body ownership in schizophrenia: evidence from the rubber hand illusion and case study of a spontaneous out-of-body experience.

    Directory of Open Access Journals (Sweden)

    Katharine N Thakkar

    Full Text Available A weakened sense of self may contribute to psychotic experiences. Body ownership, one component of self-awareness, can be studied with the rubber hand illusion (RHI. Watching a rubber hand being stroked while one's unseen hand is stroked synchronously can lead to a sense of ownership over the rubber hand, a shift in perceived position of the real hand, and a limb-specific drop in stimulated hand temperature. We aimed to assess the RHI in schizophrenia using quantifiable measures: proprioceptive drift and stimulation-dependent changes in hand temperature.The RHI was elicited in 24 schizophrenia patients and 21 matched controls by placing their unseen hand adjacent to a visible rubber hand and brushing real and rubber hands synchronously or asynchronously. Perceived finger location was measured before and after stimulation. Hand temperature was taken before and during stimulation. Subjective strength of the illusion was assessed by a questionnaire.Across groups, the RHI was stronger during synchronous stimulation, indicated by self-report and proprioceptive drift. Patients reported a stronger RHI than controls. Self-reported strength of RHI was associated with schizotypy in controls Proprioceptive drift was larger in patients, but only following synchronous stimulation. Further, we observed stimulation-dependent changes in skin temperature. During right hand stimulation, temperature dropped in the stimulated hand and rose in the unstimulated hand. Interestingly, induction of RHI led to an out-of-body experience in one patient, linking body disownership and psychotic experiences.The RHI is quantitatively and qualitatively stronger in schizophrenia. These findings suggest that patients have a more flexible body representation and weakened sense of self, and potentially indicate abnormalities in temporo-parietal networks implicated in body ownership. Further, results suggest that these body ownership disturbances might be at the heart of a subset of

  9. Pedagogical tools to explore Cartesian mind-body dualism in the classroom: philosophical arguments and neuroscience illusions.

    Science.gov (United States)

    Hamilton, Scott; Hamilton, Trevor J

    2015-01-01

    A fundamental discussion in lower-level undergraduate neuroscience and psychology courses is Descartes's "radical" or "mind-body" dualism. According to Descartes, our thinking mind, the res cogitans, is separate from the body as physical matter or substance, the res extensa. Since the transmission of sensory stimuli from the body to the mind is a physical capacity shared with animals, it can be confused, misled, or uncertain (e.g., bodily senses imply that ice and water are different substances). True certainty thus arises from within the mind and its capacity to doubt physical stimuli. Since this doubting mind is a thinking thing that is distinct from bodily stimuli, truth and certainty are reached through the doubting mind as cogito ergo sum, or the certainty of itself as it thinks: hence Descartes's famous maxim, I think, therefore I am. However, in the last century of Western philosophy, with nervous system investigation, and with recent advances in neuroscience, the potential avenues to explore student's understanding of the epistemology and effects of Cartesian mind-body dualism has expanded. This article further explores this expansion, highlighting pedagogical practices and tools instructors can use to enhance a psychology student's understanding of Cartesian dualistic epistemology, in order to think more critically about its implicit assumptions and effects on learning. It does so in two ways: first, by offering instructors an alternative philosophical perspective to dualistic thinking: a mind-body holism that is antithetical to the assumed binaries of dualistic epistemology. Second, it supplements this philosophical argument with a practical component: simple mind-body illusions that instructors may use to demonstrate contrary epistemologies to students. Combining these short philosophical and neuroscience arguments thereby acts as a pedagogical tool to open new conceptual spaces within which learning may occur.

  10. Illusions of having small or large invisible bodies influence visual perception of object size

    OpenAIRE

    Björn van der Hoort; H Henrik Ehrsson

    2016-01-01

    The size of our body influences the perceived size of the world so that objects appear larger to children than to adults. The mechanisms underlying this effect remain unclear. It has been difficult to dissociate visual rescaling of the external environment based on an individual’s visible body from visual rescaling based on a central multisensory body representation. To differentiate these potential causal mechanisms, we manipulated body representation without a visible body by taking advanta...

  11. Pedagogical tools to explore Cartesian mind-body dualism in the classroom: philosophical arguments and neuroscience illusions

    Science.gov (United States)

    Hamilton, Scott; Hamilton, Trevor J.

    2015-01-01

    A fundamental discussion in lower-level undergraduate neuroscience and psychology courses is Descartes’s “radical” or “mind-body” dualism. According to Descartes, our thinking mind, the res cogitans, is separate from the body as physical matter or substance, the res extensa. Since the transmission of sensory stimuli from the body to the mind is a physical capacity shared with animals, it can be confused, misled, or uncertain (e.g., bodily senses imply that ice and water are different substances). True certainty thus arises from within the mind and its capacity to doubt physical stimuli. Since this doubting mind is a thinking thing that is distinct from bodily stimuli, truth and certainty are reached through the doubting mind as cogito ergo sum, or the certainty of itself as it thinks: hence Descartes’s famous maxim, I think, therefore I am. However, in the last century of Western philosophy, with nervous system investigation, and with recent advances in neuroscience, the potential avenues to explore student’s understanding of the epistemology and effects of Cartesian mind-body dualism has expanded. This article further explores this expansion, highlighting pedagogical practices and tools instructors can use to enhance a psychology student’s understanding of Cartesian dualistic epistemology, in order to think more critically about its implicit assumptions and effects on learning. It does so in two ways: first, by offering instructors an alternative philosophical perspective to dualistic thinking: a mind-body holism that is antithetical to the assumed binaries of dualistic epistemology. Second, it supplements this philosophical argument with a practical component: simple mind-body illusions that instructors may use to demonstrate contrary epistemologies to students. Combining these short philosophical and neuroscience arguments thereby acts as a pedagogical tool to open new conceptual spaces within which learning may occur. PMID:26321981

  12. Endwall convective heat transfer for bluff bodies

    DEFF Research Database (Denmark)

    Wang, Lei; Salewski, Mirko; Sundén, Bengt

    2012-01-01

    The endwall heat transfer characteristics of forced flow past bluff bodies have been investigated using liquid crystal thermography (LCT). The bluff body is placed in a rectangular channel with both its ends attached to the endwalls. The Reynolds number varies from 50,000 to 100,000. In this study...

  13. Robotically enhanced rubber hand illusion.

    Science.gov (United States)

    Arata, Jumpei; Hattori, Masashi; Ichikawa, Shohei; Sakaguchi, Masamichi

    2014-01-01

    The rubber hand illusion is a well-known multisensory illusion. In brief, watching a rubber hand being stroked by a paintbrush while one's own unseen hand is synchronously stroked causes the rubber hand to be attributed to one's own body and to "feel like it's my hand." The rubber hand illusion is thought to be triggered by the synchronized tactile stimulation of both the subject's hand and the fake hand. To extend the conventional rubber hand illusion, we introduce robotic technology in the form of a master-slave telemanipulator. The developed one degree-of-freedom master-slave system consists of an exoskeleton master equipped with an optical encoder that is worn on the subject's index finger and a motor-actuated index finger on the rubber hand, which allows the subject to perform unilateral telemanipulation. The moving rubber hand illusion has been studied by several researchers in the past with mechanically connected rigs between the subject's body and the fake limb. The robotic instruments let us investigate the moving rubber hand illusion with less constraints, thus behaving closer to the classic rubber hand illusion. In addition, the temporal delay between the body and the fake limb can be precisely manipulated. The experimental results revealed that the robotic instruments significantly enhance the rubber hand illusion. The time delay is significantly correlated with the effect of the multisensory illusion, and the effect significantly decreased at time delays over 100 ms. These findings can potentially contribute to the investigations of neural mechanisms in the field of neuroscience and of master-slave systems in the field of robotics.

  14. Illusion optics

    Science.gov (United States)

    Lai, Yun; Ng, Jack; Chen, Huan-Yang; Zhang, Zhao-Qing; Chan, C. T.

    2010-09-01

    The technique of “transformation optics” establishes a correspondence between coordinate transformation and material constitutive parameters. Most of the transformation optics mappings give metamaterials that have graded positive refractive indices that can steer light in curves defined by the coordinate transformation. We will focus on those “folded-geometry mappings” that give negative refractive index materials that have special wave scattering properties. One interesting example is a kind of remote illusion device that can transform the stereoscopic image of an object into the illusion of some other object of our choice. The conceptual device can create the illusion without touching or encircling the object. For any incident wave, the device transforms the scattered waves of the original object into that of the object chosen for illusion outside a virtual boundary. We will illustrate some possible applications of this type of metamaterial remote device, including “cloaking at a distance,” partial cloaking, cloaking from an embedded device, revealing a hidden object inside a container, turning the image of one object into that of another object, and seeing through a wall. The feasibility of building this remote illusion device by metamaterials will also be discussed.

  15. The structure of conscious bodily self-perception during full-body illusions.

    Science.gov (United States)

    Dobricki, Martin; de la Rosa, Stephan

    2013-01-01

    Previous research suggests that bodily self-identification, bodily self-localization, agency, and the sense of being present in space are critical aspects of conscious full-body self-perception. However, none of the existing studies have investigated the relationship of these aspects to each other, i.e., whether they can be identified to be distinguishable components of the structure of conscious full-body self-perception. Therefore, the objective of the present investigation is to elucidate the structure of conscious full-body self-perception. We performed two studies in which we stroked the back of healthy individuals for three minutes while they watched the back of a distant virtual body being synchronously stroked with a virtual stick. After visuo-tactile stimulation, participants assessed changes in their bodily self-perception with a custom made self-report questionnaire. In the first study, we investigated the structure of conscious full-body self-perception by analyzing the responses to the questionnaire by means of multidimensional scaling combined with cluster analysis. In the second study, we then extended the questionnaire and validated the stability of the structure of conscious full-body self-perception found in the first study within a larger sample of individuals by performing a principle components analysis of the questionnaire responses. The results of the two studies converge in suggesting that the structure of conscious full-body self-perception consists of the following three distinct components: bodily self-identification, space-related self-perception (spatial presence), and agency.

  16. 虚构的幻觉——血腥的人身兽体读解%Illusions of Fiction: Interpretations of Bloody Humans with Animal Body

    Institute of Scientific and Technical Information of China (English)

    龙潜

    2011-01-01

    人类最早是从血中认识了自己的身体。崇尚武力雄霸的古希腊人,需要个人体能超乎常规,因此,希腊神话中神祗家族的虚构,满足了人类渴慕超能的幻觉。%Humans first understood their bodies through blood.The belligerent Greeks needed super physique.As a result,the fiction of the gods' family in Greek mythology met human desire for super illusions.

  17. Perception, Illusion, and Magic.

    Science.gov (United States)

    Solomon, Paul R.

    1980-01-01

    Describes a psychology course in which magical illusions were used for teaching the principles of sensation and perception. Students read psychological, philosophical, historical, and magical literature on illusion, performed a magical illusion, and analyzed the illusion in terms of the psychological principles involved. (Author/KC)

  18. Bodily Illusions Modulate Tactile Perception

    OpenAIRE

    De Vignemont, Frédérique; H. Ehrsson, Henrik; Haggard, Patrick

    2005-01-01

    Touch differs from other exteroceptive senses in that the body itself forms part of the tactile percept. Interactions between proprioception and touch provide a powerful way to investigate the implicit body representation underlying touch. Here, we demonstrate that an intrinsic primary quality of a tactile object, for example its size, is directly affected by the perceived size of the body part touching it. We elicited proprioceptive illusions that the left index finger was either elongating ...

  19. The Marble-Hand Illusion.

    Directory of Open Access Journals (Sweden)

    Irene Senna

    Full Text Available Our body is made of flesh and bones. We know it, and in our daily lives all the senses constantly provide converging information about this simple, factual truth. But is this always the case? Here we report a surprising bodily illusion demonstrating that humans rapidly update their assumptions about the material qualities of their body, based on their recent multisensory perceptual experience. To induce a misperception of the material properties of the hand, we repeatedly gently hit participants' hand with a small hammer, while progressively replacing the natural sound of the hammer against the skin with the sound of a hammer hitting a piece of marble. After five minutes, the hand started feeling stiffer, heavier, harder, less sensitive, unnatural, and showed enhanced Galvanic skin response (GSR to threatening stimuli. Notably, such a change in skin conductivity positively correlated with changes in perceived hand stiffness. Conversely, when hammer hits and impact sounds were temporally uncorrelated, participants did not spontaneously report any changes in the perceived properties of the hand, nor did they show any modulation in GSR. In two further experiments, we ruled out that mere audio-tactile synchrony is the causal factor triggering the illusion, further demonstrating the key role of material information conveyed by impact sounds in modulating the perceived material properties of the hand. This novel bodily illusion, the 'Marble-Hand Illusion', demonstrates that the perceived material of our body, surely the most stable attribute of our bodily self, can be quickly updated through multisensory integration.

  20. The Rubber Hand Illusion in Children with Autism Spectrum Disorders: Delayed Influence of Combined Tactile and Visual Input on Proprioception

    Science.gov (United States)

    Cascio, Carissa J.; Foss-Feig, Jennifer H.; Burnette, Courtney P.; Heacock, Jessica L.; Cosby, Akua A.

    2012-01-01

    In the rubber hand illusion, perceived hand ownership can be transferred to a rubber hand after synchronous visual and tactile stimulation. Perceived body ownership and self-other relation are foundational for development of self-awareness, imitation, and empathy, which are all affected in autism spectrum disorders (ASD). We examined the rubber…

  1. [Mechanism of heat transfer in various regions of human body].

    Science.gov (United States)

    Luchakov, Iu I; Nozdrachev, A D

    2009-01-01

    The processes of heat transfer in a human body were studied with the use of a mathematical model. It has been shown that only conductive or only convective heat transfer may occur in different body areas. The rate of blood-mediated heat transfer in the presence of blood circulation is many times higher than heat transfer due to temperature gradient; therefore, the convective process prevails over the conductive process. The body core contains a variety of blood vessels, and the bulk of blood concentrates there in the norm. Hence, heat transfer in it is mainly convective. In surface tissues, where the rate of blood circulation is lower and the vasculature has certain specific features, heat transfer is mainly conductive. Hence, the core and surface tissues are absolutely different body zones in terms of heat transfer.

  2. My Body Had a Mind of Its Own: On Teaching, the Illusion of Control, and the Terrifying Limits of Governmentality (Part I)

    Science.gov (United States)

    Koza, Julia Eklund

    2009-01-01

    This essay examines control discourse in and out of educational settings, arguing that illusions of control are among the means by which governance is accomplished in domains far from schools. The tactical productivity of such illusions in non-school settings "necessitates" and explicates their prevalence in education. The first installment of…

  3. Radar illusion via metamaterials

    Science.gov (United States)

    Jiang, Wei Xiang; Cui, Tie Jun

    2011-02-01

    An optical illusion is an image of a real target perceived by the eye that is deceptive or misleading due to a physiological illusion or a specific visual trick. The recently developed metamaterials provide efficient approaches to generate a perfect optical illusion. However, all existing research on metamaterial illusions has been limited to theory and numerical simulations. Here, we propose the concept of a radar illusion, which can make the electromagnetic (EM) image of a target gathered by radar look like a different target, and we realize a radar illusion device experimentally to change the radar image of a metallic target into a dielectric target with predesigned size and material parameters. It is well known that the radar signatures of metallic and dielectric objects are significantly different. However, when a metallic target is enclosed by the proposed illusion device, its EM scattering characteristics will be identical to that of a predesigned dielectric object under the illumination of radar waves. Such an illusion device will confuse the radar, and hence the real EM properties of the metallic target cannot be perceived. We designed and fabricated the radar illusion device using artificial metamaterials in the microwave frequency, and good illusion performances are observed in the experimental results.

  4. The Ehrenstein illusion

    OpenAIRE

    Dresp-Langley, Birgitta

    2009-01-01

    International audience; The original Ehrenstein illusion was first described by Walter Ehrenstein senior (Ehrenstein, 1941, 1954). It is generated by a configuration of four line segments which induce the perception of a so-called illusory figure at the centre of the configuration (Fig 1a). This illusion is part of a class of visual perceptual phenomena referred to as contrast or brightness illusions, as explained in detail in this state-of-the-art review.

  5. “I can’t tell whether it’s my hand”: a pilot study of the neurophenomenology of body representation during the rubber hand illusion in trauma-related disorders

    Science.gov (United States)

    Rabellino, Daniela; Harricharan, Sherain; Frewen, Paul A.; Burin, Dalila; McKinnon, Margaret C.; Lanius, Ruth A.

    2016-01-01

    Background Early traumatic experiences are thought to be causal factors in the development of trauma-related dissociative experiences, including depersonalization and derealization. The rubber hand illusion (RHI), a well-known paradigm that measures multi-sensorial integration of a rubber hand into one’s own body representation, has been used to investigate alterations in the experience of body ownership and of body representation. Critically, however, it has never been studied in individuals with trauma-related disorders. Objective To investigate body representation distortions occurring in trauma-related disorders in response to the RHI. Method The RHI was administered to three individuals with the dissociative subtype of posttraumatic stress disorder (PTSD), and subjective, behavioral, cardiovascular and skin conductance responses were recorded. Results Participants’ subjective experiences of the RHI were differentiated and complex. The illusion was induced following both synchronous and asynchronous brushing and variably evoked subjective distress, depersonalization and derealization experiences, tonic immobility, increased physiological arousal and flashbacks. Conclusions The present findings point towards the RHI as a strong provocation stimulus that elicits individual patterns of symptom presentation, including experiences of distress and dissociation, in individuals with trauma-related disorders, including the dissociative subtype of PTSD. Highlights of the article The rubber hand illusion (RHI) elicits distress, tonic immobility, depersonalization and derealization, and autonomic responses in individuals with trauma-related disorders, including the dissociative subtype of posttraumatic stress disorder (PTSD). RHI effects related to body misrepresentation may trigger altered experiences related to body ownership. The RHI represents a promising paradigm for studying the neurophenomenology of body distortion in individuals experiencing trauma

  6. PERFECT DEMAND ILLUSION

    Directory of Open Access Journals (Sweden)

    Alexander Yu. Sulimov

    2015-01-01

    Full Text Available The article is devoted to technique «Perfect demand illusion», which allows to strengthen the competitive advantageof retailers. Also in the paper spells out the golden rules of visual merchandising.The definition of the method «Demand illusion», formulated the conditions of its functioning, and is determined by the mainhypothesis of the existence of this method.Furthermore, given the definition of the «Perfect demand illusion», and describes its additional conditions. Also spells out the advantages of the «Perfect demandillusion», before the «Demand illusion».

  7. Visual adaptation to thin and fat bodies transfers across identity.

    Directory of Open Access Journals (Sweden)

    Dennis Hummel

    Full Text Available Visual perception is highly variable and can be influenced by the surrounding world. Previous research has revealed that body perception can be biased due to adaptation to thin or fat body shapes. The aim of the present study was to show that adaptation to certain body shapes and the resulting perceptual biases transfer across different identities of adaptation and test stimuli. We designed two similar adaptation experiments in which healthy female participants adapted to pictures of either thin or fat bodies and subsequently compared more or less distorted pictures of their own body to their actual body shape. In the first experiment (n = 16 the same identity was used as adaptation and test stimuli (i.e. pictures of the participant's own body while in the second experiment (n = 16 we used pictures of unfamiliar thin or fat bodies as adaptation stimuli. We found comparable adaptation effects in both experiments: After adaptation to a thin body, participants rated a thinner than actual body picture to be the most realistic and vice versa. We therefore assume that adaptation to certain body shapes transfers across different identities. These results raise the questions of whether some type of natural adaptation occurs in everyday life. Natural and predominant exposure to certain bodily features like body shape--especially the thin ideal in Western societies--could bias perception for these features. In this regard, further research might shed light on aspects of body dissatisfaction and the development of body image disturbances in terms of eating disorders.

  8. [A review of face illusions].

    Science.gov (United States)

    Kitaoka, Akiyoshi

    2012-07-01

    A variety of "face illusions," including the gaze illusion, face inversion effects, geometrical illusions, reversible figures, and other interesting phenomena related to face perception, are reviewed in the present report, with many sample images. The "gaze illusion" or the illusion of eye direction includes the Wollaston illusion, the luminance-induced gaze shift, the Bogart illusion, the eye-shadow-dependent gaze illusion, the Mona Lisa effect, etc. "Face inversion effects" refer to the Thatcher illusion, the fat face-thin illusion, underestimation of the upright face, the nose-shortening illusion of the inverted face, etc. "Geometrical illusions" include the Lee-Freire illusion, Yang's iris illusion, overestimation of the farther eye, the eye-shadow-dependent eye-size illusion, etc. "Reversible figures" contain the whole-part reversible figure, Rubin's vase-face illusion, or hybrid images. "Other interesting phenomena" include the flashed face distortion effect, the presidential illusion, predominance of the mouth or eyebrows over eye expression, the eye direction aftereffect, etc. It is suggested that some of these phenomena are highly specific to face perception.

  9. Convective heat transfer area of the human body.

    Science.gov (United States)

    Kurazumi, Yoshihito; Tsuchikawa, Tadahiro; Matsubara, Naoki; Horikoshi, Tetsumi

    2004-12-01

    In order to clarify the heat transfer area involved in convective heat exchange for the human body, the total body surface area of six healthy subjects was measured, and the non-convective heat transfer area and floor and chair contact areas for the following nine common body positions were measured: standing, sitting on a chair, sitting in the seiza position, sitting cross-legged, sitting sideways, sitting with both knees erect, sitting with a leg out, and the lateral and supine positions. The main non-convective heat transfer areas were: the armpits (contact between the upper arm and trunk regions), contact between the two legs, contacts between the fingers and toes, and contact between the hands and the body surface. Also, when sitting on the floor with some degree of leg contact (sitting in the seiza position, cross-legged, or sideways), there was a large non-convective heat transfer area on the thighs and legs. Even when standing or sitting in a chair, about 6-8% of the body surface did not transfer heat by convection. The results showed that the effective thermal convective area factor for the naked whole body in the standing position was 0.942. While sitting in a chair this factor was 0.860, while sitting in a chair but excluding the chair contact area it was 0.918, when sitting in the seiza position 0.818, when sitting cross-legged 0.843, in the sideways sitting position 0.855, when sitting with both knees erect 0.887, in the leg-out sitting position 0.906, while in the lateral position it was 0.877 and the supine position 0.844. For all body positions, the effective thermal convective area factor was greater than the effective thermal radiation area factor, but smaller than the total body surface area.

  10. “I can't tell whether it's my hand”: a pilot study of the neurophenomenology of body representation during the rubber hand illusion in trauma-related disorders

    Directory of Open Access Journals (Sweden)

    Daniela Rabellino

    2016-11-01

    Full Text Available Background: Early traumatic experiences are thought to be causal factors in the development of trauma-related dissociative experiences, including depersonalization and derealization. The rubber hand illusion (RHI, a well-known paradigm that measures multi-sensorial integration of a rubber hand into one's own body representation, has been used to investigate alterations in the experience of body ownership and of body representation. Critically, however, it has never been studied in individuals with trauma-related disorders. Objective: To investigate body representation distortions occurring in trauma-related disorders in response to the RHI. Method: The RHI was administered to three individuals with the dissociative subtype of posttraumatic stress disorder (PTSD, and subjective, behavioral, cardiovascular and skin conductance responses were recorded. Results: Participants’ subjective experiences of the RHI were differentiated and complex. The illusion was induced following both synchronous and asynchronous brushing and variably evoked subjective distress, depersonalization and derealization experiences, tonic immobility, increased physiological arousal and flashbacks. Conclusions: The present findings point towards the RHI as a strong provocation stimulus that elicits individual patterns of symptom presentation, including experiences of distress and dissociation, in individuals with trauma-related disorders, including the dissociative subtype of PTSD. Highlights of the article:

  11. No pain relief with the rubber hand illusion.

    Directory of Open Access Journals (Sweden)

    Rahul Mohan

    Full Text Available The sense of body ownership can be easily disrupted during illusions and the most common illusion is the rubber hand illusion. An idea that is rapidly gaining popularity in clinical pain medicine is that body ownership illusions can be used to modify pathological pain sensations and induce analgesia. However, this idea has not been empirically evaluated. Two separate research laboratories undertook independent randomized repeated measures experiments, both designed to detect an effect of the rubber hand illusion on experimentally induced hand pain. In Experiment 1, 16 healthy volunteers rated the pain evoked by noxious heat stimuli (5 s duration; interstimulus interval 25 s of set temperatures (47°, 48° and 49°C during the rubber hand illusion or during a control condition. There was a main effect of stimulus temperature on pain ratings, but no main effect of condition (p = 0.32, nor a condition x temperature interaction (p = 0.31. In Experiment 2, 20 healthy volunteers underwent quantitative sensory testing to determine heat and cold pain thresholds during the rubber hand illusion or during a control condition. Secondary analyses involved heat and cold detection thresholds and paradoxical heat sensations. Again, there was no main effect of condition on heat pain threshold (p = 0.17, nor on cold pain threshold (p = 0.65, nor on any of the secondary measures (p<0.56 for all. We conclude that the rubber hand illusion does not induce analgesia.

  12. Bodily illusions disrupt tactile sensations.

    Science.gov (United States)

    D'Amour, Sarah; Pritchett, Lisa M; Harris, Laurence R

    2015-02-01

    To accurately interpret tactile information, the brain needs to have an accurate representation of the body to which to refer the sensations. Despite this, body representation has only recently been incorporated into the study of tactile perception. Here, we investigate whether distortions of body representation affect tactile sensations. We perceptually altered the length of the arm and the width of the waist using a tendon vibration illusion and measured spatial acuity and sensitivity. Surprisingly, we found reduction in both tactile acuity and sensitivity thresholds when the arm or waist was perceptually altered, which indicates a general disruption of low-level tactile processing. We postulate that the disruptive changes correspond to the preliminary stage as the body representation starts to change and may give new insights into sensory processing in people with long-term or sudden abnormal body representation such as are found in eating disorders or following amputation.

  13. The Methadone Illusion

    Science.gov (United States)

    Lennard, Henry L.; And Others

    1972-01-01

    Methadone treatment for heroin addiction does not touch the roots of the drug problem" and to think that the use of another drug can solve the profound and complex task facing us is indeed an illusion." (Author/AL)

  14. 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.

  15. No pain relief with the rubber hand illusion.

    Science.gov (United States)

    Mohan, Rahul; Jensen, Karin B; Petkova, Valeria I; Dey, Abishikta; Barnsley, Nadia; Ingvar, Martin; McAuley, James H; Moseley, G Lorimer; Ehrsson, Henrik H

    2012-01-01

    The sense of body ownership can be easily disrupted during illusions and the most common illusion is the rubber hand illusion. An idea that is rapidly gaining popularity in clinical pain medicine is that body ownership illusions can be used to modify pathological pain sensations and induce analgesia. However, this idea has not been empirically evaluated. Two separate research laboratories undertook independent randomized repeated measures experiments, both designed to detect an effect of the rubber hand illusion on experimentally induced hand pain. In Experiment 1, 16 healthy volunteers rated the pain evoked by noxious heat stimuli (5 s duration; interstimulus interval 25 s) of set temperatures (47°, 48° and 49°C) during the rubber hand illusion or during a control condition. There was a main effect of stimulus temperature on pain ratings, but no main effect of condition (p = 0.32), nor a condition x temperature interaction (p = 0.31). In Experiment 2, 20 healthy volunteers underwent quantitative sensory testing to determine heat and cold pain thresholds during the rubber hand illusion or during a control condition. Secondary analyses involved heat and cold detection thresholds and paradoxical heat sensations. Again, there was no main effect of condition on heat pain threshold (p = 0.17), nor on cold pain threshold (p = 0.65), nor on any of the secondary measures (pillusion does not induce analgesia.

  16. Creating standards: Creating illusions?

    DEFF Research Database (Denmark)

    Linneberg, Mai Skjøtt

    written standards may open up for the creation of illusions. These are created when written standards' content is not in accordance with the perception standard adopters and standard users have of the specific practice phenomenon's content. This general theoretical argument is exemplified by the specific...

  17. Three-Body Model Analysis of Subbarrier alpha Transfer Reaction

    CERN Document Server

    Fukui, Tokuro; Yahiro, Masanobu

    2011-01-01

    Subbarrier alpha transfer reaction 13C(6Li,d)17O(6.356 MeV, 1/2+) at 3.6 MeV is analyzed with a alpha + d + 13C three-body model, and the asymptotic normalization coefficient (ANC) for alpha + 13C --> 17O(6.356 MeV, 1/2+), which essentially determines the reaction rate of 13C(alpha,n)16O, is extracted. Breakup effects of 6Li in the initial channel and those of 17O in the final channel are investigated with the continuum-discretized coupled-channels method (CDCC). The former is found to have a large back-coupling to the elastic channel, while the latter turns out significantly small. The transfer cross section calculated with Born approximation to the transition operator, including breakup states of 6Li, gives (C_{alpha 13C}{17O*})^2 =1.03 \\pm 0.29 fm^{-1}. This result is consistent with the value obtained by the previous DWBA calculation.

  18. Money illusion and coordination failure

    DEFF Research Database (Denmark)

    Fehr, Ernst; Tyran, Jean-Robert

    2007-01-01

    Economists long considered money illusion to be largely irrelevant. Here we show, however, that money illusion has powerful effects on equilibrium selection. If we represent payoffs in nominal terms, choices converge to the Pareto inferior equilibrium; however, if we lift the veil of money by rep...

  19. Do visual illusions probe the visual brain? Illusions in action without a dorsal visual stream.

    Science.gov (United States)

    Coello, Yann; Danckert, James; Blangero, Annabelle; Rossetti, Yves

    2007-04-09

    Visual illusions have been shown to affect perceptual judgements more so than motor behaviour, which was interpreted as evidence for a functional division of labour within the visual system. The dominant perception-action theory argues that perception involves a holistic processing of visual objects or scenes, performed within the ventral, inferior temporal cortex. Conversely, visuomotor action involves the processing of the 3D relationship between the goal of the action and the body, performed predominantly within the dorsal, posterior parietal cortex. We explored the effect of well-known visual illusions (a size-contrast illusion and the induced Roelofs effect) in a patient (IG) suffering bilateral lesions of the dorsal visual stream. According to the perception-action theory, IG's perceptual judgements and control of actions should rely on the intact ventral stream and hence should both be sensitive to visual illusions. The finding that IG performed similarly to controls in three different illusory contexts argues against such expectations and shows, furthermore, that the dorsal stream does not control all aspects of visuomotor behaviour. Assuming that the patient's dorsal stream visuomotor system is fully lesioned, these results suggest that her visually guided action can be planned and executed independently of the dorsal pathways, possibly through the inferior parietal lobule.

  20. Integration eller Illusion

    DEFF Research Database (Denmark)

    Rezaei, Shahamak; Goli, Marco

    2012-01-01

    Integration or illusion – a deviance perspective Denmark experienced one of its most successful periods of economic growth in 2004–2008 with a tremendous reduction of unemployment, which in June 2008 was around. 1.5 percent, far below the expected level of structural unemployment. In the wake of ...... they want and what they can, the deviance perspective, we believe, also reduces the theoretical and normative biases, that characterises the discrimination and integration framework, and provide more reliable explanations. Key Words: Migration, Anomy, Norm-Divergence, Over-Education...

  1. Humans are not fooled by size illusions in attractiveness judgements.

    Science.gov (United States)

    Bateson, Melissa; Tovée, Martin J; George, Hannah R; Gouws, Anton; Cornelissen, Piers L

    2014-03-01

    Could signallers use size contrast illusions to dishonestly exaggerate their attractiveness to potential mates? Using composite photographs of women from three body mass index (BMI) categories designed to simulate small groups, we show that target women of medium size are judged as thinner when surrounded by larger women than when surrounded by thinner women. However, attractiveness judgements of the same target women were unaffected by this illusory change in BMI, despite small true differences in the BMIs of the target women themselves producing strong effects on attractiveness. Thus, in the context of mate choice decisions, the honesty of female body size as a signal of mate quality appears to have been maintained by the evolution of assessment strategies that are immune to size contrast illusions. Our results suggest that receiver psychology is more flexible than previously assumed, and that illusions are unlikely to drive the evolution of exploitative neighbour choice in human sexual displays.

  2. The composite face illusion.

    Science.gov (United States)

    Murphy, Jennifer; Gray, Katie L H; Cook, Richard

    2017-04-01

    Few findings in cognitive science have proved as influential as the composite face effect. When the top half of one face is aligned with the bottom half of another, and presented upright, the resulting composite arrangement induces a compelling percept of a novel facial configuration. Findings obtained using composite face procedures have contributed significantly to our understanding of holistic face processing, the detrimental effects of face inversion, the development of face perception, and aberrant face perception in clinical populations. Composite paradigms continue to advance our knowledge of face perception, as exemplified by their recent use for investigating the perceptual mechanisms underlying dynamic face processing. However, the paradigm has been the subject of intense scrutiny, particularly over the last decade, and there is a growing sense that the composite face illusion, whilst easy to illustrate, is deceptively difficult to measure and interpret. In this review, we provide a focussed overview of the existing composite face literature, and identify six priorities for future research. Addressing these gaps in our knowledge will aid the evaluation and refinement of theoretical accounts of the illusion.

  3. Illusion induced overlapped optics.

    Science.gov (United States)

    Zang, XiaoFei; Shi, Cheng; Li, Zhou; Chen, Lin; Cai, Bin; Zhu, YiMing; Zhu, HaiBin

    2014-01-13

    The traditional transformation-based cloak seems like it can only hide objects by bending the incident electromagnetic waves around the hidden region. In this paper, we prove that invisible cloaks can be applied to realize the overlapped optics. No matter how many in-phase point sources are located in the hidden region, all of them can overlap each other (this can be considered as illusion effect), leading to the perfect optical interference effect. In addition, a singular parameter-independent cloak is also designed to obtain quasi-overlapped optics. Even more amazing of overlapped optics is that if N identical separated in-phase point sources covered with the illusion media, the total power outside the transformation region is N2I0 (not NI0) (I0 is the power of just one point source, and N is the number point sources), which seems violating the law of conservation of energy. A theoretical model based on interference effect is proposed to interpret the total power of these two kinds of overlapped optics effects. Our investigation may have wide applications in high power coherent laser beams, and multiple laser diodes, and so on.

  4. Humanlike robot hands controlled by brain activity arouse illusion of ownership in operators

    Science.gov (United States)

    Alimardani, Maryam; Nishio, Shuichi; Ishiguro, Hiroshi

    2013-08-01

    Operators of a pair of robotic hands report ownership for those hands when they hold image of a grasp motion and watch the robot perform it. We present a novel body ownership illusion that is induced by merely watching and controlling robot's motions through a brain machine interface. In past studies, body ownership illusions were induced by correlation of such sensory inputs as vision, touch and proprioception. However, in the presented illusion none of the mentioned sensations are integrated except vision. Our results show that during BMI-operation of robotic hands, the interaction between motor commands and visual feedback of the intended motions is adequate to incorporate the non-body limbs into one's own body. Our discussion focuses on the role of proprioceptive information in the mechanism of agency-driven illusions. We believe that our findings will contribute to improvement of tele-presence systems in which operators incorporate BMI-operated robots into their body representations.

  5. Magic and the aesthetic illusion.

    Science.gov (United States)

    Balter, Leon

    2002-01-01

    The aesthetic illusion is the subjective experience that the content of a work of art is reality. It has an intrinsic relation to magic, an intrapsychic maneuver oriented toward modification and control of the extraspyschic world, principally through ego functioning. Magic is ontogenetically and culturally archaic, expresses the omnipotence inherent in primary narcissism, and operates according to the logic of the primary process. Magic is a constituent of all ego functioning, usually latent in later development. It may persist as an archaic feature or may be evoked regressively in global or circumscribed ways. It causes a general disinhibition of instincts and impulses attended by a sense of confidence, exhiliration, and exuberance. The aesthetic illusion is a combination of illusions: (1) that the daydream embodied by the work of art is the beholder's own, the artist being ignored, and (2) that the artistically described protagonist is a real person with a real "world." The first illusion arises through the beholder's emotional-instinctual gratification from his or her own fantasy-memory constellations; the second comes about because the beholder, by taking the protagonist as proxy, mobilizes the subjective experience of the imaginary protagonist's "reality." The first illusion is necessary for the second to take place; the second establishes the aesthetic illusion proper. Both illusions are instances of magic. Accordingly, the aesthetic illusion is accompanied by a heady experience of excitement and euphoria. The relation among the aesthetic illusion, magic, and enthusiasm is illustrated by an analytic case, J. D. Salinger's "The Laughing Man," Woody Allen's Play It Again, Sam, Don Quixote, and the medieval Cult of the Saints.

  6. 7 CFR 3560.659 - Sale or transfer to nonprofit organizations and public bodies.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Sale or transfer to nonprofit organizations and... Housing Preservation § 3560.659 Sale or transfer to nonprofit organizations and public bodies. (a) Sales... housing project to a nonprofit organization or public body, two independent appraisals will be...

  7. The effect of bodily illusions on clinical pain: a systematic review and meta-analysis.

    Science.gov (United States)

    Boesch, Eva; Bellan, Valeria; Moseley, G Lorimer; Stanton, Tasha R

    2016-03-01

    This systematic review and meta-analysis critically examined the evidence for bodily illusions to modulate pain. Six databases were searched; 2 independent reviewers completed study inclusion, risk of bias assessment, and data extraction. Included studies evaluated the effect of a bodily illusion on pain, comparing results with a control group/condition. Of the 2213 studies identified, 20 studies (21 experiments) were included. Risk of bias was high due to selection bias and lack of blinding. Consistent evidence of pain decrease was found for illusions of the existence of a body part (myoelectric/Sauerbruch prosthesis vs cosmetic/no prosthesis; standardized mean differences = -1.84, 95% CI = -2.67 to -1.00) and 4 to 6 weeks of mirror therapy (standardized mean differences = -1.11, 95% CI = -1.66 to -0.56). Bodily resizing illusions had consistent evidence of pain modulation (in the direction hypothesized). Pooled data found no effect on pain for 1 session of mirror therapy or for incongruent movement illusions (except for comparisons with congruent mirrored movements: incongruent movement illusion significantly increased the odds of experiencing pain). Conflicting results were found for virtual walking illusions (both active and inactive control comparisons). Single studies suggest no effect of resizing illusions on pain evoked by noxious stimuli, no effect of embodiment illusions, but a significant pain decrease with synchronous mirrored stroking in nonresponders to traditional mirror therapy. There is limited evidence to suggest that bodily illusions can alter pain, but some illusions, namely mirror therapy, bodily resizing, and use of functional prostheses show therapeutic promise.

  8. Integration eller Illusion

    DEFF Research Database (Denmark)

    Rezaei, Shahamak; Goli, Marco

    2012-01-01

    Integration or illusion – a deviance perspective Denmark experienced one of its most successful periods of economic growth in 2004–2008 with a tremendous reduction of unemployment, which in June 2008 was around. 1.5 percent, far below the expected level of structural unemployment. In the wake...... of searching for explanations for the lack of integration, we attempt to identify and explain the deviance pattern as a product of institutionally inherent possibilities and barriers on the one hand and articulating immigrants as rational actors (not victims) on the other. We argue that deviance is not only...... a more fruitful theoretical and analytical framework than integration and discrimination. Taking departure in empirical evidence on immigrants’ preferences and behaviour as bounded rational actors, and how they actually articulate their everyday life practical experiences, including adjustment of what...

  9. The Mirrored Hand Illusion: I Control, So I Possess?

    Science.gov (United States)

    Zhou, Aibao; Zhang, Yanchi; Yin, Yulong; Yang, Yang

    2015-01-01

    Certain situations may not only cause people to misjudge external information but also distort people's perception of themselves. The present study is the first to report the mirrored hand illusion which could be generated when the experimenter imitated the fist-clenching movements of the subject synchronously. The subjects formed the illusion that the experimenter's hand was "something I can control" when being imitated synchronously. In addition, a sense of ownership over the alien hand was established by integrating multisensory signals and comparing these signals with preexisting body presentations. This method might represent a new avenue for research on the formation of self-consciousness.

  10. The Star Wars Scroll Illusion.

    Science.gov (United States)

    Shapiro, Arthur G

    2015-10-01

    The Star Wars Scroll Illusion is a dynamic version of the Leaning Tower Illusion. When two copies of a Star-Wars-like scrolling text are placed side by side (with separate vanishing points), the two scrolls appear to head in different directions even though they are physically parallel in the picture plane. Variations of the illusion are shown with one vanishing point, as well as from an inverted perspective where the scrolls appear to originate in the distance. The demos highlight the conflict between the physical lines in the picture plane and perspective interpretation: With two perspective points, the scrolling texts are parallel to each other in the picture plane but not in perspective interpretation; with one perspective point, the texts are not parallel to each other in the picture plane but are parallel to each other in perspective interpretation. The size of the effect is linearly related to the angle of rotation of the scrolls into the third dimension; the Scroll Illusion is stronger than the Leaning Tower Illusion for rotation angles between 35° and 90°. There is no effect of motion per se on the strength of the illusion.

  11. The Star Wars Scroll Illusion

    Directory of Open Access Journals (Sweden)

    Arthur G. Shapiro

    2015-09-01

    Full Text Available The Star Wars Scroll Illusion is a dynamic version of the Leaning Tower Illusion. When two copies of a Star-Wars-like scrolling text are placed side by side (with separate vanishing points, the two scrolls appear to head in different directions even though they are physically parallel in the picture plane. Variations of the illusion are shown with one vanishing point, as well as from an inverted perspective where the scrolls appear to originate in the distance. The demos highlight the conflict between the physical lines in the picture plane and perspective interpretation: With two perspective points, the scrolling texts are parallel to each other in the picture plane but not in perspective interpretation; with one perspective point, the texts are not parallel to each other in the picture plane but are parallel to each other in perspective interpretation. The size of the effect is linearly related to the angle of rotation of the scrolls into the third dimension; the Scroll Illusion is stronger than the Leaning Tower Illusion for rotation angles between 35° and 90°. There is no effect of motion per se on the strength of the illusion.

  12. The Star Wars Scroll Illusion

    Science.gov (United States)

    2015-01-01

    The Star Wars Scroll Illusion is a dynamic version of the Leaning Tower Illusion. When two copies of a Star-Wars-like scrolling text are placed side by side (with separate vanishing points), the two scrolls appear to head in different directions even though they are physically parallel in the picture plane. Variations of the illusion are shown with one vanishing point, as well as from an inverted perspective where the scrolls appear to originate in the distance. The demos highlight the conflict between the physical lines in the picture plane and perspective interpretation: With two perspective points, the scrolling texts are parallel to each other in the picture plane but not in perspective interpretation; with one perspective point, the texts are not parallel to each other in the picture plane but are parallel to each other in perspective interpretation. The size of the effect is linearly related to the angle of rotation of the scrolls into the third dimension; the Scroll Illusion is stronger than the Leaning Tower Illusion for rotation angles between 35° and 90°. There is no effect of motion per se on the strength of the illusion. PMID:27648216

  13. Convective Heat Transfer Coefficients of the Human Body under Forced Convection from Ceiling

    DEFF Research Database (Denmark)

    Kurazumi, Yoshihito; Rezgals, Lauris; Melikov, Arsen Krikor

    2014-01-01

    The average convective heat transfer coefficient for a seated human body exposed to downward flow from above was determined. Thermal manikin with complex body shape and size of an average Scandinavian female was used. The surface temperature distribution of the manikin’s body was as the skin...... of the convective heat transfer coefficient of the whole body (hc [W/(m2•K)]) was proposed: hc=4.088+6.592V1.715 for a seated naked body at 20ºC and hc=2.874+7.427V1.345 for a seated naked body at 26ºC. Differences in the convective heat transfer coefficient of the whole body in low air velocity range, V

  14. Persistent Directional Current at Equilibrium in Nonreciprocal Many-Body Near Field Electromagnetic Heat Transfer

    Science.gov (United States)

    Zhu, Linxiao; Fan, Shanhui

    2016-09-01

    We consider the consequence of nonreciprocity in near-field heat transfer by studying systems consisting of magneto-optical nanoparticles. We demonstrate that, in thermal equilibrium, a nonreciprocal many-body system in heat transfer can support a persistent directional heat current, without violating the second law of thermodynamics. Such a persistent directional heat current cannot occur in reciprocal systems, and can only arise in many-body systems in heat transfer. The use of nonreciprocity therefore points to a new regime of near-field heat transfer for the control of heat flow in the nanoscale.

  15. Creating Virtual-hand and Virtual-face Illusions to Investigate Self-representation.

    Science.gov (United States)

    Ma, Ke; Lippelt, Dominique P; Hommel, Bernhard

    2017-03-01

    Studies investigating how people represent themselves and their own body often use variants of "ownership illusions", such as the traditional rubber-hand illusion or the more recently discovered enfacement illusion. However, these examples require rather artificial experimental setups, in which the artificial effector needs to be stroked in synchrony with the participants' real hand or face-a situation in which participants have no control over the stroking or the movements of their real or artificial effector. Here, we describe a technique to establish ownership illusions in a setup that is more realistic, more intuitive, and of presumably higher ecological validity. It allows creating the virtual-hand illusion by having participants control the movements of a virtual hand presented on a screen or in virtual space in front of them. If the virtual hand moves in synchrony with the participants' own real hand, they tend to perceive the virtual hand as part of their own body. The technique also creates the virtual-face illusion by having participants control the movements of a virtual face in front of them, again with the effect that they tend to perceive the face as their own if it moves in synchrony with their real face. Studying the circumstances that illusions of this sort can be created, increased, or reduced provides important information about how people create and maintain representations of themselves.

  16. Perceiving the present: systematization of illusions or illusion of systematization?

    Science.gov (United States)

    Briscoe, Robert E

    2010-11-01

    Mark Changizi et al. (2008) claim that it is possible systematically to organize more than 50 kinds of illusions in a 7 × 4 matrix of 28 classes. This systematization, they further maintain, can be explained by the operation of a single visual processing latency correction mechanism that they call "perceiving the present" (PTP). This brief report raises some concerns about the way a number of illusions are classified by the proposed systematization. It also poses two general problems-one empirical and one conceptual-for the PTP approach.

  17. N-body Simulation of Binary Star Mass Transfer

    Science.gov (United States)

    Hutyra, Taylor; Sumpter, William

    2017-01-01

    Over 70% of the stars in our galaxy are multiple star systems, many of which are two stars that orbit around a common center of mass. The masses of the individual stars can be found using Newton’s and Kepler’s Laws. This allows astronomers to use these systems as astrophysical laboratories to study properties and processes of stars and galaxies. Among the many types observed, the dynamics of contact systems are the most interesting because they exhibit mass transfer, which changes the composition and function of both stars. The process by which this mass exchange takes place is not well understood. The lack of extensive mass transfer analysis, inadequate theoretical models, and the large time scale of this process are reasons for our limited understanding. In this work, a model was made to give astronomers a method for gaining a deeper knowledge and visual intuition of how the mass transfer between binary stars takes place. We have built the foundations for a simulation of arbitrary systems, which we plan to elaborate on in the future to include thermodynamics and nuclear processes.

  18. Neglect's perspective on the Ponzo illusion.

    Science.gov (United States)

    Sedda, A; Ferrè, E R; Striemer, C L; Bottini, G

    2013-06-01

    Visual illusions have been used to explore implicit perception in neglect. Previous studies have highlighted differences between length and surface illusion perception in neglect, but much less is known about depth illusion perception. In the Ponzo illusion (a classic depth illusion), two converging oblique lines modulate the perceived length of two horizontal lines. In the current study, we presented modified versions of the Ponzo illusion in which only one of the converging oblique lines was presented (alternatively the right or the left one). This manipulation allowed us to explore (1) how acute patients with neglect process depth illusions, and (2) whether awareness of both converging lines is necessary for the full effect of the illusion. To examine these questions, we had participants (i.e. healthy controls, patients with neglect and right brain-damaged patients) to make a perceptual judgment regarding the perceived length of the upper versus lower horizontal line within the Ponzo frame in four conditions: (1) the classic Ponzo illusion, (2) a "modified left" Ponzo illusion with a single oblique line on the left, (3) a "modified right" Ponzo illusion with a single oblique line on the right and (4) a control condition with parallel lines. The results indicated that all participants perceived the canonical Ponzo illusion and the modified right illusion. Critically, patients with neglect did not perceive the modified left illusion. In addition, for neglect patients, there was no difference in the strength of the perceived illusion when comparing the canonical illusion with the modified right illusion. Importantly, single case analysis revealed a high degree of variability in the neglect group that seemed to be linked with the amount of damage to occipital areas. Overall our results indicate that: (1) the classic Ponzo illusion might be perceived in neglect patients based solely on perception of the right side of the stimulus configuration, and (2) differences

  19. Proprioceptive movement illusions due to prolonged stimulation: reversals and aftereffects.

    Directory of Open Access Journals (Sweden)

    Tatjana Seizova-Cajic

    Full Text Available BACKGROUND: Adaptation to constant stimulation has often been used to investigate the mechanisms of perceptual coding, but the adaptive processes within the proprioceptive channels that encode body movement have not been well described. We investigated them using vibration as a stimulus because vibration of muscle tendons results in a powerful illusion of movement. METHODOLOGY/PRINCIPAL FINDINGS: We applied sustained 90 Hz vibratory stimulation to biceps brachii, an elbow flexor and induced the expected illusion of elbow extension (in 12 participants. There was clear evidence of adaptation to the movement signal both during the 6-min long vibration and on its cessation. During vibration, the strong initial illusion of extension waxed and waned, with diminishing duration of periods of illusory movement and occasional reversals in the direction of the illusion. After vibration there was an aftereffect in which the stationary elbow seemed to move into flexion. Muscle activity shows no consistent relationship with the variations in perceived movement. CONCLUSION: We interpret the observed effects as adaptive changes in the central mechanisms that code movement in direction-selective opponent channels.

  20. Rubber hand illusion affects joint angle perception.

    Directory of Open Access Journals (Sweden)

    Martin V Butz

    Full Text Available The Rubber Hand Illusion (RHI is a well-established experimental paradigm. It has been shown that the RHI can affect hand location estimates, arm and hand motion towards goals, the subjective visual appearance of the own hand, and the feeling of body ownership. Several studies also indicate that the peri-hand space is partially remapped around the rubber hand. Nonetheless, the question remains if and to what extent the RHI can affect the perception of other body parts. In this study we ask if the RHI can alter the perception of the elbow joint. Participants had to adjust an angular representation on a screen according to their proprioceptive perception of their own elbow joint angle. The results show that the RHI does indeed alter the elbow joint estimation, increasing the agreement with the position and orientation of the artificial hand. Thus, the results show that the brain does not only adjust the perception of the hand in body-relative space, but it also modifies the perception of other body parts. In conclusion, we propose that the brain continuously strives to maintain a consistent internal body image and that this image can be influenced by the available sensory information sources, which are mediated and mapped onto each other by means of a postural, kinematic body model.

  1. Neonatal and maternal body burdens of hexachlorobenzene (HCB) in mice: gestational exposure and lactational transfer

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, K.D.; Andrews, J.E.

    1985-04-01

    Hexachlorobenzene (HCB), a ubiquitous lipophilic pollutant, was readily transferred in the milk of lactating dams to their suckling neonates. Pregnant CD-1 mice were treated during gestation, and the body burdens of HCB in the neonates and the dams were determined during lactation. Also, neonates from dams treated with HCB during gestation were cross-fostered at birth to dams treated with corn oil during gestation. The body burdens of HCB were greater in the neonates exposed to HCB by lactational transfer than the neonates exposed only by gestational transfer. In many tissues, the concentration of HCB in the pups from full litter was similar to that in pups from litters reduced to two pups per litter. Lactational transfer of HCB from the dams to the pups was a major route of excretion in that 95% of HCB was depleted during 20 days of lactation. HCB depletion was similar in dams with whole litters, and those with litters reduced to two pups.

  2. Aristotle’s Illusion in Parkinson’s Disease: Evidence for Normal Interdigit Tactile Perception

    Science.gov (United States)

    Fiorio, Mirta; Marotta, Angela; Ottaviani, Sarah; Pozzer, Lara; Tinazzi, Michele

    2014-01-01

    Sensory alterations, a common feature of such movement disorders as Parkinson’s disease (PD) and dystonia, could emerge as epiphenomena of basal ganglia dysfunction. Recently, we found a selective reduction of tactile perception (Aristotle’s illusion, the illusory doubling sensation of one object when touched with crossed fingers) in the affected hand of patients with focal hand dystonia. This suggests that reduced tactile illusion might be a specific feature of this type of dystonia and could be due to abnormal somatosensory cortical activation. The aim of the current study was to investigate whether Aristotle’s illusion is reduced in the affected hand of patients with PD. We tested 15 PD patients, in whom motor symptoms were mainly localised to one side of the body, and 15 healthy controls. Three pairs of fingers were tested in crossed (evoking the illusion) or parallel position (not evoking the illusion). A sphere was placed in the contact point between the two fingers and the blindfolded participants had to say whether they felt one or two stimuli. Stimuli were applied on the affected and less or unaffected side of the PD patients. We found no difference in illusory perception between the PD patients and the controls, nor between the more affected and less/unaffected side, suggesting that Aristotle’s illusion is preserved in PD. The retained tactile illusion in PD and its reduction in focal hand dystonia suggest that the basal ganglia, which are dysfunctional in both PD and dystonia, may not be causally involved in this function. Instead, the level of activation between digits in the somatosensory cortex may be more directly involved. Finally, the similar percentage of illusion in the more affected and less or unaffected body sides indicates that the illusory perception is not influenced by the presence or amount of motor symptoms. PMID:24523929

  3. Aristotle's illusion in Parkinson's disease: evidence for normal interdigit tactile perception.

    Science.gov (United States)

    Fiorio, Mirta; Marotta, Angela; Ottaviani, Sarah; Pozzer, Lara; Tinazzi, Michele

    2014-01-01

    Sensory alterations, a common feature of such movement disorders as Parkinson's disease (PD) and dystonia, could emerge as epiphenomena of basal ganglia dysfunction. Recently, we found a selective reduction of tactile perception (Aristotle's illusion, the illusory doubling sensation of one object when touched with crossed fingers) in the affected hand of patients with focal hand dystonia. This suggests that reduced tactile illusion might be a specific feature of this type of dystonia and could be due to abnormal somatosensory cortical activation. The aim of the current study was to investigate whether Aristotle's illusion is reduced in the affected hand of patients with PD. We tested 15 PD patients, in whom motor symptoms were mainly localised to one side of the body, and 15 healthy controls. Three pairs of fingers were tested in crossed (evoking the illusion) or parallel position (not evoking the illusion). A sphere was placed in the contact point between the two fingers and the blindfolded participants had to say whether they felt one or two stimuli. Stimuli were applied on the affected and less or unaffected side of the PD patients. We found no difference in illusory perception between the PD patients and the controls, nor between the more affected and less/unaffected side, suggesting that Aristotle's illusion is preserved in PD. The retained tactile illusion in PD and its reduction in focal hand dystonia suggest that the basal ganglia, which are dysfunctional in both PD and dystonia, may not be causally involved in this function. Instead, the level of activation between digits in the somatosensory cortex may be more directly involved. Finally, the similar percentage of illusion in the more affected and less or unaffected body sides indicates that the illusory perception is not influenced by the presence or amount of motor symptoms.

  4. Aristotle's illusion in Parkinson's disease: evidence for normal interdigit tactile perception.

    Directory of Open Access Journals (Sweden)

    Mirta Fiorio

    Full Text Available Sensory alterations, a common feature of such movement disorders as Parkinson's disease (PD and dystonia, could emerge as epiphenomena of basal ganglia dysfunction. Recently, we found a selective reduction of tactile perception (Aristotle's illusion, the illusory doubling sensation of one object when touched with crossed fingers in the affected hand of patients with focal hand dystonia. This suggests that reduced tactile illusion might be a specific feature of this type of dystonia and could be due to abnormal somatosensory cortical activation. The aim of the current study was to investigate whether Aristotle's illusion is reduced in the affected hand of patients with PD. We tested 15 PD patients, in whom motor symptoms were mainly localised to one side of the body, and 15 healthy controls. Three pairs of fingers were tested in crossed (evoking the illusion or parallel position (not evoking the illusion. A sphere was placed in the contact point between the two fingers and the blindfolded participants had to say whether they felt one or two stimuli. Stimuli were applied on the affected and less or unaffected side of the PD patients. We found no difference in illusory perception between the PD patients and the controls, nor between the more affected and less/unaffected side, suggesting that Aristotle's illusion is preserved in PD. The retained tactile illusion in PD and its reduction in focal hand dystonia suggest that the basal ganglia, which are dysfunctional in both PD and dystonia, may not be causally involved in this function. Instead, the level of activation between digits in the somatosensory cortex may be more directly involved. Finally, the similar percentage of illusion in the more affected and less or unaffected body sides indicates that the illusory perception is not influenced by the presence or amount of motor symptoms.

  5. The elusive illusion: Do children (Homo sapiens) and capuchin monkeys (Cebus apella) see the Solitaire illusion?

    Science.gov (United States)

    Parrish, Audrey E; Agrillo, Christian; Perdue, Bonnie M; Beran, Michael J

    2016-02-01

    One approach to gaining a better understanding of how we perceive the world is to assess the errors that human and nonhuman animals make in perceptual processing. Developmental and comparative perspectives can contribute to identifying the mechanisms that underlie systematic perceptual errors often referred to as perceptual illusions. In the visual domain, some illusions appear to remain constant across the lifespan, whereas others change with age. From a comparative perspective, many of the illusions observed in humans appear to be shared with nonhuman primates. Numerosity illusions are a subset of visual illusions and occur when the spatial arrangement of stimuli within a set influences the perception of quantity. Previous research has found one such illusion that readily occurs in human adults, the Solitaire illusion. This illusion appears to be less robust in two monkey species, rhesus macaques and capuchin monkeys. We attempted to clarify the ontogeny of this illusion from a developmental and comparative perspective by testing human children and task-naïve capuchin monkeys in a computerized quantity judgment task. The overall performance of the monkeys suggested that they perceived the numerosity illusion, although there were large differences among individuals. Younger children performed similarly to the monkeys, whereas older children more consistently perceived the illusion. These findings suggest that human-unique perceptual experiences with the world might play an important role in the emergence of the Solitaire illusion in human adults, although other factors also may contribute.

  6. On the notion of visual illusions

    Directory of Open Access Journals (Sweden)

    Todorović Dejan

    2014-01-01

    Full Text Available The usual definitions of illusions, as incorrect perceptions or cases of discrepancies between reality and our perception of reality, have been criticized as inadequate. The reason is that it is not clear how to apply this notion in a number of interesting cases. This paper is an attempt to provide an adequate definition of illusions, appropriate for many classical phenomena usually referred to as illusions.

  7. Thermal supercurrent in non-reciprocal many-body near field electromagnetic heat transfer

    CERN Document Server

    Zhu, Linxiao

    2016-01-01

    We consider the consequence of non-reciprocity in near-field heat transfer by studying systems consisting of magneto-optical nanoparticles. We demonstrate that in thermal equilibrium, non-reciprocal many-body system can support a persistent directional heat current, i.e. thermal supercurrent, without violating the second law of thermodynamics. Such a thermal supercurrent can not occur in reciprocal systems, and can only arise in many-body systems. The use of non-reciprocity therefore points to a new regime of near-field heat transfer for the control of heat flow in the nanoscale.

  8. Advanced germanium layer transfer for ultra thin body on insulator structure

    Science.gov (United States)

    Maeda, Tatsuro; Chang, Wen-Hsin; Irisawa, Toshifumi; Ishii, Hiroyuki; Hattori, Hiroyuki; Poborchii, Vladimir; Kurashima, Yuuichi; Takagi, Hideki; Uchida, Noriyuki

    2016-12-01

    We present the HEtero-Layer Lift-Off (HELLO) technique to obtain ultra thin body (UTB) Ge on insulator (GeOI) substrates. The transferred ultra thin Ge layers are characterized by the Raman spectroscopy measurements down to the thickness of ˜1 nm, observing a strong Raman intensity enhancement for high quality GeOI structure in ultra thin regime due to quantum size effect. This advanced Ge layer transfer technique enabled us to demonstrate UTB-GeOI nMOSFETs with the body thickness of only 4 nm.

  9. Second-Order Footsteps Illusions

    Directory of Open Access Journals (Sweden)

    Akiyoshi Kitaoka

    2015-12-01

    Full Text Available In the “footsteps illusion”, light and dark squares travel at constant speed across black and white stripes. The squares appear to move faster and slower as their contrast against the stripes varies. We now demonstrate some second-order footsteps illusions, in which all edges are defined by colors or textures—even though luminance-based neural motion detectors are blind to such edges.

  10. Thermoplasticity of coupled bodies in the case of stress-dependent heat transfer

    Science.gov (United States)

    Kilikovskaya, O. A.

    1987-01-01

    The problem of the thermal stresses in coupled deformable bodies is formulated for the case where the heat-transfer coefficient at the common boundary depends on the stress-strain state of the bodies (e.g., is a function of the normal pressure at the common boundary). Several one-dimensional problems are solved in this formulation. Among these problems is the determination of the thermal stresses in an n-layer plate and in a two-layer cylinder.

  11. Illusions of empowerment?

    DEFF Research Database (Denmark)

    Chomba, Susan Wangui; Nathan, Iben; Minang, Peter A.;

    2015-01-01

    The extent to which community forestry (CF) contributes to empowerment of local communities remains hotly contested. We develop a unified theory of empowerment at the intersection of asset-based agency and institution-based opportunity and apply it to examine the extent to which the implementation...... of CF has led to local empowerment. Our empirical data are drawn from review of national level policies and a field study of Ngare Ndare Community Forest Association (CFA) in Kenya. We investigated what types of powers were transferred to the local level, how representative the local institution...... was of the local community, and how its formation and composition affected the empowerment of socially and economically differentiated groups, with competing claims over the forest resource. We found that national forest policies and actors transferred minimal powers that enabled local communities to execute...

  12. Effects of Nonequilibrium at Edge of Boundary Layer on Convective Heat Transfer to a Blunt Body

    Science.gov (United States)

    Goekcen, Tahir; Edwards, Thomas A. (Technical Monitor)

    1996-01-01

    This investigation is a continuation of a previous study on nonequilibrium convective heat transfer to a blunt body. In the previous study, for relatively high Reynolds number flows, it was found that: nonequilibrium convective heat transfer to a blunt body is not strongly dependent on freestream parameters, provided that the thermochemical equilibrium is reached at the edge of boundary layer; and successful testing of convective heat transfer in an arc-jet environment is possible by duplicating the surface pressure and total enthalpy. The nonequilibrium convective heat transfer computations are validated against the results of Fay and Riddell/Goulard theory. Present work investigates low Reynolds number conditions which are typical in an actual arc-jet flow environment. One expects that there will be departures from the Fay and Riddell/Goulard result since certain assumptions of the classical theory are not satisfied. These departures are of interest because the Fay and Riddell/Goulard formulas are extensively used in arc-jet testing (e.g., to determine the enthalpy of the flow and the catalytic efficiency of heat shield materials). For practical sizes of test materials, density of the test flow (and Reynolds number) in an arc-jet is such that thermochemical equilibrium may not be reached at the edge of boundary layer. For blunt body flows of nitrogen and air, computations will be presented to show the effects of thermochemical nonequilibrium at the boundary layer edge on nonequilibrium heat transfer.

  13. Effects of Nonequilibrium at Edge of Boundary Layer on Convective Heat Transfer to a Blunt Body

    Science.gov (United States)

    Goekcen, Tahir; Edwards, Thomas A. (Technical Monitor)

    1996-01-01

    This investigation is a continuation of a previous study on nonequilibrium convective heat transfer to a blunt body. In the previous study, for relatively high Reynolds number flows, it was found that: nonequilibrium convective heat transfer to a blunt body is not strongly dependent on freestream parameters, provided that the thermochemical equilibrium is reached at the edge of boundary layer; and successful testing of convective heat transfer in an arc-jet environment is possible by duplicating the surface pressure and total enthalpy. The nonequilibrium convective heat transfer computations are validated against the results of Fay and Riddell/Goulard theory. Present work investigates low Reynolds number conditions which are typical in an actual arc-jet flow environment. One expects that there will be departures from the Fay and Riddell/Goulard result since certain assumptions of the classical theory are not satisfied. These departures are of interest because the Fay and Riddell/Goulard formulas are extensively used in arc-jet testing (e.g., to determine the enthalpy of the flow and the catalytic efficiency of heat shield materials). For practical sizes of test materials, density of the test flow (and Reynolds number) in an arc-jet is such that thermochemical equilibrium may not be reached at the edge of boundary layer. For blunt body flows of nitrogen and air, computations will be presented to show the effects of thermochemical nonequilibrium at the boundary layer edge on nonequilibrium heat transfer.

  14. Modelling flow and heat transfer around a seated human body by computational fluid dynamics

    DEFF Research Database (Denmark)

    Sørensen, Dan Nørtoft; Voigt, Lars Peter Kølgaard

    2003-01-01

    A database (http://www.ie.dtu.dk/manikin) containing a detailed representation of the surface geometry of a seated female human body was created from a surface scan of a thermal manikin (minus clothing and hair). The radiative heat transfer coefficient and the natural convection flow around...

  15. Families of impulsive transfers between libration points in the restricted three-body problem

    Science.gov (United States)

    Lei, Hanlun; Xu, Bo

    2016-09-01

    This paper investigates families of impulsive transfer trajectories between libration points of restricted three-body problem. In practical computation, the triangular libration points L4 and L5 of Earth-Moon system are taken as the departure and arrival points, respectively. The numerical continuation technique in combination with shooting method is performed, and lots of impulsive transfers are obtained. The distribution of these transfers on the time of flight - Jacobi constant plane presents the characteristic of families. According to the symmetry property, all families of impulsive transfers are divided into two categories: families of symmetric and asymmetric transfers. In total, 28 families of symmetric transfers and 74 families of asymmetric transfers are identified. Among these families, some special families with closed characteristic curves are found. In the evolution of families, some important characteristic points are discussed, including the starting, bifurcation and ending points. About bifurcation phenomenon, a dynamical explanation is provided and then the necessary and sufficient condition of bifurcation is summarized. At last, based on the families computed, three types of impulsive transfers between libration point orbits are discussed.

  16. The role of body size in host specificity: reciprocal transfer experiments with feather lice.

    Science.gov (United States)

    Bush, Sarah E; Clayton, Dale H

    2006-10-01

    Although most parasites show at least some degree of host specificity, factors governing the evolution of specificity remain poorly understood. Many different groups of host-specific parasites show a striking correlation between parasite and host body size, suggesting that size reinforces specificity. We tested this hypothesis by measuring the relative fitness of host-specific feather lice transferred to pigeons and doves that differ in size by an order of magnitude. To test the general influence of size, we transferred unrelated groups of wing and body lice, which are specialized for different regions of the host. Lice were transferred in both directions, from a large native host species, the rock pigeon (Columba livia), to several progressively smaller hosts, and from a small native host species, the common ground dove (Columbina passerina), to several larger hosts. We measured the relative fitness (population size) of lice transferred to these novel host species after two louse generations. Neither wing lice nor body lice could survive on novel host species that were smaller in size than the native host. However, when host defense (preening behavior) was blocked, both groups survived and reproduced on all novel hosts tested. Thus, host defense interacted with host size to govern the ability of lice to establish on small hosts. Neither wing lice nor body lice could survive on larger hosts, even when preening was blocked. In summary, host size influenced the fitness of both types of feather lice, but through different mechanisms, depending on the direction of the transfer. Our results indicate that host switching is most likely between hosts of similar body size. This finding has important implications for studies of host-parasite coevolution at both the micro- and macroevolutionary scales.

  17. Elemental transfer from Chinese soil via the diet to the whole human body.

    Science.gov (United States)

    Zhu, Hong-da; Wu, Quan; Fan, Ti-Jiang; Liu, Qingfen; Zhang, We

    2008-12-01

    Based on results from recent studies of elemental dietary intake and organ or tissue content for adult Chinese men, quoted nationwide elemental concentrations in Chinese soil and newly published national average consumption of dietary foods, values of both transfer coefficients and discrimination factor (DF) for transfer from soil via the diet to both critical organs and the whole body have been calculated for important elements in radiation protection, including alkaline earths, alkali metals, rare earths and other related elements. These calculations have used both the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) model and the DF method. In the UNSCEAR model, the basic parameters used to describe the transport of radionuclides are the transfer coefficients P(ij), which describe the relationship of concentrations or other amounts between compartment i and the following compartment j, whereas the DF is the ratio between the transfer coefficients for one element and a chemically similar element. From a comparison of the transfer coefficients of different elements for a particular transport pathway, those for alkaline earths are generally speaking higher than those for halogen elements and alkali metals, whereas those for rare earth elements, U and Th are lower. Relative to Ca, the DFs of transfer from soil to diet and from diet to critical organs or the whole body for the other alkaline earth elements and Pb are all less than 1, the DFs for the other elements decrease with increasing or decreasing atomic number. For alkali metals, the DFs of transfer from diet to critical organs and the whole body seem to increase with increasing atomic number, but those from soil to diet decrease with increasing atomic number.

  18. Temporal processing characteristics of the Ponzo illusion.

    Science.gov (United States)

    Schmidt, Filipp; Haberkamp, Anke

    2016-03-01

    Many visual illusions result from assumptions of our visual system that are based on its long-term adaptation to our visual environment. Thus, visual illusions provide the opportunity to identify and learn about these fundamental assumptions. In this paper, we investigate the Ponzo illusion. Although many previous studies researched visual processing of the Ponzo illusion, only very few considered temporal processing aspects. However, it is well known that our visual percept is modulated by temporal factors. First, we used the Ponzo illusion as prime in a response priming task to test whether it modulates subsequent responses to the longer (or shorter) of two target bars. Second, we used the same stimuli in a perceptual task to test whether the Ponzo illusion is effective for very short presentation times (12 ms). We observed considerable priming effects that were of similar magnitude as those of a control condition. Moreover, the variations in the priming effects as a function of prime-target stimulus-onset asynchrony were very similar to that of the control condition. However, when analyzing priming effects as a function of participants' response speed, effects for the Ponzo illusion increased in slower responses. We conclude that although the illusion is established rapidly within the visual system, the full integration of context information is based on more time-consuming and later visual processing.

  19. "Madame Bovary": Illusion and Reality. [Lesson Plan].

    Science.gov (United States)

    Carangelo, Audrey

    Based on Gustave Flaubert's novel "Madame Bovary," this lesson plan presents activities designed to help students explore the theme of "illusion versus reality" in the novel; identify and list alternate themes in the novel; and cite specific examples of illusion versus reality from the novel. It includes objectives, materials, procedures,…

  20. [Sensory illusions in hang-gliding].

    Science.gov (United States)

    Bousquet, F; Bizeau, A; Resche-Rigon, P; Taillemite, J P; De Rotalier

    1997-01-01

    Sensory illusions in hang-gliding and para-gliding. Hang-gliding and para-gliding are at the moment booming sports. Sensory illusions are physiological phenomena sharing the wrong perception of the pilote's real position in space. These phenomena are very familiar to aeroplane pilotes, they can also be noticed on certain conditions with hang-gliding pilotes. There are many and various sensory illusions, but only illusions of vestibular origin will be dealt with in this article. Vestibular physiology is reminded with the working principle of a semicircular canal. Physiology and laws of physics explain several sensory illusions, especially when the pilote loses his visual landmarks: flying through a cloud, coriolis effect. Also some specific stages of hang-gliding foster those phenomena: spiraling downwards, self-rotation, following an asymetric closing of the parachute, spin on oneself. Therefore a previous briefing for the pilotes seems necessary.

  1. The rubber hand illusion in complex regional pain syndrome: preserved ability to integrate a rubber hand indicates intact multisensory integration.

    Science.gov (United States)

    Reinersmann, Annika; Landwehrt, Julia; Krumova, Elena K; Peterburs, Jutta; Ocklenburg, Sebastian; Güntürkün, Onur; Maier, Christoph

    2013-09-01

    In patients with complex regional pain syndrome (CRPS) type 1, processing of static tactile stimuli is impaired, whereas more complex sensory integration functions appear preserved. This study investigated higher order multisensory integration of body-relevant stimuli using the rubber hand illusion in CRPS patients. Subjective self-reports and skin conductance responses to watching the rubber hand being harmed were compared among CRPS patients (N=24), patients with upper limb pain of other origin (N=21, clinical control group), and healthy subjects (N=24). Additionally, the influence of body representation (body plasticity [Trinity Assessment of Body Plasticity], neglect-like severity symptoms), and clinical signs of illusion strength were investigated. For statistical analysis, 1-way analysis of variance, t test, Pearson correlation, with α=0.05 were used. CRPS patients did not differ from healthy subjects and the control group with regard to their illusion strength as assessed by subjective reports or skin conductance response values. Stronger left-sided rubber hand illusions were reported by healthy subjects and left-side-affected CRPS patients. Moreover, for this subgroup, illness duration and illusion strength were negatively correlated. Overall, severity of neglect-like symptoms and clinical signs were not related to illusion strength. However, patients with CRPS of the right hand reported significantly stronger neglect-like symptoms and significantly lower illusion strength of the affected hand than patients with CRPS of the left hand. The weaker illusion of CRPS patients with strong neglect-like symptoms on the affected hand supports the role of top-down processes modulating body ownership. Moreover, the intact ability to perceive illusory ownership confirms the notion that, despite impaired processing of proprioceptive or tactile input, higher order multisensory integration is unaffected in CRPS.

  2. Towards a General Equation for the Survival of Microbes Transferred between Solar System Bodies

    Science.gov (United States)

    Fries, M.; Steele, A.

    2014-01-01

    It should be possible to construct a general equation describing the survival of microbes transferred between Solar System bodies. Such an equation will be useful for constraining the likelihood of transfer of viable organisms between bodies throughout the lifetime of the Solar System, and for refining Planetary Protection constraints placed on future missions. We will discuss the construction of such an equation, present a plan for definition of pertinent factors, and will describe what research will be necessary to quantify those factors. Description: We will examine the case of microbes transferred between Solar System bodies as residents in meteorite material ejected from one body (the "intial body") and deposited on another (the "target body"). Any microbes transferred in this fashion will experience four distinct phases between their initial state on the initial body, up to the point where they colonize the target body. Each of these phases features phenomena capable of reducing or exterminating the initial microbial population. They are: 1) Ejection: Material is ejected from the initial body, imparting shock followed by rapid desiccation and cooling. 2) Transport: Material travels through interplanetary space to the target body, exposing a hypothetical microbial population to extended desiccation, irradiation, and temperature extremes. 3) Infall: Material is deposited on the target body, diminishing the microbial population through shock, mass loss, and heating. 4) Adaptation: Any microbes which survive the previous three phases must then adapt to new chemophysical conditions of the target body. Differences in habitability between the initial and target bodies dominate this phase. A suitable general-form equation can be assembled from the above factors by defining the initial number of microbes in an ejected mass and applying multiplicitive factors based on the physical phenomena inherent to each phase. It should be possible to present the resulting equation

  3. Perception, illusions and Bayesian inference.

    Science.gov (United States)

    Nour, Matthew M; Nour, Joseph M

    2015-01-01

    Descriptive psychopathology makes a distinction between veridical perception and illusory perception. In both cases a perception is tied to a sensory stimulus, but in illusions the perception is of a false object. This article re-examines this distinction in light of new work in theoretical and computational neurobiology, which views all perception as a form of Bayesian statistical inference that combines sensory signals with prior expectations. Bayesian perceptual inference can solve the 'inverse optics' problem of veridical perception and provides a biologically plausible account of a number of illusory phenomena, suggesting that veridical and illusory perceptions are generated by precisely the same inferential mechanisms.

  4. Temperature Evaluation of Heat Transferring Body while Preparing Temperature Chart of Heating Technologies and Metal Thermal Treatment

    Directory of Open Access Journals (Sweden)

    A. P. Nesenchuk

    2011-01-01

    Full Text Available The paper considers problems pertaining to temperature evaluation of a heat transferring body in the operational space of high temperature installations. A formula for evaluation of this temperature has been written down in the paper. Calculation of a heating transferring body (furnace makes it possible to realize temperature chart parameters in the plant heating technologies and steel thermal treatment.

  5. Exploring the subjective experience of the 'rubber hand' illusion

    Directory of Open Access Journals (Sweden)

    Camila eValenzuela Moguillansky

    2013-10-01

    Full Text Available Despite the fact that the rubber hand illusion (RHI is an experimental paradigm that has been widely used in the last 14 years to investigate different aspects of the sense of bodily self, very few studies have sought to investigate the subjective nature of the experience that the RHI evokes. The present study investigates the phenomenology of the RHI through a specific elicitation method. More particularly, this study aim at assessing whether the conditions usually used as control in the RHI have an impact in the sense of body ownership and at determining whether there are different stages in the emergence of the illusion. The results indicate that far from being 'all or nothing,' the illusion induced by the RHI protocol involves nuances in the type of perceptual changes that it creates. These perceptual changes affect not only the participants' perception of the rubber hand but also the perception of their real hand. In addition, perceptual effects may vary greatly between participants and, importantly, they evolve over time.

  6. Live births after polar body biopsy and frozen-thawed cleavage stage embryo transfer: case report

    OpenAIRE

    Guimar?es, Fernando; Roque,Matheus; Valle, Marcello; Kostolias, Alessandra; Azevedo, Rodrigo A de; Martinhago, Ciro D; Sampaio, Marcos; Geber,Selmo

    2016-01-01

    Pre-implantation genetic diagnosis (PGD) or screening (PGS) technology, has emerged and developed in the past few years, benefiting couples as it allows the selection and transfer of healthy embryos during IVF treatments. These techniques can be performed in oocytes (polar-body biopsy) or embryos (blastomere or trophectoderm biopsy). In this case report, we describe the first two live births to be published in Brazil after a polar-body (PB) biopsy. In case 1, a 42-year-old was submitted to PB...

  7. NUMERICAL SIMULATIONS OF A CENTERED CONDUCTING BODY ON NATURAL CONVECTION AND HEAT TRANSFER IN AN ENCLOSURE

    Institute of Scientific and Technical Information of China (English)

    LI Guang-zheng; HUANG Jian-chun

    2005-01-01

    Numerical simulations are performed for laminar natural convection heat transfer from a centered conducting body enclosed in a square cavity. A high accuracy unsteady numerical method is used, combining the unique condition of the pressure, the convergent solutions and the stream-function value of the inside heat-conducting body are given simultaneously. Two examples are simulated with this numerical method and compared with the experimental results. The results of the numerical solutions are consistent with the experimental results. It shows that the numerical method is valid and feasible.

  8. THEORETICAL STUDY OF HEAT TRANSFER ENHANCEMENT IN PIPE WITH POROUS BODY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A theoretical investigation of the fluid flow and heat transferin a pipe with porous body of high porosity twis ted by metal wire was carried out. A theoretical model of a circular pipe with porous matrix attached at the channel wall and extended inward the centerline was set up. Through ana lyzing the flow in the porous matrix by the Brinkman-extend ed-Darcy equation and through including the effect of disper sion by adding the dispersion coefficient into the energy equa tion, the theoretical solutions of velocity distribution and temperature fields were obtained. Finally the effect of the properties of the porous matrix on the flow and heat transfer in the porous body was studied, which indicates that dispersion can really enhance the heat transfer in pipe.

  9. The costs and benefits of positive illusions.

    Science.gov (United States)

    Makridakis, Spyros; Moleskis, Andreas

    2015-01-01

    Positive illusions are associated with unrealistic optimism about the future and an inflated assessment of one's abilities. They are prevalent in normal life and are considered essential for maintaining a healthy mental state, although, there are disagreements to the extent to which people demonstrate these positive illusions and whether they are beneficial or not. But whatever the situation, it is hard to dismiss their existence and their positive and/or negative influence on human behavior and decision making in general. Prominent among illusions is that of control, that is "the tendency for people to overestimate their ability to control events." This paper describes positive illusions, their potential benefits but also quantifies their costs in five specific fields (gambling, stock and other markets, new firms and startups, preventive medicine and wars). It is organized into three parts. First the psychological reasons giving rise to positive illusions are described and their likely harm and benefits stated. Second, their negative consequences are presented and their costs are quantified in five areas seriously affected with emphasis to those related to the illusion of control that seems to dominate those of unrealistic optimism. The costs involved are huge and serious efforts must be undertaken to understand their enormity and steps taken to avoid them in the future. Finally, there is a concluding section where the challenges related to positive illusions are noted and directions for future research are presented.

  10. Effects of mass addition on blunt-body boundary-layer transition and heat transfer

    Science.gov (United States)

    Kaattari, G. E.

    1978-01-01

    The model bodies tested at Mach number 7.32 were hemispheres, blunt cones, and spherical segments. The mass addition consisted of air ejected through porous forward surfaces of the models. The experimental data consisted of heat transfer measurements from which boundary layer transitions were deduced. The data verified various applicable boundary layer codes in the laminar and transitional flow regimes. Empirical heating rate data correlations were developed for the laminar and turbulent flow regimes.

  11. Exploring the factors that encourage the illusions of control: the case of preventive illusions.

    Science.gov (United States)

    Blanco, Fernando; Matute, Helena

    2015-01-01

    Most previous research on illusions of control focused on generative scenarios, in which participants' actions aim to produce a desired outcome. By contrast, the illusions that may appear in preventive scenarios, in which actions aim to prevent an undesired outcome before it occurs, are less known. In this experiment, we studied two variables that modulate generative illusions of control, the probability with which the action takes place, P(A), and the probability of the outcome, P(O), in two different scenarios: generative and preventive. We found that P(O) affects the illusion in symmetrical, opposite directions in each scenario, while P(A) is positively related to the magnitude of the illusion. Our conclusion is that, in what concerns the illusions of control, the occurrence of a desired outcome is equivalent to the nonoccurrence of an undesired outcome, which explains why the P(O) effect is reversed depending on the scenario.

  12. Optical Illusions and Effects on Clothing Design

    Directory of Open Access Journals (Sweden)

    Saliha AĞAÇ

    2015-06-01

    Full Text Available “Visual perception” is in the first ranking between the types of perception. Gestalt Theory of the major psychological theories are used in how visual perception realizes and making sense of what is effective in this process. In perception stage brain tak es into account not only stimulus from eyes but also expectations arising from previous experience and interpreted the stimulus which are not exist in the real world as if they were there. Misperception interpretations that brain revealed are called as “Pe rception Illusion” or “Optical Illusion” in psychology. Optical illusion formats come into existence due to factors such as brightness, contrast, motion, geometry and perspective, interpretation of three - dimensional images, cognitive status and color. Opti cal illusions have impacts of different disciplines within the study area on people. Among the most important types of known optical illusion are Oppel - Kundt, Curvature - Hering, Helzholtz Sqaure, Hermann Grid, Muller - Lyler, Ebbinghaus and Ponzo illusion etc . In fact, all the optical illusions are known to be used in numerous area with various techniques and different product groups like architecture, fine arts, textiles and fashion design from of old. In recent years, optical illusion types are frequently us ed especially within the field of fashion design in the clothing model, in style, silhouette and fabrics. The aim of this study is to examine the clothing design applications where optical illusion is used and works done in this subject. Some research of the design with the changing fashion of clothes of different types of optical illusions is discussed with examples of their effects on visual perception. In the study, optical illusory clothing models are scanned by visual analysis from documents like film , video, picture, web pages. The findings were analyzed in terms of the surface and design and effects of the optical illusion on clothing design has tried to put

  13. Design of optical switches by illusion optics

    Science.gov (United States)

    Shoorian, H. R.; Abrishamian, M. S.

    2013-05-01

    In this paper, illusion optics theory is employed to form Bragg gratings in an optical waveguide in order to design an optical switch. By using an illusion device at a certain distance from the waveguide, the effective refractive index of the waveguide is remotely modulated, turning the waveguide into a distributed Bragg reflector (DBR) which blocks the waves at a stop band. By removing the illusion device, the waves propagate through the waveguide again. In addition, this method is used to remotely tune DBR optical properties such as resonant frequency and bandwidth in a wide range, which leads to a tunable filter for optical switching applications. Finally, using an illusion device at a distance, an optical cavity is created by inserting defects remotely in a DBR without any physical damage in the primary device.

  14. Coral reef fish perceive lightness illusions

    Science.gov (United States)

    Simpson, Elisha E.; Marshall, N. Justin; Cheney, Karen L.

    2016-01-01

    Visual illusions occur when information from images are perceived differently from the actual physical properties of the stimulus in terms of brightness, size, colour and/or motion. Illusions are therefore important tools for sensory perception research and from an ecological perspective, relevant for visually guided animals viewing signals in heterogeneous environments. Here, we tested whether fish perceived a lightness cube illusion in which identical coloured targets appear (for humans) to return different spectral outputs depending on the apparent amount of illumination they are perceived to be under. Triggerfish (Rhinecanthus aculeatus) were trained to peck at coloured targets to receive food rewards, and were shown to experience similar shifts in colour perception when targets were placed in illusory shadows. Fish therefore appear to experience similar simultaneous contrast mechanisms to humans, even when targets are embedded in complex, scene-type illusions. Studies such as these help unlock the fundamental principles of visual system mechanisms. PMID:27748401

  15. Illusion optics in chaotic light

    Science.gov (United States)

    Zhang, Su-Heng; Gan, Shu; Xiong, Jun; Zhang, Xiangdong; Wang, Kaige

    2010-08-01

    The time-reversal process provides the possibility to counteract the time evolution of a physical system. Recent research has shown that such a process can occur in the first-order field correlation of chaotic light and result in the spatial interference and phase-reversal diffraction in an unbalanced interferometer. Here we report experimental investigations on the invisibility cloak and illusion phenomena in chaotic light. In an unbalanced interferometer illuminated by thermal light, we have observed the cloak effect and the optical transformation of one object into another object. The experimental results can be understood by the phase-reversal diffraction, and they demonstrate the theoretical proposal of similar effects in complementary media.

  16. Antigravity hills are visual illusions.

    Science.gov (United States)

    Bressan, Paola; Garlaschelli, Luigi; Barracano, Monica

    2003-09-01

    Antigravity hills, also known as spook hills or magnetic hills, are natural places where cars put into neutral are seen to move uphill on a slightly sloping road, apparently defying the law of gravity. We show that these effects, popularly attributed to gravitational anomalies, are in fact visual illusions. We re-created all the known types of antigravity spots in our laboratory using tabletop models; the number of visible stretches of road, their slant, and the height of the visible horizon were systematically varied in four experiments. We conclude that antigravity-hill effects follow from a misperception of the eye level relative to gravity, caused by the presence of either contextual inclines or a false horizon line.

  17. [Perceived quality: illusion or perception].

    Science.gov (United States)

    Cárcamo, C R

    2011-01-01

    Patients as human beings determined by their structure cannot, while having an experience, distinguish between an illusion and reality, therefore they experience the different domains of existence and the different domains of reality. For them, the perception of service quality is experienced as a personal domain of reality, and this reality is a personal construction, generating as many realities as patients perceiving their experience with elements of their experience, whose distinctions that validate it are not necessarily shared or agreed. Health management must abandon the idea in that it is possible to build an objective quality service, to be able to make progress in building effective communication strategies and common consensus criteria for a quality service of distinction, in order to achieve effective satisfaction and patient loyalty.

  18. Creating illusion in computer aided performance

    OpenAIRE

    Marshall, Joe

    2009-01-01

    This thesis studies the creation of illusion in computer aided performance. Illusion is created here by using deceptions, and a design framework is presented which suggests several different deception strategies which may be useful. The framework has been developed in an iterative process in tandem with the development of 3 real world performances which were used to explore deception strategies. The first case study presents a system for augmenting juggling performance. The techniques tha...

  19. Elevator Illusion and Gaze Direction in Hypergravity

    Science.gov (United States)

    Cohen, Malcolm M.; Hargens, Alan (Technical Monitor)

    1995-01-01

    A luminous visual target in a dark hypergravity (Gz greater than 1) environment appears to be elevated above its true physical position. This "elevator illusion" has been attributed to changes in oculomotor control caused by increased stimulation of the otolith organs. Data relating the magnitude of the illusion to the magnitude of the changes in oculomotor control have been lacking. The present study provides such data.

  20. The Onset Time of the Ownership Sensation in the Moving Rubber Hand Illusion

    Science.gov (United States)

    Kalckert, Andreas; Ehrsson, H. H.

    2017-01-01

    The rubber hand illusion (RHI) is a perceptual illusion whereby a model hand is perceived as part of one’s own body. This illusion has been extensively studied, but little is known about the temporal evolution of this perceptual phenomenon, i.e., how long it takes until participants start to experience ownership over the model hand. In the present study, we investigated a version of the rubber hand experiment based on finger movements and measured the average onset time in active and passive movement conditions. This comparison enabled us to further explore the possible role of intentions and motor control processes that are only present in the active movement condition. The results from a large group of healthy participants (n = 117) showed that the illusion of ownership took approximately 23 s to emerge (active: 22.8; passive: 23.2). The 90th percentile occurs in both conditions within approximately 50 s (active: 50; passive: 50.6); therefore, most participants experience the illusion within the first minute. We found indirect evidence of a facilitatory effect of active movements compared to passive movements, and we discuss these results in the context of our current understanding of the processes underlying the moving RHI. PMID:28344566

  1. The tilt illusion: phenomenology and functional implications.

    Science.gov (United States)

    Clifford, Colin W G

    2014-11-01

    The perceived orientation of a line or grating is affected by the orientation structure of the surrounding image: the tilt illusion. Here, I offer a selective review of the literature on the tilt illusion, focusing on functional aspects. The review explores the merits of mechanistic accounts of the tilt illusion based upon sensory gain control in which neuronal responses are normalized by the pooled activity of other units. The role of inhibition between orientation-selective neurons is discussed, and it is argued that their associated disinhibition must also be taken into account in order to model the full angular dependence of the tilt illusion on surround orientation. Parallels are drawn with adaptation as modulation by the temporal rather than spatial context within which an image fragment is processed. The chromatic selectivity of the tilt illusion and the extent of its dependence on the visibility of the surround are used to infer characteristics of the neuronal normalization pools and the loci in the cortical processing hierarchy at which gain control operates. Finally, recent evidence is discussed as to the possible clinical relevance of the tilt illusion as a biomarker for schizophrenia.

  2. The time constant of the somatogravic illusion.

    Science.gov (United States)

    Correia Grácio, B J; de Winkel, K N; Groen, E L; Wentink, M; Bos, J E

    2013-02-01

    Without visual feedback, humans perceive tilt when experiencing a sustained linear acceleration. This tilt illusion is commonly referred to as the somatogravic illusion. Although the physiological basis of the illusion seems to be well understood, the dynamic behavior is still subject to discussion. In this study, the dynamic behavior of the illusion was measured experimentally for three motion profiles with different frequency content. Subjects were exposed to pure centripetal accelerations in the lateral direction and were asked to indicate their tilt percept by means of a joystick. Variable-radius centrifugation during constant angular rotation was used to generate these motion profiles. Two self-motion perception models were fitted to the experimental data and were used to obtain the time constant of the somatogravic illusion. Results showed that the time constant of the somatogravic illusion was on the order of two seconds, in contrast to the higher time constant found in fixed-radius centrifugation studies. Furthermore, the time constant was significantly affected by the frequency content of the motion profiles. Motion profiles with higher frequency content revealed shorter time constants which cannot be explained by self-motion perception models that assume a fixed time constant. Therefore, these models need to be improved with a mechanism that deals with this variable time constant. Apart from the fundamental importance, these results also have practical consequences for the simulation of sustained accelerations in motion simulators.

  3. Spatial disorientation: more than just illusion.

    Science.gov (United States)

    Cheung, Bob

    2013-11-01

    Despite aggressive efforts in spatial disorientation (SD) research, hardware development, and training, the operational impact of SD in terms of crew and aircraft losses remains significant. Current training in spatial orientation is primarily composed of didactic lectures on the anatomy and physiology of the sensory systems. Significant efforts have been concentrated on reproducing various types of visual and vestibular "illusions" that pilots might encounter in flight, with limited and varying success. Unfortunately, the terms of "SD" and "illusion" have been used synonymously, leading to the general belief that if one were to be exposed to a specific type of illusion, one can prevent or avoid SD mishaps. Another setback is the inability of ground-based devices to reproduce the flight envelope. Often the demonstration of a specific illusion ends abruptly without further explanation or how these illusions can affect pilot performance. Demonstration of illusions seldom deals with the precipitating factors. We should provide pilots with skills to anticipate and assess the risk of SD during mission planning. Pilots should be sensitized to the physical and mental performance decrement during sensory conflicts and inadequacies. Recommendations should also be made on possible ways to recover from SD should they become disoriented. Special attention should be drawn to the properties of various flight displays that may contribute to SD. G tolerance and disorientation should be examined together in high performance aircraft as there is a close relationship between exposure to acceleration and maintaining orientation. The motto for counteracting SD is: anticipate, avoid, and counteract SD.

  4. Low-Thrust Orbital Transfers in the Two-Body Problem

    Directory of Open Access Journals (Sweden)

    A. A. Sukhanov

    2012-01-01

    Full Text Available Low-thrust transfers between given orbits within the two-body problem are considered; the thrust is assumed power limited. A simple method for obtaining the transfer trajectories based on the linearization of the motion near reference orbits is suggested. Required calculation accuracy can be reached by means of use of a proper number of the reference orbits. The method may be used in the case of a large number of the orbits around the attracting center; no averaging is necessary in this case. The suggested method also is applicable to the cases of partly given final orbit and if there are constraints on the thrust direction. The method gives an optimal solution to the linearized problem which is not optimal for the original nonlinear problem; the difference between the optimal solutions to the original and linearized problems is estimated using a numerical example. Also examples illustrating the method capacities are given.

  5. Cloaks and antiobject-independent illusion optics based on illusion media

    Science.gov (United States)

    Li, Zhou; Zang, XiaoFei; Cai, Bin; Shi, Cheng; Zhu, YiMing

    2013-11-01

    Based on the transformation optics, we propose a new strategy of illusion media consisting of homogeneous and anisotropic materials. By utilizing the illusion media, invisible cloak is theoretically realized, in which objects covered with the illusion media could not be detected. The cloak here allows neither the propagation of light around the concealed region nor compensates the scattering field of object outside the media. What the cloak does is to shift the region into another place where outside the trace of light, so that objects in that region can disappear. Another application of the illusion media is to create the antiobject-independent illusion optics which means that two objects appear to be like some other objects of our choice. Finite element simulations for two-dimensional cases have been performed to prove these ideas.

  6. Tissue Liquefaction Liposuction for Body Contouring and Autologous Fat Transfer: A Retrospective Review Over 3 Years

    Science.gov (United States)

    Godek, Christopher P.

    2016-01-01

    Objective: Tissue liquefaction lipoplasty is a novel, low-energy method cleared for use in aesthetic body contouring and autologous fat transfer. This is a retrospective review of the clinical effectiveness and safety of a liquefaction lipoplasty system for liposuction and autologous fat transfer. Methods: A retrospective review was done evaluating all liquefaction lipoplasty procedures with or without autologous fat transfer performed by a single surgeon (March 2013 to June 2016). Patient demographics, operative details, and any complications were tabulated from patient charts. A typical case reported is presented with pre-/postoperative photographs. Results: Two hundred fifty-five consecutive liquefaction lipoplasty procedures were performed over 39 months. The average lipoaspirate volume was 1208 ± 991 mL and the average fat graft volume was 322 ± 277 mL. The overall complication rate was 9 of 255 (3.52%). There were 2 episodes of seroma (0.78%) that were aspirated and 2 episodes of cellulitis (0.78%) that responded to oral antibiotics. In the autologous fat transfer cohort, there were 5 of 103 (4.85%) cases of mild to moderate fat necrosis, with 1 patient requiring return to the operating room for removal of an oil cyst. No revisions of donor sites were required. Conclusions: Liquefaction lipoplasty appears safe for liposuction and autologous fat transfer, with a complication profile that is comparable with other widely used forms of suction-assisted liposuction. The liquefaction lipoplasty technology also provides potential time savings in the operating room that can minimize surgeon fatigue when harvesting large volumes of high-quality fat. Liquefaction lipoplasty appears to have advantages for both the patient and the surgeon, and further studies are underway. PMID:28077985

  7. Three-Body Model Calculation of Spin Distribution in Two-Nucleon Transfer Reaction

    CERN Document Server

    Ogata, Kazuyuki; Chiba, Satoshi

    2011-01-01

    The differential cross sections of two-nucleon transfer reactions 238U(18O,16O)240U around 10 MeV per nucleon are calculated by one-step Born-approximation with a 16O+2n+238U three-body model. The three-body wave function in the initial channel is obtained with the continuum-discretized coupled-channels method, and that in the final channel is evaluated with adiabatic approximation. The resulting cross sections have a peak around the grazing angle, and the spin distribution, i.e., the cross section at the peak as a function of the transferred spin, is investigated. The shape of the spin distribution is found not sensitive to the incident energies, optical potentials, and treatment of the breakup channels both in the initial and final states, while it depends on the excitation energy of the residual nucleus 240U. The peak of the spin distribution moves to the large-spin direction as the excitation energy increases. To fulfill the condition that the peak position should not exceeds 10 hbar, which is necessary f...

  8. Rich Pinch: Perception of Object Movement with Tactile Illusion.

    Science.gov (United States)

    Lee, Jaedong; Kim, Youngsun; Kim, Gerard

    2015-09-01

    Vibrotactile feedback is an effective and economical approach for enriching interactive feedback. However, its effects are mostly limited to providing supplementary alarms or conveying the sense of simple object presence or contact. In this paper, we propose a novel tactile feedback method, called Rich Pinch, based on the "out of body" tactile illusion for selecting and manipulating a virtual object using a two-finger pinch gesture. Rich Pinch uses vibration motors attached only to the two fingertips, but can induce illusory feedback, such as tactile touch/contact and directional movement, as felt from the space between the fingers. We first experimentally verify that the "out of body" illusion technique does in fact exist when applied between the fingertips. Then we compare three different tactile rendering functions to illustrate different resulting perceptual scales and argue to use the tangent-based interpolation in its actual application for a better user performance and experience due to its near-linear perceptual response. Finally, we assess the user experience (focusing on the perception of the object movement of the selected object) of the proposed pinch method by comparing it to the conventional contact-based method. Our results indicate that, with Rich Pinch, users were able to perceive rich dynamic feedback, and clearly preferred it over the conventional method.

  9. The Application of the Optical Illusion Principle in Clothing Design%视错觉原理在女装款式设计中的应用

    Institute of Scientific and Technical Information of China (English)

    许平山; 宿伟

    2015-01-01

    The principle of optical illusion is applied in designing the clothing to perfect the body defects, which plays an important role in the design of special individuals. This paper, based on the principle of optical illusion and the specific examples of dress design, mainly researches the application relationship between the principle of optical illusion and clothing design. Besides, it discusses the influence of shape illusion, the division illusion, the comparison illusion on the styles of human body dressing in order to explore the feasible way to connecting the principle of optical illusion with the real situation of dressing.%利用视错觉原理设计的服装能有效修正人体的体型缺陷,对个性化人群的服装设计起到了十分重要的作用. 以视错觉原理为依据,以款式设计实例为手段,探索视错觉原理与款式设计之间的应用关系,重点探讨了形状视错、分割视错、对比视错对人体着装款式设计的影响,提出把视错觉理论与着装实际相结合的可行性的策略.

  10. A gestalt account of lightness illusions.

    Science.gov (United States)

    Gilchrist, Alan

    2014-01-01

    Illusions of lightness offer valuable clues to how lightness values are computed by the visual system. The traditional domain of lightness illusions must be expanded to include failures of constancy, as there is no distinction between these categories. Just as lightness is (relatively) constant in the face of changes in illumination level, so it is equally constant in the face of changes in background reflectance. Simultaneous lightness contrast, the most familiar lightness illusion, is fairly weak, and represents a failure of background-independent lightness constancy. It is argued that a combination of the highest-luminance rule of anchoring plus the Kardos idea of codetermination can account for most lightness illusions. Kardos suggested that the lightness value of a target surface is partly determined relative to the field of illumination (or framework) in which it is embedded, and partly relative to the neighboring field of illumination. Although Kardos did not apply his principle of codetermination to failures of background-independent constancy such as the simultaneous contrast illusion, this can be done rather easily by defining a framework as a perceptual group instead of identifying it strictly with an objective field of illumination.

  11. Geometric-optical illusions at isoluminance.

    Science.gov (United States)

    Hamburger, Kai; Hansen, Thorsten; Gegenfurtner, Karl R

    2007-12-01

    The idea of a largely segregated processing of color and form was initially supported by observations that geometric-optical illusions vanish under isoluminance. However, this finding is inconsistent with some psychophysical studies and also with physiological evidence showing that color and luminance are processed together by largely overlapping sets of neurons in the LGN, in V1, and in extrastriate areas. Here we examined the strength of nine geometric-optical illusions under isoluminance (Delboeuf, Ebbinghaus, Hering, Judd, Müller-Lyer, Poggendorff, Ponzo, Vertical, Zöllner). Subjects interactively manipulated computer-generated line drawings to counteract the illusory effect. In all cases, illusions presented under isoluminance (both for colors drawn from the cardinal L-M or S-(L+M) directions of DKL color space) were as effective as the luminance versions (both for high and low contrast). The magnitudes of the illusion effects were highly correlated across subjects for the different conditions. In two additional experiments we determined that the strong illusions observed under isoluminance were not due to individual deviations from the photometric point of isoluminance or due to chromatic aberrations. Our findings show that our conscious percept is affected similarly for both isoluminance and luminance conditions, suggesting that the joint processing for chromatic and luminance defined contours may extend well beyond early visual areas.

  12. Illusions and Cloaks for Surface Waves

    Science.gov (United States)

    McManus, T. M.; Valiente-Kroon, J. A.; Horsley, S. A. R.; Hao, Y.

    2014-08-01

    Ever since the inception of Transformation Optics (TO), new and exciting ideas have been proposed in the field of electromagnetics and the theory has been modified to work in such fields as acoustics and thermodynamics. The most well-known application of this theory is to cloaking, but another equally intriguing application of TO is the idea of an illusion device. Here, we propose a general method to transform electromagnetic waves between two arbitrary surfaces. This allows a flat surface to reproduce the scattering behaviour of a curved surface and vice versa, thereby giving rise to perfect optical illusion and cloaking devices, respectively. The performance of the proposed devices is simulated using thin effective media with engineered material properties. The scattering of the curved surface is shown to be reproduced by its flat analogue (for illusions) and vice versa for cloaks.

  13. Homo Novus - A Human Without Illusions

    CERN Document Server

    Frey, Ulrich J; Willführ, Kai P

    2010-01-01

    Converging evidence from disciplines including sociobiology, evolutionary psychology and human biology forces us to adopt a new idea of what it means to be a human. As cherished concepts such as free will, naïve realism, humans as creation's crowning glory fall and our moral roots in ape group dynamics become clearer, we have to take leave of many concepts that have been central to defining our humanness. What emerges is a new human, the homo novus, a human being without illusions. Leading authors from many different fields explore these issues by addressing these illusions and providing evidence for the need to switch to this new idea of man, in spite of understandable reluctance to let go of our most beloved illusions.

  14. Illusion of Control in a Brownian Game

    CERN Document Server

    Satinover, J B

    2007-01-01

    Both single-player Parrondo games (SPPG) and multi-player Parrondo games (MPPG) display the Parrondo Effect (PE) wherein two or more individually fair (or Llosing) games yield a net winning outcome if alternated periodically or randomly. (There is a more formal, less restrictive definition of the PE.) We illustrate that, when subject to an elementary optimization rule, the PG displays degraded rather than enhanced returns. Optimization provides only the illusion of control, when low-entropy strategies (i.e. which use more information) under-perform random strategies (with maximal entropy). This illusion is unfortuntately widespread in many human attempts to manage or predict complex systems. For the PG, the illusion is especially striking in that the optimization rule reverses an already paradoxical-seeming positive gain - the Parrondo effect proper - and turns it negative. While this phenomenon has been previously demonstrated using somewhat artificial conditions in the MPPG (L. Dinios and J.M.R. Parrondo. E...

  15. Model of Illusions and Virtual Reality.

    Science.gov (United States)

    Gonzalez-Franco, Mar; Lanier, Jaron

    2017-01-01

    In Virtual Reality (VR) it is possible to induce illusions in which users report and behave as if they have entered into altered situations and identities. The effect can be robust enough for participants to respond "realistically," meaning behaviors are altered as if subjects had been exposed to the scenarios in reality. The circumstances in which such VR illusions take place were first introduced in the 80's. Since then, rigorous empirical evidence has explored a wide set of illusory experiences in VR. Here, we compile this research and propose a neuroscientific model explaining the underlying perceptual and cognitive mechanisms that enable illusions in VR. Furthermore, we describe the minimum instrumentation requirements to support illusory experiences in VR, and discuss the importance and shortcomings of the generic model.

  16. Teaching Mathematics Understandings for Transfer

    Science.gov (United States)

    Jones, Jennifer L.; Jones, Karrie A.; Vermette, Paul J.

    2009-01-01

    Promoting student understanding for transfer is an illusive hallmark of effective mathematics instruction. While much research has shown the necessity of promoting understanding for transfer, less attention has been paid to actual pedagogical strategies that can be used to promote transfer of mathematical ideas. Using Fogarty et al. (1992, "How to…

  17. Charge-Transfer Excited States in Aqueous DNA: Insights from Many-Body Green's Function Theory

    Science.gov (United States)

    Yin, Huabing; Ma, Yuchen; Mu, Jinglin; Liu, Chengbu; Rohlfing, Michael

    2014-06-01

    Charge-transfer (CT) excited states play an important role in the excited-state dynamics of DNA in aqueous solution. However, there is still much controversy on their energies. By ab initio many-body Green's function theory, together with classical molecular dynamics simulations, we confirm the existence of CT states at the lower energy side of the optical absorption maximum in aqueous DNA as observed in experiments. We find that the hydration shell can exert strong effects (˜1 eV) on both the electronic structure and CT states of DNA molecules through dipole electric fields. In this case, the solvent cannot be simply regarded as a macroscopic screening medium as usual. The influence of base stacking and base pairing on the CT states is also discussed.

  18. Intermolecular Singlet and Triplet Exciton Transfer Integrals from Many-Body Green's Functions Theory.

    Science.gov (United States)

    Wehner, Jens; Baumeier, Björn

    2017-03-08

    A general approach to determine orientation and distance-dependent effective intermolecular exciton transfer integrals from many-body Green's functions theory is presented. On the basis of the GW approximation and the Bethe-Salpeter equation (BSE), a projection technique is employed to obtain the excitonic coupling by forming the expectation value of a supramolecular BSE Hamiltonian with electron-hole wave functions for excitations localized on two separated chromophores. Within this approach, accounting for the effects of coupling mediated by intermolecular charge transfer (CT) excitations is possible via perturbation theory or a reduction technique. Application to model configurations of pyrene dimers shows an accurate description of short-range exchange and long-range Coulomb interactions for the coupling of singlet and triplet excitons. Computational parameters, such as the choice of the exchange-correlation functional in the density-functional theory (DFT) calculations that underly the GW-BSE steps and the convergence with the number of included CT excitations, are scrutinized. Finally, an optimal strategy is derived for simulations of full large-scale morphologies by benchmarking various approximations using pairs of dicyanovinyl end-capped oligothiophenes (DCV5T), which are used as donor material in state-of-the-art organic solar cells.

  19. Impulse waves generated by snow avalanches: Momentum and energy transfer to a water body

    Science.gov (United States)

    Zitti, Gianluca; Ancey, Christophe; Postacchini, Matteo; Brocchini, Maurizio

    2016-12-01

    When a snow avalanche enters a body of water, it creates an impulse wave whose effects may be catastrophic. Assessing the risk posed by such events requires estimates of the wave's features. Empirical equations have been developed for this purpose in the context of landslides and rock avalanches. Despite the density difference between snow and rock, these equations are also used in avalanche protection engineering. We developed a theoretical model which describes the momentum transfers between the particle and water phases of such events. Scaling analysis showed that these momentum transfers were controlled by a number of dimensionless parameters. Approximate solutions could be worked out by aggregating the dimensionless numbers into a single dimensionless group, which then made it possible to reduce the system's degree of freedom. We carried out experiments that mimicked a snow avalanche striking a reservoir. A lightweight granular material was used as a substitute for snow. The setup was devised so as to satisfy the Froude similarity criterion between the real-world and laboratory scenarios. Our experiments in a water channel showed that the numerical solutions underestimated wave amplitude by a factor of 2 on average. We also compared our experimental data with those obtained by Heller and Hager (2010), who used the same relative particle density as in our runs, but at higher slide Froude numbers.

  20. Spectrum of Quantum Transfer Matrices via Classical Many-Body Systems

    CERN Document Server

    Gorsky, A; Zotov, A

    2014-01-01

    In this paper we clarify the relationship between inhomogeneous quantum spin chains and classical integrable many-body systems. It provides an alternative (to the nested Bethe ansatz) method for computation of spectra of the spin chains. Namely, the spectrum of the quantum transfer matrix for the inhomogeneous ${\\mathfrak g}{\\mathfrak l}_n$-invariant XXX spin chain on $N$ sites with twisted boundary conditions can be found in terms of velocities of particles in the rational $N$-body Ruijsenaars-Schneider model. The possible values of the velocities are to be found from intersection points of two Lagrangian submanifolds in the phase space of the classical model. One of them is the Lagrangian hyperplane corresponding to fixed coordinates of all $N$ particles and the other one is an $N$-dimensional Lagrangian submanifold obtained by fixing levels of $N$ classical Hamiltonians in involution. The latter are determined by eigenvalues of the twist matrix. To support this picture, we give a direct proof that the eige...

  1. An advanced computational bioheat transfer model for a human body with an embedded systemic circulation.

    Science.gov (United States)

    Coccarelli, Alberto; Boileau, Etienne; Parthimos, Dimitris; Nithiarasu, Perumal

    2016-10-01

    In the present work, an elaborate one-dimensional thermofluid model for a human body is presented. By contrast to the existing pure conduction-/perfusion-based models, the proposed methodology couples the arterial fluid dynamics of a human body with a multi-segmental bioheat model of surrounding solid tissues. In the present configuration, arterial flow is included through a network of elastic vessels. More than a dozen solid segments are employed to represent the heat conduction in the surrounding tissues, and each segment is constituted by a multilayered circular cylinder. Such multi-layers allow flexible delineation of the geometry and incorporation of properties of different tissue types. The coupling of solid tissue and fluid models requires subdivision of the arterial circulation into large and small arteries. The heat exchange between tissues and arterial wall occurs by convection in large vessels and by perfusion in small arteries. The core region, including the heart, provides the inlet conditions for the fluid equations. In the proposed model, shivering, sweating, and perfusion changes constitute the basis of the thermoregulatory system. The equations governing flow and heat transfer in the circulatory system are solved using a locally conservative Galerkin approach, and the heat conduction in the surrounding tissues is solved using a standard implicit backward Euler method. To investigate the effectiveness of the proposed model, temperature field evolutions are monitored at different points of the arterial tree and in the surrounding tissue layers. To study the differences due to flow-induced convection effects on thermal balance, the results of the current model are compared against those of the widely used modelling methodologies. The results show that the convection significantly influences the temperature distribution of the solid tissues in the vicinity of the arteries. Thus, the inner convection has a more predominant role in the human body heat

  2. Applying the Helmholtz Illusion to Fashion: Horizontal Stripes Won't Make You Look Fatter

    Directory of Open Access Journals (Sweden)

    Peter Thompson

    2011-01-01

    Full Text Available A square composed of horizontal lines appears taller and narrower than an identical square made up of vertical lines. Reporting this illusion, Hermann von Helmholtz noted that such illusions, in which filled space seems to be larger than unfilled space, were common in everyday life, adding the observation that ladies' frocks with horizontal stripes make the figure look taller. As this assertion runs counter to modern popular belief, we have investigated whether vertical or horizontal stripes on clothing should make the wearer appear taller or fatter. We find that a rectangle of vertical stripes needs to be extended by 7.1% vertically to match the height of a square of horizontal stripes and that a rectangle of horizontal stripes must be made 4.5% wider than a square of vertical stripes to match its perceived width. This illusion holds when the horizontal or vertical lines are on the dress of a line drawing of a woman. We have examined the claim that these effects apply only for 2-dimensional figures in an experiment with 3-D cylinders and find no support for the notion that horizontal lines would be ‘fattening’ on clothes. Significantly, the illusion persists when the horizontal or vertical lines are on pictures of a real half-body mannequin viewed stereoscopically. All the evidence supports Helmholtz's original assertion.

  3. Illusory Tactile Motion Perception: An Analog of the Visual Filehne Illusion.

    Science.gov (United States)

    Moscatelli, Alessandro; Hayward, Vincent; Wexler, Mark; Ernst, Marc O

    2015-09-28

    We continually move our body and our eyes when exploring the world, causing our sensory surfaces, the skin and the retina, to move relative to external objects. In order to estimate object motion consistently, an ideal observer would transform estimates of motion acquired from the sensory surface into fixed, world-centered estimates, by taking the motion of the sensor into account. This ability is referred to as spatial constancy. Human vision does not follow this rule strictly and is therefore subject to perceptual illusions during eye movements, where immobile objects can appear to move. Here, we investigated whether one of these, the Filehne illusion, had a counterpart in touch. To this end, observers estimated the movement of a surface from tactile slip, with a moving or with a stationary finger. We found the perceived movement of the surface to be biased if the surface was sensed while moving. This effect exemplifies a failure of spatial constancy that is similar to the Filehne illusion in vision. We quantified this illusion by using a Bayesian model with a prior for stationarity, applied previously in vision. The analogy between vision and touch points to a modality-independent solution to the spatial constancy problem.

  4. Symbol recognition produced by points of tactile stimulation: the illusion of linear continuity.

    Science.gov (United States)

    Gonzales, G R

    1996-11-01

    To determine whether tactile receptive communication is possible through the use of a mechanical device that produces the phi phenomenon on the body surface. Twenty-six subjects (11 blind and 15 sighted participants) were tested with use of a tactile communication device (TCD) that produces an illusion of linear continuity forming numbers on the dorsal aspect of the wrist. Recognition of a number or number set was the goal. A TCD with protruding and vibrating solenoids produced sequentially delivered points of cutaneous stimulation along a pattern resembling numbers and created the illusion of dragging a vibrating stylet to form numbers, similar to what might be felt by testing for graphesthesia. Blind subjects recognized numbers with fewer trials than did sighted subjects, although all subjects were able to recognize all the numbers produced by the TCD. Subjects who had been blind since birth and had no prior tactile exposure to numbers were able to draw the numbers after experiencing them delivered by the TCD even though they did not recognize their meaning. The phi phenomenon is probably responsible for the illusion of continuous lines in the shape of numbers as produced by the TCD. This tactile illusion could potentially be used for more complex tactile communications such as letters and words.

  5. Applying the Helmholtz illusion to fashion: horizontal stripes won't make you look fatter.

    Science.gov (United States)

    Thompson, Peter; Mikellidou, Kyriaki

    2011-01-01

    A square composed of horizontal lines appears taller and narrower than an identical square made up of vertical lines. Reporting this illusion, Hermann von Helmholtz noted that such illusions, in which filled space seems to be larger than unfilled space, were common in everyday life, adding the observation that ladies' frocks with horizontal stripes make the figure look taller. As this assertion runs counter to modern popular belief, we have investigated whether vertical or horizontal stripes on clothing should make the wearer appear taller or fatter. We find that a rectangle of vertical stripes needs to be extended by 7.1% vertically to match the height of a square of horizontal stripes and that a rectangle of horizontal stripes must be made 4.5% wider than a square of vertical stripes to match its perceived width. This illusion holds when the horizontal or vertical lines are on the dress of a line drawing of a woman. We have examined the claim that these effects apply only for 2-dimensional figures in an experiment with 3-D cylinders and find no support for the notion that horizontal lines would be 'fattening' on clothes. Significantly, the illusion persists when the horizontal or vertical lines are on pictures of a real half-body mannequin viewed stereoscopically. All the evidence supports Helmholtz's original assertion.

  6. When is fiscal adjustment an illusion?

    NARCIS (Netherlands)

    Easterly, W; de Haan, J; Gali, G

    1999-01-01

    Fiscal adjustment is an illusion when it lowers the budget deficit or public debt but leaves government net worth unchanged. Conventional measures of the budget deficit largely show the change in public sector debt. Ideally, the measured deficit would reflect the change in Public sector net worth. M

  7. What visual illusions teach us about schizophrenia

    Directory of Open Access Journals (Sweden)

    Charles-Edouard eNotredame

    2014-08-01

    Full Text Available Illusion, namely a mismatch between the objective and perceived properties of an object present in the environment, is a common feature of visual perception, both in normal and pathological conditions. This makes illusion a valuable tool with which to explore normal perception and its impairments. Although still debated, the hypothesis of a modified, and typically diminished, susceptibility to illusions in schizophrenia patients is supported by a growing number of studies. The current paper aimed to review how illusions have been used to explore and reveal the core features of visual perception in schizophrenia from a psychophysical, neurophysiological and functional point of view. We propose an integration of these findings into a common hierarchical Bayesian inference framework. The Bayesian formalism considers perception as the optimal combination between sensory evidence and prior knowledge, thereby highlighting the interweaving of perceptions and beliefs. Notably, it offers a holistic and convincing explanation for the perceptual changes observed in schizophrenia that might be ideally tested using illusory paradigms, as well as potential paths to explore neural mechanisms. Implications for psychopathology (in terms of positive symptoms, subjective experience or behavior disruptions are critically discussed.

  8. Identity and Violence: The Illusion of Destiny

    Directory of Open Access Journals (Sweden)

    Prem Bahadur Chalaune

    2011-04-01

    Full Text Available Amartya Sen, (2006. Identity and Violence: The Illusion of Destiny. London: Penguin Books.( pp 215 Price: £ 14.99DOI: 10.3126/dsaj.v4i0.4525 Dhaulagiri Journal of Sociology and Anthropology Vol.4 2010 pp.261-268

  9. Positive illusions about one's partner's physical attractiveness

    NARCIS (Netherlands)

    Barelds-Dijkstra, Pieternel; Barelds, Dick P. H.

    2008-01-01

    This study examined couples' ratings of self and partner physical attractiveness. On the basis of the theory of positive illusions, it was expected that individuals would rate their partners as more attractive than their partners would rate themselves. Both members of 93 heterosexual couples, with a

  10. Positive illusions about one's partner's physical attractiveness

    NARCIS (Netherlands)

    Barelds-Dijkstra, Pieternel; Barelds, Dick P. H.

    2008-01-01

    This study examined couples' ratings of self and partner physical attractiveness. On the basis of the theory of positive illusions, it was expected that individuals would rate their partners as more attractive than their partners would rate themselves. Both members of 93 heterosexual couples, with a

  11. Learning with Animation and Illusions of Understanding

    Science.gov (United States)

    Paik, Eugene S.; Schraw, Gregory

    2013-01-01

    The illusion of understanding hypothesis asserts that, when people are learning with multimedia presentations, the addition of animation can affect metacognitive monitoring such that they perceive the presentation to be easier to understand and develop more optimistic metacomprehension. As a result, learners invest less cognitive effort when…

  12. Positive illusions about one's partner's physical attractiveness

    NARCIS (Netherlands)

    Barelds-Dijkstra, Pieternel; Barelds, Dick P. H.

    This study examined couples' ratings of self and partner physical attractiveness. On the basis of the theory of positive illusions, it was expected that individuals would rate their partners as more attractive than their partners would rate themselves. Both members of 93 heterosexual couples, with a

  13. When is fiscal adjustment an illusion?

    NARCIS (Netherlands)

    Easterly, W; de Haan, J; Gali, G

    Fiscal adjustment is an illusion when it lowers the budget deficit or public debt but leaves government net worth unchanged. Conventional measures of the budget deficit largely show the change in public sector debt. Ideally, the measured deficit would reflect the change in Public sector net worth.

  14. Development of the False-Memory Illusion

    Science.gov (United States)

    Brainerd, C. J.; Forrest, T. J.; Karibian, D.; Reyna, V. F.

    2006-01-01

    The counterintuitive developmental trend in the Deese-Roediger-McDermott (DRM) illusion (that false-memory responses increase with age) was investigated in learning-disabled and nondisabled children from the 6- to 14-year-old age range. Fuzzy-trace theory predicts that because there are qualitative differences in how younger versus older children…

  15. Learning with Animation and Illusions of Understanding

    Science.gov (United States)

    Paik, Eugene S.; Schraw, Gregory

    2013-01-01

    The illusion of understanding hypothesis asserts that, when people are learning with multimedia presentations, the addition of animation can affect metacognitive monitoring such that they perceive the presentation to be easier to understand and develop more optimistic metacomprehension. As a result, learners invest less cognitive effort when…

  16. Multisensory Illusions and the Temporal Binding Window

    Directory of Open Access Journals (Sweden)

    Ryan A Stevenson

    2011-10-01

    Full Text Available The ability of our sensory systems to merge sensory information from distinct modalities is remarkable. One stimulus characteristic utilized in this operation is temporal coincidence. Auditory and visual information are integrated within a narrow range of temporal offsets, known as the temporal binding window (TBW, which varies between individuals, stimulus type, and task. In this series of experiments, we assessed the relationship within individuals between the width of their TBW and their ability to integrate audiovisual information. The TBW was measured through a perceived subjective simultaneity task. In conjunction with this, we measured each individual's ability to integrate auditory and visual information with two multisensory illusions, the McGurk effect and Flashbeep illusion. The results from these studies demonstrate that the TBW is highly correlated with the individual's ability to integrate. These relationships were seen in only the right TBW, in which visual presentations preceded auditory presentations, a finding that is ecologically logical. However, differences were seen between the two illusory conditions, where the McGurk effect was stronger in individuals with narrow TBWs, again, an ecologically logical finding. The opposite relationship was seen with flashbeep illusion, possibly due to inherent asynchronies in the illusion.

  17. [Workaholism: between illusion and addiction].

    Science.gov (United States)

    Elowe, J

    2010-09-01

    Workaholism surfaced some years ago as a veritable addiction in the wide sense of the term, dependence. It differs from other sorts of dependence in that it is very often viewed in a positive perspective in the sense that it conveys to the person concerned the illusion of well-being, as well as a motivation and dedication in their professional activity. During the past 30 years, several authors have attempted to define this concept and to determine its characteristics. Robinson believes that workaholics have an approach to life whereby their work feeds on time, energy and physical activity. This provokes consequences that affect their physical health and interpersonal relationships. They have a tendency to live in the future rather than in the present. For Scott, Moore and Micelli , the compulsion for work is not necessarily viewed as being detrimental to one's health. Spence and Robbins highlight the notion of the pleasure experienced at work in their theoretical approach. The prevalence of the dependence on work is estimated at between 27 and 30% in the general population. It is correlated to the number of hours of work per week and tends to be higher as annual revenue increases. The sex ratio is 1, and the parents of children 5 to 18 years of age are the most susceptible to considering themselves workaholics. The physical and psychological consequences of professional exhaustion are characterized primarily by the decrease in self-esteem, symptoms of fatigue, anxiety, depression, irritability and the manifestation of physical problems including cardiovascular ailments, as evidenced by hypertension, as well as heart and kidney complications. All the theoretical point of views, from the psychoanalytical models to the contemporary models, highlight self esteem as being the centerpiece of the question regarding the problem of workaholism. In fact, the narcissism articulated from the sociological evolution of our western way of life permits us to delineate the psychic

  18. Heat transfer in supersonic dusty-gas flow past a blunt body with inertial particle deposition effect

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Heat transfer in a supersonic steady flow of a dilute dusty-gas past a sphere is considered at large and moderate Reynolds numbers. For the regime of inertial particle deposition on the frontal surface of the body, a parametric study of maximum increase in the particle-induced heat flux at the stagnation point is performed over a wide range of the Reynolds number, the particle inertia parameter, the ratio of the phase specific heats, and the body surface temperature.

  19. Neurophysiological Correlates of the Rubber Hand Illusion in Late Evoked and Alpha/Beta Band Activity

    Directory of Open Access Journals (Sweden)

    Isa S. Rao

    2017-07-01

    Full Text Available The rubber hand illusion (RHI allows insights into how the brain resolves conflicting multisensory information regarding body position and ownership. Previous neuroimaging studies have reported a variety of neurophysiological correlates of illusory hand ownership, with conflicting results likely originating from differences in experimental parameters and control conditions. Here, we overcome these limitations by using a fully automated and precisely-timed visuo-tactile stimulation setup to record evoked responses and oscillatory responses in participants who felt the RHI. Importantly, we relied on a combination of experimental conditions to rule out confounds of attention, body-stimulus position and stimulus duration and on the combination of two control conditions to identify neurophysiological correlates of illusory hand ownership. In two separate experiments we observed a consistent illusion-related attenuation of ERPs around 330 ms over frontocentral electrodes, as well as decreases of frontal alpha and beta power during the illusion that could not be attributed to changes in attention, body-stimulus position or stimulus duration. Our results reveal neural correlates of illusory hand ownership in late and likely higher-order rather than early sensory processes, and support a role of premotor and possibly intraparietal areas in mediating illusory body ownership.

  20. The mirror illusion: does proprioceptive drift go hand in hand with sense of agency?

    Science.gov (United States)

    Tajima, Daisuke; Mizuno, Tota; Kume, Yuichiro; Yoshida, Takako

    2015-01-01

    Vection can be regarded as the illusion of "whole-body" position perception. In contrast, the mirror illusion is that of "body-part" position perception. When participants viewed their left hands in a mirror positioned along the midsaggital axis while moving both hands synchronously, they hardly noticed the spatial offset between the hand in the mirror and the obscured real right hand. This illusion encompasses two phenomena: proprioceptive drift and sense of agency. Proprioceptive drift represented a perceptual change in the position of the obscured hand relative to that of the hand in the mirror. Sense of agency referred to the participants' subjective sense of controlling body image as they would their own bodies. We examined the spatial offset between these two phenomena. Participants responded to a two-alternative forced choice (2AFC) question regarding the subjective position of their right hands and questionnaires regarding sense of agency at various positions of the right hand. We analyzed the 2AFC data using a support vector machine and compared its classification result and the questionnaire results. Our data analysis suggested that the two phenomena were observed in concentric space, but the estimated range of the proprioceptive drift was slightly narrower than the range of agency. Although this outcome can be attributed to differences in measurement or analysis, to our knowledge, this is the first report to suggest that proprioceptive drift and sense of agency are concentric and almost overlap.

  1. The Thatcher illusion: rotating the viewer instead of the picture.

    Science.gov (United States)

    Lobmaier, Janek S; Mast, Fred W

    2007-01-01

    Faces are difficult to recognise when presented upside down. This effect of face inversion was effectively demonstrated with the 'Thatcher illusion' by Thompson (1980 Perception 9 483-484). It has been tacitly assumed that this effect is due to inversion relative to retinal coordinates. Here we tested whether it is due to egocentric (i.e. retinal) inversion or whether the orientation of the body with respect to gravity also influences the face-inversion effect. A 3-D human turntable was used to test subjects in 5 different body-tilt (roll) orientations: 0 degree, 45 degrees, 90 degrees, 135 degrees, and 180 degrees. The stimuli consisted of 4 'normal' and 4 'thatcherised' faces and were presented in 8 different orientations in the picture plane. The subjects had to decide in a yes-no task whether the faces were 'normal' or 'thatcherised'. Analysis of the d' values revealed a significant effect of stimulus orientation and body tilt. The significant effect of body tilt was due to a drop in d' values in the 135 degrees orientation. This result is compared to findings of studies on the subjective visual vertical, where larger errors occurred in body-tilt orientations between 90 degrees and 180 degrees. The present findings suggest that the face-inversion effect relies mainly on retinal coordinates, but that in head-down body-tilt orientations around 135 degrees the gravitational reference frame has a major influence on the perception of faces.

  2. Eggs illusion: Local shape deformation generated by a grid pattern.

    Science.gov (United States)

    Qian, Kun; Mitsudo, Hiroyuki

    2016-12-01

    In this study, we report a new visual shape illusion, the eggs illusion, in which circular disks located at the midpoints between adjacent grid intersections are perceived as being deformed to ellipses. In Experiment 1, we examined the eggs illusion by using a matching method and found that grid luminance and patch size play a critical role in producing the illusory deformation. In Experiment 2, we employed several types of elliptic or circular patches to examine the conditions in which the illusory deformation was cancelled or weakened. We observed that the illusory deformation was dependent on local grid orientation. Based on these results, we found several common features between the eggs illusion and the scintillating grid illusion. This resemblance suggests a possibility that similar mechanisms underlie the two phenomena. In addition to the scintillating grid illusion, we also considered several known perceptual phenomena that might be related to the eggs illusion, i.e., the apparent size illusion, the shape-contrast effect, and the Orbison illusion. Finally, we discuss the role of orientation processing in generating the eggs illusion.

  3. Spectrum of quantum transfer matrices via classical many-body systems

    Energy Technology Data Exchange (ETDEWEB)

    Gorsky, A. [ITEP,Bolshaya Cheremushkinskaya str. 25, 117218, Moscow (Russian Federation); MIPT,Inststitutskii per. 9, 141700, Dolgoprudny, Moscow region (Russian Federation); Zabrodin, A. [ITEP,Bolshaya Cheremushkinskaya str. 25, 117218, Moscow (Russian Federation); MIPT,Inststitutskii per. 9, 141700, Dolgoprudny, Moscow region (Russian Federation); Institute of Biochemical Physics,Kosygina str. 4, 119991, Moscow (Russian Federation); National Research University Higher School of Economics,Myasnitskaya str. 20, 101000, Moscow (Russian Federation); Zotov, A. [ITEP,Bolshaya Cheremushkinskaya str. 25, 117218, Moscow (Russian Federation); MIPT,Inststitutskii per. 9, 141700, Dolgoprudny, Moscow region (Russian Federation); Steklov Mathematical Institute, RAS,Gubkina str. 8, 119991, Moscow (Russian Federation)

    2014-01-15

    In this paper we clarify the relationship between inhomogeneous quantum spin chains and classical integrable many-body systems. It provides an alternative (to the nested Bethe ansatz) method for computation of spectra of the spin chains. Namely, the spectrum of the quantum transfer matrix for the inhomogeneous gl{sub n}-invariant XXX spin chain on N sites with twisted boundary conditions can be found in terms of velocities of particles in the rational N-body Ruijsenaars-Schneider model. The possible values of the velocities are to be found from intersection points of two Lagrangian submanifolds in the phase space of the classical model. One of them is the Lagrangian hyperplane corresponding to fixed coordinates of all N particles and the other one is an N-dimensional Lagrangian submanifold obtained by fixing levels of N classical Hamiltonians in involution. The latter are determined by eigenvalues of the twist matrix. To support this picture, we give a direct proof that the eigenvalues of the Lax matrix for the classical Ruijsenaars-Schneider model, where velocities of particles are substituted by eigenvalues of the spin chain Hamiltonians, calculated through the Bethe equations, coincide with eigenvalues of the twist matrix, with certain multiplicities. We also prove a similar statement for the gl{sub n} Gaudin model with N marked points (on the quantum side) and the Calogero-Moser system with N particles (on the classical side). The realization of the results obtained in terms of branes and supersymmetric gauge theories is also discussed.

  4. The human alimentary tract transfer and body retention of environmental polonium-210.

    Science.gov (United States)

    Hunt, G J; Rumney, H S

    2007-12-01

    This paper presents the results of a 4 year study to investigate the human alimentary tract transfer factor (f(A) value) and body retention of 210 Po in shellfish. In the first 3 years, mussels (Mytilus edulis L.), cockles (Cerastoderma edule L.) and brown meat from crab (Cancer pagurus L.) were successively studied. In each year five volunteers (from a pool of seven) ate a suitable portion of the shellfish and provided 24 h samples of excreta usually for 3 days before and for at least 7 days during and after eating. Subsamples of shellfish were analysed to determine the intakes of 210 Po. Faeces were analysed and the data used to assess apparent fA values. Urine samples were analysed in the mussel and crab studies to provide urinary excretion parameters. Pb-210 was also analysed during the mussel study; the levels were low, leading to large uncertainties, but confirming the negligible effect of radioactive decay to its granddaughter 210 Po in the main study. In the fourth year, larger samples of brown crab meat were eaten by five volunteers and faecal samples were taken at suitable times over periods of up to 43 days to study body retention of 210 Po. The first approximately 7 days provided additional data on fA values. Pooled results for the apparent fA for the whole study lay in the range 0.15-0.65 with a mean of 0.46; corrections for endogenous excretion suggest a true fA value of approximately 0.51, supporting the value of 0.5 currently used by the International Commission on Radiological Protection (ICRP). The retention data suggest a biological half-time of about 40 days, in broad consistency with the 50 days currently used by the ICRP. Thus there is no strong evidence from this study suggesting a change in dose coefficient for 210 Po. Full experimental data are provided to allow independent further interpretation.

  5. Visual illusion of tool use recalibrates tactile perception.

    Science.gov (United States)

    Miller, Luke E; Longo, Matthew R; Saygin, Ayse P

    2017-02-11

    Brief use of a tool recalibrates multisensory representations of the user's body, a phenomenon called tool embodiment. Despite two decades of research, little is known about its boundary conditions. It has been widely argued that embodiment requires active tool use, suggesting a critical role for somatosensory and motor feedback. The present study used a visual illusion to cast doubt on this view. We used a mirror-based setup to induce a visual experience of tool use with an arm that was in fact stationary. Following illusory tool use, tactile perception was recalibrated on this stationary arm, and with equal magnitude as physical use. Recalibration was not found following illusory passive tool holding, and could not be accounted for by sensory conflict or general interhemispheric plasticity. These results suggest visual tool-use signals play a critical role in driving tool embodiment.

  6. Inducing illusory ownership of a virtual body

    Directory of Open Access Journals (Sweden)

    Mel Slater

    2009-09-01

    Full Text Available We discuss three experiments that investigate how virtual limbs and bodies can come to feel like real limbs and bodies. The first experiment shows that an illusion of ownership of a virtual arm appearing to project out of a person’s shoulder can be produced by tactile stimulation on a person’s hidden real hand and synchronous stimulation on the seen virtual hand. The second shows that the illusion can be produced by synchronous movement of the person’s hidden real hand and a virtual hand. The third shows that a weaker form of the illusion can be produced when a brain-computer interface is employed to move the virtual hand by means of motor imagery without any tactile stimulation. We discuss related studies that indicate that the ownership illusion may be generated for an entire body. This has important implications for the scientific understanding of body ownership and several practical applications.

  7. A sensational illusion: vision-touch synaesthesia and the rubber hand paradigm.

    Science.gov (United States)

    Aimola Davies, Anne M; White, Rebekah C

    2013-03-01

    For individuals with vision-touch synaesthesia, the sight of touch on another person elicits synaesthetic tactile sensation on the observer's own body. Here we used the traditional rubber hand paradigm (Botvinick and Cohen, 1998) and a no-touch rubber hand paradigm to investigate and to authenticate synaesthetic tactile sensation. In the traditional rubber hand paradigm, the participant views a prosthetic hand being touched by the Examiner while the participant's hand - hidden from view - is also touched by the Examiner. Synchronous stimulation of the prosthetic hand and the participant's hidden hand elicits the rubber hand illusion. It may seem to the participant that she is feeling touch at the location of the viewed prosthetic hand - visual capture of touch, and that the prosthetic hand is the participant's own hand - illusion of ownership. Thus, for participants who experience the traditional rubber hand illusion, tactile sensation on the participant's hidden hand is referred to the prosthetic hand. In our no-touch rubber hand paradigm, the participant views a prosthetic hand being touched by the Examiner but the participant's hand - hidden from view - is not touched by the Examiner. Questionnaire ratings indicated that only individuals with vision-touch synaesthesia experienced the no-touch rubber hand illusion. Thus, synaesthetic tactile sensation on the (untouched) hidden hand was referred to the prosthetic hand. These individuals also demonstrated proprioceptive drift (a change, from baseline, in proprioceptively perceived position) of the hidden hand towards the location of the prosthetic hand, and a pattern of increased proprioceptive drift with increased trial duration (60 sec, 180 sec, 300 sec). The no-touch rubber hand paradigm was an excellent method to authenticate vision-touch synaesthesia because participants were naïve about the rubber hand illusion, and they could not have known how they were expected to perform on either the traditional or the

  8. Brain Process for Perception of the “Out of the Body” Tactile Illusion for Virtual Object Interaction

    Directory of Open Access Journals (Sweden)

    Hye Jin Lee

    2015-04-01

    Full Text Available “Out of the body” tactile illusion refers to the phenomenon in which one can perceive tactility as if emanating from a location external to the body without any stimulator present there. Taking advantage of such a tactile illusion is one way to provide and realize richer interaction feedback without employing and placing actuators directly at all stimulation target points. However, to further explore its potential, it is important to better understand the underlying physiological and neural mechanism. As such, we measured the brain wave patterns during such tactile illusion and mapped out the corresponding brain activation areas. Participants were given stimulations at different levels with the intention to create veridical (i.e., non-illusory and phantom sensations at different locations along an external hand-held virtual ruler. The experimental data and analysis indicate that both veridical and illusory sensations involve, among others, the parietal lobe, one of the most important components in the tactile information pathway. In addition, we found that as for the illusory sensation, there is an additional processing resulting in the delay for the ERP (event-related potential and involvement by the limbic lobe. These point to regarding illusion as a memory and recognition task as a possible explanation. The present study demonstrated some basic understanding; how humans process “virtual” objects and the way associated tactile illusion is generated will be valuable for HCI (Human-Computer Interaction.

  9. Brain Process for Perception of the “Out of the Body” Tactile Illusion for Virtual Object Interaction

    Science.gov (United States)

    Lee, Hye Jin; Lee, Jaedong; Kim, Chi Jung; Kim, Gerard J.; Kim, Eun-Soo; Whang, Mincheol

    2015-01-01

    “Out of the body” tactile illusion refers to the phenomenon in which one can perceive tactility as if emanating from a location external to the body without any stimulator present there. Taking advantage of such a tactile illusion is one way to provide and realize richer interaction feedback without employing and placing actuators directly at all stimulation target points. However, to further explore its potential, it is important to better understand the underlying physiological and neural mechanism. As such, we measured the brain wave patterns during such tactile illusion and mapped out the corresponding brain activation areas. Participants were given stimulations at different levels with the intention to create veridical (i.e., non-illusory) and phantom sensations at different locations along an external hand-held virtual ruler. The experimental data and analysis indicate that both veridical and illusory sensations involve, among others, the parietal lobe, one of the most important components in the tactile information pathway. In addition, we found that as for the illusory sensation, there is an additional processing resulting in the delay for the ERP (event-related potential) and involvement by the limbic lobe. These point to regarding illusion as a memory and recognition task as a possible explanation. The present study demonstrated some basic understanding; how humans process “virtual” objects and the way associated tactile illusion is generated will be valuable for HCI (Human-Computer Interaction). PMID:25835301

  10. Does the Ebbinghaus Illusion Affect Optimal Pointing?

    Directory of Open Access Journals (Sweden)

    M Lages

    2012-07-01

    Full Text Available We investigated speeded pointing movements (Trommershauser, Maloney, and Landy, 2003 in the presence of the Ebbinghaus illusion. Franz et al (2000 reported systematic effects of the Ebbinghaus illusion on grasping movements, contradicting earlier results (Aglioti, et al, 1995 and casting doubt on a strict dissociation between action and perception (Goodale and Milner, 1992. Here, we try to extend this finding by explicitly manipulating the consequence of motor actions in a speeded pointing task. We hypothesised that large, medium, and small circular surrounds induce the perception of smaller, unchanged, and larger target and penalty areas at the centre. If subjects take the visual illusion into account, then on average they should overshoot, hit, and undershoot the optimal point in the three illusion conditions, respectively. Subjects were asked to hit a circular target area on a touch screen with their right index finger. They were awarded +100 points for hitting the target, and in separate conditions either lost 0 or 500 points when touching an overlapping red penalty area. Feedback was provided at the end of each trial so the subjects could monitor their total score and gauge their performance. Participants were trained in 240 trials before performing the experiment in two blocks of 120 trials for each penalty condition with large, medium, and small surround stimuli randomly intermixed. Preliminary results from 12 observers indicate a significant effect of penalty on pointing position (F1,11=21.3, p=0.001 but no statistically significant effect for the Ebbinghaus illusion (F2,22=1.14, p=0.34. Results from a size adjustment task at the end of the experiment suggest that the perceived size of target and penalty area changed as predicted (large: −1.5, medium: 0.7, and small: 1.5 pixels but that the effect was too weak to systematically influence pointing. In conclusion, we found no clear evidence that the Ebbinghaus illusion can bias optimal

  11. The mirror illusion: does proprioceptive drift go hand in hand with sense of agency?

    Directory of Open Access Journals (Sweden)

    Daisuke eTAJIMA

    2015-02-01

    Full Text Available Vection can be regarded as the illusion of ‘whole-body’ position perception. In contrast, the mirror illusion is that of ‘body-part’ position perception. When participants viewed their left hands in a mirror positioned along the midsaggital axis while moving both hands synchronously, they hardly noticed the spatial offset between the hand in the mirror and the obscured real right hand. This illusion encompasses two phenomena: proprioceptive drift and sense of agency. Proprioceptive drift represented a perceptual change in the position of the obscured hand relative to that of the hand in the mirror. Sense of agency referred to the participants’ subjective sense of controlling body image as they would their own bodies. We examined the spatial offset between these two phenomena. Participants responded to a two-alternative forced choice (2AFC question regarding the subjective position of their right hands and questionnaires regarding sense of agency at various positions of the right hand. We analysed the 2AFC data using a support vector machine and compared its classification result and the questionnaire results. Our data analysis suggested that the two phenomena were observed in concentric space, but the estimated range of the proprioceptive drift was slightly narrower than the range of agency. Although this outcome can be attributed to differences in measurement or analysis, to our knowledge, this is the first report to suggest that proprioceptive drift and sense of agency are concentric and almost overlap.

  12. Decreased Corticospinal Excitability after the Illusion of Missing Part of the Arm.

    Science.gov (United States)

    Kilteni, Konstantina; Grau-Sánchez, Jennifer; Veciana De Las Heras, Misericordia; Rodríguez-Fornells, Antoni; Slater, Mel

    2016-01-01

    Previous studies on body ownership illusions have shown that under certain multimodal conditions, healthy people can experience artificial body-parts as if they were part of their own body, with direct physiological consequences for the real limb that gets 'substituted.' In this study we wanted to assess (a) whether healthy people can experience 'missing' a body-part through illusory ownership of an amputated virtual body, and (b) whether this would cause corticospinal excitability changes in muscles associated with the 'missing' body-part. Forty right-handed participants saw a virtual body from a first person perspective but for half of them the virtual body was missing a part of its right arm. Single pulse transcranial magnetic stimulation was applied before and after the experiment to left and right motor cortices. Motor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) and the extensor digitorum communis (EDC) of each hand. We found that the stronger the illusion of amputation and arm ownership, the more the reduction of MEP amplitudes of the EDC muscle for the contralateral sensorimotor cortex. In contrast, no association was found for the EDC amplitudes in the ipsilateral cortex and for the FDI amplitudes in both contralateral and ipsilateral cortices. Our study provides evidence that a short-term illusory perception of missing a body-part can trigger inhibitory effects on corticospinal pathways and importantly in the absence of any limb deafferentation or disuse.

  13. Decreased corticospinal excitability after the illusion of missing part of the arm

    Directory of Open Access Journals (Sweden)

    Konstantina eKilteni

    2016-04-01

    Full Text Available Previous studies on body ownership illusions have shown that under certain multimodal conditions, healthy people can experience artificial body-parts as if they were part of their own body, with direct physiological consequences for the real limb that gets ‘substituted’. In this study we wanted to assess (a whether healthy people can experience ‘missing’ a body-part through illusory ownership of an amputated virtual body, and (b whether this would cause corticospinal excitability changes in muscles associated with the ‘missing’ body-part. Forty right-handed participants saw a virtual body from a first person perspective but for half of them the virtual body was missing a part of its right arm. Single pulse transcranial magnetic stimulation was applied before and after the experiment to left and right motor cortices. Motor evoked potentials (MEPs were recorded from the first dorsal interosseous (FDI and the extensor digitorum communis (EDC of each hand. We found that the stronger the illusion of amputation and arm ownership, the more the reduction of MEP amplitudes of the EDC muscle for the contralateral sensorimotor cortex. In contrast, no association was found for the EDC amplitudes in the ipsilateral cortex and for the FDI amplitudes in both contralateral and ipsilateral cortices. Our study provides evidence that a short-term illusory perception of missing a body-part can trigger inhibitory effects on corticospinal pathways and importantly in the absence of any limb deafferentation or disuse.

  14. Decreased Corticospinal Excitability after the Illusion of Missing Part of the Arm

    Science.gov (United States)

    Kilteni, Konstantina; Grau-Sánchez, Jennifer; Veciana De Las Heras, Misericordia; Rodríguez-Fornells, Antoni; Slater, Mel

    2016-01-01

    Previous studies on body ownership illusions have shown that under certain multimodal conditions, healthy people can experience artificial body-parts as if they were part of their own body, with direct physiological consequences for the real limb that gets ‘substituted.’ In this study we wanted to assess (a) whether healthy people can experience ‘missing’ a body-part through illusory ownership of an amputated virtual body, and (b) whether this would cause corticospinal excitability changes in muscles associated with the ‘missing’ body-part. Forty right-handed participants saw a virtual body from a first person perspective but for half of them the virtual body was missing a part of its right arm. Single pulse transcranial magnetic stimulation was applied before and after the experiment to left and right motor cortices. Motor evoked potentials (MEPs) were recorded from the first dorsal interosseous (FDI) and the extensor digitorum communis (EDC) of each hand. We found that the stronger the illusion of amputation and arm ownership, the more the reduction of MEP amplitudes of the EDC muscle for the contralateral sensorimotor cortex. In contrast, no association was found for the EDC amplitudes in the ipsilateral cortex and for the FDI amplitudes in both contralateral and ipsilateral cortices. Our study provides evidence that a short-term illusory perception of missing a body-part can trigger inhibitory effects on corticospinal pathways and importantly in the absence of any limb deafferentation or disuse. PMID:27148005

  15. Positive and negative affect in illusion of control

    OpenAIRE

    Novović Zdenka; Kovač Aleksandra; Đurić Veljko; Biro Mikloš

    2012-01-01

    Research regarding the illusion of control was dominated by the studies examining the effect of depressive affect on the overestimation of control over uncontrollable events. However, the relative contributions of high Negative Affect (NA) and low Positive Affect (PA), as underlying dimensions of depressive states, has remained unclear. This study researched how both PA and NA had affected the illusion of control. Two weeks before illusion induction, trait PA and NA of 54 first-year uni...

  16. Geometrical illusions are not always where you think they are

    Directory of Open Access Journals (Sweden)

    Jacques eNinio

    2014-10-01

    Full Text Available Geometrical illusions are known through a small core of classical illusions that were discovered in the second half of the 19th century. Most experimental studies and most theoretical discussions revolve around this core of illusions, as though all other illusions were obvious variants of these. Yet, many illusions, mostly described by German authors at the same time or at the beginning of the 20th century have been forgotten and are awaiting their rehabilitation. Recently, several new illusions were discovered, mainly by Italian authors, and they do not seem to take place into any current classification. Among the principles that are invoked to explain the illusions, there are principles relating to the metric aspects (contrast, assimilation, shrinkage, expansion, attraction of parallels principles relating to orientations (regression to right angles, orthogonal expansion or, more recently, to gestalt effects. It is possible to oppose, to many a classical stimulus, an illusion that apparently contradicts the lesson derived from this stimulus. Furthermore, some well-known illusory patterns may not be illusions at all, they capture legitimate paradoxes of shape perception.Here, metric effects are discussed within a measurement framework, in which the geometric illusions are the outcome of a measurement process. There would be a main convexity bias in the measures: the measured value m(x of an extant x would grow more than proportionally with x. This convexity principle, completed by a principle of compromise for conflicting measures can replace, for a large number of patterns, both the assimilation and the contrast effects. We know from evolutionary theory that the most pertinent classification criteria may not be the most salient ones (e.g., a dolphin is not a mammal. In order to obtain an objective classification of illusions, I initiated with Kevin O’Regan systematic work on orientation profiles (describing how the strength of an illusion

  17. Sex differences in susceptibility to the Poggendorff illusion.

    Science.gov (United States)

    Declerck, Carolyn; De, Brabander Bert

    2002-02-01

    This study presents experimental results indicating that there are sex differences in the susceptibility to a geometric optical illusion. Participants (57 male and 39 female undergraduate students) performed 3 trials on a test involving the Poggendorff illusion. Analysis indicated that the magnitude of the illusion diminished significantly with each trial and that the percent perceived error was significantly larger for women than for men. This finding is consistent with the numerous studies which have indicated better visuospatial abilities for men than for women.

  18. 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.

  19. P1-19: Horizontal Vertical Illusion by Touch

    Directory of Open Access Journals (Sweden)

    Yoshinari Kinoshita

    2012-10-01

    Full Text Available Revesz (1934 Zeitschrift fur PsychologieBd. 1, Kap 20 and Bean (1938 Journal of Experimental Psychology 22 283–289. reported almost all the geometrical optical illusions existed in a tactual mode. Such a study can examine theories of visual illusions with modality-free theories. A number of articles have been devoted to the theory that repeated judgments decline the magnitude of visual illusion. In the current study, we examine whether repeated judgments decline the magnitude of geometrical haptic illusion. The Fick illusion (i.e., a horizontal vertical illusion was investigated. A graphics Braille display with 32×48 dots was used to present an inverted T haptically without vision. The horizontal line was consistently 49.2 mm long, and the vertical line was varied in each trial. Three subjects with normal sight participated. They judged which line was longer than the other. The point of subjective equality at which the subject perceives the two lines to be the same was measured using the method of constant stimuli. In the first session the mean PSE was about 13%; to compensate for the illusion, the vertical line must be set physically shorter than the horizontal line. We found that repeated judgments produced a reduction in illusion magnitude and dissolved the illusion entirely.

  20. Anomalous Mirror Symmetry Generated by Optical Illusion

    Directory of Open Access Journals (Sweden)

    Kokichi Sugihara

    2016-04-01

    Full Text Available This paper introduces a new concept of mirror symmetry, called “anomalous mirror symmetry”, which is physically impossible but can be perceived by human vision systems because of optical illusion. This symmetry is characterized geometrically and a method for creating cylindrical surfaces that create this symmetry is constructed. Examples of solid objects constructed by a 3D printer are also shown.

  1. Zen Mountains: An Illusion of Perceptual Transparency

    OpenAIRE

    2015-01-01

    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 illu...

  2. Unique Optical Illusions From A Magician's Perspective

    Science.gov (United States)

    Rosenthal, Ken

    1983-10-01

    The stage and close-up magicians have employed various types of optical effects in the presentation of magic illusions. Although certain magical effects "are done with mirrors", many other feats of magic employ no mirrors at all, but other optical-type devices in certain instances. The magician has relied on his magical creativity, misdirection, and showmanship, often more than certain optical and engineering-type devices for achievement of the magical effect. However, certain technical devices have always been a part of the magician's "bag-of-tricks". A brief overview of the magic, patent, and engineering literature is presented detailing what optical devices and effects magicians have and will continue to use. An important criterion is that the optical effect, however simple or complex, when combined with the intended illusion, give the audience the experience of an entertaining, mysterious, magical effect--not a science class type demonstration. Several examples are presented of optical effects in magic tricks which have been successfully employed. The main purpose of this paper is not to expose the secrets of magic, but to allow the optical engineer to gain an appreciation and understanding of how the magician develops and performs new effects, so that new optical devices and techniques might find their place in a show of illusions.

  3. The Thatcher illusion in humans and monkeys.

    Science.gov (United States)

    Dahl, Christoph D; Logothetis, Nikos K; Bülthoff, Heinrich H; Wallraven, Christian

    2010-10-01

    Primates possess the remarkable ability to differentiate faces of group members and to extract relevant information about the individual directly from the face. Recognition of conspecific faces is achieved by means of holistic processing, i.e. the processing of the face as an unparsed, perceptual whole, rather than as the collection of independent features (part-based processing). The most striking example of holistic processing is the Thatcher illusion. Local changes in facial features are hardly noticeable when the whole face is inverted (rotated 180 degrees ), but strikingly grotesque when the face is upright. This effect can be explained by a lack of processing capabilities for locally rotated facial features when the face is turned upside down. Recently, a Thatcher illusion was described in the macaque monkey analogous to that known from human investigations. Using a habituation paradigm combined with eye tracking, we address the critical follow-up questions raised in the aforementioned study to show the Thatcher illusion as a function of the observer's species (humans and macaques), the stimulus' species (humans and macaques) and the level of perceptual expertise (novice, expert).

  4. Illusion of control in a Brownian game

    Science.gov (United States)

    Satinover, J. B.; Sornette, D.

    2007-12-01

    Both single-player Parrondo games (SPPG) and multi-player Parrondo games (MPPG) display the Parrondo effect (PE) wherein two or more individually fair (or losing) games yield a net winning outcome if alternated periodically or randomly. (There is a more formal, less restrictive definition of the PE.) We illustrate that, when subject to an elementary optimization rule, the PG displays degraded rather than enhanced returns. Optimization provides only the illusion of control, when low-entropy strategies (i.e., which use more information) under-perform random strategies (with maximal entropy). This illusion is unfortunately widespread in many human attempts to manage or predict complex systems. For the PG, the illusion is especially striking in that the optimization rule reverses an already paradoxical-seeming positive gain-the Parrondo effect proper-and turns it negative. While this phenomenon has been previously demonstrated using somewhat artificial conditions in the MPPG [L. Dinis, J.M.R. Parrondo, Europhys. Lett. 63 (2003) 319; J.M.R. Parrondo, L. Dinis, J. Buceta, K. Lindenberg, Advances in Condensed Matter and Statistical Mechanics, E. Korutcheva, R. Cuerno (Eds.), Nova Science Publishers, New York, 2003], we demonstrate it in the natural setting of a history-dependent SPPG.

  5. Brightness illusion in the guppy (Poecilia reticulata).

    Science.gov (United States)

    Agrillo, Christian; Miletto Petrazzini, Maria Elena; Bisazza, Angelo

    2016-02-01

    A long-standing debate surrounds the issue of whether human and nonhuman species share similar perceptual mechanisms. One experimental strategy to compare visual perception of vertebrates consists in assessing how animals react in the presence of visual illusions. To date, this methodological approach has been widely used with mammals and birds, while few studies have been reported in distantly related species, such as fish. In the present study we investigated whether fish perceive the brightness illusion, a well-known illusion occurring when 2 objects, identical in physical features, appear to be different in brightness. Twelve guppies (Poecilia reticulata) were initially trained to discriminate which rectangle was darker or lighter between 2 otherwise identical rectangles. Three different conditions were set up: neutral condition between rectangle and background (same background used for both darker and lighter rectangle); congruent condition (darker rectangle in a darker background and lighter rectangle in a lighter background); and incongruent condition (darker rectangle in a lighter background and lighter rectangle in a darker background). After reaching the learning criterion, guppies were presented with the illusory pattern: 2 identical rectangles inserted in 2 different backgrounds. Guppies previously trained to select the darker rectangle showed a significant choice of the rectangle that appears to be darker by human observers (and vice versa). The human-like performance exhibited in the presence of the illusory pattern suggests the existence of similar perceptual mechanisms between humans and fish to elaborate the brightness of objects.

  6. Multisensory stimulation can induce an illusion of larger belly size in immersive virtual reality.

    Directory of Open Access Journals (Sweden)

    Jean-Marie Normand

    Full Text Available BACKGROUND: Body change illusions have been of great interest in recent years for the understanding of how the brain represents the body. Appropriate multisensory stimulation can induce an illusion of ownership over a rubber or virtual arm, simple types of out-of-the-body experiences, and even ownership with respect to an alternate whole body. Here we use immersive virtual reality to investigate whether the illusion of a dramatic increase in belly size can be induced in males through (a first person perspective position (b synchronous visual-motor correlation between real and virtual arm movements, and (c self-induced synchronous visual-tactile stimulation in the stomach area. METHODOLOGY: Twenty two participants entered into a virtual reality (VR delivered through a stereo head-tracked wide field-of-view head-mounted display. They saw from a first person perspective a virtual body substituting their own that had an inflated belly. For four minutes they repeatedly prodded their real belly with a rod that had a virtual counterpart that they saw in the VR. There was a synchronous condition where their prodding movements were synchronous with what they felt and saw and an asynchronous condition where this was not the case. The experiment was repeated twice for each participant in counter-balanced order. Responses were measured by questionnaire, and also a comparison of before and after self-estimates of belly size produced by direct visual manipulation of the virtual body seen from the first person perspective. CONCLUSIONS: The results show that first person perspective of a virtual body that substitutes for the own body in virtual reality, together with synchronous multisensory stimulation can temporarily produce changes in body representation towards the larger belly size. This was demonstrated by (a questionnaire results, (b the difference between the self-estimated belly size, judged from a first person perspective, after and before the

  7. Computational fluid dynamics analysis of drag and convective heat transfer of individual body segments for different cyclist positions.

    Science.gov (United States)

    Defraeye, Thijs; Blocken, Bert; Koninckx, Erwin; Hespel, Peter; Carmeliet, Jan

    2011-06-03

    This study aims at investigating drag and convective heat transfer for cyclists at a high spatial resolution. Such an increased spatial resolution, when combined with flow-field data, can increase insight in drag reduction mechanisms and in the thermo-physiological response of cyclists related to heat stress and hygrothermal performance of clothing. Computational fluid dynamics (steady Reynolds-averaged Navier-Stokes) is used to evaluate the drag and convective heat transfer of 19 body segments of a cyclist for three different cyclist positions. The influence of wind speed on the drag is analysed, indicating a pronounced Reynolds number dependency on the drag, where more streamlined positions show a dependency up to higher Reynolds numbers. The drag and convective heat transfer coefficient (CHTC) of the body segments and the entire cyclist are compared for all positions at racing speeds, showing high drag values for the head, legs and arms and high CHTCs for the legs, arms, hands and feet. The drag areas of individual body segments differ markedly for different cyclist positions whereas the convective heat losses of the body segments are found to be less sensitive to the position. CHTC-wind speed correlations are derived, in which the power-law exponent does not differ significantly for the individual body segments for all positions, where an average value of 0.84 is found. Similar CFD studies can be performed to assess drag and CHTCs at a higher spatial resolution for applications in other sport disciplines, bicycle equipment design or to assess convective moisture transfer.

  8. Does the experience of ownership over a rubber hand change body size perception in anorexia nervosa patients?

    NARCIS (Netherlands)

    Keizer, Anouk; Smeets, Monique A M; Postma, Albert; van Elburg, Annemarie; Dijkerman, H. Chris

    2014-01-01

    Anorexia nervosa (AN) patients show disturbances in body size experience. Here, malleability of body representation was assessed by inducing the Rubber Hand Illusion (RHI). Specifically the impact of the illusion on body size estimation was investigated.Thirty AN patients and thirty healthy females

  9. Determination of time of death in forensic science via a 3-D whole body heat transfer model.

    Science.gov (United States)

    Bartgis, Catherine; LeBrun, Alexander M; Ma, Ronghui; Zhu, Liang

    2016-12-01

    This study is focused on developing a whole body heat transfer model to accurately simulate temperature decay in a body postmortem. The initial steady state temperature field is simulated first and the calculated weighted average body temperature is used to determine the overall heat transfer coefficient at the skin surface, based on thermal equilibrium before death. The transient temperature field postmortem is then simulated using the same boundary condition and the temperature decay curves at several body locations are generated for a time frame of 24h. For practical purposes, curve fitting techniques are used to replace the simulations with a proposed exponential formula with an initial time delay. It is shown that the obtained temperature field in the human body agrees very well with that in the literature. The proposed exponential formula provides an excellent fit with an R(2) value larger than 0.998. For the brain and internal organ sites, the initial time delay varies from 1.6 to 2.9h, when the temperature at the measuring site does not change significantly from its original value. The curve-fitted time constant provides the measurement window after death to be between 8h and 31h if the brain site is used, while it increases 60-95% at the internal organ site. The time constant is larger when the body is exposed to colder air, since a person usually wears more clothing when it is cold outside to keep the body warm and comfortable. We conclude that a one-size-fits-all approach would lead to incorrect estimation of time of death and it is crucial to generate a database of cooling curves taking into consideration all the important factors such as body size and shape, environmental conditions, etc., therefore, leading to accurate determination of time of death.

  10. The illusion of common ground

    DEFF Research Database (Denmark)

    Cowley, Stephen; Harvey, Matthew

    2016-01-01

    , together with concerted bodily (and vocal) activity, serve to organize, regulate and coordinate both attention and the verbal and non-verbal activity that it gives rise to. Since wordings are normative, they can be used to develop skills for making cultural sense of environments and other peoples’ doings...... isolated individuals “use” language to communicate. Autonomous cognitive agents are said to use words to communicate inner thoughts and experiences; in such a framework, ‘common ground’ describes a body of information that people allegedly share, hold common, and use to reason about how intentions have...... language to synergetic coordination between biological agents who draw on wordings to act within cultural ecosystems. Crucially, human coordination depends on, not just bodies, but also salient patterns of articulatory movement (‘wordings’). These rich patterns function as non-local resources that...

  11. Virtual reality and virtual bodies

    Science.gov (United States)

    Richards, Catherine; Korba, Larry W.; Shaw, Christopher D.; Green, Mark

    1994-04-01

    There are many ways to produce the sense of `presence' or telepresence in the user of virtual reality. For example attempting to increase the realism of the visual environment is a commonly accepted strategy. In contrast, this paper explores a way for the user to feel present in an unrealistic virtual body. It investigates an unusual approach, proprioceptive illusions. Proprioceptive or body illusions are used to generate and explore the experience of virtuality and presence outside of the normal body limits. These projects are realized in art installations.

  12. Energy drinks: potions of illusion.

    Science.gov (United States)

    Bedi, Nidhi; Dewan, Pooja; Gupta, Piyush

    2014-07-01

    Energy drinks are widely consumed by adolescents as these claim to improve performance, endurance and alertness. Recent reports have shown that there are no real health benefits of these drinks. On the contrary, certain adverse effects due to energy drinks have come to the forefront, casting a big question-mark on their safety and utility. This review discusses the present status of energy drinks, their active ingredients and their safety. We conclude that energy drinks, despite having some short pleasant effects, can be harmful for the body and are best avoided.

  13. Bond-order potential for magnetic body-centered-cubic iron and its transferability

    Science.gov (United States)

    Lin, Yi-Shen; Mrovec, M.; Vitek, V.

    2016-06-01

    We derived and thoroughly tested a bond-order potential (BOP) for body-centered-cubic (bcc) magnetic iron that can be employed in atomistic calculations of a broad variety of crystal defects that control structural, mechanical, and thermodynamic properties of this technologically important metal. The constructed BOP reflects correctly the mixed nearly free electron and covalent bonding arising from the partially filled d band as well as the ferromagnetism that is actually responsible for the stability of the bcc structure of iron at low temperatures. The covalent part of the cohesive energy is determined within the tight-binding bond model with the Green's function of the Schrödinger equation determined using the method of continued fractions terminated at a sufficient level of the moments of the density of states. This makes the BOP an O (N ) method usable for very large numbers of particles. Only d d bonds are included explicitly, but the effect of s electrons on the covalent energy is included via their screening of the corresponding d d bonds. The magnetic part of the cohesive energy is included using the Stoner model of itinerant magnetism. The repulsive part of the cohesive energy is represented, as in any tight-binding scheme, by an empirical formula. Its functional form is physically justified by studies of the repulsion in face-centered-cubic (fcc) solid argon under very high pressure where the repulsion originates from overlapping s and p closed-shell electrons just as it does from closed-shell s electrons in transition metals squeezed into the ion core under the influence of the large covalent d bonding. Testing of the transferability of the developed BOP to environments significantly different from those of the ideal bcc lattice was carried out by studying crystal structures and magnetic states alternative to the ferromagnetic bcc lattice, vacancies, divacancies, self-interstitial atoms (SIAs), paths continuously transforming the bcc structure to

  14. Optical Illusions: A Presentation for High School Mathematics Students.

    Science.gov (United States)

    Brandes, Louis Grant

    1983-01-01

    Optical illusions are assumed to be of interest to high school mathematics students. The article indicates how a topic can be both educational and entertaining. Readers are invited to try to construct some illusions on their own, and to see if they can classify them. (MP)

  15. [The Hermann grid illusion: the classic textbook interpretation is obsolete].

    Science.gov (United States)

    Bach, M

    2009-10-01

    The Hermann grid is an optical illusion in which the crossings of white grid lines appear darker than the grid lines outside the crossings. The illusion disappears when one fixates the crossings. The discoverer, Ludimar Hermann (1838-1914), interpreted the illusion as evidence for lateral connections in the retina. In most textbooks on sensory physiology and ophthalmology, the Hermann grid illusion serves to illustrate "lateral inhibition." This paper summarises new findings that show that the classic explanation is incomplete. In 2004, a seemingly subtle modification, a small undulation of the grid lines, was shown to demolish the illusion. In 2007, a more convincing explanation appeared: An artificial neural network was trained for "lightness constancy"- the ability of our visual system to interpret luminance in the interest of object recognition, independent of illumination. After having learned lightness constancy, the network was subjected to a number of lightness illusions, among them the Hermann grid illusion. An analysis of the coupling constants of this neural network promises to further our understanding of the Hermann grid illusion.

  16. Computer Generated Optical Illusions: A Teaching and Research Tool.

    Science.gov (United States)

    Bailey, Bruce; Harman, Wade

    Interactive computer-generated simulations that highlight psychological principles were investigated in this study in which 33 female and 19 male undergraduate college student volunteers of median age 21 matched line and circle sizes in six variations of Ponzo's illusion. Prior to working with the illusions, data were collected based on subjects'…

  17. The Thatcher Illusion and Face Processing in Infancy

    Science.gov (United States)

    Bertin, Evelin; Bhatt, Ramesh S.

    2004-01-01

    Adults readily detect changes in face patterns brought about by the inversion of eyes and mouth when the faces are viewed upright but not when they are viewed upside down. Research suggests that this illusion (the Thatcher illusion) is caused by the interfering effects of face inversion on the processing of second-order relational information…

  18. Perceiving the Present and a Systematization of Illusions

    Science.gov (United States)

    Changizi, Mark A.; Hsieh, Andrew; Nijhawan, Romi; Kanai, Ryota; Shimojo, Shinsuke

    2008-01-01

    Over the history of the study of visual perception there has been great success at discovering countless visual illusions. There has been less success in organizing the overwhelming variety of illusions into empirical generalizations (much less explaining them all via a unifying theory). Here, this article shows that it is possible to…

  19. Positive illusions about a partner's physical attractiveness and relationship quality

    NARCIS (Netherlands)

    Barelds, Dick P. H.; Dijkstra, Pieternel

    2009-01-01

    The present research examined the existence of positive illusions about a partner's physical attractiveness and its relations to relationship quality. Positive illusions were assumed to exist when individuals rated their partner as more attractive than their partner rated him or herself. In two Dutc

  20. Positive illusions about a partner's physical attractiveness and relationship quality

    NARCIS (Netherlands)

    Barelds, Dick P. H.; Dijkstra, Pieternel

    The present research examined the existence of positive illusions about a partner's physical attractiveness and its relations to relationship quality. Positive illusions were assumed to exist when individuals rated their partner as more attractive than their partner rated him or herself. In two

  1. The Function of the Illusions of Control and Freedom

    Science.gov (United States)

    Lefcourt, Herbert M.

    1973-01-01

    Argues that while freedom and control are both illusions, inventions of man to make sense of his experience, they do have consequences; and presents research evidence that the loss of the illusion of freedom may have untoward consequences for the way men live. (Author/JM)

  2. Forward Association, Backward Association, and the False-Memory Illusion

    Science.gov (United States)

    Brainerd, C. J.; Wright, Ron

    2005-01-01

    In the Deese-Roediger-McDermott false-memory illusion, forward associative strength (FAS) is unrelated to the strength of the illusion; this is puzzling, because high-FAS lists ought to share more semantic features with critical unpresented words than should low-FAS lists. The authors show that this null result is probably a truncated range…

  3. Do Visual Illusions Probe the Visual Brain?: Illusions in Action without a Dorsal Visual Stream

    Science.gov (United States)

    Coello, Yann; Danckert, James; Blangero, Annabelle; Rossetti, Yves

    2007-01-01

    Visual illusions have been shown to affect perceptual judgements more so than motor behaviour, which was interpreted as evidence for a functional division of labour within the visual system. The dominant perception-action theory argues that perception involves a holistic processing of visual objects or scenes, performed within the ventral,…

  4. Do Visual Illusions Probe the Visual Brain?: Illusions in Action without a Dorsal Visual Stream

    Science.gov (United States)

    Coello, Yann; Danckert, James; Blangero, Annabelle; Rossetti, Yves

    2007-01-01

    Visual illusions have been shown to affect perceptual judgements more so than motor behaviour, which was interpreted as evidence for a functional division of labour within the visual system. The dominant perception-action theory argues that perception involves a holistic processing of visual objects or scenes, performed within the ventral,…

  5. Many-body heat radiation and heat transfer in the presence of a nonabsorbing background medium

    Science.gov (United States)

    Müller, Boris; Incardone, Roberta; Antezza, Mauro; Emig, Thorsten; Krüger, Matthias

    2017-02-01

    Heat radiation and near-field radiative heat transfer can be strongly manipulated by adjusting geometrical shapes, optical properties, or the relative positions of the objects involved. Typically, these objects are considered as embedded in vacuum. By applying the methods of fluctuational electrodynamics, we derive general closed-form expressions for heat radiation and heat transfer in a system of N arbitrary objects embedded in a passive nonabsorbing background medium. Taking into account the principle of reciprocity, we explicitly prove the symmetry and positivity of transfer in any such system. Regarding applications, we find that the heat radiation of a sphere as well as the heat transfer between two parallel plates is strongly enhanced by the presence of a background medium. Regarding near- and far-field transfer through a gas like air, we show that a microscopic model (based on gas particles) and a macroscopic model (using a dielectric contrast) yield identical results. We also compare the radiative transfer through a medium like air and the energy transfer found from kinetic gas theory.

  6. A real-life illusion of assimilation in the human face: eye size illusion caused by eyebrows and eye shadow.

    Science.gov (United States)

    Morikawa, Kazunori; Matsushita, Soyogu; Tomita, Akitoshi; Yamanami, Haruna

    2015-01-01

    Does an assimilative illusion like the Delboeuf illusion occur in the human face? We investigated factors that might influence the perceived size of the eyes in a realistic face. Experiment 1 manipulated the position of the eyebrows (high or low), the presence/absence of eye shadow, and the viewing distance (0.6 m or 5 m), then measured the perceived eye size using a psychophysical method. The results showed that low eyebrows (i.e., closer to the eyes) make the eyes appear larger, suggesting that the assimilation of eyes into the eyebrows is stronger when the eye-eyebrow distance is shorter. The results also demonstrated that the application of eye shadow also makes the eyes look larger. Moreover, the effect of eye shadow is more pronounced when viewed from a distance. In order to investigate the mechanism of the eye size illusion demonstrated in Experiment 1, Experiment 2 measured the magnitude of the Delboeuf illusion at a viewing distance of 0.6 m or 5 m, with or without gray gradation simulating the eye shadow that was used in Experiment 1. The experiment demonstrated that the Delboeuf illusion is modulated by viewing distance and gradation in the same way as the eye size illusion. These results suggest that the eye size illusion induced by the eyebrows and the Delboeuf illusion involve the same mechanism, and that eye shadow causes the assimilation of the eyes into itself and enhances assimilation between the eyes and the eyebrows.

  7. Influence of Turbulence Parameters, Reynolds Number, and Body Shape on Stagnation-Region Heat Transfer

    Science.gov (United States)

    Vanfossen, G. James; Simoneau, Robert J.; Ching, Chan Y.

    1994-01-01

    The purpose of the present work was threefold: (1) to determine if a free-stream turbulence length scale existed that would cause the greatest augmentation in stagnation-region heat transfer over laminar levels; (2) to investigate the effect of velocity gradient on stagnation-region heat transfer augmentation by free-stream turbulence; and (3) to develop a prediction tool for stagnation heat transfer in the presence of free-stream turbulence. Heat transfer was measured in the stagnation region of four models with elliptical leading edges that had ratios of major to minor axes of 1:1, 1.5:1, 2.25:1, and 3:1. Five turbulence-generating grids were fabricated; four were square mesh, biplane grids made from square bars. The fifth grid was an array of fine parallel wires that were perpendicular to the model spanwise direction. Heat transfer data were taken at Reynolds numbers ranging from 37 000 to 228 000. Turbulence intensities were in the range of 1.1 to 15.9% while the ratio of integral length scale to leading-edge diameter ranged from 0.05 to 0.30. Stagnation-point velocity gradient was varied by nearly 50%. Stagnation-region heat transfer augmentation was found to increase with decreasing length scale but no optimum length scale was found. Heat transfer augmentation due to turbulence was found to be unaffected by the velocity gradient near the leading edge. A correlation was developed that fit heat transfer data for the square-bar grids to within +/- 4%.

  8. Exploring the subjective experience of the “rubber hand” illusion

    Science.gov (United States)

    Valenzuela Moguillansky, Camila; O'Regan, J. Kevin; Petitmengin, Claire

    2013-01-01

    Despite the fact that the rubber hand illusion (RHI) is an experimental paradigm that has been widely used in the last 14 years to investigate different aspects of the sense of bodily self, very few studies have sought to investigate the subjective nature of the experience that the RHI evokes. The present study investigates the phenomenology of the RHI through a specific elicitation method. More particularly, this study aims at assessing whether the conditions usually used as control in the RHI have an impact in the sense of body ownership and at determining whether there are different stages in the emergence of the illusion. The results indicate that far from being “all or nothing,” the illusion induced by the RHI protocol involves nuances in the type of perceptual changes that it creates. These perceptual changes affect not only the participants' perception of the rubber hand but also the perception of their real hand. In addition, perceptual effects may vary greatly between participants and, importantly, they evolve over time. PMID:24167480

  9. Perceiving a stranger's voice as being one's own: a 'rubber voice' illusion?

    Directory of Open Access Journals (Sweden)

    Zane Z Zheng

    Full Text Available We describe an illusion in which a stranger's voice, when presented as the auditory concomitant of a participant's own speech, is perceived as a modified version of their own voice. When the congruence between utterance and feedback breaks down, the illusion is also broken. Compared to a baseline condition in which participants heard their own voice as feedback, hearing a stranger's voice induced robust changes in the fundamental frequency (F0 of their production. Moreover, the shift in F0 appears to be feedback dependent, since shift patterns depended reliably on the relationship between the participant's own F0 and the stranger-voice F0. The shift in F0 was evident both when the illusion was present and after it was broken, suggesting that auditory feedback from production may be used separately for self-recognition and for vocal motor control. Our findings indicate that self-recognition of voices, like other body attributes, is malleable and context dependent.

  10. On the role of spatial phase and phase correlation in vision, illusion and cognition

    Directory of Open Access Journals (Sweden)

    Evgeny eGladilin

    2015-04-01

    Full Text Available Numerous findings indicate that spatial phase bears an important cognitive information. Distortion of phase affects topology of edge structures and makes images unrecognizable. In turn, appropriately phase-structured patterns give rise to various illusions of virtual image content and apparent motion. Despite a large body of phenomenological evidence not much is known yet about the role of phase information in neural mechanisms of visual perception and cognition. Here, we are concerned with analysis of the role of spatial phase in computational and biological vision, emergence of visual illusions and pattern recognition. We hypothesize that fundamental importance of phase information for invariant retrieval of structural image features and motion detection promoted development of phase-based mechanisms of neural image processing in course of evolution of biological vision. Using an extension of Fourier phase correlation technique, we show that the core functions of visual system such as motion detection and pattern recognition can be facilitated by the same basic mechanism. Our analysis suggests that emergence of visual illusions can be attributed to presence of coherently phase-shifted repetitive patterns as well as the effects of acuity compensation by saccadic eye movements. We speculate that biological vision relies on perceptual mechanisms effectively similar to phase correlation, and predict neural features of visual pattern (dissimilarity that can be used for experimental validation of our hypothesis of 'cognition by phase correlation'.

  11. Numerical investigation of incompressible fluid flow and heat transfer across a bluff body in a channel flow

    Directory of Open Access Journals (Sweden)

    Taymaz Imdat

    2015-01-01

    Full Text Available The Lattice Boltzmann Method is applied to computationally investigate the laminar flow and heat transfer of an incompressible fluid with constant material properties in a two-dimensional channel with a built-in bluff body. In this study, a triangular prism is taken as the bluff body. Not only the momentum transport, but also the energy transport is modeled by the Lattice Boltzmann Method. A uniform lattice structure with a single time relaxation rule is used. For obtaining a higher flexibility on the computational grid, interpolation methods are applied, where the information is transferred from the lattice structure to the computational grid by Lagrange interpolation. The flow is investigated for different Reynolds numbers, while keeping the Prandtl number at the constant value of 0.7. The results show how the presence of a triangular prism effects the flow and heat transfer patterns for the steady-state and unsteady-periodic flow regimes. As an assessment of the accuracy of the developed Lattice Boltzmann code, the results are compared with those obtained by a commercial Computational Fluid Dynamics code. It is observed that the present Lattice Boltzmann code delivers results that are of similar accuracy to the well-established Computational Fluid Dynamics code, with much smaller computational time for the prediction of the unsteady phenomena.

  12. Neural Correlates of the Poggendorff Illusion Driven by Illusory Contour: An fMRI Study

    OpenAIRE

    Qi Chen; Li Li

    2011-01-01

    The Poggendorff illusion is a well-documented geometric illusion that involves the brain's perception of the interaction between oblique lines and object contours: an oblique line is apparently misaligned once interrupted by two parallel contours. This illusion occurs even when the parallel contours are defined subjectively or illusorily. In this fMRI study, we adopted a 4 (type of stimuli: Poggendorff illusion under real contour and its corresponding control condition; Poggendorff illusion u...

  13. Magic, illusions, and bloopers and blunders in optics

    Science.gov (United States)

    Fischer, Robert E.

    2001-12-01

    This paper presents the use of optics as it relates to the various forms of illusions and magic, and we will present many of the best optical illusions to demonstrate the use of optics. In magic and visual illusions, objects are made to appear different from how we expect them to appear. Performing such illusions show us things that are impossible based on our preconceived knowledge base. This includes levitation, sawing a lady in half, or creating other similar effects. Optical illusions often take the form of illusions of relative size, shifting perception of items, and other ways of fooling the eye, the mind and the brain. These effects are all highly deceiving to the viewer. In addition to optical illusions, there is close up, parlor and stage magic. These would include classical effects as well as contemporary effects with items such as cards, coins, rings, etc. Here too the goal of the magician is to totally mystify the audience. Another topic of the paper is

  14. Do domestic dogs (Canis lupus familiaris) perceive the Delboeuf illusion?

    Science.gov (United States)

    Miletto Petrazzini, Maria Elena; Bisazza, Angelo; Agrillo, Christian

    2017-05-01

    In the last decade, visual illusions have been repeatedly used as a tool to compare visual perception among species. Several studies have investigated whether non-human primates perceive visual illusions in a human-like fashion, but little attention has been paid to other mammals, and sensitivity to visual illusions has been never investigated in the dog. Here, we studied whether domestic dogs perceive the Delboeuf illusion. In human and non-human primates, this illusion creates a misperception of item size as a function of its surrounding context. To examine this effect in dogs, we adapted the spontaneous preference paradigm recently used with chimpanzees. Subjects were presented with two plates containing food. In control trials, two different amounts of food were presented in two identical plates. In this circumstance, dogs were expected to select the larger amount. In test trials, equal food portion sizes were presented in two plates differing in size: if dogs perceived the illusion as primates do, they were expected to select the amount of food presented in the smaller plate. Dogs significantly discriminated the two alternatives in control trials, whereas their performance did not differ from chance in test trials with the illusory pattern. The fact that dogs do not seem to be susceptible to the Delboeuf illusion suggests a potential discontinuity in the perceptual biases affecting size judgments between primates and dogs.

  15. Using visuo-kinetic virtual reality to induce illusory spinal movement: the MoOVi Illusion.

    Science.gov (United States)

    Harvie, Daniel S; Smith, Ross T; Hunter, Estin V; Davis, Miles G; Sterling, Michele; Moseley, G Lorimer

    2017-01-01

    Illusions that alter perception of the body provide novel opportunities to target brain-based contributions to problems such as persistent pain. One example of this, mirror therapy, uses vision to augment perceived movement of a painful limb to treat pain. Since mirrors can't be used to induce augmented neck or other spinal movement, we aimed to test whether such an illusion could be achieved using virtual reality, in advance of testing its potential therapeutic benefit. We hypothesised that perceived head rotation would depend on visually suggested movement. In a within-subjects repeated measures experiment, 24 healthy volunteers performed neck movements to 50(o) of rotation, while a virtual reality system delivered corresponding visual feedback that was offset by a factor of 50%-200%-the Motor Offset Visual Illusion (MoOVi)-thus simulating more or less movement than that actually occurring. At 50(o) of real-world head rotation, participants pointed in the direction that they perceived they were facing. The discrepancy between actual and perceived direction was measured and compared between conditions. The impact of including multisensory (auditory and visual) feedback, the presence of a virtual body reference, and the use of 360(o) immersive virtual reality with and without three-dimensional properties, was also investigated. Perception of head movement was dependent on visual-kinaesthetic feedback (p = 0.001, partial eta squared = 0.17). That is, altered visual feedback caused a kinaesthetic drift in the direction of the visually suggested movement. The magnitude of the drift was not moderated by secondary variables such as the addition of illusory auditory feedback, the presence of a virtual body reference, or three-dimensionality of the scene. Virtual reality can be used to augment perceived movement and body position, such that one can perform a small movement, yet perceive a large one. The MoOVi technique tested here has clear potential for assessment and

  16. TRANSFER

    African Journals Online (AJOL)

    “Chemistry Department, Kenyatta University, P. 0. Box 43844 ... harvester (X) [L 2] in a manner consistent with the following Forster equation for long range energy transfer [3-7]. .... sensitive foods, chemical reactors and essences. Recently we ...

  17. Defensive activation during the rubber hand illusion: Ownership versus proprioceptive drift.

    Science.gov (United States)

    Riemer, Martin; Bublatzky, Florian; Trojan, Jörg; Alpers, Georg W

    2015-07-01

    A strong link between body perception and emotional experience has been proposed. To examine the interaction between body perception and anticipatory anxiety, two well-established paradigms were combined: The rubber hand illusion (RHI) and the threat-of-shock paradigm. An artificial hand and the participants' own hand (hidden from sight) were touched synchronously or asynchronously, while either threat-of-shock or safety was cued. Potentiated startle reflexes and enhanced skin conductance responses were observed during threat as compared to safety conditions, but threat conditions did not interact with illusory body perceptions. Thus, defense system activation was not modulated by altered body representations. Physiological responses increased with the sense of ownership for the artificial limb, but not with proprioceptive drift towards its location. The results indicate that ownership ratings and proprioceptive drift capture different aspects of the RHI. The study presents a new approach to investigate the relationship between body representations and emotional states.

  18. Overlapping illusions by transformation optics without any negative refraction material

    Science.gov (United States)

    Sun, Fei; He, Sailing

    2016-01-01

    A novel method to achieve an overlapping illusion without any negative refraction index material is introduced with the help of the optic-null medium (ONM) designed by an extremely stretching spatial transformation. Unlike the previous methods to achieve such an optical illusion by transformation optics (TO), our method can achieve a power combination and reshape the radiation pattern at the same time. Unlike the overlapping illusion with some negative refraction index material, our method is not sensitive to the loss of the materials. Other advantages over existing methods are discussed. Numerical simulations are given to verify the performance of the proposed devices.

  19. BETWEEN KNOWING AND BELIEVING: SALVAGING ILLUSION'S RIGHTFUL PLACE IN PSYCHOANALYSIS.

    Science.gov (United States)

    Tuch, Richard

    2016-01-01

    Illusion has historically received insufficient psychoanalytic attention, even though it plays an indispensable and adaptive role that helps protect individuals from becoming traumatized by the most psychically noxious aspects of reality. Trauma is mitigated by an individual's knowing about the existence of such realities yet simultaneously believing them non-existent, with neither position granted exclusivity. Psychoanalytic theory is surprisingly predicated on the employment of illusions that picture an individual capable of controlling the potentially traumatic actions of others, just so long as the individual effectively manages his own intrapsychic processes (wishes, fantasies, impulses, etc.). The role of illusion in everyday life is highlighted.

  20. Open active cloaking and illusion devices for the Laplace equation

    Science.gov (United States)

    Ma, Qian; Yang, Fan; Jin, Tian Yu; Lei Mei, Zhong; Cui, Tie Jun

    2016-04-01

    We propose open active cloaking and illusion devices for the Laplace equation. Compared with the closed configurations of active cloaking and illusion devices, we focus on improving the distribution schemes for the controlled sources, which do not have to surround the protected object strictly. Instead, the controlled sources can be placed in several small discrete clusters, and produce the desired voltages along the controlled boundary, to actively hide or disguise the protected object. Numerical simulations are performed with satisfactory results, which are further validated by experimental measurements. The open cloaking and illusion devices have many advantages over the closed configurations in various potential applications.

  1. Global search for low-thrust transfers to the Moon in the planar circular restricted three-body problem

    Science.gov (United States)

    Oshima, Kenta; Campagnola, Stefano; Yanao, Tomohiro

    2017-02-01

    This paper globally searches for low-thrust transfers to the Moon in the planar, circular, restricted, three-body problem. Propellant-mass optimal trajectories are computed with an indirect method, which implements the necessary conditions of optimality based on the Pontryagin principle. We present techniques to reduce the dimension of the set over which the required initial costates are searched. We obtain a wide range of Pareto solutions in terms of time of flight and mass consumption. Using the Tisserand-Poincaré graph, a number of solutions are shown to exploit high-altitude lunar flybys to reduce fuel consumption.

  2. Global search for low-thrust transfers to the Moon in the planar circular restricted three-body problem

    Science.gov (United States)

    Oshima, Kenta; Campagnola, Stefano; Yanao, Tomohiro

    2017-06-01

    This paper globally searches for low-thrust transfers to the Moon in the planar, circular, restricted, three-body problem. Propellant-mass optimal trajectories are computed with an indirect method, which implements the necessary conditions of optimality based on the Pontryagin principle. We present techniques to reduce the dimension of the set over which the required initial costates are searched. We obtain a wide range of Pareto solutions in terms of time of flight and mass consumption. Using the Tisserand-Poincaré graph, a number of solutions are shown to exploit high-altitude lunar flybys to reduce fuel consumption.

  3. Centre of Gravity Plethysmography--A Means of Detecting Mass Transfer of Fluid within the Body.

    Science.gov (United States)

    Buck, Michael

    1988-01-01

    Describes the monitoring of the redistribution of blood by using a technique which detects changes in the center of gravity of the body. Provides information about the principles and application, construction of apparatus, operating routines, and use of the computer as a recorder. Includes suggested investigations, demonstrations, and diagrams.…

  4. Klubi Illusion toob Tartusse New Yorgi ja Londoni / Riho Laurisaar

    Index Scriptorium Estoniae

    Laurisaar, Riho

    2006-01-01

    Stalini-aegses kinohoones Tartus avati suurlinlik klubi "Illusion". Sisekujunduses pole jälgitud kindlat stiili, koos on kitsh ja glamuur, klassika ja ajalooline arhitektuur. Sisearhitekt Jaanis Ilves

  5. Paradoxical form of filled/empty optical illusion.

    Science.gov (United States)

    Wackermann, Jiri; Kastner, Kristina

    2009-01-01

    The filled/empty illusion (Oppel-Kundt) is one of the oldest geometrical-optical illusions, but the determinants of the illusion are not yet sufficiently understood. We studied magnitude of the illusory effect as a function of the height of vertical strokes subdividing a spatial extension of fixed length, using the psychophysical standard-variable matching paradigm. For vertical strokes shorter than, or of the same height as strokes delimiting the standard, the length was over-reproduced consistently with earlier studies of the illusion. However, for vertical strokes three times longer than the delimiters, the illusory effect paradoxically decreased, and attained negative values in two of six subjects. The magnitude of the effect thus depends on the patterning of the space between the delimiters, not merely on the number of subdividing elements.

  6. Creation of Ghost Illusions Using Metamaterials in Wave Dynamics

    CERN Document Server

    Jiang, Weixiang; Han, Tiancheng; Zhang, Shuang; Cui, Tiejun

    2013-01-01

    The creation of wave-dynamic illusion functionality is of great interests to various scientific communities, which can potentially transform an actual perception into the pre-controlled perception, thus empowering unprecedented applications in the advanced-material science, camouflage, cloaking, optical and/or microwave cognition, and defense security, etc. By using the space transformation theory and engineering capability of metamaterials, we propose and realize a functional ghost illusion device, which is capable of creating wave-dynamic virtual ghost images off the original object's position under the illumination of electromagnetic waves. The scattering signature of the object is thus ghosted and perceived as multiple ghost targets with different geometries and compositions. The ghost-illusion material, being inhomogeneous and anisotropic, was realized by thousands of varying unit cells working at non-resonance. The experimental demonstration of the ghost illusion validates our theory of scattering metam...

  7. Detecting Groupthink: Methods for Observing the Illusion of Unanimity.

    Science.gov (United States)

    Cline, Rebecca J. Welch

    1990-01-01

    Reconceptualizes groupthink symptoms as observable group interaction patterns. Proposes two coding systems for detecting the illusion of unanimity symptom, detecting both degree of unanimity and degree of the illusory versus substantive nature of that unanimity. (SR)

  8. Illusion versus Reality: Children's Understanding of Temperature Adaptation.

    Science.gov (United States)

    Arnold, Kevin D.; And Others

    1986-01-01

    Compares kindergartners' and third and sixth graders' understanding of an illusion reported by the philosopher John Locke, in which two hands simultaneously experience two different temperatures from a container of water at one temperature. (HOD)

  9. Orientation-sensitivity to facial features explains the Thatcher illusion.

    Science.gov (United States)

    Psalta, Lilia; Young, Andrew W; Thompson, Peter; Andrews, Timothy J

    2014-10-09

    The Thatcher illusion provides a compelling example of the perceptual cost of face inversion. The Thatcher illusion is often thought to result from a disruption to the processing of spatial relations between face features. Here, we show the limitations of this account and instead demonstrate that the effect of inversion in the Thatcher illusion is better explained by a disruption to the processing of purely local facial features. Using a matching task, we found that participants were able to discriminate normal and Thatcherized versions of the same face when they were presented in an upright orientation, but not when the images were inverted. Next, we showed that the effect of inversion was also apparent when only the eye region or only the mouth region was visible. These results demonstrate that a key component of the Thatcher illusion is to be found in orientation-specific encoding of the expressive features (eyes and mouth) of the face.

  10. Tony Kushner's "The Illusion" and Comedy's "Traversal of the Fantasy"

    National Research Council Canada - National Science Library

    Wolfe, Graham

    2011-01-01

    The author discusses Tony Kushner's "The Illusion," drawing upon the work of Slavoj Zizek and Alenka Zupancic, whose Lacan-inspired philosophy reflects the play's own fascination with the paradoxes...

  11. Positive illusions about a partner's personality and relationship quality

    NARCIS (Netherlands)

    Barelds, Dick P. H.; Dijkstra, Pieternel

    2011-01-01

    Previous studies have shown individuals to hold positive biases about their relationships. The present study examined positive illusions about a partner's specific personality characteristics in relation to relationship quality and personality. Both partners of 120 heterosexual couples participated

  12. The Müller-Lyer illusion in ant foraging.

    Science.gov (United States)

    Sakiyama, Tomoko; Gunji, Yukio-Pegio

    2013-01-01

    The Müller-Lyer illusion is a classical geometric illusion in which the apparent (perceived) length of a line depends on whether the line terminates in an arrow tail or arrowhead. This effect may be caused by economic compensation for the gap between the physical stimulus and visual fields. Here, we show that the Müller-Lyer illusion can also be produced by the foraging patterns of garden ants (Lasius niger) and that the pattern obtained can be explained by a simple, asynchronously updated foraging ant model. Our results suggest that the geometric illusion may be a byproduct of the foraging process, in which local interactions underlying efficient exploitation can also give rise to global exploration, and that visual information processing in human could implement similar modulation between local efficient processing and widespread computation.

  13. The Muller-Lyer illusion in ant foraging.

    Directory of Open Access Journals (Sweden)

    Tomoko Sakiyama

    Full Text Available The Müller-Lyer illusion is a classical geometric illusion in which the apparent (perceived length of a line depends on whether the line terminates in an arrow tail or arrowhead. This effect may be caused by economic compensation for the gap between the physical stimulus and visual fields. Here, we show that the Müller-Lyer illusion can also be produced by the foraging patterns of garden ants (Lasius niger and that the pattern obtained can be explained by a simple, asynchronously updated foraging ant model. Our results suggest that the geometric illusion may be a byproduct of the foraging process, in which local interactions underlying efficient exploitation can also give rise to global exploration, and that visual information processing in human could implement similar modulation between local efficient processing and widespread computation.

  14. Klubi Illusion toob Tartusse New Yorgi ja Londoni / Riho Laurisaar

    Index Scriptorium Estoniae

    Laurisaar, Riho

    2006-01-01

    Stalini-aegses kinohoones Tartus avati suurlinlik klubi "Illusion". Sisekujunduses pole jälgitud kindlat stiili, koos on kitsh ja glamuur, klassika ja ajalooline arhitektuur. Sisearhitekt Jaanis Ilves

  15. Positive illusions about a partner's personality and relationship quality

    NARCIS (Netherlands)

    Barelds, Dick P. H.; Dijkstra, Pieternel

    Previous studies have shown individuals to hold positive biases about their relationships. The present study examined positive illusions about a partner's specific personality characteristics in relation to relationship quality and personality. Both partners of 120 heterosexual couples participated

  16. Becoming angular momentum density flow through nonlinear mass transfer into a gravitating spheroidal body

    Science.gov (United States)

    Krot, A. M.

    2009-04-01

    A statistical theory for a cosmological body forming based on the spheroidal body model has been proposed in the works [1]-[4]. This work studies a slowly evolving process of gravitational condensation of a spheroidal body from an infinitely distributed gas-dust substance in space. The equation for an initial evolution of mass density function of a gas-dust cloud is considered here. It is found this equation coincides completely with the analogous equation for a slowly gravitational compressed spheroidal body [5]. A conductive flow in dissipative systems was investigated by I. Prigogine in his works (see, for example, [6], [7]). As it has been found in [2], [5], there exists a conductive antidiffusion flow in a slowly compressible gravitating spheroidal body. Applying the equation of continuity to this conductive flow density we obtain a linear antidiffusion equation [5]. However, if an intensity of conductive flow density increases sharply then the linear antidiffusion equation becomes a nonlinear one. Really, it was pointed to [6] analogous linear equations of diffusion or thermal conductivity transform in nonlinear equations respectively. In this case, the equation of continuity describes a nonlinear mass flow being a source of instabilities into a gravitating spheroidal body because the gravitational compression factor G is a function of not only time but a mass density. Using integral substitution we can reduce a nonlinear antidiffusion equation to the linear antidiffusion equation relative to a new function. If the factor G can be considered as a specific angular momentum then the new function is an angular momentum density. Thus, a nonlinear momentum density flow induces a flow of angular momentum density because streamlines of moving continuous substance come close into a gravitating spheroidal body. Really, the streamline approach leads to more tight interactions of "liquid particles" that implies a superposition of their specific angular momentums. This

  17. ILLUSION, DISILLUSION, AND IRONY IN PSYCHOANALYSIS.

    Science.gov (United States)

    Steiner, John

    2016-04-01

    The author draws a parallel between an analyst listening to a patient and a member of an audience watching a play. In both situations, it is important to be able to adopt a dual identity in order to participate in the action through identification and then to withdraw from the identification to adopt the position of an observer. The author discusses two plays, Ibsen's The Wild Duck (1884) and Sophocles's Oedipus the King (5th century BC, a), and concludes that an ironic attitude to these works can help the spectator to adopt these dual identities and to recognize the value of truth, while at the same time appreciating that reality can be harsh and sometimes unbearable. A similar ironic vision in relation to his patients can enable the analyst to retain a respect for truth alongside a sympathetic awareness of the need for illusion.

  18. Alternative energies - the illusion and the facts

    Energy Technology Data Exchange (ETDEWEB)

    Schnell, P.

    1981-08-31

    Alternative eneriges and energy techniques are evaluated very differently from the point of view of their contribution to energy supply. The present article attempts to make a reasonable estimate of their possibilities and limits. It is found that, from the potenial inexhaustible energies, only a fraction can actually be utilised in a reasonable manner. Although it is an illusion - by wider utilisation of inexhaustible energies to dispense with nuclear energy also, in the long view a notable contribution is to be expected for world energy supply. The existing structures of the electricity economy in the Federal Republic of Germany offer adequate provision for an initial exploitation of the, here severely limited, potential of inexhaustible energies.

  19. Women in Illusion:An Analysis of Women Characters in The Glass Menagerie

    Institute of Scientific and Technical Information of China (English)

    王冬梅

    2009-01-01

    The paper tries to analyze women characters in Tennessee Williams' Drama The Glass Menagerie.Laura and Amanda,the daughter and the mother,represent the delicate and fragile southern female images.They both feel desper-ate about the reality and retreat to their own world of illusions.Laura,because of her crippled body,cannot face the or-dinary problems of life and withdraws into the world of glass animals.Amanda Wingfield is unable to face the harsh struggle for survival,constantly retreats to her past memories.

  20. Two Left Hands, Ten Interlaced Fingers: A New Rubber Hand Illusion.

    Science.gov (United States)

    White, Rebekah C; Bowen, Dillon; Dumbalska, Tsvetomira; Hoeger, Katharine; Mok, Anastasia Y S

    2016-03-01

    A variation on the rubber hand paradigm elicits an illusion in which the participant's sense of body ownership can switch back and forth between two viewed prosthetic hands. The interlaced fingers paradigm involves three prosthetic left hands: Two are positioned in full view of the participant, with their fingers interlaced, and the fingers of a third prosthetic hand are interlaced with the fingers of the participant's left hand, which is hidden from view. The examiner alternates brushstrokes to the two viewed prosthetic hands, while administering synchronous brushstrokes to the participant's hidden hand. Most participants experience ownership for the prosthetic hand that is being stroked at a given moment.

  1. Mercury Retrograde Effect in Capital Markets: Truth or Illusion?

    Directory of Open Access Journals (Sweden)

    Murgea Aurora

    2016-06-01

    Full Text Available From the most ancient times, the astrological beliefs have played an important role in human history, thinking, world-views, language and other elements of social culture. The practice of relating the movement of celestial bodies to events in financial markets is relatively newer but despite the inconsistency between financial astrology and standard economic or financial theory, it seems to be largely spread among capital market traders. This paper evaluates one of the astrological effects on the capital market, more precisely the Mercury retrograde effect on US capital market. Despite the fact that it is just an optical illusion the astrological tradition says that Mercury retrograde periods are characterized by confusion and miscommunications. The trades could be less effective, the individuals more prone to make mistakes so there is a long-held belief that it is better to avoid set plans during Mercury retrograde, signing contracts, starting new ventures or open new stock market positions. The main findings of this study are lower return’s volatilities in the Mercury retrograde periods, inconsistent with the astrologic theories assumptions but consistent with the idea that trader’s beliefs in Mercury retrograde effect could change the market volatility exactly in the opposite sense than the predicted one.

  2. Exploring the Impact of Ketamine on the Experience of Illusory Body Ownership

    NARCIS (Netherlands)

    Morgan, Hannah L.; Turner, Danielle C.; Corlett, Philip R.; Absalom, Anthony R.; Adapa, Ram; Arana, Fernando S.; Pigott, Jennifer; Gardner, Jenny; Everitt, Jessica; Haggard, Patrick; Fletcher, Paul C.

    2011-01-01

    Background: Our sense of body ownership is profound and familiar, yet it may be misleading. In the rubber-hand illusion, synchronous tactile and visual stimulation lead to the experience that a rubber hand is actually one's own. This illusion is stronger in schizophrenia. Given the evidence that

  3. Exploring the Impact of Ketamine on the Experience of Illusory Body Ownership

    NARCIS (Netherlands)

    Morgan, Hannah L.; Turner, Danielle C.; Corlett, Philip R.; Absalom, Anthony R.; Adapa, Ram; Arana, Fernando S.; Pigott, Jennifer; Gardner, Jenny; Everitt, Jessica; Haggard, Patrick; Fletcher, Paul C.

    2011-01-01

    Background: Our sense of body ownership is profound and familiar, yet it may be misleading. In the rubber-hand illusion, synchronous tactile and visual stimulation lead to the experience that a rubber hand is actually one's own. This illusion is stronger in schizophrenia. Given the evidence that ket

  4. A moving-barber-pole illusion.

    Science.gov (United States)

    Sun, Peng; Chubb, Charles; Sperling, George

    2014-05-01

    In the barber-pole illusion (BPI), a diagonally moving grating is perceived as moving vertically because of the shape of the vertically oriented window through which it is viewed-a strong shape-motion interaction. We introduce a novel stimulus-the moving barber pole-in which a diagonal, drifting sinusoidal carrier is windowed by a raised, vertical, drifting sinusoidal modulator that moves independently of the carrier. In foveal vision, the moving-barber-pole stimulus can be perceived as several active barber poles drifting horizontally but also as other complex dynamic patterns. In peripheral vision, pure vertical motion (the moving-barber-pole illusion [MBPI]) is perceived for a wide range of conditions. In foveal vision, the MBPI is observed, but only when the higher-order modulator motion is masked. Theories to explain the BPI make indiscriminable predictions in a standard barber-pole display. But, in moving-barber-pole stimuli, the motion directions of features (e.g., end stops) of the first-order carrier and of the higher-order modulator are all different from the MBPI. High temporal frequency stimuli viewed peripherally greatly reduce the effectiveness of higher-order motion mechanisms and, ideally, isolate a single mechanism responsible for the MBPI. A three-stage motion-path integration mechanism that (a) computes local motion energies, (b) integrates them for a limited time period along various spatial paths, and (c) selects the path with the greatest motion energy, quantitatively accounts for these high-frequency data. The MBPI model also accounts for the perceived motion-direction in peripherally viewed moving-barber-pole stimuli that do and do not exhibit the MBPI over the entire range of modulator (0-10 Hz) and carrier (2.5-10 Hz) temporal frequencies tested.

  5. Frenkel and Charge-Transfer Excitations in Donor-acceptor Complexes from Many-Body Green's Functions Theory.

    Science.gov (United States)

    Baumeier, Björn; Andrienko, Denis; Rohlfing, Michael

    2012-08-14

    Excited states of donor-acceptor dimers are studied using many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation. For a series of prototypical small-molecule based pairs, this method predicts energies of local Frenkel and intermolecular charge-transfer excitations with the accuracy of tens of meV. Application to larger systems is possible and allowed us to analyze energy levels and binding energies of excitons in representative dimers of dicyanovinyl-substituted quarterthiophene and fullerene, a donor-acceptor pair used in state of the art organic solar cells. In these dimers, the transition from Frenkel to charge transfer excitons is endothermic and the binding energy of charge transfer excitons is still of the order of 1.5-2 eV. Hence, even such an accurate dimer-based description does not yield internal energetics favorable for the generation of free charges either by thermal energy or an external electric field. These results confirm that, for qualitative predictions of solar cell functionality, accounting for the explicit molecular environment is as important as the accurate knowledge of internal dimer energies.

  6. An Experimental Research on Causal Illusion (in Chinese)

    OpenAIRE

    Shao, Z. F.; Zhao, J.

    2004-01-01

    The research examined humans’ causal attribution of response-outcome under controllable and uncontrollable conditions respectively and attempted to find out whether providing appropriate external cues could be beneficial to them in making accurate judgments. The results indicate: 1) under controllable conditions, the delay of feedback might lead to causal illusion; 2) under uncontrollable conditions, the subjects developed superstition and illusion of control rather than helplessness; 3) prov...

  7. Many-Body Theory of Ultrafast Demagnetization and Angular Momentum Transfer in Ferromagnetic Transition Metals.

    Science.gov (United States)

    Töws, W; Pastor, G M

    2015-11-20

    Exact calculated time evolutions in the framework of a many-electron model of itinerant magnetism provide new insights into the laser-induced ultrafast demagnetization observed in ferromagnetic (FM) transition metal thin films. The interplay between local spin-orbit interactions and interatomic hopping is shown to be at the origin of the observed postexcitation breakdown of FM correlations between highly stable local magnetic moments. The mechanism behind spin- and angular-momentum transfer is revealed from a microscopic perspective by rigorously complying with all fundamental conservation laws. An energy-resolved analysis of the time evolution shows that the efficiency of the demagnetization process reaches almost 100% in the excited states.

  8. Perspectives and possible applications of the rubber hand and virtual hand illusion in non-invasive rehabilitation: technological improvements and their consequences.

    Science.gov (United States)

    Christ, Oliver; Reiner, Miriam

    2014-07-01

    This review introduces theoretical aspects of the rubber hand illusion (RHI) and virtual hand illusion (VHI), and discusses their possible clinical applications. It also presents technical improvements regarding the realization of the RHI and VHI and their relation to rehabilitation issues. There is presently little evidence describing the value of the RHI and VHI as indices in the diagnosis or treatment of different pathologies, likely because of a lack of standardization in reporting the results of RHI and VHI studies. In contrast, a new emerging "out-of-body illusion" appears to be an interesting new approach; however, as in RHI and VHI, there are additional consequences regarding its application in clinical settings because of its technological demands. This review considers the acceptance of technology and the realization of immersion/presence in the context of virtual rehabilitation.

  9. Vertical-horizontal illusion: one eye is better than two.

    Science.gov (United States)

    Prinzmetal, W; Gettleman, L

    1993-01-01

    The vertical-horizontal illusion is the tendency for observers to overestimate the length of a vertical line relative to a horizontal line that has the same length. One explanation of this illusion is that the visual field is elongated in the horizontal direction, and that the vertical-horizontal illusion is a kind of framing effect (Künnapas, 1957a, 1957b, 1957c). Since the monocular visual field is less asymmetric than the combined visual field, this theory predicts that the illusion should be reduced with monocular presentation. This prediction was tested in five experiments, in which the vertical-horizontal illusion was examined in a variety of situations--including observers seated upright versus reclined 90 degrees, monocular presentation with the dominant versus the nondominant eye, viewing in the dark versus in the light, and viewing with asymmetrical frames of reference. The illusion was reliably reduced with monocular presentation under conditions that affected the asymmetry of the phenomenal visual field.

  10. The Emergence of Figural Effects in the Watercolor Illusion

    Science.gov (United States)

    Pinna, Baingio; Penna, Maria Pietronilla

    The watercolor illusion is characterized by a large-scale assimilative color spreading (coloration effect) emanating from thin colored edges. The watercolor illusion enhances the figural properties of the colored areas and imparts to the surrounding area the perceptual status of background. This work explores interactions between cortical boundary and surface processes by presenting displays and psychophysical experiments that exhibit new properties of the watercolor illusion. The watercolor illusion is investigated as supporting a new principle of figure-ground organization when pitted against principles of surroundedness, relative orientation, and Prägnanz. The work demonstrated that the watercolor illusion probes a unique combination of visual processes that set it apart from earlier Gestalt principles, and can compete successfully against them. This illusion exemplifies how long-range perceptual effects may be triggered by spatially sparse information. All the main effects are explained by the FACADE model of biological vision, which clarifies how local properties control depthful filling-in of surface lightness and color.

  11. New model of angular momentum transfer from the rotating central body of a two-body system into the orbital motion of this system (with application to the earth-moon system)

    CERN Document Server

    Schmutzer, E

    2005-01-01

    In a previous paper we treated within the framework of our Projective Unified Field Theory (Schmutzer 2004, Schmutzer 2005a) the 2-body system (e.g. earth-moon system) with a rotating central body in a rather abstract manner. Here a concrete model of the transfer of angular momentum from the rotating central body to the orbital motion of the whole 2-body system is presented, where particularly the transfer is caused by the inhomogeneous gravitational force of the moon acting on the oceanic waters of the earth, being modeled by a spherical shell around the solid earth. The theory is numerically tested. Key words: transfer of angular momentum from earth to moon, action of the gravitational force of the moon on the waters of the earth.

  12. Strongly coupled near-field radiative and conductive heat transfer between planar bodies

    Science.gov (United States)

    Messina, Riccardo; Jin, Weiliang; Rodriguez, Alejandro W.

    2016-09-01

    We study the interplay of conductive and radiative heat transfer (RHT) in planar geometries and predict that temperature gradients induced by radiation can play a significant role on the behavior of RHT with respect to gap sizes, depending largely on geometric and material parameters and not so crucially on operating temperatures. Our findings exploit rigorous calculations based on a closed-form expression for the heat flux between two plates separated by vacuum gaps d and subject to arbitrary temperature profiles, along with an approximate but accurate analytical treatment of coupled conduction-radiation in this geometry. We find that these effects can be prominent in typical materials (e.g., silica and sapphire) at separations of tens of nanometers, and can play an even larger role in metal oxides, which exhibit moderate conductivities and enhanced radiative properties. Broadly speaking, these predictions suggest that the impact of RHT on thermal conduction, and vice versa, could manifest itself as a limit on the possible magnitude of RHT at the nanoscale, which asymptotes to a constant (the conductive transfer rate when the gap is closed) instead of diverging at short separations.

  13. A specialized bird pollination system with a bellows mechanism for pollen transfer and staminal food body rewards.

    Science.gov (United States)

    Dellinger, Agnes S; Penneys, Darin S; Staedler, Yannick M; Fragner, Lena; Weckwerth, Wolfram; Schönenberger, Jürg

    2014-07-21

    Bird pollination has evolved repeatedly among flowering plants but is almost exclusively characterized by passive transfer of pollen onto the bird and by nectar as primary reward [1, 2]. Food body rewards are exceedingly rare among eudicot flowering plants and are only known to occur on sterile floral organs [3]. In this study, we report an alternative bird pollination mechanism involving bulbous stamen appendages in the Neotropical genus Axinaea (Melastomataceae). We studied the pollination process by combining pollination experiments, video monitoring, and detailed analyses of stamen structure and metabolomic composition. We show that the bulbous stamen appendages, which are consumed by various species of passerines (Thraupidae, Fringillidae), are bifunctional during the pollination process. First, the appendages work as bellows organs in a unique pollen expulsion mechanism activated by the passerines. As the birds seize an appendage with their beaks in order to remove it from the flower for consumption, air contained in the appendage's aerenchymatous tissue is pressed into the hollow anther. The resulting air flow causes the expulsion of a pollen jet and the deposition of pollen on the bird's head and beak. Second, the stamen appendages provide a hexose-rich, highly nutritious (15,100 J/g) food body reward for the pollinating passerines. This discovery expands our knowledge of flowering plant pollination systems and provides the first report of highly specialized bellows organs for active pollen transfer in flowering plants. In addition, this is the only known case of a food body reward associated with reproductive structures in the eudicot clade of flowering plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Calculation of convective heat transfer on highly blunt bodies at flow incidence

    Science.gov (United States)

    Li, C. P.

    1989-01-01

    An implicit finite-difference code is used to study three-dimensional viscous heat-conducting flows over the forebody of hypersonic vehicles. In the method, adaptive grids are generated to the shock and body contour, and local flow gradients and total enthalpy are used to control numerical dissipation. Typical axisymmetric configurations of a sphere, ellipsoid, and flat-face disk are considered, along with the cases of a blunt 70-deg cone at 0 and 20 deg flow incidences and an asymmetric 60-deg cone raked off at a 73-deg angle.

  15. The magnetic touch illusion: A perceptual correlate of visuo-tactile integration in peripersonal space.

    Science.gov (United States)

    Guterstam, Arvid; Zeberg, Hugo; Özçiftci, Vedat Menderes; Ehrsson, H Henrik

    2016-10-01

    To accurately localize our limbs and guide movements toward external objects, the brain must represent the body and its surrounding (peripersonal) visual space. Specific multisensory neurons encode peripersonal space in the monkey brain, and neurobehavioral studies have suggested the existence of a similar representation in humans. However, because peripersonal space lacks a distinct perceptual correlate, its involvement in spatial and bodily perception remains unclear. Here, we show that applying brushstrokes in mid-air at some distance above a rubber hand-without touching it-in synchrony with brushstrokes applied to a participant's hidden real hand results in the illusory sensation of a "magnetic force" between the brush and the rubber hand, which strongly correlates with the perception of the rubber hand as one's own. In eight experiments, we characterized this "magnetic touch illusion" by using quantitative subjective reports, motion tracking, and behavioral data consisting of pointing errors toward the rubber hand in an intermanual pointing task. We found that the illusion depends on visuo-tactile synchrony and exhibits similarities with the visuo-tactile receptive field properties of peripersonal space neurons, featuring a non-linear decay at 40cm that is independent of gaze direction and follows changes in the rubber hand position. Moreover, the "magnetic force" does not penetrate physical barriers, thus further linking this phenomenon to body-specific visuo-tactile integration processes. These findings provide strong support for the notion that multisensory integration within peripersonal space underlies bodily self-attribution. Furthermore, we propose that the magnetic touch illusion constitutes a perceptual correlate of visuo-tactile integration in peripersonal space.

  16. Review on modeling heat transfer and thermoregulatory responses in human body.

    Science.gov (United States)

    Fu, Ming; Weng, Wenguo; Chen, Weiwang; Luo, Na

    2016-12-01

    Several mathematical models of human thermoregulation have been developed, contributing to a deep understanding of thermal responses in different thermal conditions and applications. In these models, the human body is represented by two interacting systems of thermoregulation: the controlling active system and the controlled passive system. This paper reviews the recent research of human thermoregulation models. The accuracy and scope of the thermal models are improved, for the consideration of individual differences, integration to clothing models, exposure to cold and hot conditions, and the changes of physiological responses for the elders. The experimental validated methods for human subjects and manikin are compared. The coupled method is provided for the manikin, controlled by the thermal model as an active system. Computational Fluid Dynamics (CFD) is also used along with the manikin or/and the thermal model, to evaluate the thermal responses of human body in various applications, such as evaluation of thermal comfort to increase the energy efficiency, prediction of tolerance limits and thermal acceptability exposed to hostile environments, indoor air quality assessment in the car and aerospace industry, and design protective equipment to improve function of the human activities.

  17. Illusions in the spatial sense of the eye: geometrical-optical illusions and the neural representation of space.

    Science.gov (United States)

    Westheimer, Gerald

    2008-09-01

    Differences between the geometrical properties of simple configurations and their visual percept are called geometrical-optical illusions. They can be differentiated from illusions in the brightness or color domains, from ambiguous figures and impossible objects, from trompe l'oeil and perspective drawing with perfectly valid views, and from illusory contours. They were discovered independently by several scientists in a short time span in the 1850's. The clear distinction between object and visual space that they imply allows the question to be raised whether the transformation between the two spaces can be productively investigated in terms of differential geometry and metrical properties. Perceptual insight and psychophysical research prepares the ground for investigation of the neural representation of space but, because visual attributes are processed separately in parallel, one looks in vain for a neural map that is isomorphic with object space or even with individual forms it contains. Geometrical-optical illusions help reveal parsing rules for sensory signals by showing how conflicts are resolved when there is mismatch in the output of the processing modules for various primitives as a perceptual pattern's unitary structure is assembled. They point to a hierarchical ordering of spatial primitives: cardinal directions and explicit contours predominate over oblique orientation and implicit contours (Poggendorff illusion); rectilinearity yields to continuity (Hering illusion), point position and line length to contour orientation (Ponzo). Hence the geometrical-optical illusions show promise as analytical tools in unraveling neural processing in vision.

  18. Convective heat transfer from a nude body under calm conditions: assessment of the effects of walking with a thermal manikin.

    Science.gov (United States)

    Oliveira, A Virgílio M; Gaspar, Adélio R; Francisco, Sara C; Quintela, Divo A

    2012-03-01

    The present experimental work is dedicated to the analysis of the effect of walking on the thermal insulation of the air layer (I (a)) and on the convective heat transfer coefficients (h (conv)) of the human body. Beyond the standing static posture, three step rates were considered: 20, 30 and 45 steps/min. This corresponds to walking speeds of approximately 0.23, 0.34 and 0.51 m/s, respectively. The experiments took place in a climate chamber with an articulated thermal manikin with 16 independent parts. The indoor environment was controlled through the inner wall temperatures since the objective of the tests was restricted to the influence of the walking movements under calm conditions. Five set points were selected: 10, 15, 20, 25 and 30°C, and the operative temperature within the test chamber varied between 11.9 and 29.6°C. The highest and lowest I ( a ) values obtained were equal to 0.87 and 0.71 clo, respectively, and the reduction in insulation due to walking ranged between 9.8 and 11.5%. The convective coefficients (h (conv)) for the whole body and for the different body segments were also determined for each step rate. In the case of the whole body, for the standing static reference posture, the mean value of h (conv) was equal to 3.3 W/m(2)°C and a correlation [Nu = Nu(Gr)] for natural convection is also presented in good agreement with previous results. For the other postures, the values of h (conv) were equal to 3.7, 3.9 and 4.2 W/m(2)°C, respectively for 20, 30 and 45 steps/min.

  19. Information processing correlates of a size-contrast illusion

    Directory of Open Access Journals (Sweden)

    Jason M Gold

    2014-02-01

    Full Text Available Perception is often influenced by context. A well-known class of perceptual context effects is perceptual contrast illusions, in which proximate stimulus regions interact to alter the perception of various stimulus attributes, such as perceived brightness, color and size. Although the phenomenal reality of contrast effects is well documented, in many cases the connection between these illusions and how information is processed by perceptual systems is not well understood. Here, we use noise as a tool to explore the information processing correlates of one such contrast effect: the Ebbinghaus-Titchener size-contrast illusion. In this illusion, the perceived size of a central dot is significantly altered by the sizes of a set of surrounding dots, such that the presence of larger surrounding dots tends to reduce the perceived size of the central dot (and vise-versa. In our experiments, we first replicated previous results that have demonstrated the subjective reality of the Ebbinghaus-Titchener illusion. We then used visual noise in a detection task to probe the manner in which observers processed information when experiencing the illusion. By correlating the noise with observers’ classification decisions, we found that the sizes of the surrounding contextual elements had a direct influence on the relative weight observers assigned to regions within and surrounding the central element. Specifically, observers assigned relatively more weight to the surrounding region and less weight to the central region in the presence of smaller surrounding contextual elements. These results offer new insights into the connection between the subjective experience of size-contrast illusions and their associated information processing correlates.

  20. Seeing Is the Hardest Thing to See: Using Illusions to Teach Visual Perception

    Science.gov (United States)

    Riener, Cedar

    2015-01-01

    This chapter describes three examples of using illusions to teach visual perception. The illusions present ways for students to change their perspective regarding how their eyes work and also offer opportunities to question assumptions regarding their approach to knowledge.

  1. The human touch: skin temperature during the rubber hand illusion in manual and automated stroking procedures.

    Directory of Open Access Journals (Sweden)

    Marieke Rohde

    Full Text Available A difference in skin temperature between the hands has been identified as a physiological correlate of the rubber hand illusion (RHI. The RHI is an illusion of body ownership, where participants perceive body ownership over a rubber hand if they see it being stroked in synchrony with their own occluded hand. The current study set out to replicate this result, i.e., psychologically induced cooling of the stimulated hand using an automated stroking paradigm, where stimulation was delivered by a robot arm (PHANToM(TM force-feedback device. After we found no evidence for hand cooling in two experiments using this automated procedure, we reverted to a manual stroking paradigm, which is closer to the one employed in the study that first produced this effect. With this procedure, we observed a relative cooling of the stimulated hand in both the experimental and the control condition. The subjective experience of ownership, as rated by the participants, by contrast, was strictly linked to synchronous stroking in all three experiments. This implies that hand-cooling is not a strict correlate of the subjective feeling of hand ownership in the RHI. Factors associated with the differences between the two designs (differences in pressure of tactile stimulation, presence of another person that were thus far considered irrelevant to the RHI appear to play a role in bringing about this temperature effect.

  2. The Human Touch: Skin Temperature during the Rubber Hand Illusion in Manual and Automated Stroking Procedures

    Science.gov (United States)

    Rohde, Marieke; Wold, Andrew; Karnath, Hans-Otto; Ernst, Marc O.

    2013-01-01

    A difference in skin temperature between the hands has been identified as a physiological correlate of the rubber hand illusion (RHI). The RHI is an illusion of body ownership, where participants perceive body ownership over a rubber hand if they see it being stroked in synchrony with their own occluded hand. The current study set out to replicate this result, i.e., psychologically induced cooling of the stimulated hand using an automated stroking paradigm, where stimulation was delivered by a robot arm (PHANToMTM force-feedback device). After we found no evidence for hand cooling in two experiments using this automated procedure, we reverted to a manual stroking paradigm, which is closer to the one employed in the study that first produced this effect. With this procedure, we observed a relative cooling of the stimulated hand in both the experimental and the control condition. The subjective experience of ownership, as rated by the participants, by contrast, was strictly linked to synchronous stroking in all three experiments. This implies that hand-cooling is not a strict correlate of the subjective feeling of hand ownership in the RHI. Factors associated with the differences between the two designs (differences in pressure of tactile stimulation, presence of another person) that were thus far considered irrelevant to the RHI appear to play a role in bringing about this temperature effect. PMID:24260454

  3. Relationship between sensitivity to visuotactile temporal discrepancy and the rubber hand illusion.

    Science.gov (United States)

    Shimada, Sotaro; Suzuki, Tatsuya; Yoda, Naohiko; Hayashi, Tomoya

    2014-08-01

    The rubber-hand illusion (RHI) is that the subject feels the visually presented tactile stimulation of an artificial (rubber) hand as their own tactile sensation and is caused by stimulating the rubber and real hands synchronously. Our previous study showed that the RHI was greatly reduced as the visual feedback delay of the tactile stimulation of the hand became longer. In the present study, we investigate the relationship between the attenuation of the RHI and the detection of the delay in two experiments: (1) an RHI experiment and (2) a visuotactile asynchrony detection experiment, in which the subjects underwent tactile stimulation of their hand and judged whether visual feedback was consistent with the touch sensation. In line with our previous study, the RHI was significantly reduced as the delay lengthened. Interestingly, proprioceptive drift declined linearly as the delay increased, while the delay detection rate was better fitted by a non-linear (logistic) function. The illusion score showed the intermittent pattern. We suggest that proprioceptive drift is relevant to the processing of the body schema, whereas the delay detection and the subjective feeling of the RHI are more related to the body image processing.

  4. Thermoregulation during flight: body temperature and sensible heat transfer in free-ranging Brazilian free-tailed bats (Tadarida brasiliensis).

    Science.gov (United States)

    Reichard, Jonathan D; Fellows, Spenser R; Frank, Alexander J; Kunz, Thomas H

    2010-01-01

    Bat wings are important for thermoregulation, but their role in heat balance during flight is largely unknown. More than 80% of the energy consumed during flight generates heat as a by-product, and thus it is expected that bat wings should dissipate large amounts of heat to prevent hyperthermia. We measured rectal (T(r)) and surface (T(s)) temperatures of Brazilian free-tailed bats (Tadarida brasiliensis) as they emerged from and returned to their daytime roosts and calculated sensible heat transfer for different body regions (head, body, wings, and tail membrane). Bats' T(r) decreased from 36.8°C during emergence flights to 34.4°C during returns, and T(s) scaled positively with ambient temperature (T(a)). Total radiative heat loss from bats was significantly greater for a radiative sink to the night sky than for a sink with temperature equal to T(a). We found that free-ranging Brazilian free-tailed bats, on average, do not dissipate heat from their wings by convection but instead dissipate radiative heat (L) to the cloudless night sky during flight ([Formula: see text] W). However, within the range of T(a) measured in this study, T. brasiliensis experienced net heat loss between evening emergence and return flights. Regional hypothermia reduces heat loss from wings that are exposed to potentially high convective fluxes. Additional research is needed to establish the role of wings in evaporative cooling during flight in bats.

  5. Pathological gamblers are more vulnerable to the illusion of control in a standard associative learning task

    OpenAIRE

    Orgaz, Cristina; Estévez, Ana; Matute, Helena

    2013-01-01

    An illusion of control is said to occur when a person believes that he or she controls an outcome that is uncontrollable. Pathological gambling has often been related to an illusion of control, but the assessment of the illusion has generally used introspective methods in domain-specific (i.e., gambling) situations. The illusion of control of pathological gamblers, however, could be a more general problem, affecting other aspects of their daily life. Thus, we tested them using a standard asso...

  6. Time course of the effect of the Muller-Lyer illusion on saccades and perceptual judgments

    OpenAIRE

    Brouwer, A.J. de; Brenner, E.; Medendorp, W. P.; Smeets, J. B. J.

    2014-01-01

    The amplitude of saccadic eye movements is affected by size illusions such as the Muller-Lyer illusion, but this effect varies highly between studies. Here we examine the origin of this variability by testing the influence of three temporal factors on the effect of the Muller-Lyer illusion: presentation time, response delay, and saccade latency. Subjects performed reflexive saccades, deferred saccades, and memory-guided saccades along the shaft of the illusion. We evaluated the time course of...

  7. Adaptation to Coriolis perturbations of voluntary body sway transfers to preprogrammed fall-recovery behavior.

    Science.gov (United States)

    Bakshi, Avijit; Ventura, Joel; DiZio, Paul; Lackner, James R

    2014-03-01

    In a rotating environment, goal-oriented voluntary movements are initially disrupted in trajectory and endpoint, due to movement-contingent Coriolis forces, but accuracy is regained with additional movements. We studied whether adaptation acquired in a voluntary, goal-oriented postural swaying task performed during constant-velocity counterclockwise rotation (10 RPM) carries over to recovery from falling induced using a hold and release (H&R) paradigm. In H&R, standing subjects actively resist a force applied to their chest, which when suddenly released results in a forward fall and activation of an automatic postural correction. We tested H&R postural recovery in subjects (n = 11) before and after they made voluntary fore-aft swaying movements during 20 trials of 25 s each, in a counterclockwise rotating room. Their voluntary sway about their ankles generated Coriolis forces that initially induced clockwise deviations of the intended body sway paths, but fore-aft sway was gradually restored over successive per-rotation trials, and a counterclockwise aftereffect occurred during postrotation attempts to sway fore-aft. In H&R trials, we examined the initial 10- to 150-ms periods of movement after release from the hold force, when voluntary corrections of movement path are not possible. Prerotation subjects fell directly forward, whereas postrotation their forward motion was deviated significantly counterclockwise. The postrotation deviations were in a direction consistent with an aftereffect reflecting persistence of a compensation acquired per-rotation for voluntary swaying movements. These findings show that control and adaptation mechanisms adjusting voluntary postural sway to the demands of a new force environment also influence the automatic recovery of posture.

  8. A method for generating an illusion of backwards time travel using immersive virtual reality-an exploratory study.

    Science.gov (United States)

    Friedman, Doron; Pizarro, Rodrigo; Or-Berkers, Keren; Neyret, Solène; Pan, Xueni; Slater, Mel

    2014-01-01

    We introduce a new method, based on immersive virtual reality (IVR), to give people the illusion of having traveled backwards through time to relive a sequence of events in which they can intervene and change history. The participant had played an important part in events with a tragic outcome-deaths of strangers-by having to choose between saving 5 people or 1. We consider whether the ability to go back through time, and intervene, to possibly avoid all deaths, has an impact on how the participant views such moral dilemmas, and also whether this experience leads to a re-evaluation of past unfortunate events in their own lives. We carried out an exploratory study where in the "Time Travel" condition 16 participants relived these events three times, seeing incarnations of their past selves carrying out the actions that they had previously carried out. In a "Repetition" condition another 16 participants replayed the same situation three times, without any notion of time travel. Our results suggest that those in the Time Travel condition did achieve an illusion of "time travel" provided that they also experienced an illusion of presence in the virtual environment, body ownership, and agency over the virtual body that substituted their own. Time travel produced an increase in guilt feelings about the events that had occurred, and an increase in support of utilitarian behavior as the solution to the moral dilemma. Time travel also produced an increase in implicit morality as judged by an implicit association test. The time travel illusion was associated with a reduction of regret associated with bad decisions in their own lives. The results show that when participants have a third action that they can take to solve the moral dilemma (that does not immediately involve choosing between the 1 and the 5) then they tend to take this option, even though it is useless in solving the dilemma, and actually results in the deaths of a greater number.

  9. Overdistribution illusions: Categorical judgments produce them, confidence ratings reduce them.

    Science.gov (United States)

    Brainerd, C J; Nakamura, K; Reyna, V F; Holliday, R E

    2017-01-01

    Overdistribution is a form of memory distortion in which an event is remembered as belonging to too many episodic states, states that are logically or empirically incompatible with each other. We investigated a response formatting method of suppressing 2 basic types of overdistribution, disjunction and conjunction illusions, which parallel some classic illusions in the judgment and decision making literature. In this method, subjects respond to memory probes by rating their confidence that test cues belong to specific episodic states (e.g., presented on List 1, presented on List 2), rather than by making the usual categorical judgments about those states. The central prediction, which was derived from the task calibration principle of fuzzy-trace theory, was that confidence ratings should reduce overdistribution by diminishing subjects' reliance on noncompensatory gist memories. The data of 3 experiments agreed with that prediction. In Experiment 1, there were reliable disjunction illusions with categorical judgments but not with confidence ratings. In Experiment 2, both response formats produced reliable disjunction illusions, but those for confidence ratings were much smaller than those for categorical judgments. In Experiment 3, there were reliable conjunction illusions with categorical judgments but not with confidence ratings. Apropos of recent controversies over confidence-accuracy correlations in memory, such correlations were positive for hits, negative for correct rejections, and the 2 types of correlations were of equal magnitude. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  10. Directional organization and shape formation: new illusions and Helmholtz's Square.

    Science.gov (United States)

    Pinna, Baingio

    2015-01-01

    According to Helmholtz's Square illusion, a square appears wider when it is filled with vertical lines and higher when filled with horizontal lines (Helmholtz von, 1866). Recently, Pinna (2010a) demonstrated that the grouping of small squares on the basis of the similarity principle influences also perception of their shape and of the whole emerging shapes. The direction imparted by grouping is the main attribute that influences the shape by polarizing it in the same direction both globally and locally. The rectangle illusion is opposite to what expected on the basis of Helmholtz's Square illusion. Aim of this work is to solve the antinomy between the two sets of illusions and to demonstrate a common explanation based on the interaction between different sources of directional organization. This was accomplished by introducing some new phenomena and through phenomenological experiments proving the role played by the directional shape organization in shape formation. According to our results, Helmholtz's square illusion shows at least two synergistic sources of directional organization: the direction of the grouping of the lines due to their similarity of the luminance contrast and the direction of the grouping of the lines due to the good continuation.

  11. Subjective illusion of control modulates striatal reward anticipation in adolescence.

    Science.gov (United States)

    Lorenz, Robert C; Gleich, Tobias; Kühn, Simone; Pöhland, Lydia; Pelz, Patricia; Wüstenberg, Torsten; Raufelder, Diana; Heinz, Andreas; Beck, Anne

    2015-08-15

    The perception of control over the environment constitutes a fundamental biological adaptive mechanism, especially during development. Previous studies comparing an active choice condition with a passive no-choice condition showed that the neural basis of this mechanism is associated with increased activity within the striatum and the prefrontal cortex. In the current study, we aimed to investigate whether subjective belief of control in an uncertain gambling situation induces elevated activation in a cortico-striatal network. We investigated 79 adolescents (age range: 13-16years) during reward anticipation with a slot machine task using functional magnetic resonance imaging. We assessed post-experimentally whether the participants experienced a subjective illusion of control on winning or losing in this task that was objectively not given. Nineteen adolescents experienced an illusion of control during slot machine gambling. This illusion of control group showed an increased neural activity during reward anticipation within a cortico-striatal network including ventral striatum (VS) as well as right inferior frontal gyrus (rIFG) relative to the group reporting no illusion of control. The rIFG activity was inversely associated with impulsivity in the no illusion of control group. The subjective belief about control led to an elevated ventral striatal activity, which is known to be involved in the processing of reward. This finding strengthens the notion that subjectively perceived control, not necessarily the objective presence of control, affects striatal reward-related processing.

  12. Illusions of causality at the heart of pseudoscience.

    Science.gov (United States)

    Matute, Helena; Yarritu, Ion; Vadillo, Miguel A

    2011-08-01

    Pseudoscience, superstitions, and quackery are serious problems that threaten public health and in which many variables are involved. Psychology, however, has much to say about them, as it is the illusory perceptions of causality of so many people that needs to be understood. The proposal we put forward is that these illusions arise from the normal functioning of the cognitive system when trying to associate causes and effects. Thus, we propose to apply basic research and theories on causal learning to reduce the impact of pseudoscience. We review the literature on the illusion of control and the causal learning traditions, and then present an experiment as an illustration of how this approach can provide fruitful ideas to reduce pseudoscientific thinking. The experiment first illustrates the development of a quackery illusion through the testimony of fictitious patients who report feeling better. Two different predictions arising from the integration of the causal learning and illusion of control domains are then proven effective in reducing this illusion. One is showing the testimony of people who feel better without having followed the treatment. The other is asking participants to think in causal terms rather than in terms of effectiveness. ©2010 The British Psychological Society.

  13. The cutaneous rabbit illusion affects human primary sensory cortex somatotopically.

    Directory of Open Access Journals (Sweden)

    Felix Blankenburg

    2006-03-01

    Full Text Available We used functional magnetic resonance imaging (fMRI to study neural correlates of a robust somatosensory illusion that can dissociate tactile perception from physical stimulation. Repeated rapid stimulation at the wrist, then near the elbow, can create the illusion of touches at intervening locations along the arm, as if a rabbit hopped along it. We examined brain activity in humans using fMRI, with improved spatial resolution, during this version of the classic cutaneous rabbit illusion. As compared with control stimulation at the same skin sites (but in a different order that did not induce the illusion, illusory sequences activated contralateral primary somatosensory cortex, at a somatotopic location corresponding to the filled-in illusory perception on the forearm. Moreover, the amplitude of this somatosensory activation was comparable to that for veridical stimulation including the intervening position on the arm. The illusion additionally activated areas of premotor and prefrontal cortex. These results provide direct evidence that illusory somatosensory percepts can affect primary somatosensory cortex in a manner that corresponds somatotopically to the illusory percept.

  14. Cost curves for the navigation between families of low energy Fast Periodic Transfer Orbits in the Earth-Moon planar circular restricted Three Body Problem.

    Science.gov (United States)

    Marcuzzi, J. P.; Leiva, A. M.; Briozzo, C. B.

    Using characteristic curves of low energy fast periodic transfer orbits in the Earth-Moon planar circular restricted three body problem we constructed cost curves that enable the study of maneuvers between them. In an appropiate surface of section the numerical diagrams show regions where transfer maneuvers involve lower costs and that would allow determine family members which make the propelent minimum for these maneuvers. FULL TEXT IN SPANISH.

  15. Individual Differences in the Rubber Hand Illusion Are Related to Sensory Suggestibility.

    Science.gov (United States)

    Marotta, Angela; Tinazzi, Michele; Cavedini, Clelia; Zampini, Massimiliano; Fiorio, Mirta

    2016-01-01

    In the rubber hand illusion (RHI), watching a rubber hand being stroked in synchrony with one's own hidden hand may induce a sense of ownership over the rubber hand. The illusion relies on bottom-up multisensory integration of visual, tactile, and proprioceptive information, and on top-down processes through which the rubber hand is incorporated into pre-existing representations of the body. Although the degree of illusory experience varies largely across individuals, the factors influencing individual differences are unknown. We investigated whether sensory suggestibility might modulate susceptibility to the RHI. Sensory suggestibility is a personality trait related to how individuals react to sensory information. Because of its sensory nature, this trait could be relevant for studies using the RHI paradigm. Seventy healthy volunteers were classified by Sensory Suggestibility Scale (SSS) scores as having high or low suggestibility and assigned to either a high- (High-SSS) or a low-suggestibility (Low-SSS) group. Two components of the RHI were evaluated in synchronous and asynchronous stroking conditions: subjective experience of sense of ownership over the rubber hand via a 9-statement questionnaire, and proprioceptive drift as measured with a ruler. The High-SSS group was generally more susceptible to the subjective component; in the synchronous condition, they rated the statement assessing the sense of ownership higher than the Low-SSS group. The scores for this statement significantly correlated with the total SSS score, indicating that the higher the sensory suggestibility, the stronger the sense of ownership. No effect of sensory suggestibility on proprioceptive drift was observed, suggesting that the effect is specific for the subjective feeling of ownership. This study demonstrates that sensory suggestibility may contribute to participants' experience of the illusion and should be considered when using the RHI paradigm.

  16. The brain creates illusions not just for us: sharks (Chiloscyllium griseum) can "see the magic" as well.

    Science.gov (United States)

    Fuss, Theodora; Bleckmann, Horst; Schluessel, Vera

    2014-01-01

    Bamboo sharks (Chiloscyllium griseum) were tested for their ability to perceive subjective and illusionary contours as well as line length illusions. Individuals were first trained to differentiate between squares, triangles, and rhomboids in a series of two alternative forced-choice experiments. Transfer tests then elucidated whether Kanizsa squares and triangles, grating gaps and phase shifted abutting gratings were also perceived and distinguished. The visual systems of most vertebrates and even invertebrates perceive illusionary contours despite the absence of physical luminance, color or textural differences. Sharks are no exception to the rule; all tasks were successfully mastered within 3-24 training sessions, with sharks discriminating between various sets of Kanizsa figures and alternative stimuli, as well as between subjective contours in >75% of all tests. However, in contrast to Kanizsa figures and subjective contours, sharks were not deceived by Müller-Lyer (ML) illusions. Here, two center lines of equal length are comparatively set between two arrowheads or -tails, in which case the line featuring the two arrow tails appears to be longer to most humans, primates and birds. In preparation for this experiment, lines of varying length, and lines of unequal length randomly featuring either two arrowheads or -tails on their ends, were presented first. Both sets of lines were successfully distinguished by most sharks. However, during presentation of the ML illusions sharks failed to succeed and succumbed either to side preferences or chose according to chance.

  17. The brain creates illusions not just for us: sharks (Chiloscyllium griseum can ‘see the magic’ as well.

    Directory of Open Access Journals (Sweden)

    Theodora eFuss

    2014-03-01

    Full Text Available Bamboo sharks (Chiloscyllium griseum were tested for their ability to perceive subjective and illusionary contours as well as line length illusions. Individuals were first trained to differentiate between squares, triangles and rhomboids in a series of two alternative forced-choice experiments. Transfer tests then elucidated whether Kanizsa squares and triangles, grating gaps and phase shifted abutting gratings were also perceived and distinguished. The visual systems of most vertebrates and even invertebrates perceive illusionary contours despite the absence of physical luminance, colour or textural differences. Sharks are no exception to the rule; all tasks were successfully mastered within 3 to 24 training sessions, with sharks discriminating between various sets of Kanizsa figures and alternative stimuli, as well as between subjective contours in >75% of all tests. However, in contrast to Kanizsa figures and subjective contours, sharks were not deceived by Müller-Lyer (ML illusions. Here, two centre lines of equal length are comparatively set between two arrowheads or –tails, in which case the line featuring the two arrow tails appears to be longer to most humans, primates and birds. In preparation for this experiment, lines of varying length, and lines of unequal length randomly featuring either two arrowheads or -tails on their ends, were presented first. Both sets of lines were successfully distinguished by most sharks. However, during presentation of the ML illusions sharks failed to succeed and succumbed either to side preferences or chose according to chance.

  18. Source illusion devices for flexural Lamb waves using elastic metasurfaces

    CERN Document Server

    Liu, Yongquan; Liu, Fu; Diba, Owen; Lamb, Alistair; Li, Jensen

    2016-01-01

    Metamaterials with the transformation method has greatly promoted the development in achieving invisibility and illusion for various classical waves. However, the requirement of tailor-made bulk materials and extreme constitutive parameters associated to illusion designs hampers its further progress. Inspired by recent demonstrations of metasurfaces in achieving reduced versions of electromagnetic cloaks, we propose and experimentally demonstrate source illusion devices to manipulate flexural waves using metasurfaces. The approach is particularly useful for elastic waves due to the lack of form-invariance in usual transformation methods. We demonstrate metasurfaces for shifting, transforming and splitting a point source with "space-coiling" structures. The effects are found to be broadband and robust against a change of source position, with agreement from numerical simulations and Huygens-Fresnel theory. The proposed approach provides an avenue to generically manipulate guided elastic waves in solids, and is...

  19. Understanding human perception by human-made illusions.

    Science.gov (United States)

    Carbon, Claus-Christian

    2014-01-01

    IT MAY BE FUN TO PERCEIVE ILLUSIONS, BUT THE UNDERSTANDING OF HOW THEY WORK IS EVEN MORE STIMULATING AND SUSTAINABLE: They can tell us where the limits and capacity of our perceptual apparatus are found-they can specify how the constraints of perception are set. Furthermore, they let us analyze the cognitive sub-processes underlying our perception. Illusions in a scientific context are not mainly created to reveal the failures of our perception or the dysfunctions of our apparatus, but instead point to the specific power of human perception. The main task of human perception is to amplify and strengthen sensory inputs to be able to perceive, orientate and act very quickly, specifically and efficiently. The present paper strengthens this line of argument, strongly put forth by perceptual pioneer Richard L. Gregory (e.g., Gregory, 2009), by discussing specific visual illusions and how they can help us to understand the magic of perception.

  20. Effect of flanking sounds on the auditory continuity illusion.

    Directory of Open Access Journals (Sweden)

    Maori Kobayashi

    Full Text Available BACKGROUND: The auditory continuity illusion or the perceptual restoration of a target sound briefly interrupted by an extraneous sound has been shown to depend on masking. However, little is known about factors other than masking. METHODOLOGY/PRINCIPAL FINDINGS: We examined whether a sequence of flanking transient sounds affects the apparent continuity of a target tone alternated with a bandpass noise at regular intervals. The flanking sounds significantly increased the limit of perceiving apparent continuity in terms of the maximum target level at a fixed noise level, irrespective of the frequency separation between the target and flanking sounds: the flanking sounds enhanced the continuity illusion. This effect was dependent on the temporal relationship between the flanking sounds and noise bursts. CONCLUSIONS/SIGNIFICANCE: The spectrotemporal characteristics of the enhancement effect suggest that a mechanism to compensate for exogenous attentional distraction may contribute to the continuity illusion.

  1. Binocular disparity as an explanation for the moon illusion

    CERN Document Server

    Antonides, Joseph

    2013-01-01

    We present another explanation for the moon illusion, in which the moon looks larger near the horizon than near the zenith. In our model, the sky is considered a spatially contiguous and geometrically smooth surface. When an object (like the moon) breaks the contiguity of the surface, humans perceive an occlusion of the surface rather than an object appearing through a hole. Binocular vision dictates that the moon is distant, but this perception model dictates that the moon is closer than the sky. To solve the dilemma, the brain distorts the projections of the moon to increase the binocular disparity, which results in increase of the angular size of the moon. The degree of the distortion depends upon the apparent distance to the sky, which is influenced by the surrounding objects and the condition of the sky. The closer the sky appears, the stronger the illusion. At the zenith, few distance cues are present, causing difficulty with distance estimation and weakening the illusion.

  2. Three-dimensional visual illusion of graphic painting

    Institute of Scientific and Technical Information of China (English)

    于静

    2012-01-01

    Visual illusion is the visual design of a special category.It is a set of technology and art in one of a unique form of artistic expression.Visual illusion can give people a taste of the spirit, with strong cultural con- tent and artistic appeal.So by this way of painting, it has a clever and unique perspective. Aspect If the plane can be realistic paintings to life, then the three-dimensional, two-dimensional space can be called even more powerful by aspects.

  3. Homogeneous illusion device exhibiting transformed and shifted scattering effect

    Science.gov (United States)

    Mei, Jin-Shuo; Wu, Qun; Zhang, Kuang; He, Xun-Jun; Wang, Yue

    2016-06-01

    Based on the theory of transformation optics, a type of homogeneous illusion device exhibiting transformed and shifted scattering effect is proposed in this paper. The constitutive parameters of the proposed device are derived, and full-wave simulations are performed to validate the electromagnetic properties of transformed and shifted scattering effect. The simulation results show that the proposed device not only can visually shift the image of target in two dimensions, but also can visually transform the shape of target. It is expected that such homogeneous illusion device could possess potential applications in military camouflage and other field of electromagnetic engineering.

  4. Design of optical cloaks and illusion devices along a circumferential direction in curvilinear coordinates

    Science.gov (United States)

    Chen, Tungyang; Yu, Shang-Ru

    2010-11-01

    We propose a cloaking and illusion device of circumferential topology based on the concept of transformation optics. The device is capable to cloak an object and/or simultaneously generate illusion images along a circumferential direction in curvilinear orthogonal coordinates. This feature allows us to construct multiple illusions in different ways, irrespective of the profile and direction of incident wave. Particularly when the device is served as a building brick of a larger device, one can generate a circumferential array of illusions in a periodic or any preferred pattern. We demonstrate the effectiveness of the proposed illusion devices by carrying out full wave simulations based on finite element calculations.

  5. Using visuo-kinetic virtual reality to induce illusory spinal movement: the MoOVi Illusion

    Directory of Open Access Journals (Sweden)

    Daniel S. Harvie

    2017-02-01

    Full Text Available Background Illusions that alter perception of the body provide novel opportunities to target brain-based contributions to problems such as persistent pain. One example of this, mirror therapy, uses vision to augment perceived movement of a painful limb to treat pain. Since mirrors can’t be used to induce augmented neck or other spinal movement, we aimed to test whether such an illusion could be achieved using virtual reality, in advance of testing its potential therapeutic benefit. We hypothesised that perceived head rotation would depend on visually suggested movement. Method In a within-subjects repeated measures experiment, 24 healthy volunteers performed neck movements to 50o of rotation, while a virtual reality system delivered corresponding visual feedback that was offset by a factor of 50%–200%—the Motor Offset Visual Illusion (MoOVi—thus simulating more or less movement than that actually occurring. At 50o of real-world head rotation, participants pointed in the direction that they perceived they were facing. The discrepancy between actual and perceived direction was measured and compared between conditions. The impact of including multisensory (auditory and visual feedback, the presence of a virtual body reference, and the use of 360o immersive virtual reality with and without three-dimensional properties, was also investigated. Results Perception of head movement was dependent on visual-kinaesthetic feedback (p = 0.001, partial eta squared = 0.17. That is, altered visual feedback caused a kinaesthetic drift in the direction of the visually suggested movement. The magnitude of the drift was not moderated by secondary variables such as the addition of illusory auditory feedback, the presence of a virtual body reference, or three-dimensionality of the scene. Discussion Virtual reality can be used to augment perceived movement and body position, such that one can perform a small movement, yet perceive a large one. The Mo

  6. The Poggendorff illusion driven by real and illusory contour: Behavioral and neural mechanisms.

    Science.gov (United States)

    Shen, Lu; Zhang, Ming; Chen, Qi

    2016-05-01

    The Poggendorff illusion refers to the phenomenon that the human brain misperceives a diagonal line as being apparently misaligned once the diagonal line is interrupted by two parallel edges, and the size of illusion is negatively correlated with the angle of interception of the oblique, i.e. the sharper the oblique angle, the larger the illusion. This optical illusion can be produced by both real and illusory contour. In this fMRI study, by parametrically varying the oblique angle, we investigated the shared and specific neural mechanisms underlying the Poggendorff illusion induced by real and illusory contour. At the behavioral level, not only the real but also the illusory contours were capable of inducing significant Poggendorff illusion. The size of illusion induced by the real contour, however, was larger than that induced by the illusory contour. At the neural level, real and illusory contours commonly activated more dorsal visual areas, and the real contours specifically activated more ventral visual areas. More importantly, examinations on the parametric modulation effects of the size of illusion revealed the specific neural mechanisms underlying the Poggendorff illusion induced by the real and the illusory contours, respectively. Left precentral gyrus and right middle occipital cortex were specifically involved in the Poggendorff illusion induced by the real contour. On the other hand, bilateral intraparietal sulcus (IPS) and right lateral occipital complex (LOC) were specifically involved in the Poggendorff illusion induced by the illusory contour. Functional implications of the above findings were further discussed.

  7. The Pareidolia Test: A Simple Neuropsychological Test Measuring Visual Hallucination-Like Illusions.

    Directory of Open Access Journals (Sweden)

    Yasuyuki Mamiya

    Full Text Available Visual hallucinations are a core clinical feature of dementia with Lewy bodies (DLB, and this symptom is important in the differential diagnosis and prediction of treatment response. The pareidolia test is a tool that evokes visual hallucination-like illusions, and these illusions may be a surrogate marker of visual hallucinations in DLB. We created a simplified version of the pareidolia test and examined its validity and reliability to establish the clinical utility of this test.The pareidolia test was administered to 52 patients with DLB, 52 patients with Alzheimer's disease (AD and 20 healthy controls (HCs. We assessed the test-retest/inter-rater reliability using the intra-class correlation coefficient (ICC and the concurrent validity using the Neuropsychiatric Inventory (NPI hallucinations score as a reference. A receiver operating characteristic (ROC analysis was used to evaluate the sensitivity and specificity of the pareidolia test to differentiate DLB from AD and HCs.The pareidolia test required approximately 15 minutes to administer, exhibited good test-retest/inter-rater reliability (ICC of 0.82, and moderately correlated with the NPI hallucinations score (rs = 0.42. Using an optimal cut-off score set according to the ROC analysis, and the pareidolia test differentiated DLB from AD with a sensitivity of 81% and a specificity of 92%.Our study suggests that the simplified version of the pareidolia test is a valid and reliable surrogate marker of visual hallucinations in DLB.

  8. Illusions of causality: how they bias our everyday thinking and how they could be reduced.

    Science.gov (United States)

    Matute, Helena; Blanco, Fernando; Yarritu, Ion; Díaz-Lago, Marcos; Vadillo, Miguel A; Barberia, Itxaso

    2015-01-01

    Illusions of causality occur when people develop the belief that there is a causal connection between two events that are actually unrelated. Such illusions have been proposed to underlie pseudoscience and superstitious thinking, sometimes leading to disastrous consequences in relation to critical life areas, such as health, finances, and wellbeing. Like optical illusions, they can occur for anyone under well-known conditions. Scientific thinking is the best possible safeguard against them, but it does not come intuitively and needs to be taught. Teaching how to think scientifically should benefit from better understanding of the illusion of causality. In this article, we review experiments that our group has conducted on the illusion of causality during the last 20 years. We discuss how research on the illusion of causality can contribute to the teaching of scientific thinking and how scientific thinking can reduce illusion.

  9. Illusions of causality: how they bias our everyday thinking and how they could be reduced

    Science.gov (United States)

    Matute, Helena; Blanco, Fernando; Yarritu, Ion; Díaz-Lago, Marcos; Vadillo, Miguel A.; Barberia, Itxaso

    2015-01-01

    Illusions of causality occur when people develop the belief that there is a causal connection between two events that are actually unrelated. Such illusions have been proposed to underlie pseudoscience and superstitious thinking, sometimes leading to disastrous consequences in relation to critical life areas, such as health, finances, and wellbeing. Like optical illusions, they can occur for anyone under well-known conditions. Scientific thinking is the best possible safeguard against them, but it does not come intuitively and needs to be taught. Teaching how to think scientifically should benefit from better understanding of the illusion of causality. In this article, we review experiments that our group has conducted on the illusion of causality during the last 20 years. We discuss how research on the illusion of causality can contribute to the teaching of scientific thinking and how scientific thinking can reduce illusion. PMID:26191014

  10. Illusions of causality: How they bias our everyday thinking and how they could be reduced

    Directory of Open Access Journals (Sweden)

    Helena eMatute

    2015-07-01

    Full Text Available Illusions of causality occur when people develop the belief that there is a causal connection between two events that are actually unrelated. Such illusions have been proposed to underlie pseudoscience and superstitious thinking, sometimes leading to disastrous consequences in relation to critical life areas, such as health, finances, and wellbeing. Like optical illusions, they can occur for anyone under well-known conditions. Scientific thinking is the best possible safeguard against them, but it does not come intuitively and needs to be taught. Teaching how to think scientifically should benefit from better understanding of the illusion of causality. In this article, we review experiments that our group has conducted on the illusion of causality during the last 20 years. We discuss how research on the illusion of causality can contribute to the teaching of scientific thinking and how scientific thinking can reduce illusion.

  11. Self-face recognition shares brain regions active during proprioceptive illusion in the right inferior fronto-parietal superior longitudinal fasciculus III network.

    Science.gov (United States)

    Morita, Tomoyo; Saito, Daisuke N; Ban, Midori; Shimada, Koji; Okamoto, Yuko; Kosaka, Hirotaka; Okazawa, Hidehiko; Asada, Minoru; Naito, Eiichi

    2017-04-21

    Proprioception is somatic sensation that allows us to sense and recognize position, posture, and their changes in our body parts. It pertains directly to oneself and may contribute to bodily awareness. Likewise, one's face is a symbol of oneself, so that visual self-face recognition directly contributes to the awareness of self as distinct from others. Recently, we showed that right-hemispheric dominant activity in the inferior fronto-parietal cortices, which are connected by the inferior branch of the superior longitudinal fasciculus (SLF III), is associated with proprioceptive illusion (awareness), in concert with sensorimotor activity. Herein, we tested the hypothesis that visual self-face recognition shares brain regions active during proprioceptive illusion in the right inferior fronto-parietal SLF III network. We scanned brain activity using functional magnetic resonance imaging while twenty-two right-handed healthy adults performed two tasks. One was a proprioceptive illusion task, where blindfolded participants experienced a proprioceptive illusion of right hand movement. The other was a visual self-face recognition task, where the participants judged whether an observed face was their own. We examined whether the self-face recognition and the proprioceptive illusion commonly activated the inferior fronto-parietal cortices connected by the SLF III in a right-hemispheric dominant manner. Despite the difference in sensory modality and in the body parts involved in the two tasks, both tasks activated the right inferior fronto-parietal cortices, which are likely connected by the SLF III, in a right-side dominant manner. Here we discuss possible roles for right inferior fronto-parietal activity in bodily awareness and self-awareness. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  12. The "motion silencing" illusion results from global motion and crowding.

    Science.gov (United States)

    Turi, Marco; Burr, David

    2013-04-18

    Suchow and Alvarez (2011) recently devised a striking illusion, where objects changing in color, luminance, size, or shape appear to stop changing when they move. They refer to the illusion as "motion silencing of awareness to visual change." Here we present evidence that the illusion results from two perceptual processes: global motion and crowding. We adapted Suchow and Alvarez's stimulus to three concentric rings of dots, a central ring of "target dots" flanked on either side by similarly moving flanker dots. Subjects had to identify in which of two presentations the target dots were continuously changing (sinusoidally) in size, as distinct from the other interval in which size was constant. The results show: (a) Motion silencing depends on target speed, with a threshold around 0.2 rotations per second (corresponding to about 10°/s linear motion). (b) Silencing depends on both target-flanker spacing and eccentricity, with critical spacing about half eccentricity, consistent with Bouma's law. (c) The critical spacing was independent of stimulus size, again consistent with Bouma's law. (d) Critical spacing depended strongly on contrast polarity. All results imply that the "motion silencing" illusion may result from crowding.

  13. Experimental realization of a broadband illusion optics device

    CERN Document Server

    Li, Chao; Liu, Xiao; Li, Fang; Fang, Guangyou; Chen, Huanyang; Chan, C T

    2010-01-01

    We experimentally demonstrate the first metamaterial "illusion optics" device - an "invisible gateway" by using a transmission-line medium. The device contains an open channel that can block electromagnetic waves at a particular frequency range. We also demonstrate that such a device can work in a broad frequency range.

  14. Remote nano-optical beam focusing lens by illusion optics

    Science.gov (United States)

    Margousi, David; Shoorian, Hamed Reza

    2014-08-01

    In this paper, as a new application of illusion optics, a nano-optical plasmonic focusing lens structure is proposed to manipulate the light remotely by employing illusion optics theory. Plasmonic nano-optic lenses that enable super-focusing beyond the diffraction limit have been proposed as an alternative to the conventional dielectric-based refractive lenses. In the presence of an illusion device, the electromagnetic plane-waves can penetrate into a metal layer and a clear focus appears. When the illusion device is removed, waves are blocked to transmit through the metal wall. In comparison with conventional methods, our proposed method avoids any physical changes or damages in the original structure. The proposed structure can be realized by isotropic layered materials, using effective medium theory. The special feature of the proposed structure and the device concepts introduced in this work gives it an opportunity to be used as a flexible element in ultrahigh nano-scale integrated circuits for miniaturization and tuning purposes.

  15. Social misdirection fails to enhance a magic illusion.

    Science.gov (United States)

    Cui, Jie; Otero-Millan, Jorge; Macknik, Stephen L; King, Mac; Martinez-Conde, Susana

    2011-01-01

    Visual, multisensory and cognitive illusions in magic performances provide new windows into the psychological and neural principles of perception, attention, and cognition. We investigated a magic effect consisting of a coin "vanish" (i.e., the perceptual disappearance of a coin after a simulated toss from hand to hand). Previous research has shown that magicians can use joint attention cues such as their own gaze direction to strengthen the observers' perception of magic. Here we presented naïve observers with videos including real and simulated coin tosses to determine if joint attention might enhance the illusory perception of simulated coin tosses. The observers' eye positions were measured, and their perceptual responses simultaneously recorded via button press. To control for the magician's use of joint attention cues, we occluded his head in half of the trials. We found that subjects did not direct their gaze at the magician's face at the time of the coin toss, whether the face was visible or occluded, and that the presence of the magician's face did not enhance the illusion. Thus, our results show that joint attention is not necessary for the perception of this effect. We conclude that social misdirection is redundant and possibly detracting to this very robust sleight-of-hand illusion. We further determined that subjects required multiple trials to effectively distinguish real from simulated tosses; thus the illusion was resilient to repeated viewing.

  16. Face Processing at Birth: A Thatcher Illusion Study

    Science.gov (United States)

    Leo, Irene; Simion, Francesca

    2009-01-01

    The present study was aimed at exploring newborns' ability to recognize configural changes within real face images by testing newborns' sensitivity to the Thatcher illusion. Using the habituation procedure, newborns' ability to discriminate between an unaltered face image and the same face with the eyes and the mouth 180 degrees rotated (i.e.…

  17. Empathy in intimate relationships : The role of positive illusions

    NARCIS (Netherlands)

    Dijkstra, Pieternel; Barelds, Dick P.H.; Groothof, Hinke A.K.; Van Bruggen, Marnix

    2014-01-01

    Previous studies have shown empathy to be an important aspect of a high quality intimate relationship. Likewise, positive illusions about a partner's characteristics have been shown to contribute to relationship quality. The present study connects these issues by examining the degree to which

  18. Mathematics Induction in School; An Illusion of Rigor.

    Science.gov (United States)

    Lowenthal, Francis; Eisenberg, Theodore

    1992-01-01

    Discusses the mathematical, philosophical, and pedagogical problems in the theorem of mathematical induction. Argues that mathematical induction is a meta-theorem, that is a theorem within a theorem, whose pitfalls and illusions of rigor should be discussed before implementation into the school curriculum. (MDH)

  19. Visual illusions and direct perception : Elaborating on Gibson's insights

    NARCIS (Netherlands)

    de Wit, Matthieu M.; van der Kamp, John; Withagen, Rob

    2015-01-01

    Gibson argued that illusory pictorial displays contain "inadequate" information (1966, p. 288) but also that a "very special kind of selective attention" (p.313) can dispel the illusion -suggesting that adequate perceptual information could in fact be potentially available to observers. The present

  20. Trend of Average Wages as Indicator of Hypothetical Money Illusion

    Directory of Open Access Journals (Sweden)

    Julian Daszkowski

    2010-06-01

    Full Text Available The definition of wage in Poland not before 1998 includes any value of social security contribution. Changed definition creates higher level of reported wages, but was expected not to influence the take home pay. Nevertheless, the trend of average wages, after a short period, has returned to its previous line. Such effect is explained in the term of money illusion.

  1. Social Misdirection Fails to Enhance a Magic Illusion

    Science.gov (United States)

    Cui, Jie; Otero-Millan, Jorge; Macknik, Stephen L.; King, Mac; Martinez-Conde, Susana

    2011-01-01

    Visual, multisensory and cognitive illusions in magic performances provide new windows into the psychological and neural principles of perception, attention, and cognition. We investigated a magic effect consisting of a coin “vanish” (i.e., the perceptual disappearance of a coin after a simulated toss from hand to hand). Previous research has shown that magicians can use joint attention cues such as their own gaze direction to strengthen the observers’ perception of magic. Here we presented naïve observers with videos including real and simulated coin tosses to determine if joint attention might enhance the illusory perception of simulated coin tosses. The observers’ eye positions were measured, and their perceptual responses simultaneously recorded via button press. To control for the magician’s use of joint attention cues, we occluded his head in half of the trials. We found that subjects did not direct their gaze at the magician’s face at the time of the coin toss, whether the face was visible or occluded, and that the presence of the magician’s face did not enhance the illusion. Thus, our results show that joint attention is not necessary for the perception of this effect. We conclude that social misdirection is redundant and possibly detracting to this very robust sleight-of-hand illusion. We further determined that subjects required multiple trials to effectively distinguish real from simulated tosses; thus the illusion was resilient to repeated viewing. PMID:22046155

  2. Empathy in intimate relationships : The role of positive illusions

    NARCIS (Netherlands)

    Dijkstra, Pieternel; Barelds, Dick P.H.; Groothof, Hinke A.K.; Van Bruggen, Marnix

    2014-01-01

    Previous studies have shown empathy to be an important aspect of a high quality intimate relationship. Likewise, positive illusions about a partner's characteristics have been shown to contribute to relationship quality. The present study connects these issues by examining the degree to which indivi

  3. The continuous Wagon Wheel Illusion is object-based.

    Science.gov (United States)

    VanRullen, Rufin

    2006-11-01

    The occurrence of perceived reversed motion while observers view a periodic, continuously moving stimulus (the "continuous Wagon Wheel Illusion") has been taken as evidence that some aspects of motion perception rely on discrete sampling of visual information. The spatial extent of this sampling is currently under debate. When two separate motion stimuli are viewed simultaneously, the illusion of reversed motion rarely occurs for both objects together: this rules out global sampling of the visual field. The same result holds when the objects are superimposed by transparency: this argues against location-based sampling. Here we show that the sampling is in fact object-based: we use a rotating ring stimulus split in two halves. When the two halves move in opposite directions, appearing to belong to separate objects, perceptual reversals occur in either half at a time, but rarely in both. When the two halves physically move in compatible directions, they generally appear to reverse simultaneously: the illusion keeps the perceptual object united. Rather than the local low-level properties of the motion stimulus (which are comparable in both cases), it is thus the high-level organization of the scene that determines the extent of perceived motion reversals. These results imply that the continuous Wagon Wheel Illusion, and any discrete perceptual sampling that may cause it, is restricted to the object of our attention.

  4. Social misdirection fails to enhance a magic illusion

    Directory of Open Access Journals (Sweden)

    Jie eCui

    2011-09-01

    Full Text Available Visual, multisensory and cognitive illusions in magic performances provide new windows into the psychological and neural principles of perception, attention and cognition. We investigated a magic effect consisting of a coin vanish (i.e. the perceptual disappearance of a coin after a simulated toss from hand to hand. Previous research has shown that magicians can use joint attention cues such as their own gaze direction to strengthen the observers’ perception of magic. Here we presented naïve observers with videos including real and simulated coin tosses to determine if joint attention might enhance the illusory perception of simulated coin tosses. The observers’ eye positions were measured, and their perceptual responses simultaneously recorded via button press. To control for the magician’s use of joint attention cues, we occluded his head in half of the trials. We found that subjects did not direct their gaze at the magician’s face at the time of the coin toss, whether the face was visible or occluded, and that the presence of the magician’s face did not enhance the illusion. Thus, our results show that joint attention is not necessary for the perception of this effect. We conclude that social misdirection is redundant and possibly detracting to this very robust sleight-of-hand illusion. We further determined that subjects required multiple trials to effectively distinguish real from simulated tosses; thus the illusion was resilient to repeated viewing.

  5. The McGurk Illusion in the Oddity Task

    DEFF Research Database (Denmark)

    Andersen, Tobias

    2010-01-01

    Despite many studies of audiovisual integration in speech perception very few studies have addressed the issue of cross- modal response bias. Using synthetic acoustic speech, the current study demonstrates the McGurk illusion in the oddity task which is not prone to cross-modal response bias...

  6. An ordinal model of the McGurk illusion

    DEFF Research Database (Denmark)

    Andersen, Tobias

    2011-01-01

    an ordinal model, in which the response categories are ordered cyclically, that can account for the McGurk illusion. We compare this model to the Fuzzy Logical Model of Perception (FLMP), which is not an ordinal model, based on an original data set. While the FLMP fitted the data better than the ordinal...

  7. Effect of field-of-view on the Coriolis illusion

    NARCIS (Netherlands)

    Groen, E.L.; Muis, H.; Kooi, F.L.

    2008-01-01

    Tilting the head during rotation about an Earth-vertical axis produces cross-coupled stimulation of the semicircular canals. Without visual feedback on the actual self-motion, this leads to the so-called Coriolis illusion. We investigated the effect of the field-of-view (FOV) on the magnitude and du

  8. Geometrical illusions are not always where you think they are: a review of some classical and less classical illusions, and ways to describe them.

    Science.gov (United States)

    Ninio, Jacques

    2014-01-01

    Geometrical illusions are known through a small core of classical illusions that were discovered in the second half of the nineteenth century. Most experimental studies and most theoretical discussions revolve around this core of illusions, as though all other illusions were obvious variants of these. Yet, many illusions, mostly described by German authors at the same time or at the beginning of the twentieth century have been forgotten and are awaiting their rehabilitation. Recently, several new illusions were discovered, mainly by Italian authors, and they do not seem to take place into any current classification. Among the principles that are invoked to explain the illusions, there are principles relating to the metric aspects (contrast, assimilation, shrinkage, expansion, attraction of parallels) principles relating to orientations (regression to right angles, orthogonal expansion) or, more recently, to gestalt effects. Here, metric effects are discussed within a measurement framework, in which the geometric illusions are the outcome of a measurement process. There would be a main "convexity" bias in the measures: the measured value m(x) of an extant x would grow more than proportionally with x. This convexity principle, completed by a principle of compromise for conflicting measures can replace, for a large number of patterns, both the assimilation and the contrast effects. We know from evolutionary theory that the most pertinent classification criteria may not be the most salient ones (e.g., a dolphin is not a fish). In order to obtain an objective classification of illusions, I initiated with Kevin O'Regan systematic work on "orientation profiles" (describing how the strength of an illusion varies with its orientation in the plane). We showed first that the Zöllner illusion already exists at the level of single stacks, and that it does not amount to a rotation of the stacks. Later work suggested that it is best described by an "orthogonal expansion

  9. Quadri-stability of a spatially ambiguous auditory illusion

    Directory of Open Access Journals (Sweden)

    Constance May Bainbridge

    2015-01-01

    Full Text Available In addition to vision, audition plays an important role in sound localization in our world. One way we estimate the motion of an auditory object moving towards or away from us is from changes in volume intensity. However, the human auditory system has unequally distributed spatial resolution, including difficulty distinguishing sounds in front versus behind the listener. Here, we introduce a novel quadri-stable illusion, the Transverse-and-Bounce Auditory Illusion, which combines front-back confusion with changes in volume levels of a nonspatial sound to create ambiguous percepts of an object approaching and withdrawing from the listener. The sound can be perceived as traveling transversely from front to back or back to front, or bouncing to remain exclusively in front of or behind the observer. Here we demonstrate how human listeners experience this illusory phenomenon by comparing ambiguous and unambiguous stimuli for each of the four possible motion percepts. When asked to rate their confidence in perceiving each sound’s motion, participants reported equal confidence for the illusory and unambiguous stimuli. Participants perceived all four illusory motion percepts, and could not distinguish the illusion from the unambiguous stimuli. These results show that this illusion is effectively quadri-stable. In a second experiment, the illusory stimulus was looped continuously in headphones while participants identified its perceived path of motion to test properties of perceptual switching, locking, and biases. Participants were biased towards perceiving transverse compared to bouncing paths, and they became perceptually locked into alternating between front-to-back and back-to-front percepts, perhaps reflecting how auditory objects commonly move in the real world. This multi-stable auditory illusion opens opportunities for studying the perceptual, cognitive, and neural representation of objects in motion, as well as exploring multimodal perceptual

  10. Asymmetric effects of luminance and chrominance in the watercolor illusion

    Directory of Open Access Journals (Sweden)

    Andrew eCoia

    2014-09-01

    Full Text Available When bounded by a line of sufficient contrast, the desaturated hue of a colored line will spread over an enclosed area, an effect known as the watercolor illusion. The contrast of the two lines can be in luminance, chromaticity, or a combination of both. The effect is most salient when the enclosing line has greater contrast with the background than the line that induces the spreading color. In most prior experiments with watercolor spreading, the luminance of both lines has been lower than the background. An achromatic version of the illusion exists where a dark line will spread while being bounded by either a darker or brighter line. In a previous study we measured the strength of the watercolor effect in which the colored inducing line was isoluminant to the background, and found an illusion for both brighter and darker achromatic outer contours. We also found the strength of spreading is stronger for bluish (+S cone input colors compared to yellowish (-S cone input ones, when bounded by a dark line. The current study set out to measure the hue dependence of the watercolor illusion when inducing colors are flanked with brighter (increment as opposed to darker outer lines. The asymmetry in the watercolor effect with S cone input was enhanced when the inducing contrast was an increment rather than a decrement. Further experiments explored the relationship between the perceived contrast of these chromatic lines when paired with luminance increments and decrements and revealed that the perceived contrast of luminance increments and decrements is dependent on which isoluminant color they are paired with. In addition to known hue asymmetries in the watercolor illusion there are asymmetries between luminance increments and decrements that are also hue dependent. These latter asymmetries may be related to the perceived contrast of the hue/luminance parings.

  11. Spatiotemporal cortical activation underlies the Müller-Lyer illusion: an event-related potentials study.

    Science.gov (United States)

    Zhang, Songyan; Du, Xue; Wu, Xin; Wei, Dongtao; Zhang, Meng; Qiu, Jiang

    2013-12-04

    Event-related brain potentials (ERPs) were used to examine the electrophysiological correlates of the visual illusion effect in the Müller-Lyer illusion tasks. The participants were presented with the context of a horizontal line with two symmetric inward-pointing arrowheads or outward-pointing arrowheads, and then, they were asked to indicate whether they perceived an increase or a decrease in the line length. The behavioral results showed that there were significant differences among the four types of tasks, which meant that participants could understand different mean illusion magnitudes. The ERP results showed that both the illusion-45 and the illusion-135 elicited a more negative ERP deflection (N180-280) than did the illusion-225 and illusion-315 between 180 and 280 ms. In addition, the strong illusion stimuli elicited a more positive ERP deflection (P280-450) than did the weak illusion stimuli between 280 and 450 ms after the onset of the stimuli. Dipole source analysis of the difference wave (illusion-135-illusion-225) indicated that one generator localized in the left lateral occipital cortex and the difference wave (illusion-45-illusion-135) indicated that one generator localized in the left lingual gyrus. Our results led us to conclude that the ERP deflection in the different illusory strength might be related to the theory of attention resource distribution or because of the inverse optics problem. Then, the early visual areas lateral occipital cortex and the lingual gyrus near to the visual cortex could contribute to integrated processing in the illusory contours and top-down control processing because of the visual experiences.

  12. ESTIMATION OF MASS MOMENT OF INERTIA OF HUMAN BODY, WHEN BENDING FORWARD, FOR THE DESIGN OF A SELF-TRANSFER ROBOTIC FACILITY

    Directory of Open Access Journals (Sweden)

    R. HARI KRISHNAN

    2016-02-01

    Full Text Available Knowledge of Mass Moment of Inertia of human body and its segments are necessary for various problems in biomechanics and its applications. This paper focusses on the estimation of Moment of Inertia of a human body when bending forward, which is needed for designing a robotic self-transfer facility for elderly and disabled. This paper also covers a brief review on studies of different anthropometric data like mass of the body segments, Centre of Mass, radius of gyration, etc. Using these data and certain assumptions, Mass Moment of Inertia of human body bending forward is estimated by applying laws of basic mechanics. This estimated value is then validated using a solid modelling CAD software.

  13. Commentary on the Radius of the Sun: Optical Illusion or Manifestation of a Real Surface?

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-04-01

    Full Text Available In modern solar theory, the photospheric surface merely act s as an optical illusion. Gases cannot support the existence of such a boundary. Conve rsely, the liquid metallic hydrogen model supports the idea that the Sun has a distinct s urface. Observational as- tronomy continues to report increasingly precise measures of solar radius and diameter. Even the smallest temporal variations in these parameters w ould have profound impli- cations relative to modeling the Sun and understanding clim ate fluctuations on Earth. A review of the literature convincingly demonstrates that th e solar body does indeed pos- sess a measurable radius which provides, along with previou s discussions (Robitaille P.M. On the Presence of a Distinct Solar Surface: A Reply to He rv ́e Faye. Progr. Phys. , 2011, v. 3, 75–78., the twenty-first line of evidence that t he Sun is comprised of condensed-matter.

  14. A study on some optical illusions based upon the theory of inducing field.

    Science.gov (United States)

    Ge, Sheng; Saito, Takashi; Wu, Jing-Long; Iramina, K

    2006-01-01

    The study of optical illusion is an important method to elucidate the mechanism of visual perception. However, many details about the cause of optical illusions are still unclear. In this research, based on the characteristic of the physiological structure of the retina, we proposed an on-center receptive field model of the retina. Using this model, we simulated the distributions of the inducing field of some visual stimulus. Comparing to the past studies' results, the validity of the proposed model was proofed. Furthermore, we simulated the distributions of the inducing field of some typical illusions. The simulation results can explain these illusion phenomenon rationally. Therefore, it suggested that some of illusions are probably engendered by the distributions of the inducing field in the retina which generated by the illusions stimuli. The practicality of the proposed model was also verified.

  15. The Moses, mega-Moses, and Armstrong illusions: integrating language comprehension and semantic memory.

    Science.gov (United States)

    Shafto, M; MacKay, D G

    2000-09-01

    This study develops a new theory of the Moses illusion, observed in responses to general knowledge questions such as, "How many animals of each kind did Moses take on the Ark?" People often respond "two" rather than "zero" despite knowing that Noah, not Moses, launched the Ark. Our theory predicted two additional types of conceptual error demonstrated here: the Armstrong and mega-Moses illusions. The Armstrong illusion involved questions resembling, "What was the famous line uttered by Louis Armstrong when he first set foot on the moon?" People usually comprehend such questions as valid, despite knowing that Louis Armstrong was a jazz musician who never visited the moon. This Armstrong illusion was not due to misperceiving the critical words (Louis Armstrong), and occurred as frequently as the Moses illusion (with critical words embedded in identical sentential contexts), but less frequently than the mega-Moses illusion caused when Moses and Armstrong factors were combined.

  16. Factors affecting the haptic filled-space illusion for dynamic touch.

    Science.gov (United States)

    Sanders, Abram F J; Kappers, Astrid M L

    2009-02-01

    In the haptic filled-space illusion for active dynamic touch, observers move their fingertip across an unfilled extent or an extent filled with intermediate stimulations. Previous researchers have reported lengths of filled extents to be overestimated, but the parameters affecting the strength of the illusion are still largely unknown. In the current research, we show that the illusion persists when intermediate stimulations do not provide information about the extent's length. In addition, the results show that the strength of the illusion increases with the number of filler elements. In contrast with earlier research, we control for movement speed differences between filled and unfilled extents. The results suggest that the strength of the illusion is independent of the overall average movement speed. Insight into factors affecting the strength of the illusion may provide a better understanding of the kinematic mechanisms underlying haptic length perception.

  17. Effect of different flow regimes on free convection heat transfer from isothermal convex bodies over all range of Rayleigh and Prandtl numbers

    Science.gov (United States)

    Arabi, Pouria; Jafarpur, Khosrow

    2016-08-01

    In the present study, effect of different flow regimes on free convection heat transfer has been examined. In the light of this, a novel analytical method is developed to calculate free convection heat transfer from isothermal convex bodies with arbitrary shape over all range of Rayleigh number in fluids with any Prandtl number. The crux of this method is based on the concept of dynamic behaviors existing in natural convection flow. In the previous models the Body Gravity Function (BGF) and Turbulent Function (TF) have been taken as constant values. In this study, BGF accounts for the effect of body shape and orientation with respect to gravity vector in laminar free convection. Besides, TF accounts for the impact of Prandtl number, body shape and orientation with regard to gravity vector in turbulent free convection. By contrast, it is shown that these two parameters undergo a change through the variation of Rayleigh number and cannot be considered as a constant. These two parameters are modeled based upon the thermal resistance concept. Moreover, two transition criteria happening in free convection heat transfer will be obtained according to this new analytical method (conduction-laminar and laminar-turbulent transitions). Finally, three models (models 1, 2 and 3) are proposed for calculation free convection heat transfer and present results for ten isothermal convex bodies with various aspect ratios (0.298 ≤ √ A /P ≤ 2.470) have been compared with the available experimental and numerical data. Here, the results of model 2 are almost equal to those of model 3. Also, the results of model 1 are more precise than those of model 3 while the parameters computation of model 1 is more intricate in comparison with model 3. On the one hand, the model 1 has an average difference <6 % vis-à-vis numerical data in entire range of Rayleigh number (laminar and turbulent). On the other hand, the average difference of model 1 is not more than 8 % versus experimental data

  18. Many body heat radiation and heat transfer in the presence of a non-absorbing background medium

    CERN Document Server

    Müller, Boris; Antezza, Mauro; Emig, Thorsten; Krüger, Matthias

    2016-01-01

    Heat radiation and near-field radiative heat transfer can be strongly manipulated by adjusting geometrical shapes, optical properties, or the relative positions of the objects involved. Typically these objects are considered as embedded in vacuum. By applying the methods of fluctuational electrodynamics, we derive general closed-form expressions for heat radiation and heat transfer in a system of $N$ arbitrary objects embedded in a passive non-absorbing background medium. Taking into account the principle of reciprocity, we explicitly prove the symmetry and positivity of transfer in any such system. Regarding applications, we find that the heat radiation of a sphere as well as the heat transfer between two parallel plates is strongly enhanced by the presence of a background medium. Regarding near- and far-field transfer through a gas like air, we show that a microscopic model (based on gas particles) and a macroscopic model (using a dielectric contrast) yield identical results. We also compare the radiative t...

  19. Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

    Directory of Open Access Journals (Sweden)

    Min Du

    2012-11-01

    Full Text Available Intra-Body Communication (IBC, which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results.

  20. In-situ electric field in human body model in different postures for wireless power transfer system in an electrical vehicle.

    Science.gov (United States)

    Shimamoto, Takuya; Laakso, Ilkka; Hirata, Akimasa

    2015-01-07

    The in-situ electric field of an adult male model in different postures is evaluated for exposure to the magnetic field leaked from a wireless power transfer system in an electrical vehicle. The transfer system is located below the centre of the vehicle body and the transferred power and frequency are 7 kW and 85 kHz, respectively. The in-situ electric field is evaluated for a human model (i) crouching near the vehicle, (ii) lying on the ground with or without his arm stretched, (iii) sitting in the driver's seat, and (iv) standing on a transmitting coil without a receiving coil. In each scenario, the maximum in-situ electric fields are lower than the allowable limit prescribed by international guidelines, although the local magnetic field strength in regions of the human body is higher than the allowable external magnetic field strength. The highest in-situ electric field is observed when the human body model is placed on the ground with his arm extended toward the coils, because of a higher magnetic field around the arm.

  1. Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

    Science.gov (United States)

    Chen, Xi Mei; Mak, Peng Un; Pun, Sio Hang; Gao, Yue Ming; Lam, Chan-Tong; Vai, Mang I.; Du, Min

    2012-01-01

    Intra-Body Communication (IBC), which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM) field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE) technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER) performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results. PMID:23443387

  2. Simulating Visual Learning and Optical Illusions via a Network-Based Genetic Algorithm

    Science.gov (United States)

    Siu, Theodore; Vivar, Miguel; Shinbrot, Troy

    We present a neural network model that uses a genetic algorithm to identify spatial patterns. We show that the model both learns and reproduces common visual patterns and optical illusions. Surprisingly, we find that the illusions generated are a direct consequence of the network architecture used. We discuss the implications of our results and the insights that we gain on how humans fall for optical illusions

  3. Cortical responses to the mirror box illusion: a high-resolution EEG study.

    Science.gov (United States)

    Egsgaard, Line Lindhardt; Petrini, Laura; Christoffersen, Giselle; Arendt-Nielsen, Lars

    2011-12-01

    The mirror box illusion has proven a helpful therapy in pathologies such as phantom limb pain, and although the effect has been suggested to be a result of the interaction between pain, vision, touch, and proprioception, the mechanisms are still unknown. Multichannel (124) brain responses were investigated in healthy men (N = 11) and women (N = 14) during the mirror box illusion. Tactile somatosensory evoked potentials were recorded from the right thumb during two control conditions and two illusions: (control 1) no mirror: looking at the physical right thumb during stimulation, (control 2) no mirror: looking at the physical left thumb during stimulation, (illusion 1) mirror: the illusion that both thumbs were stimulated, and (illusion 2) mirror: the illusion that none of the thumbs were stimulated. In men, a significant medial shift in the y coordinate of the N70 dipole in illusion 2 (P = 0.021) was found when compared with illusion 1. No dipole shift was found for women. Additionally, men showed higher prevalence of P180 cingulate cortex activation during illusion 2 when compared with control 1 and 2 (P = 0.002). During illusion 2, the degree of conformity with the statement "The hand in the mirror feels like my other hand" was negatively correlated with the N70 x coordinate for men and positively correlated with the N70 z coordinate for women. In conclusion, short-term cortical plasticity can be induced by a mismatch between visual input and location of tactile stimulation in men. The present study suggests that gender differences exist in the perception of the mirror box illusion.

  4. Negative polarity illusions and the format of hierarchical encodings in memory.

    Science.gov (United States)

    Parker, Dan; Phillips, Colin

    2016-12-01

    Linguistic illusions have provided valuable insights into how we mentally navigate complex representations in memory during language comprehension. Two notable cases involve illusory licensing of agreement and negative polarity items (NPIs), where comprehenders fleetingly accept sentences with unlicensed agreement or an unlicensed NPI, but judge those same sentences as unacceptable after more reflection. Existing accounts have argued that illusions are a consequence of faulty memory access processes, and make the additional assumption that the encoding of the sentence remains fixed over time. This paper challenges the predictions made by these accounts, which assume that illusions should generalize to a broader set of structural environments and a wider range of syntactic and semantic phenomena. We show across seven reading-time and acceptability judgment experiments that NPI illusions can be reliably switched "on" and "off", depending on the amount of time from when the potential licensor is processed until the NPI is encountered. But we also find that the same profile does not extend to agreement illusions. This contrast suggests that the mechanisms responsible for switching the NPI illusion on and off are not shared across all illusions. We argue that the contrast reflects changes over time in the encoding of the semantic/pragmatic representations that can license NPIs. Just as optical illusions have been informative about the visual system, selective linguistic illusions are informative not only about the nature of the access mechanisms, but also about the nature of the encoding mechanisms.

  5. Illusion thermodynamics: A camouflage technique changing an object into another one with arbitrary cross section

    Science.gov (United States)

    He, Xiao; Wu, Linzhi

    2014-12-01

    The previously reported magical thermal devices, such as the thermal invisible cloak and the thermal concentrator, are generalized into one general case named here thermal illusion device. The thermal illusion device is displayed by the design of a thermal reshaper which can reshape an arbitrary thermal object into another one with arbitrary cross section. General expressions of the material parameters for the thermal reshaper are derived unambiguously to greatly facilitate the design of general thermal illusion device. We believe that this work will broaden the current research and pave a path to the thermal invisibility. Numerical simulations show good agreement with the analytical results of the thermal illusion device.

  6. Illusion thermodynamics: A camouflage technique changing an object into another one with arbitrary cross section

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiao; Wu, Linzhi, E-mail: wlz@hit.edu.cn [Center for Composite Materials, Harbin Institute of Technology, Harbin 150001 (China)

    2014-12-01

    The previously reported magical thermal devices, such as the thermal invisible cloak and the thermal concentrator, are generalized into one general case named here thermal illusion device. The thermal illusion device is displayed by the design of a thermal reshaper which can reshape an arbitrary thermal object into another one with arbitrary cross section. General expressions of the material parameters for the thermal reshaper are derived unambiguously to greatly facilitate the design of general thermal illusion device. We believe that this work will broaden the current research and pave a path to the thermal invisibility. Numerical simulations show good agreement with the analytical results of the thermal illusion device.

  7. Apparent size contrasts of retinal images and size constancy as determinants of the moon illusion.

    Science.gov (United States)

    Smith, O W; Smith, P C; Geist, C C; Zimmermann, R R

    1978-06-01

    Kaufman and Rock (1962) and Rock and Kaufman (1962) concluded that the moon illusion is a function of and attributable to apparent distance. They also reported a large framing effect as an exception. Analysis of the effect suggests two components which can account for the illusion independently of apparent distance. These are apparent size contrasts of visual images of discriminable features or objects of the earth with the moon's image and size constancy of the features or objects plus the interactions of the two. Apparent distances to horizons are always a consequence of the necessary conditions for the illusion. They are related to the illusion but are not a determinant of it.

  8. Experimental demonstration of illusion optics with ``external cloaking'' effects

    Science.gov (United States)

    Li, Chao; Liu, Xiao; Liu, Guochang; Li, Fang; Fang, Guangyou

    2011-08-01

    A metamaterial "illusion optics" with "complementary medium" and "restoring medium" is designed by using inductor-capacitor (L-C) network medium. The unprecedented effects of "external cloaking" and "transforming one object to appear as another" are demonstrated experimentally. We also demonstrate that the non-resonant nature of the L-C network decreases the sensitivity of the "external cloaking" effect to the variation of the frequency and results in an acceptable bandwidth of the whole device.

  9. Overlapped illusion optics: a perfect lens brings a brighter feature

    Science.gov (United States)

    Xu, Yadong; Du, Shengwang; Gao, Lei; Chen, Huanyang

    2011-02-01

    In this paper, we show that a perfect lens can be employed to make multiple objects appear like only one object in the far field, leading to a new concept in illusion optics. Numerical simulations have been performed to verify the functionalities for both passive and active objects. The conceptual device can be utilized to enhance the illumination brightness for both incoherent and coherent systems.

  10. The Viewing-from-Above Bias and the Silhouette Illusion

    Directory of Open Access Journals (Sweden)

    Nikolaus F Troje

    2010-12-01

    Full Text Available The silhouette illusion published online a number of years ago by the Japanese Flash designer Nobuyuki Kayahara has received substantial attention from the online community. One feature that seems to make it interesting is an apparent rotational bias: Observers see it spinning more often clockwise than counter-clockwise. Here, we show that this rotational bias is in fact due to the visual system's preference for viewpoints from above rather than from below.

  11. Social misdirection fails to enhance a magic illusion

    OpenAIRE

    Jie eCui; Jorge eOtero-Millan; Macknik, Stephen L.; Mac eKing; Susana eMartinez-Conde

    2011-01-01

    Visual, multisensory and cognitive illusions in magic performances provide new windows into the psychological and neural principles of perception, attention, and cognition. We investigated a magic effect consisting of a coin “vanish” (i.e., the perceptual disappearance of a coin after a simulated toss from hand to hand). Previous research has shown that magicians can use joint attention cues such as their own gaze direction to strengthen the observers’ perception of magic. Here we presented n...

  12. Spatial frequency doubling - Retinal or central. [visual illusion

    Science.gov (United States)

    Richards, W.; Felton, T. B.

    1973-01-01

    When a wide field is sinusoidally modulated both in space and in time, the spatial frequency of the pattern will appear doubled at high rates of modulation. Kelly (1966) proposed that this illusion is due to temporal integration of the nonlinear brightness response of the visual system. The anatomical locus of this temporal integrator is uncertain, and could be subcortical. Results indicate that spatial frequency doubling follows binocular disparity detection and is thus a cortical phenomenon.

  13. Overlapped illusion optics: a perfect lens brings a brighter feature

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yadong; Gao Lei; Chen Huanyang [School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006 (China); Du Shengwang, E-mail: kenyon@ust.hk [Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2011-02-15

    In this paper, we show that a perfect lens can be employed to make multiple objects appear like only one object in the far field, leading to a new concept in illusion optics. Numerical simulations have been performed to verify the functionalities for both passive and active objects. The conceptual device can be utilized to enhance the illumination brightness for both incoherent and coherent systems.

  14. Click'n'Roll: No Evidence of Illusion of Control

    OpenAIRE

    Filippin, Antonio; Crosetto, Paolo

    2015-01-01

    Evidence of Illusion of Control – the fact that people believe to have control over pure chance events – is a recurrent finding in experimental psychology. Results in economics find instead little to no support. In this paper we test whether this dissonant result across disciplines is due to the fact that economists have implemented only one form of illusory control. We identify and separately tests in an incentive-compatible design two types of control: a) over the resolution of uncertainty,...

  15. Cortical evoked potentials to an auditory illusion: binaural beats.

    Science.gov (United States)

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2009-08-01

    To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

  16. Transformation magneto-statics and illusions for magnets

    OpenAIRE

    Fei Sun; Sailing He

    2014-01-01

    Based on the form-invariant of Maxwell’s equations under coordinate transformations, we extend the theoryof transformation optics to transformation magneto-statics, which can design magnets through coordinatetransformations. Some novel DC magnetic field illusions created by magnets (e.g. rescaling magnets,cancelling magnets and overlapping magnets) are designed and verified by numerical simulations. Ourresearch will open a new door to designing magnets and controlling DC magnetic fields. ...

  17. Stubbornly Persistent Illusion The Essential Scientific Works of Albert Einstein

    CERN Document Server

    Hawking, Stephen

    2009-01-01

    With commentary by the greatest physicist of our time, Stephen Hawking, this anthology has garnered impressive reviews. PW has called it "a gem of a collection" while New Scientist magazine notes the "thrill of reading Einstein's own words." From the writings that revealed the famous Theory of Relativity, to other papers that shook the scientific world of the 20th century, A Stubbornly Persistent Illusion belongs in every science fan's library

  18. Perception, action, and Roelofs effect: a mere illusion of dissociation.

    Directory of Open Access Journals (Sweden)

    Paul Dassonville

    2004-11-01

    Full Text Available A prominent and influential hypothesis of vision suggests the existence of two separate visual systems within the brain, one creating our perception of the world and another guiding our actions within it. The induced Roelofs effect has been described as providing strong evidence for this perception/action dissociation: When a small visual target is surrounded by a large frame positioned so that the frame's center is offset from the observer's midline, the perceived location of the target is shifted in the direction opposite the frame's offset. In spite of this perceptual mislocalization, however, the observer can accurately guide movements to the target location. Thus, perception is prone to the illusion while actions seem immune. Here we demonstrate that the Roelofs illusion is caused by a frame-induced transient distortion of the observer's apparent midline. We further demonstrate that actions guided to targets within this same distorted egocentric reference frame are fully expected to be accurate, since the errors of target localization will exactly cancel the errors of motor guidance. These findings provide a mechanistic explanation for the various perceptual and motor effects of the induced Roelofs illusion without requiring the existence of separate neural systems for perception and action. Given this, the behavioral dissociation that accompanies the Roelofs effect cannot be considered evidence of a dissociation of perception and action. This indicates a general need to re-evaluate the broad class of evidence purported to support this hypothesized dissociation.

  19. Illusion of control: the role of personal involvement.

    Science.gov (United States)

    Yarritu, Ion; Matute, Helena; Vadillo, Miguel A

    2014-01-01

    The illusion of control consists of overestimating the influence that our behavior exerts over uncontrollable outcomes. Available evidence suggests that an important factor in development of this illusion is the personal involvement of participants who are trying to obtain the outcome. The dominant view assumes that this is due to social motivations and self-esteem protection. We propose that this may be due to a bias in contingency detection which occurs when the probability of the action (i.e., of the potential cause) is high. Indeed, personal involvement might have been often confounded with the probability of acting, as participants who are more involved tend to act more frequently than those for whom the outcome is irrelevant and therefore become mere observers. We tested these two variables separately. In two experiments, the outcome was always uncontrollable and we used a yoked design in which the participants of one condition were actively involved in obtaining it and the participants in the other condition observed the adventitious cause-effect pairs. The results support the latter approach: Those acting more often to obtain the outcome developed stronger illusions, and so did their yoked counterparts.

  20. Application of Intelligent Design of Optical Illusions in Fashion Design%智能化视幻图案在服装设计中的应用

    Institute of Scientific and Technical Information of China (English)

    张琼

    2016-01-01

    基于互联网多媒体服装设计技术,智能化视幻图案可使服饰作品带给人全新视觉感受,它可以调整人体比例,美化身形,增加服饰的趣味性,提供丰富的视觉效果.文中针对服装设计中智能化视幻图案的发展及特点进行讨论,为智能化视幻图案的应用提供参考.%Based on the Internet multimedia fashion design technology,intelligent optical illusions design can bring a brand-new visual experience to dress.It can adjust body proportion,beautify body,make dress more interesting,provide a rich visual effect.In this paper,the development of the intelligent design of optical illusions in clothing design and characteristics were studied,which provide theoretical basis for the application of intelligent design of optical illusions.

  1. A standing posture is associated with increased susceptibility to the sound-induced flash illusion in fall-prone older adults.

    Science.gov (United States)

    Stapleton, John; Setti, Annalisa; Doheny, Emer P; Kenny, Rose Anne; Newell, Fiona N

    2014-02-01

    Recent research has provided evidence suggesting a link between inefficient processing of multisensory information and incidence of falling in older adults. Specifically, Setti et al. (Exp Brain Res 209:375-384, 2011) reported that older adults with a history of falling were more susceptible than their healthy, age-matched counterparts to the sound-induced flash illusion. Here, we investigated whether balance control in fall-prone older adults was directly associated with multisensory integration by testing susceptibility to the illusion under two postural conditions: sitting and standing. Whilst standing, fall-prone older adults had a greater body sway than the age-matched healthy older adults and their body sway increased when presented with the audio-visual illusory but not the audio-visual congruent conditions. We also found an increase in susceptibility to the sound-induced flash illusion during standing relative to sitting for fall-prone older adults only. Importantly, no performance differences were found across groups in either the unisensory or non-illusory multisensory conditions across the two postures. These results suggest an important link between multisensory integration and balance control in older adults and have important implications for understanding why some older adults are prone to falling.

  2. A method for generating an illusion of backwards time travel using immersive virtual reality - an exploratory study

    Directory of Open Access Journals (Sweden)

    Doron eFriedman

    2014-09-01

    Full Text Available We introduce a new method, based on immersive virtual reality, to give people the illusion of having travelled backwards through time to relive a sequence of events in which they can intervene and change history. The participant had played an important part in events with a tragic outcome - deaths of strangers – by having to choose between saving 5 people or 1. We consider whether the ability to go back through time, and intervene, to possibly avoid all deaths, has an impact on how the participant views such moral dilemmas, and also whether this experience leads to a re-evaluation of past unfortunate events in their own lives. We carried out an exploratory study where in the ‘Time Travel’ condition 16 participants relived these events three times, seeing incarnations of their past selves carrying out the actions that they had previously carried out. In a ‘Repetition’ condition another 16 participants replayed the same situation three times, without any notion of time travel. Our results suggest that those in the Time Travel condition did achieve an illusion of ‘time travel’ provided that they also experienced an illusion of presence in the virtual environment, body ownership and agency over the virtual body that substituted their own. Time travel produced an increase in guilt feelings about the events that had occurred, and an increase in support of utilitarian behavior as the solution to the moral dilemma. Time travel also produced an increase in implicit morality as judged by an implicit association test. The time travel illusion was associated with a reduction of regret associated with bad decisions in their own lives. The results show that when participants have a third action that they can take to solve the moral dilemma (that does not immediately involve choosing between the 1 and the 5 then they tend to take this option, even though it is useless in solving the dilemma, and actually results in the deaths of a greater number.

  3. Cash Component of Conditional Cash Transfer Program Is Associated with Higher Body Mass Index and Blood Pressure in Adults12

    Science.gov (United States)

    Fernald, Lia C. H.; Gertler, Paul J.; Hou, Xiaohui

    2008-01-01

    The cash component of Oportunidades, a large conditional cash transfer (CCT) program in Mexico, has previously been shown to be associated with better outcomes for child growth and development. The objective of this analysis was to determine whether the cash transfers were also associated with positive outcomes for adult health. Oportunidades was originally randomized across 506 rural (Oportunidades's requirements for the entire period, but some received higher cumulative cash transfers because they were living in communities randomized to begin receiving transfers earlier and/or they accumulated cash at a faster rate because they had more school-aged children at baseline. Our primary findings were that a doubling of cumulative cash transfers to the household was associated with higher BMI (β = +0.83, 95% CI 0.46, 1.20; P Oportunidades has been portrayed as a model for CCT programs worldwide, but the results reported here support the notion that the cash component of Oportunidades may be negatively associated with some adult health outcomes. PMID:18936227

  4. Cash component of conditional cash transfer program is associated with higher body mass index and blood pressure in adults.

    Science.gov (United States)

    Fernald, Lia C H; Gertler, Paul J; Hou, Xiaohui

    2008-11-01

    The cash component of Oportunidades, a large conditional cash transfer (CCT) program in Mexico, has previously been shown to be associated with better outcomes for child growth and development. The objective of this analysis was to determine whether the cash transfers were also associated with positive outcomes for adult health. Oportunidades was originally randomized across 506 rural (Oportunidades's requirements for the entire period, but some received higher cumulative cash transfers because they were living in communities randomized to begin receiving transfers earlier and/or they accumulated cash at a faster rate because they had more school-aged children at baseline. Our primary findings were that a doubling of cumulative cash transfers to the household was associated with higher BMI (beta = +0.83, 95% CI 0.46, 1.20; P Oportunidades has been portrayed as a model for CCT programs worldwide, but the results reported here support the notion that the cash component of Oportunidades may be negatively associated with some adult health outcomes.

  5. Effects of Surface Recombination on Heat Transfer to Bodies in a High Enthalpy Stream of Partially Dissociated Nitrogen

    Science.gov (United States)

    Winkler, Ernest L..; Griffin, Roy N., Jr.

    1961-01-01

    Heat-transfer rates to two surfaces having widely different catalytic effectiveness are compared at a Mach number of 6 in a low-density stream of partially dissociated nitrogen. The heat-transfer rate to a polished copper cylinder is twice as great as the heat-transfer rate to a silicon-monoxide-coated cylinder when the stream total energy content is 9000 Btu/lb. Various methods for determining the stream energy content, the stream velocity, and the stream Mach number have been developed and compared. It is shown that methods for estimating the stream energy content by means of purely aerodynamic concepts may neglect the sizable fraction of the stream energy contained in molecular dissociation.

  6. Modifying Bodily Self-Awareness during Acupuncture Needle Stimulation Using the Rubber Hand Illusion

    Directory of Open Access Journals (Sweden)

    Dong-Seon Chang

    2013-01-01

    Full Text Available Background. The rubber hand illusion (RHI is an experimental paradigm that manipulates important aspects of body self-awareness. Objectives. We were interested in whether modifying bodily self-awareness by manipulation of body ownership and visual expectations using the RHI would change the subjective perception of pain as well as the autonomic response to acupuncture needle stimulation. Methods. Acupuncture needle stimulation was applied to the real hand during the RHI with (experiment 1 or without (experiment 2 visual expectation while measuring concurrent autonomic changes such as the skin conductance response (SCR. Subjective responses such as perception of the RHI and perceived pain were measured by questionnaires. Results. In experiment 1, the amplitude of the increase in SCR was visibly higher during the synchronous session compared with that of the asynchronous session. In experiment 2, the amplitude of the increase of SCR was lower for the synchronous session compared with that for the asynchronous session. Comparing these two experiments, the visual expectation of needle stimulation produced a greater autonomic response to acupuncture stimulation. Conclusions. Our findings suggest that the sympathetic response to acupuncture needle stimulation is primarily influenced by visual expectation rather than by modifications of body ownership.

  7. Modifying Bodily Self-Awareness during Acupuncture Needle Stimulation Using the Rubber Hand Illusion.

    Science.gov (United States)

    Chang, Dong-Seon; Kim, Yun-Ji; Lee, Soon-Ho; Lee, Hyejung; Lee, In-Seon; Park, Hi-Joon; Wallraven, Christian; Chae, Younbyoung

    2013-01-01

    Background. The rubber hand illusion (RHI) is an experimental paradigm that manipulates important aspects of body self-awareness. Objectives. We were interested in whether modifying bodily self-awareness by manipulation of body ownership and visual expectations using the RHI would change the subjective perception of pain as well as the autonomic response to acupuncture needle stimulation. Methods. Acupuncture needle stimulation was applied to the real hand during the RHI with (experiment 1) or without (experiment 2) visual expectation while measuring concurrent autonomic changes such as the skin conductance response (SCR). Subjective responses such as perception of the RHI and perceived pain were measured by questionnaires. Results. In experiment 1, the amplitude of the increase in SCR was visibly higher during the synchronous session compared with that of the asynchronous session. In experiment 2, the amplitude of the increase of SCR was lower for the synchronous session compared with that for the asynchronous session. Comparing these two experiments, the visual expectation of needle stimulation produced a greater autonomic response to acupuncture stimulation. Conclusions. Our findings suggest that the sympathetic response to acupuncture needle stimulation is primarily influenced by visual expectation rather than by modifications of body ownership.

  8. Low body mass index compromises live birth rate in fresh transfer in vitro fertilization cycles: a retrospective study in a Chinese population.

    Science.gov (United States)

    Cai, Jiali; Liu, Lanlan; Zhang, Junwen; Qiu, Huiling; Jiang, Xiaoming; Li, Ping; Sha, Aiguo; Ren, Jianzhi

    2017-02-01

    To evaluate the effects of low body mass index (BMI) on in vitro fertilization (IVF) outcomes in fresh transfer cycles. Retrospective cohort study. University-affiliated hospital. A total of 4,798 cycles with conventional stimulation and fresh transfer in a single IVF center during the period 2013-2014. Low BMI (Live birth rate per fresh embryo transfer. Low BMI was associated with reduced live birth rates and increased miscarriage rates compared with normal weight, controlling for important covariates known to influence IVF outcomes. Patient age was the most potent confounder, causing a 10.5% reduction in the odds ratio (OR) for live birth between the groups compared. When an interaction term (age × BMI) was introduced, the OR for live birth was reduced in cycles of those aged ≥35 years compared with cycles of those aged 28-34 years, whereas the change in OR between cycles in those aged <28 and cycles in those aged 28-34 years was insignificant. Low BMI is associated with negative outcomes in fresh transfer cycles, especially for women of advanced age. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  9. Do Children with Autism Perceive Second-Order Relational Features? The Case of the Thatcher Illusion

    Science.gov (United States)

    Rouse, Helen; Donnelly, Nick; Hadwin, Julie A.; Brown, Tony

    2004-01-01

    Background: This study presents two experiments that investigated whether children with autism were susceptible to the Thatcher illusion. Perception of the Thatcher illusion requires being able to compute second-order configural relations for facial stimuli. Method: In both experiments children with autism were matched for non-verbal and verbal…

  10. The Bicycle Illusion: Sidewalk Science Informs the Integration of Motion and Shape Perception

    Science.gov (United States)

    Masson, Michael E. J.; Dodd, Michael D.; Enns, James T.

    2009-01-01

    The authors describe a new visual illusion first discovered in a natural setting. A cyclist riding beside a pair of sagging chains that connect fence posts appears to move up and down with the chains. In this illusion, a static shape (the chains) affects the perception of a moving shape (the bicycle), and this influence involves assimilation…

  11. The Occurrence Rate of the Fission Illusion Differs Depending on the Complexity of Visual Stimuli

    Directory of Open Access Journals (Sweden)

    Yasuhiro Takeshima

    2011-10-01

    Full Text Available A fission illusion (also named a double—flash illusion is a famous phenomenon of audio-visual interaction, in which a single brief flash is perceived as two flashes when presented simultaneously with two brief beeps (Shames, Kamitani, & Shimojo, 2000; 2002. The fission illusion has been investigated using relatively simple visual stimuli like single circle. Thus the illusion has not been examined by using complex visual stimuli. Markovic & Gvozdenovic (2001 reported that the processing of complex visual stimuli tends to be delayed. Therefore, the complexity of visual stimuli may affect the occurrence rate of the fission illusion, since this illusion is generated in the process that copes with visual and auditory stimuli in a short time. The present study examined the differences in illusory occurrence rates by manipulating the complexity of visual stimuli. We used the patterns proposed by Garner & Clement (1963 to control the complexity. The results indicated that it was more difficult to induce the fission illusion by using complex visual stimuli than it was by using simple stimuli. Thus, the present study suggested that the occurrence rate of the fission illusion differed depending on the perceptual efficiency in the coding process of visual stimuli. This study was supported by Grant-in-Aid for Specifically Promoted Research (No. 19001004.

  12. Pathological gamblers are more vulnerable to the illusion of control in a standard associative learning task.

    Science.gov (United States)

    Orgaz, Cristina; Estévez, Ana; Matute, Helena

    2013-01-01

    An illusion of control is said to occur when a person believes that he or she controls an outcome that is uncontrollable. Pathological gambling has often been related to an illusion of control, but the assessment of the illusion has generally used introspective methods in domain-specific (i.e., gambling) situations. The illusion of control of pathological gamblers, however, could be a more general problem, affecting other aspects of their daily life. Thus, we tested them using a standard associative learning task which is known to produce illusions of control in most people under certain conditions. The results showed that the illusion was significantly stronger in pathological gamblers than in a control undiagnosed sample. This suggests (1) that the experimental tasks used in basic associative learning research could be used to detect illusions of control in gamblers in a more indirect way, as compared to introspective and domain-specific questionnaires; and (2), that in addition to gambling-specific problems, pathological gamblers may have a higher-than-normal illusion of control in their daily life.

  13. Pathological gamblers are more vulnerable to the illusion of control in a standard associative learning task

    Directory of Open Access Journals (Sweden)

    Cristina eOrgaz

    2013-06-01

    Full Text Available An illusion of control is said to occur when a person believes that he or she controls an outcome that is uncontrollable. Pathological gambling has often been related to an illusion of control, but the assessment of the illusion has generally used introspective methods in domain-specific (i.e., gambling situations. The illusion of control of pathological gamblers, however, could be a more general problem, affecting other aspects of their daily life. Thus, we tested them using a standard associative learning task which is known to produce illusions of control in most people under certain conditions. The results showed that the illusion was significantly stronger in pathological gamblers than in a control undiagnosed sample. This suggests (a that the experimental tasks used in basic associative learning research could be used to detect illusions of control in gamblers in a more indirect way, as compared to introspective and domain-specific questionnaires; and (b, that in addition to gambling-specific problems, pathological gamblers may have a higher-than-normal illusion of control in their daily life.

  14. Perception of the Auditory-Visual Illusion in Speech Perception by Children with Phonological Disorders

    Science.gov (United States)

    Dodd, Barbara; McIntosh, Beth; Erdener, Dogu; Burnham, Denis

    2008-01-01

    An example of the auditory-visual illusion in speech perception, first described by McGurk and MacDonald, is the perception of [ta] when listeners hear [pa] in synchrony with the lip movements for [ka]. One account of the illusion is that lip-read and heard speech are combined in an articulatory code since people who mispronounce words respond…

  15. Individual Differences in the Multisensory Temporal Binding Window Predict Susceptibility to Audiovisual Illusions

    Science.gov (United States)

    Stevenson, Ryan A.; Zemtsov, Raquel K.; Wallace, Mark T.

    2012-01-01

    Human multisensory systems are known to bind inputs from the different sensory modalities into a unified percept, a process that leads to measurable behavioral benefits. This integrative process can be observed through multisensory illusions, including the McGurk effect and the sound-induced flash illusion, both of which demonstrate the ability of…

  16. Pulsatile flow and heat transfer of a magneto-micropolar fluid through a stenosed artery under the influence of body acceleration

    CERN Document Server

    Shit, G C

    2012-01-01

    With an aim to investigate the effect of externally imposed body acceleration and magnetic field on pulsatile flow of blood through an arterial segment having stenosis is under consideration in this paper. The flow of blood is presented by a unsteady micropolar fluid and the heat transfer characteristics have been taken into account. The non-linear equations that governing the flow are solved numerically using finite difference technique by employing a suitable coordinate transformation. The numerical results have been observed for axial and microrotation component of velocity, fluid acceleration, wall shear stress(WSS), flow resistance, temperature and the volumetric flow rate. It thus turns out that the rate of heat transfer increases with the increase of Hartmann number $H$, while the wall shear stress has a reducing effect on the Hartmann number $H$ and an enhancing effect on microrotation parameter $K$ as well as the constriction height $\\delta$.

  17. Refractive error and monocular viewing strengthen the hollow-face illusion.

    Science.gov (United States)

    Hill, Harold; Palmisano, Stephen; Matthews, Harold

    2012-01-01

    We measured the strength of the hollow-face illusion--the 'flipping distance' at which perception changes between convex and concave--as a function of a lens-induced 3 dioptre refractive error and monocular/binocular viewing. Refractive error and closing one eye both strengthened the illusion to approximately the same extent. The illusion was weakest viewed binocularly without refractive error and strongest viewed monocularly with it. This suggests binocular cues disambiguate the illusion at greater distances than monocular cues, but that both are disrupted by refractive error. We argue that refractive error leaves the ambiguous low-spatial-frequency shading information critical to the illusion largely unaffected while disrupting other, potentially disambiguating, depth/distance cues.

  18. Causes of Fiscal Illusion: Lack of Information or Lack of Attention?

    DEFF Research Database (Denmark)

    Bækgaard, Martin; Serritzlew, Søren; Blom-Hansen, Jens

    2016-01-01

    the implications of fiscal illusions, whereas the question why fiscal illusions occur at all has received less attention. According to the standard argument, individuals base their opinion of policy proposals on a valuation of benefits and costs. We formalize the standard argument and show that it is a special......According to fiscal illusion theory, voters misperceive fiscal parameters because of incomplete information. The costs of public services are underestimated, implying that if voters had full information, their support for public services would drop. The literature has focused on testing...... case of the attention model of fiscal illusion. In this model, opinion depends on the saliency of attributes of the proposal. We show that the attention model can better explain fiscal illusion by deriving competing hypotheses, which are tested in a survey experiment. We conclude that the mechanism...

  19. Boundary Element Method(BEM) for Solving Normal or Inverse Bio—heat Transfer Problem of Biological Bodies with Complex Shape

    Institute of Scientific and Technical Information of China (English)

    RenZePei; LiuJing; 等

    1995-01-01

    The application of BEM for solving normal or inverse bio-heat transfer problems of biological bodies with complex shapes is discussed and a new method for non-invasive reconstruction of the spatial temperature field and the non-homogeneous heat source is proposed in this paper,Tikhonov's (1979) regularization technique is used to improve the performance of ill-posed equations in the process of solving for inverse problems.The feasibility of the above mentioned method was verified by the numerical test results of a two-dimensional steady state problem.This method has laid the theoretical foundation for developing a bimedical instrument and respective software used in the non-invasive monitoring of the spatial temperature field of biological bodies.

  20. Lightness of Munker-White illusion and Simultaneous-Contrast illusion: Establishing an ordinal lightness relation among minimum and split-frame presentations

    OpenAIRE

    Li, Ang; Tavantzis, Michael-John; Yazdanbakhsh, Arash

    2009-01-01

    The achromatic Munker-White illusion and the Simultaneous-Contrast illusion have been used extensively in vision studies to understand how the figural configuration of a stimulus can affect the perceived lightness of its components in human perception. Yet, previous modeling and psychophysics studies did not directly compare the illusions’ lightness with controlled parameters of minimum stripes and split-frame presentations, which are useful in testing model predictions and in correlating neu...

  1. The Hollow-Face Illusion in Infancy: Do Infants See a Screen Based Rotating Hollow Mask as Hollow?

    Directory of Open Access Journals (Sweden)

    Aki Tsuruhara

    2011-06-01

    Full Text Available We investigated whether infants experience the hollow-face illusion using a screen-based presentation of a rotating hollow mask. In experiment 1 we examined preferential looking between rotating convex and concave faces. Adults looked more at the concave—illusory convex—face which appears to counter rotate. Infants of 7- to 8-month-old infants preferred the convex face, and 5- to 6-month-olds showed no preference. While older infants discriminate, their preference differed from that of adults possibly because they don't experience the illusion or counter rotation. In experiment 2 we tested preference in 7- to 8-month-olds for angled convex and concave static faces both before and after habituation to the stimuli shown in experiment 1. The infants showed a novelty preference for the static shape opposite to the habituation stimulus, together with a general preference for the static convex face. This shows that they discriminate between convex and concave faces and that habituation to either transfers across a change in view. Seven- to eight-month-olds have been shown to discriminate direction of rigid rotation on the basis of perspective changes. Our results suggest that this, perhaps together with a weaker bias to perceive faces as convex, allows these infants to see the screen-based hollow face as hollow even though adults perceive it as convex.

  2. Spectral transfer functions of body waver propagating through a stratified medium. Part I: Basic theory by means of matrix propagators

    Energy Technology Data Exchange (ETDEWEB)

    Macia, R.; Correig, A.M.

    1987-01-01

    Seismic wave propagation is described by a second order differential equation for medium desplacement. By Fourier transforming with respect to time and space, wave equation transforms into a system of first order linear differential equations for the Fourier transform of displacement and stress. This systen of differential equations is solved by means of Matrx Propagator and applied to the propagation of body waves in stratified media. The matrix propagators corresponding to P-SV and SH waves in homogeneous medium are found as an intermediate step to obtain the spectral response of body waves propagating through a stratified medium with homogeneous layers. (Author)

  3. Which way is down? Positional distortion in the tilt illusion.

    Science.gov (United States)

    Tomassini, Alessandro; Solomon, Joshua Adam; Morgan, Michael John

    2014-01-01

    Contextual information can have a huge impact on our sensory experience. The tilt illusion is a classic example of contextual influence exerted by an oriented surround on a target's perceived orientation. Traditionally, the tilt illusion has been described as the outcome of inhibition between cortical neurons with adjacent receptive fields and a similar preference for orientation. An alternative explanation is that tilted contexts could produce a re-calibration of the subjective frame of reference. Although the distinction is subtle, only the latter model makes clear predictions for unoriented stimuli. In the present study, we tested one such prediction by asking four naive subjects to estimate three positions (4, 6, and 8 o'clock) on an imaginary clock face within a tilted surround. To indicate their estimates, they used either an unoriented dot or a line segment, with one endpoint at fixation in the middle of the surround. The surround's tilt was randomly chosen from a set of orientations (± 75°, ± 65°, ± 55°, ± 45°, ± 35°, ± 25°, ± 15°, ± 5° with respect to vertical) across trials. Our results showed systematic biases consistent with the tilt illusion in both conditions. Biases were largest when observers attempted to estimate the 4 and 8 o'clock positions, but there was no significant difference between data gathered with the dot and data gathered with the line segment. A control experiment confirmed that biases were better accounted for by a local coordinate shift than to torsional eye movements induced by the tilted context. This finding supports the idea that tilted contexts distort perceived positions as well as perceived orientations and cannot be readily explained by lateral interactions between orientation selective cells in V1.

  4. Identifying the number and location of body worn sensors to accurately classify walking, transferring and sedentary activities.

    Science.gov (United States)

    Aziz, Omar; Robinovitch, Stephen N; Park, Edward J

    2016-08-01

    In order to perform fall risk assessments using wearable inertial sensors in older adults in their natural settings where falls are likely to occur, a first step is to automatically segment and classify sensor signals of human movements into the known `activities of interest'. Sensor data from such activities can later be used through quantitative and qualitative analysis for differentiating fallers from non-fallers. In this study, ten young adults participated in experimental trials involving several variations of walking, transferring and sedentary activities. Data from tri-axial accelerometers and gyroscopes were used to classify the aforementioned three categories using a multiclass support vector machine algorithm. Our results showed 100% accuracy in distinguishing walking, transferring and sedentary activities using data from a three-sensor combination of sternum and both ankles.

  5. An ordinal model of the McGurk illusion

    DEFF Research Database (Denmark)

    Andersen, Tobias

    2011-01-01

    Audiovisual information is integrated in speech perception. One manifestation of this is the McGurk illusion in which watching the articulating face alters the auditory phonetic percept. Understanding this phenomenon fully requires a computational model with predictive power. Here, we describe...... model it also employed 30 free parameters where the ordinal model needed only 14. Testing the predictive power of the models using a form of cross-validation we found that, although both models performed rather poorly, the ordinal model performed better than the FLMP. Based on these findings we suggest...

  6. An Illusion Of Development A nd Technological Decline In Poland

    Directory of Open Access Journals (Sweden)

    Jolanta Sala

    2010-12-01

    Full Text Available Professional IT specialists are still bei ng shocked by inadequacy between the fast IT development in 1970’s and technological decline in 21st century. The stagnation of ICT technologies and their application in social and economic practices in Poland inspired the authors to search for causes and conditions. The authors present the divergent interpretations of New Entrepreneurship st ate from the perspective of micro and macroeconomics. The analyses showed that either “new” or “old” economics is not going to develop without proper economic, institut ional, regulative or social and cultural changes. Unfortunately, the transformation of past two decades is an illusion of development.

  7. Modeling and simulation the computer science of illusion

    CERN Document Server

    Raczynski, Stanislaw

    2006-01-01

    Simulation is the art of using tools - physical or conceptual models, or computer hardware and software, to attempt to create the illusion of reality. The discipline has in recent years expanded to include the modelling of systems that rely on human factors and therefore possess a large proportion of uncertainty, such as social, economic or commercial systems. These new applications make the discipline of modelling and simulation a field of dynamic growth and new research. Stanislaw Raczynski outlines the considerable and promising research that is being conducted to counter the problems of

  8. Fun with maths and physics: brain teasers tricks illusions

    CERN Document Server

    Perelman, Yakov

    2013-01-01

    Fun with Maths and Physics details a large number of intriguing physics experiments, entertaining mathematics problems, and amazing optical illusions.The book’s main objective is to arouse the reader’s scientific imagination, teach him to think in a scientific manner, and create in his mind a variety of associations between physical knowledge and a large number of real daily life observations.Immensely instructive and entertaining, it has been one of the best sellers in Russia during the first part of last century.

  9. The Poggendorff illusion effect influenced by top-down control: evidence from an event-related brain potential study.

    Science.gov (United States)

    Liao, Shu; Su, Yanhua; Wu, Xin; Qiu, Jiang

    2011-10-26

    Event-related brain potentials were used to examine the neural correlates of the visual illusion effect in the Poggendorff illusion. In this study, there were three tasks, namely, illusion task 1, illusion task 2 (similar to the classical Poggendorff figures, where the two oblique lines in which individuals were prone to judge to be collinear, were not collinear in fact), and baseline task. Scalp event-related brain potential analysis revealed that (a) both illusion task 1 and illusion task 2 elicited a more negative event-related brain potential deflection (N400-600) than did baseline task, approximately 400 ms after onset of the stimuli, and (b) high-level cognitive control system is, through enhancing the influence of the context on identifying the relationships of the two oblique lines, involved in generating the Poggendorff illusion.

  10. Toward transferable interatomic van der Waals interactions without electrons: The role of multipole electrostatics and many-body dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Bereau, Tristan, E-mail: bereau@mpip-mainz.mpg.de [Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany and Department of Chemistry, University of Basel, 4056 Basel (Switzerland); Lilienfeld, O. Anatole von [Department of Chemistry, Institute of Physical Chemistry, University of Basel, 4056 Basel, Switzerland and Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-07-21

    We estimate polarizabilities of atoms in molecules without electron density, using a Voronoi tesselation approach instead of conventional density partitioning schemes. The resulting atomic dispersion coefficients are calculated, as well as many-body dispersion effects on intermolecular potential energies. We also estimate contributions from multipole electrostatics and compare them to dispersion. We assess the performance of the resulting intermolecular interaction model from dispersion and electrostatics for more than 1300 neutral and charged, small organic molecular dimers. Applications to water clusters, the benzene crystal, the anti-cancer drug ellipticine—intercalated between two Watson-Crick DNA base pairs, as well as six macro-molecular host-guest complexes highlight the potential of this method and help to identify points of future improvement. The mean absolute error made by the combination of static electrostatics with many-body dispersion reduces at larger distances, while it plateaus for two-body dispersion, in conflict with the common assumption that the simple 1/R{sup 6} correction will yield proper dissociative tails. Overall, the method achieves an accuracy well within conventional molecular force fields while exhibiting a simple parametrization protocol.

  11. Pinhole Viewing Strengthens the Hollow-Face Illusion

    Directory of Open Access Journals (Sweden)

    Trent Koessler

    2015-08-01

    Full Text Available A hollow (concave mask appears convex when viewed from beyond a certain distance even when viewed stereoscopically—this is the hollow-face illusion. At close viewing distances, the same mask is seen as hollow even when disparity information is eliminated by monocular viewing. A potential source of nonpictorial, monocular information that favors a veridical percept at close distances is accommodation in conjunction with focus blur. In this article, we used pinhole viewing to minimize this potential source of information and test whether it affects whether a hollow mask is seen as veridical (concave or illusory (convex. Since monocular viewing also facilitates the illusory (convex percept, it was included in the design both as a comparison and to test whether any effect of accommodation depends on vergence. Pinhole viewing was found favor the illusory percept, and its effect was at least as large as, and added to, that of monocular viewing. A control experiment using tinted glasses that attenuate illumination at least as much as the pinholes did not strengthen the illusion ruling out explanations in terms of reduced luminance. For pinhole viewing, there was no difference between monocular and binocular conditions. The results are interpreted as evidence that focus driven depth information affects perceived three-dimensional shape at close distances even when other sources of depth information are available. The lack of a difference between monocular and binocular pinhole viewing suggests that, by disrupting accommodation, pinholes may also interfere with linked vergence cues to depth.

  12. Changes in visual function during the Coriolis illusion.

    Science.gov (United States)

    Horng, Chi-Ting; Liu, Chung-Cheng; Kuo, Daih-Iluang; Shieh, Po-Chuen; Wu, Yi-Chang; Chen, Jiann-Torng; Tsai, Ming-Ling

    2009-04-01

    The Coriolis illusion produces spatial disorientation and is, therefore, dangerous for pilots. It is not known whether it also affects visual function (visual acuity and stereopsis). There were 18 subjects (15 men and 3 women, mean age 24.7 yr) enrolled in the study. A spatial disorientation simulator was used to produce Coriolis stimulation. The visual acuity of the subjects was evaluated with the Rosenbaum Vision Card before and during Coriolis stimulation. Stereopsis was measured with the Titmus stereo test. Throughout the experiments, eyeball movements were observed on a television monitor. Electrooculography (EOG) and electroencephalography (EEG) were also documented. Before Coriolis stimulation, the visual acuity and stereopsis of all subjects were 20/20 and 40 s of arc, respectively. During the Coriolis illusion, the visual acuity of nine subjects (50%) remained 20/20, whereas the visual acuity of the others (50%) dropped by two lines. The stereopsis of most subjects (77.8%) decreased to 800 arc-seconds or less. Rhythmic nystagmus was observed, while EOG amplitudes were significantly elevated compared with those at baseline (9.41 +/- 0.26 microv2 and 8.45 +/- 0.36 microv2, respectively). EEG activity (frequency) was also greater than at baseline (13.15 +/- 0.84 Hz and 11.94 +/- 1.20 Hz, respectively; P < 0.05). During Coriolis stimulation, the visual acuity of the subjects remained stable, but their stereopsis was reduced. Further study is warranted.

  13. An illusion of control modulates the reluctance to tempt fate

    Directory of Open Access Journals (Sweden)

    Chloe L. Swirsky

    2011-10-01

    Full Text Available The tempting fate effect is that the probability of a fateful outcome is deemed higher following an action that ``tempts'' the outcome than in the absence of such an action. In this paper we evaluate the hypothesis that the effect is due to an illusion of control induced by a causal framing of the situation. Causal frames require that the action make a difference to an outcome and that the action precedes the outcome. If an illusion of control modulates the reluctance to tempt fate, then actions that make a difference to well-being and that occur prior to the outcome should tempt fate most strongly. In Experiments 1--3 we varied whether the action makes a difference and the temporal order of action and outcome. In Experiment 4 we tested whether an action can tempt fate if all outcomes are negative. The results of all four experiments supported our hypothesis that the tempting fate effect depends on a causal construal that gives rise to a false sense of control.

  14. Geometric illusions in astronauts during long-duration spaceflight.

    Science.gov (United States)

    Clément, Gilles; Skinner, Anna; Richard, Ghislaine; Lathan, Corinna

    2012-10-24

    In our previous studies, we have shown that the occurrence of geometric illusions was reduced in vestibular patients who presented signs of otolith disorders and when healthy observers were tilted relative to gravity. We hypothesized that the alteration in the gravitational (otolith) input was responsible for this change, presumably because of a connection between vestibular and visual-spatial cognitive functions. In this study, we repeated similar experiments in astronauts during long-duration spaceflight. In agreement with the data of otolithic patients, the inverted-T geometric illusion was less present in the astronauts in 0 g than in 1g. In addition, the vertical length of drawings made by astronauts in orbit was shorter than that on the ground. This result is also comparable with the otolithic patients who perceived the vertical length of line drawings to be smaller than healthy individuals. We conclude that the impairment in the processing of gravitational input in long-duration astronauts affects their mental representation of the vertical dimension similar to the otolithic patients. The astronauts, however, recover to baseline levels within 1 week after returning to Earth.

  15. Reduced susceptibility to the sound-induced flash fusion illusion in schizophrenia.

    Science.gov (United States)

    Vanes, Lucy D; White, Thomas P; Wigton, Rebekah L; Joyce, Dan; Collier, Tracy; Shergill, Sukhi S

    2016-11-30

    Schizophrenia is characterised by the presence of abnormal complex sensory perceptual experiences. Such experiences could arise as a consequence of dysfunctional multisensory integration. We used the sound-induced flash illusion paradigm, which probes audiovisual integration using elementary visual and auditory cues, in a sample of individuals with schizophrenia (n=40) and matched controls (n=22). Signal detection theory analyses were performed to characterise patients' and controls' sensitivity in distinguishing 1 and 2 flashes under varying auditory conditions. Both groups experienced significant fission illusions (whereby one visual flash, accompanied by two auditory beeps, is misperceived as two flashes) and fusion illusions (whereby two flashes, accompanied by one beep, are perceived as one flash). Patients showed significantly lower fusion illusion rates compared to HC, while the fission illusion occurred similarly frequently in both groups. However, using an SDT approach, we compared illusion conditions with unimodal visual conditions, and found that illusory visual perception was overall more strongly influenced by auditory input in HC compared to patients for both illusions. This suggests that multisensory integration may be impaired on a low perceptual level in SZ.

  16. Preliminary study to investigate the Delboeuf illusion in ring-tailed lemurs (Lemur catta: Methodological Challenges.

    Directory of Open Access Journals (Sweden)

    Maria Santacà

    2017-08-01

    Full Text Available Visual illusions are commonly used in animal cognition studies to compare visual perception among vertebrates. To date, researchers have focused their attention mainly on birds and mammals, especially apes and monkeys, but no study has investigated sensitivity to visual illusions in prosimians. Here we investigated whether lemurs (Lemur catta perceive the Delboeuf illusion, a well-known illusion that occurs when subjects misperceive the relative size of an item because of its surrounding context. In particular, we adopted the spontaneous preference paradigm used in chimpanzees and observed lemurs’ ability to select the larger amount of food. In control trials, we presented two different amounts of food on two identical plates. In test trials, we presented equal food portion sizes on two plates differing in size: If lemurs were sensitive to the illusion, they were expected to select the food portion presented on the smaller plate. In control trials, they exhibited poor performance compared to other mammals previously observed, being able to discriminate between the two quantities only in the presence of a 0.47 ratio. This result prevented us from drawing any conclusion regarding the subjects’ susceptibility to the Delboeuf illusion. In test trials with the illusory pattern, however, the subjects’ choices did not differ from chance. Our data suggest that the present paradigm is not optimal for testing the perception of the Delboeuf illusion in lemurs and highlight the importance of using different methodological approaches to assess the perceptual mechanisms underlying size discrimination among vertebrates.

  17. The visual phantom illusion: A perceptual product of surface completion depending on brightness and contrast.

    Science.gov (United States)

    Kitaoka, Akiyoshi; Gyoba, Jiro; Sakurai, Kenzo

    2006-01-01

    The visual phantom illusion was first discovered by Rosenbach in 1902 and named 'moving phantoms' by Tynan and Sekuler in 1975 because of its strong dependence on motion. It was later revealed that phantoms can be generated by flickering the grating (flickering phantoms) or by low-luminance stationary gratings under dark adaptation (stationary phantoms). Although phantoms are much more visible at scotopic or mesopic adaptation levels (scotopic phantoms) than at photopic levels, we proposed a new phantom illusion which is fully visible in photopic vision (photopic phantoms). In 2001, we revealed that the visual phantom illusion is a higher-order perceptual construct or a Gestalt, which depends on the mechanism of perceptual transparency. Perceptual transparency is known as a perceptual product based upon brightness and contrast. We furthermore manifested the shared mechanisms between visual phantoms and neon color spreading or between visual phantoms and the Petter effect. In our recent study, the visual phantom illusion can also be seen with a stimulus of contrast-modulated gratings. We assume that this effect also depends on perceptual transparency induced by contrast modulation. Moreover, we found that the Craik-O'Brien-Cornsweet effect and other brightness illusions can generate the visual phantom illusion. In any case, we explain the visual phantom illusion in terms of surface completion, which is given by perceptual transparency.

  18. Auralization of CFD Vorticity Using an Auditory Illusion

    Science.gov (United States)

    Volpe, C. R.

    2005-12-01

    One way in which scientists and engineers interpret large quantities of data is through a process called visualization, i.e. generating graphical images that capture essential characteristics and highlight interesting relationships. Another approach, which has received far less attention, is to present complex information with sound. This approach, called ``auralization" or ``sonification", is the auditory analog of visualization. Early work in data auralization frequently involved directly mapping some variable in the data to a sound parameter, such as pitch or volume. Multi-variate data could be auralized by mapping several variables to several sound parameters simultaneously. A clear drawback of this approach is the limited practical range of sound parameters that can be presented to human listeners without exceeding their range of perception or comfort. A software auralization system built upon an existing visualization system is briefly described. This system incorporates an aural presentation synchronously and interactively with an animated scientific visualization, so that alternate auralization techniques can be investigated. One such alternate technique involves auditory illusions: sounds which trick the listener into perceiving something other than what is actually being presented. This software system will be used to present an auditory illusion, known for decades among cognitive psychologists, which produces a sound that seems to ascend or descend endlessly in pitch. The applicability of this illusion for presenting Computational Fluid Dynamics data will be demonstrated. CFD data is frequently visualized with thin stream-lines, but thicker stream-ribbons and stream-tubes can also be used, which rotate to convey fluid vorticity. But a purely graphical presentation can yield drawbacks of its own. Thicker stream-tubes can be self-obscuring, and can obscure other scene elements as well, thus motivating a different approach, such as using sound. Naturally

  19. Adoptive transfer of Mammaglobin-A epitope specific CD8 T cells combined with a single low dose of total body irradiation eradicates breast tumors.

    Science.gov (United States)

    Lerret, Nadine M; Rogozinska, Magdalena; Jaramillo, Andrés; Marzo, Amanda L

    2012-01-01

    Adoptive T cell therapy has proven to be beneficial in a number of tumor systems by targeting the relevant tumor antigen. The tumor antigen targeted in our model is Mammaglobin-A, expressed by approximately 80% of human breast tumors. Here we evaluated the use of adoptively transferred Mammaglobin-A specific CD8 T cells in combination with low dose irradiation to induce breast tumor rejection and prevent relapse. We show Mammaglobin-A specific CD8 T cells generated by DNA vaccination with all epitopes (Mammaglobin-A2.1, A2.2, A2.4 and A2.6) and full-length DNA in vivo resulted in heterogeneous T cell populations consisting of both effector and central memory CD8 T cell subsets. Adoptive transfer of spleen cells from all Mammaglobin-A2 immunized mice into tumor-bearing SCID/beige mice induced tumor regression but this anti-tumor response was not sustained long-term. Additionally, we demonstrate that only the adoptive transfer of Mammaglobin-A2 specific CD8 T cells in combination with a single low dose of irradiation prevents tumors from recurring. More importantly we show that this single dose of irradiation results in the down regulation of the macrophage scavenger receptor 1 on dendritic cells within the tumor and reduces lipid uptake by tumor resident dendritic cells potentially enabling the dendritic cells to present tumor antigen more efficiently and aid in tumor clearance. These data reveal the potential for adoptive transfer combined with a single low dose of total body irradiation as a suitable therapy for the treatment of established breast tumors and the prevention of tumor recurrence.

  20. Crossed hands strengthen and diversify proprioceptive drift in the self-touch illusion

    Directory of Open Access Journals (Sweden)

    Kenri eKodaka

    2014-06-01

    Full Text Available In the self-touch illusion (STI, some can feel that both hands are touching each other even when they are separated actually. This is achieved by giving synchronized touches to both hands. Because the STI involves both hands (an administrating hand and a receptive hand of a single person, two types of proprioceptive drifts (PDs simultaneously occur in such a way that both hands are attracted to each other. It is known that the PD distance is generally larger for the administrating hand than for the receptive hand when the two hands are uncrossed. However, it remains unclear why such an asymmetrical relationship is observed universally. In this study, we conducted two types of experiment to induce the STI. The first experiment involved four conditions combining a factor of whether the hands are uncrossed or crossed and a factor of whether the administrating hand is resting or active on the surface, with the receptive (left hand located at the body's midline. The result demonstrated that crossing hands and resting on surface (ROS induced the STI. Specifically, crossing hands enhanced the amount of PD distance by more than 2 or 3 times. Moreover, it is interesting that strong PD with dominance of the receptive hand, which did not appear in the uncrossed condition, was observed frequently. The second experiment collected seven illusion-sensitive subjects from the first experiment, all of whom had a strong tendency to feel the self-touch, and examined the effect of the location of the body midline on the PD when hands are crossed with the administrating hand ROS. The result demonstrated that the dominant hand on the PD completely differed among subjects, but was relatively stable over the midline position and time in the same person. We also found that a small number of subjects exhibited quite a different pattern of the PD in the identical posture. On the basis of the results, we analyze in detail how the dominant hand on the PD is determined in the

  1. Visual Illusion and Its Application%视错觉及其应用

    Institute of Scientific and Technical Information of China (English)

    马先兵; 孙水发; 夏平; 龚国强

    2012-01-01

    Vision is the most important way for human beings to obtain the external information. Owing to human own physical and psychological factors as well as the influences of the external factors, such as the light, shape, color and so forth, there will be an visual errors occurred, the errors also be named optical illusion. This paper systematically analyzes the various phenomenon or causes in visual illusion, as the result, visual illusion was divided into 5 categories: pathological illusion, dynamic illusion, geometry illusion, color illusion, contour illusion. On the basis of this, the paper introduces the vision illusion application, especially in image fusion realized in matlab.%视觉足人类获取外部信息的最重要方式。但由于人类自身的生理、心理因素以及外界光、形、色等因素的干扰,会产生视觉误差,即视错觉。本章系统的分析了视错觉产生原因,按不同的现象和成因把视错觉分成病理视错觉、动态视错觉、几何视错觉、颜色视错觉、轮廓错觉等5类。在此基础上介绍了视错觉的应用,特别介绍了其在图像融合中的应用,并用matlab实现了图像的融合。

  2. Reducing the illusion of control when an action is followed by an undesired outcome.

    Science.gov (United States)

    Matute, Helena; Blanco, Fernando

    2014-08-01

    The illusion of control is the belief that our behavior produces an effect that is actually independent from it. This illusion is often at the core of superstitious and pseudoscientific thinking. Although recent research has proposed several evidence-based strategies that can be used to reduce the illusion, the majority of these experiments have involved positive illusions-that is, those in which the potential outcomes are desired (e.g., recovery from illness or earning points). By contrast, many real-life superstitions and pseudosciences are tied to negative illusions-that is, those in which the potential consequences are undesired. Examples are walking under a ladder, breaking a mirror, or sitting in row 13, all of which are supposed to generate bad luck. Thus, the question is whether the available evidence on how to reduce positive illusions would also apply to situations in which the outcomes are undesired. We conducted an experiment in which participants were exposed to undesired outcomes that occurred independently of their behavior. One strategy that has been shown to reduce positive illusions consists of warning people that the outcomes might have alternative causes, other than the participants' actions, and telling them that the best they can do to find out whether an alternative cause is at work is to act on only about 50% of the trials. When we gave our participants this information in an experiment in which the outcomes were undesired, their illusion was enhanced rather than reduced, contrary to what happens when the outcome is desired. This suggests that the strategies that reduce positive illusions may work in just the opposite way when the outcome is undesired.

  3. Effectiveness of transcranial direct current stimulation and visual illusion on neuropathic pain in spinal cord injury.

    Science.gov (United States)

    Soler, Maria Dolors; Kumru, Hatice; Pelayo, Raul; Vidal, Joan; Tormos, Josep Maria; Fregni, Felipe; Navarro, Xavier; Pascual-Leone, Alvaro

    2010-09-01

    The aim of this study was to evaluate the analgesic effect of transcranial direct current stimulation of the motor cortex and techniques of visual illusion, applied isolated or combined, in patients with neuropathic pain following spinal cord injury. In a sham controlled, double-blind, parallel group design, 39 patients were randomized into four groups receiving transcranial direct current stimulation with walking visual illusion or with control illusion and sham stimulation with visual illusion or with control illusion. For transcranial direct current stimulation, the anode was placed over the primary motor cortex. Each patient received ten treatment sessions during two consecutive weeks. Clinical assessment was performed before, after the last day of treatment, after 2 and 4 weeks follow-up and after 12 weeks. Clinical assessment included overall pain intensity perception, Neuropathic Pain Symptom Inventory and Brief Pain Inventory. The combination of transcranial direct current stimulation and visual illusion reduced the intensity of neuropathic pain significantly more than any of the single interventions. Patients receiving transcranial direct current stimulation and visual illusion experienced a significant improvement in all pain subtypes, while patients in the transcranial direct current stimulation group showed improvement in continuous and paroxysmal pain, and those in the visual illusion group improved only in continuous pain and dysaesthesias. At 12 weeks after treatment, the combined treatment group still presented significant improvement on the overall pain intensity perception, whereas no improvements were reported in the other three groups. Our results demonstrate that transcranial direct current stimulation and visual illusion can be effective in the management of neuropathic pain following spinal cord injury, with minimal side effects and with good tolerability.

  4. Early and late beta-band power reflect audiovisual perception in the McGurk illusion.

    Science.gov (United States)

    Roa Romero, Yadira; Senkowski, Daniel; Keil, Julian

    2015-04-01

    The McGurk illusion is a prominent example of audiovisual speech perception and the influence that visual stimuli can have on auditory perception. In this illusion, a visual speech stimulus influences the perception of an incongruent auditory stimulus, resulting in a fused novel percept. In this high-density electroencephalography (EEG) study, we were interested in the neural signatures of the subjective percept of the McGurk illusion as a phenomenon of speech-specific multisensory integration. Therefore, we examined the role of cortical oscillations and event-related responses in the perception of congruent and incongruent audiovisual speech. We compared the cortical activity elicited by objectively congruent syllables with incongruent audiovisual stimuli. Importantly, the latter elicited a subjectively congruent percept: the McGurk illusion. We found that early event-related responses (N1) to audiovisual stimuli were reduced during the perception of the McGurk illusion compared with congruent stimuli. Most interestingly, our study showed a stronger poststimulus suppression of beta-band power (13-30 Hz) at short (0-500 ms) and long (500-800 ms) latencies during the perception of the McGurk illusion compared with congruent stimuli. Our study demonstrates that auditory perception is influenced by visual context and that the subsequent formation of a McGurk illusion requires stronger audiovisual integration even at early processing stages. Our results provide evidence that beta-band suppression at early stages reflects stronger stimulus processing in the McGurk illusion. Moreover, stronger late beta-band suppression in McGurk illusion indicates the resolution of incongruent physical audiovisual input and the formation of a coherent, illusory multisensory percept.

  5. Refugee experiences of individual basic body awareness therapy and the level of transference into daily life. An interview study

    DEFF Research Database (Denmark)

    Madsen, Trine Stårup; Carlsson, Jessica; Nordbrandt, Maja;

    2016-01-01

    the data. PARTICIPANTS: Three traumatised refugees with PTSD who had completed 14-20 individual BBAT sessions. RESULTS: The participants experienced the movements in BBAT as small and simple with big effects. BBAT was found to relieve pain and tension, bring peace of mind and body, and make it easier...... to sleep. Regular practice was necessary, as were instructions from a physiotherapist, to get the effect from BBAT. Positive changes in the contact to oneself and others were experienced and new coping strategies were developed. CONCLUSION: Traumatised refugees experienced positive effects from BBAT...

  6. 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.

  7. Multisensory integration in the Muller-Lyer illusion: from vision to haptics.

    Science.gov (United States)

    Mancini, Flavia; Bricolo, Emanuela; Vallar, Giuseppe

    2010-04-01

    The Muller-Lyer figure is a powerful illusion in both vision and touch, although it is still unclear whether the visual and haptic illusory effects are due to modality-specific or shared processes. In order to investigate the hypothesis of a common underlying mechanism, the performance of 24 undergraduates in a manual bisection task of the Judd variant of the Muller-Lyer figure was assessed under visual, haptic, and visuo-haptic presentations (Experiment 1). In the bimodal condition participants saw the arrowheads on the front and touched the shaft on the back of a stimulus-supporting board. Illusory effects were comparable in touch and vision and were present, albeit reduced, in the bimodal visuo-haptic condition. In Experiment 2 we used the bimodal task of Experiment 1, manipulating the spatial position of the horizontal shaft on the backside of the board. The visual arrowheads affected haptic bisection, bringing about the illusory effects, only when the shaft was aligned with them. In conclusion, illusory effects transfer cross-modally from vision to haptics only in the presence of spatial coincidence, which appears to be a crucial factor for cross-modal integration. Implications for multisensory processes are discussed.

  8. Toward transferable interatomic van der Waals potentials: The role of multipole electrostatics and many-body dispersion without electrons

    CERN Document Server

    Bereau, Tristan

    2014-01-01

    We estimate polarizabilities of atoms in molecules without electron density, using a Voronoi partitioning approach instead. The resulting atomic dispersion coefficients are calculated, as well as many-body dispersion effects on intermolecular potential energies. We also estimate contributions from multipole electrostatics and compare them to dispersion. We assess the performance of the resulting intermolecular potential from dispersion and electrostatics for more than 1,300 neutral and charged, small organic molecular dimers. Applications to water clusters, the benzene crystal, the anti-cancer drug ellipticine---intercalated between two Watson-Crick DNA base pairs, as well as six macro-molecular host-guest complexes highlight the potential of this method and help to identify points of future improvement. Overall, the method achieves an accuracy well within sophisticated empirical force fields, such as OPLS and Amber FF03, while exhibiting a simple parametrization protocol without the need for experimental inp...

  9. Getting real about Semantic Illusions : Rethinking the functional role of the P600 in language comprehension

    NARCIS (Netherlands)

    Brouwer, Harm; Fitz, Hartmut; Hoeks, John

    2012-01-01

    In traditional theories of language comprehension, syntactic and semantic processing are inextricably linked. This assumption has been challenged by the 'Semantic: Illusion Effect' found in studies using Event Related brain Potentials. Semantically anomalous sentences did not produce the expected in

  10. Three-dimensional broadband acoustic illusion cloak for sound-hard boundaries of curved geometry

    Science.gov (United States)

    Kan, Weiwei; Liang, Bin; Li, Ruiqi; Jiang, Xue; Zou, Xin-Ye; Yin, Lei-Lei; Cheng, Jianchun

    2016-11-01

    Acoustic illusion cloaks that create illusion effects by changing the scattered wave have many potential applications in a variety of scenarios. However, the experimental realization of generating three-dimensional (3D) acoustic illusions under detection of broadband signals still remains challenging despite the paramount importance for practical applications. Here we report the design and experimental demonstration of a 3D broadband cloak that can effectively manipulate the scattered field to generate the desired illusion effect near curved boundaries. The designed cloak simply comprises positive-index anisotropic materials, with parameters completely independent of either the cloaked object or the boundary. With the ability of manipulating the scattered field in 3D space and flexibility of applying to arbitrary geometries, our method may take a major step toward the real world application of acoustic cloaks and offer the possibilities of building advanced acoustic devices with versatile functionalities.

  11. Effectiveness of transcranial direct current stimulation and visual illusion on neuropathic pain in spinal cord injury

    National Research Council Canada - National Science Library

    Soler, Maria Dolors; Kumru, Hatice; Pelayo, Raul; Vidal, Joan; Tormos, Josep Maria; Fregni, Felipe; Navarro, Xavier; Pascual-Leone, Alvaro

    2010-01-01

    ... with neuropathic pain following spinal cord injury. In a sham controlled, double-blind, parallel group design, 39 patients were randomized into four groups receiving transcranial direct current stimulation with walking visual illusion or with control...

  12. Mouth reversal extinguishes mismatch negativity induced by the McGurk illusion

    DEFF Research Database (Denmark)

    Eskelund, Kasper; Andersen, Tobias

    2013-01-01

    The sight of articulatory mouth movements (visual speech) influences auditory speech perception. This is demonstrated by the McGurk illusion in which incongruent visual speech alters the auditory phonetic percept. In behavioral studies, reversal of the vertical mouth direction has been reported...... cortex. Mismatch Negativity (MMN) is a component in the auditory Event-Related Potential (ERP) that is elicited by a change in the auditory percept. It has been shown that the McGurk illusion can induce a MMN. We conducted an experiment in which the MMN could be elicited by the McGurk illusion induced...... by visual speech with either upright (unaltered) or vertically reversed mouth area. In a preliminary analysis, we found a Mismatch Negativity component induced by the McGurk illusion for 6 of 17 participants at electrode Cz when the mouth area was upright. In comparison, these participants produced...

  13. Tüür, Erkki-Sven: Architectonics VI. Passion. Illusion / Guy S. Rickards

    Index Scriptorium Estoniae

    Rickards, Guy S.

    1996-01-01

    Uuest heliplaadist "Tüür, Erkki-Sven: Architectonics VI. Passion. Illusion. Crystallisatio. Requiem. Estonian Philharmonic Chamber Choir, Tallinn Chamber Orchestra, Tõnu Kaljuste. ECM New Series 449 459-2 (64 minutes: DDD)

  14. Tüür, Erkki-Sven: Architectonics VI. Passion. Illusion / Guy S. Rickards

    Index Scriptorium Estoniae

    Rickards, Guy S.

    1996-01-01

    Uuest heliplaadist "Tüür, Erkki-Sven: Architectonics VI. Passion. Illusion. Crystallisatio. Requiem. Estonian Philharmonic Chamber Choir, Tallinn Chamber Orchestra, Tõnu Kaljuste. ECM New Series 449 459-2 (64 minutes: DDD)

  15. Implementation and Assessment of an Intervention to Debias Adolescents against Causal Illusions: e71303

    National Research Council Canada - National Science Library

    Itxaso Barberia; Fernando Blanco; Carmelo P Cubillas; Helena Matute

    2013-01-01

      Researchers have warned that causal illusions are at the root of many superstitious beliefs and fuel many people's faith in pseudoscience, thus generating significant suffering in modern society...

  16. San Lorenzo and the Poggendorff Illusion in Ravenna

    Directory of Open Access Journals (Sweden)

    Olga Daneyko

    2011-06-01

    Full Text Available In the Mausoleum of Galla Placidia (Ravenna, Italy, the San Lorenzo lunette shows two peculiar visual effects: a transparency effect of gold seen through gold and perceptual collinearity between two parts of a cross which are physically misaligned. Both effects are found within the area of the halo surrounding the saint's head. In this work we addressed the problem posed by the physical misalignment of the cross. Our hypothesis is that the physical misalignment went unnoticed throughout history because the artist produced a perceptual alignment to correct for the Poggendorff illusion. Hence, we asked observers to align two ends of a cross in a reproduction showing the silhouette of San Lorenzo's torso holding the cross. Results support our hypothesis: both direction and magnitude of adjustments comply with the alignment in the original mosaic.

  17. San Lorenzo and the Poggendorff illusion in Ravenna.

    Science.gov (United States)

    Daneyko, Olga; Stucchi, Natale; Zavagno, Daniele

    2011-01-01

    In the Mausoleum of Galla Placidia (Ravenna, Italy), the San Lorenzo lunette shows two peculiar visual effects: a transparency effect of gold seen through gold and perceptual collinearity between two parts of a cross which are physically misaligned. Both effects are found within the area of the halo surrounding the saint's head. In this work we addressed the problem posed by the physical misalignment of the cross. Our hypothesis is that the physical misalignment went unnoticed throughout history because the artist produced a perceptual alignment to correct for the Poggendorff illusion. Hence, we asked observers to align two ends of a cross in a reproduction showing the silhouette of San Lorenzo's torso holding the cross. Results support our hypothesis: both direction and magnitude of adjustments comply with the alignment in the original mosaic.

  18. DEMAND ILLUSION AS A WAY TO REDUCE COSTS

    Directory of Open Access Journals (Sweden)

    Kirill N. Sosnovskij

    2014-01-01

    Full Text Available Article devoted to a technique that reduces costs to retailers, as well as increase the speed of discounted products. This article deals with the laws of visual merchandising that have a significant impact on the implementation of the company’s products. The analysis of the first law, with the subsequent introduction into it of a new additional method. Consider the effect of «Illusion of deficit» arising from the application of the proposed method. The article also defines the basic hypothesis of the existence of methods and effect, and the conditions for their effective implementation. To confirm the effectiveness of the developed method, quantitative surveys are conducted for different age groups creating situational model, which allows respondents to feel as a consumer.

  19. Creating illusions of past encounter through brief exposure.

    Science.gov (United States)

    Brown, Alan S; Marsh, Elizabeth J

    2009-05-01

    Titchener (1928) suggested that briefly glancing at a scene could make it appear strangely familiar when it was fully processed moments later. The closest laboratory demonstration used words as stimuli, and showed that briefly glancing at a to-be-judged word increased the subject's belief that it had been presented in an earlier study list (Jacoby & Whitehouse, 1989). We evaluated whether a hasty glance could elicit a false belief in a prior encounter, from a time and place outside of the experiment. This goal precluded using word stimuli, so we had subjects evaluate unfamiliar symbols. Each symbol was preceded by a brief exposure to an identical symbol, a different symbol, or no symbol. A brief glance at an identical symbol increased attributions to preexperimental experience, relative to a glance at a different symbol or no symbol, providing a possible mechanism for common illusions of false recognition.

  20. The Effects of Tai Chi Practice on Intermuscular Beta Coherence and the Rubber Hand Illusion.

    Science.gov (United States)

    Kerr, Catherine E; Agrawal, Uday; Nayak, Sandeep

    2016-01-01

    Tai Chi (TC) is a slow-motion contemplative exercise that is associated with improvements in sensorimotor measures, including decreased force variability, enhanced tactile acuity, and improved proprioception, especially in elderly populations. Here, we carried out two studies evaluating the effect of TC practice on measures associated with sensorimotor processing. In study 1, we evaluated TC's effects on an oscillatory parameter associated with motor function, beta rhythm (15-30 Hz) coherence, focusing specifically on beta rhythm intermuscular coherence (IMC), which is tightly coupled to beta corticomuscular coherence (CMC). We utilized electromyography (EMG) to compare beta IMC in older TC practitioners with age-matched controls, as well as novices with advanced TC practitioners. Given previous findings of elevated, maladaptive beta coherence in older subjects, we hypothesized that increased TC practice would be associated with a monotonic decrease in beta IMC, but rather discovered that novice practitioners manifested higher beta IMC than both controls and advanced practitioners, forming an inverted U-shaped practice curve. This finding suggests that TC practice elicits complex changes in sensory and motor processes over the developmental lifespan of TC training. In study 2, we focused on somatosensory (e.g., tactile and proprioceptive) responses to the rubber hand illusion (RHI) in a middle-aged TC group, assessing whether responses to the illusion became dampened with greater cumulative practice. As hypothesized, TC practice was associated with decreased likelihood to misattribute tactile stimulation during the RHI to the rubber hand, although there was no effect of TC practice on measures of proprioception or on subjective reports of ownership. These studies provide preliminary evidence that TC practice both modulates beta network coherence in a non-linear fashion, perhaps as a result of the focus on not only efferent motor but also afferent sensory activity

  1. Motion illusions in optical art presented for long durations are temporally distorted.

    Science.gov (United States)

    Nather, Francisco Carlos; Mecca, Fernando Figueiredo; Bueno, José Lino Oliveira

    2013-01-01

    Static figurative images implying human body movements observed for shorter and longer durations affect the perception of time. This study examined whether images of static geometric shapes would affect the perception of time. Undergraduate participants observed two Optical Art paintings by Bridget Riley for 9 or 36 s (group G9 and G36, respectively). Paintings implying different intensities of movement (2.0 and 6.0 point stimuli) were randomly presented. The prospective paradigm in the reproduction method was used to record time estimations. Data analysis did not show time distortions in the G9 group. In the G36 group the paintings were differently perceived: that for the 2.0 point one are estimated to be shorter than that for the 6.0 point one. Also for G36, the 2.0 point painting was underestimated in comparison with the actual time of exposure. Motion illusions in static images affected time estimation according to the attention given to the complexity of movement by the observer, probably leading to changes in the storage velocity of internal clock pulses.

  2. Perceptual drifts of real and artificial limbs in the rubber hand illusion.

    Science.gov (United States)

    Fuchs, Xaver; Riemer, Martin; Diers, Martin; Flor, Herta; Trojan, Jörg

    2016-01-01

    In the rubber hand illusion (RHI), transient embodiment of an artificial hand is induced. An often-used indicator for this effect is the "proprioceptive drift", a localization bias of the real hand towards the artificial hand. This measure suggests that the real hand is attracted by the artificial hand. Principles of multisensory integration, however, rather suggest that conflicting sensory information is combined in a "compromise" fashion and that hands should rather be attracted towards each other. Here, we used a new variant of the RHI paradigm in which participants pointed at the artificial hand. Our results indicate that the perceived positions of the real and artificial hand converge towards each other: in addition to the well-known drift of the real hand towards the artificial hand, we also found an opposite drift of the artificial hand towards the real hand. Our results contradict the notion of perceptual substitution of the real hand by the artificial hand. Rather, they are in line with the view that vision and proprioception are fused into an intermediate percept. This is further evidence that the perception of our body is a flexible multisensory construction that is based on integration principles.

  3. Near-death experiences: the experience of the self as real and not as an illusion.

    Science.gov (United States)

    van Lommel, Pim

    2011-10-01

    Because the publication of several prospective studies on near-death experience (NDE) in survivors of cardiac arrest have shown strikingly similar results and conclusions, the phenomenon of the NDE can no longer be scientifically ignored. The NDE is an authentic experience that cannot be simply reduced to imagination, fear of death, hallucination, psychosis, the use of drugs, or oxygen deficiency. Patients appear to be permanently changed by an NDE during a cardiac arrest of only some minutes' duration. It is a scientific challenge to discuss new hypotheses that could explain the possibility of a clear and enhanced consciousness--with memories, self-identity, cognition, and emotions--during a period of apparent coma. The current materialistic view of the relationship between consciousness and the brain, as held by most physicians, philosophers, and psychologists, seems to be too restricted for a proper understanding of this phenomenon. There are good reasons to assume that our consciousness, with the continuous experience of self, does not always coincide with the functioning of our brain: enhanced or nonlocal consciousness, with unaltered self-identity, apparently can be experienced independently from the lifeless body. People are convinced that the self they experienced during their NDE is a reality and not an illusion.

  4. Mind Reading in Stage Magic: The “Second Sight” Illusion, Media, and Mediums

    OpenAIRE

    Katharina Rein

    2015-01-01

    This article analyzes the late-nineteenth-century stage illusion “The Second Sight,” which seemingly demonstrates the performers’ telepathic abilities. The illusion is on the one hand regarded as an expression of contemporary trends in cultural imagination as it seizes upon notions implied by spiritualism as well as utopian and dystopian ideas associated with technical media. On the other hand, the spread of binary code in communication can be traced along with the development of the "Second ...

  5. Alpha-band oscillations reflect altered multisensory processing of the McGurk illusion in schizophrenia

    Directory of Open Access Journals (Sweden)

    Yadira eRoa Romero

    2016-02-01

    Full Text Available The formation of coherent multisensory percepts requires integration of stimuli across the multiple senses. Patients with schizophrenia (ScZ often experience a loss of coherent perception and hence, they might also show dysfunctional multisensory processing. In this high-density electroencephalography study we investigated the neural signatures of the McGurk illusion, as a phenomenon of speech-specific multisensory processing. In the McGurk illusion lip movements are paired with incongruent auditory syllables, which can induce a fused percept. In ScZ patients and healthy controls we compared neural oscillations and event-related potentials (ERPs to congruent audiovisual speech stimuli and McGurk illusion trials, where a visual /ga/ and an auditory /pa/ was often perceived as /ka/. There were no significant group differences in illusion rates. However, we found larger short latency ERPs to McGurk illusion compared with congruent trials in controls, whereas they were reduced in ScZ patients, indicating an early audiovisual processing deficit. Moreover, we observed stronger suppression of medio-central alpha-band power (8-10 Hz, 550-700 ms in response to McGurk illusion compared with control trials in the control group. The reversed pattern was found in SCZ patients. Within groups, alpha-band suppression was negatively correlated with the McGurk illusion rate in ScZ patients, while the correlation tended to be positive in controls. The topography of alpha-band effects suggests an involvement of auditory and/or frontal structures. Our study suggests that early ERPs and later alpha-band oscillations reflect abnormal multisensory processing of the McGurk illusion in schizophrenia.

  6. The impact of visual illusions on perception, action planning, and motor performance.

    Science.gov (United States)

    Wood, Greg; Vine, Samuel J; Wilson, Mark R

    2013-07-01

    The present study extended recent research revealing that illusions can influence performance in golf putting (Witt, Linkenauger, & Proffitt Psychological Science, 23, 397-399, 2012), by exploring the potential mediating roles of attention and action planning. Glover and Dixon's (Journal of Experimental Psychology. Human Perception and Performance, 27, 560-572, 2001) planning-control model suggests that both perceptual and movement-planning processes are prone to illusion-based bias. We therefore predicted that both the perception of target size and a measure of attentional control related to movement planning in golf putting (the quiet eye) would be influenced by the illusion. Moreover, as performance could not be corrected using online control (once the ball was struck), we predicted that these biases would also influence performance. We therefore proposed a three-stage process by which illusory context biases perceptual processes, which in turn bias subsequent attentional control related to movement planning, which in turn biases motor performance. Forty novice golfers completed an Ebbinghaus illusion putting task that was designed to manipulate their perceptions of target size, while quiet eye duration and performance (mean radial error) were measured. The results indicated that the illusion was effective in facilitating differences in perceived target size, with perceptually bigger holes promoting longer quiet eye durations and more accurate putting. Follow-up mediation analyses revealed that illusion-based differences in size perception partially mediated illusion-based differences in both quiet eye duration and performance. Moreover, the relationship between illusion-based differences in quiet eye duration and performance was also significant. Future research should further test this three-stage process of bias in other far-aiming tasks in which online control cannot be used.

  7. Fiscal illusion and the shadow economy: Two sides of the same coin?

    OpenAIRE

    Buehn, Andreas; DELL'ANNO, Roberto; Schneider, Friedrich

    2013-01-01

    This paper presents an empirical analysis of the relationship between fiscal illusion and the shadow economy for 104 countries over the period 1989–2009. We argue that both unobservable phenomena are closely linked to each other, as the creation of a fiscal illusion may be helpful if governments want to control shadow economic activities. Using a MIMIC model with two latent variables we confirm previous findings on the driving forces of the shadow economy and identify the main determinants an...

  8. A Film Buff’s Paradox: The Evolution of Illusion vs. Reality

    Directory of Open Access Journals (Sweden)

    Armand Amini

    2015-07-01

    Full Text Available In this cinematic realm, the concept of illusion vs. reality is a theme that has attracted artistic exploration, and has proven to be an enduring and significant storytelling framework in the realm of contemporary cinema. This theme of illusion vs. reality is witnessed in films from as far back as George Méliès 1902 A Trip to the Moon, to the 1964 version of Mary Poppins, to contemporary offerings such as The Matrix in 1999.

  9. Audition influences color processing in the sound-induced visual flash illusion

    OpenAIRE

    Mishra, Jyoti; Martinez, Antigona; Hillyard, Steven A.

    2013-01-01

    Multisensory interactions can lead to illusory percepts, as exemplified by the sound-induced extra flash illusion (SIFI: Shams et al., 2000, 2002). In this illusion, an audio-visual stimulus sequence consisting of two pulsed sounds and a light flash presented within a 100 ms time window generates the visual percept of two flashes. Here, we used colored visual stimuli to investigate whether concurrent auditory stimuli can affect the perceived features of the illusory flash. Zero, one or two pu...

  10. Individual Differences in the Multisensory Temporal Binding Window Predict Susceptibility to Audiovisual Illusions

    OpenAIRE

    Stevenson, Ryan A.; Raquel K Zemtsov; Wallace, Mark T.

    2012-01-01

    Human multisensory systems are known to bind inputs from the different sensory modalities into a unified percept, a process that leads to measurable behavioral benefits. This integrative process can be observed through multisensory illusions, including the McGurk effect and the sound-induced flash illusion, both of which demonstrate the ability of one sensory modality to modulate perception in a second modality. Such multisensory integration is highly dependent upon the temporal relationship ...

  11. Theoretical assessment of the maximum obtainable power in wireless power transfer constrained by human body exposure limits in a typical room scenario.

    Science.gov (United States)

    Chen, Xi Lin; De Santis, Valerio; Umenei, Aghuinyue Esai

    2014-07-07

    In this study, the maximum received power obtainable through wireless power transfer (WPT) by a small receiver (Rx) coil from a relatively large transmitter (Tx) coil is numerically estimated in the frequency range from 100 kHz to 10 MHz based on human body exposure limits. Analytical calculations were first conducted to determine the worst-case coupling between a homogeneous cylindrical phantom with a radius of 0.65 m and a Tx coil positioned 0.1 m away with the radius ranging from 0.25 to 2.5 m. Subsequently, three high-resolution anatomical models were employed to compute the peak induced field intensities with respect to various Tx coil locations and dimensions. Based on the computational results, scaling factors which correlate the cylindrical phantom and anatomical model results were derived. Next, the optimal operating frequency, at which the highest transmitter source power can be utilized without exceeding the exposure limits, is found to be around 2 MHz. Finally, a formulation is proposed to estimate the maximum obtainable power of WPT in a typical room scenario while adhering to the human body exposure compliance mandates.

  12. Impact of erosion and transfer processes in Polycyclic Aromatic Hydrocarbon contamination of water bodies in the Seine River basin (France)

    Science.gov (United States)

    Gateuille, David; Evrard, Olivier; Moreau-Guigon, Elodie; Chevreuil, Marc; Mouchel, Jean-Marie

    2014-05-01

    Polycyclic Aromatic Hydrocarbons (PAHs) reach problematic concentrations in water and sediment of numerous streams of the world. In the Seine River (France), they prevent to achieve the good chemical status enforced by European law. However, the provenance and the fate of PAHs found in rivers are still poorly understood. Here, we combined chemical and fallout radionuclide measurements conducted on a large number of suspended sediment (SS) (n = 231) and soil (n = 37) samples collected at 62 sites during an entire hydrological year. A model was developed to estimate mean PAH concentration in sediment from the population density in the drainage area and good relationships were found during both low stage and flood periods. Influence of human population also appeared to be stronger during the latter period. However, some discrepancies between measured and modeled PAH concentrations were observed and the role of the origin of SS was investigated. During the low flow period, the observed differences were explained by the provenance of river sediment (agricultural topsoil vs. eroded channel banks). Time-averaged PAH concentrations measured in suspended sediment collected in the catchments where erosion of agricultural topsoil dominated were systematically higher than the predicted values. On the contrary, in the catchments where erosion mainly occurred in deep soil or river embankment, the supply of particles protected from atmospheric fallout contamination led to measure concentrations below the predicted values. As this relationship between population density and SS contamination was no longer valid during the flood period, the role of transfer times was also investigated. The percentages of freshly eroded sediment in samples were determined by comparing the 7Be/210Pb ratio in rainfall and SS. An annual turn-over cycle of sediment was observed but no relationship was found between PAH contamination and residence times of particles within rivers. This result suggested

  13. Proprioceptive drift in the rubber hand illusion is intensified following 1 Hz TMS of the left EBA

    Directory of Open Access Journals (Sweden)

    Andrew eWold

    2014-06-01

    Full Text Available The rubber hand illusion (RHI is a paradigm used to induce an illusory feeling of owning a dummy hand through congruent multisensory stimulation. Thus, it can grant insights into how our brain represents our body as our own. Recent research has demonstrated an involvement of the extrastriate body area (EBA, an area of the brain that is typically implicated in the perception of non-face body parts, in illusory body ownership. In this experiment we sought causal evidence for the involvement of the EBA in the RHI. 16 participants took part in a sham controlled, 1 Hz repetitive TMS (1200 pulse experiment where they received synchronous (RHI condition or asynchronous (control stroking and were asked to report the perceived location of their real hand as well as the intensity and the temporal onset of experienced ownership of the dummy hand. Following TMS of the left EBA, participants misjudged their real hand's location significantly more towards the rubber hand during synchronous stroking than after sham stimulation. This difference in proprioceptive drift provides the first causal evidence that the EBA is involved in the RHI and subsequently in body representation and further supports the view that the EBA is necessary for multimodal integration.

  14. La Grande Guerra fra realtà ed illusione: La Grande Illusion e l’immaginario

    Directory of Open Access Journals (Sweden)

    Simone Di Blasi

    2015-12-01

    Full Text Available The aim of this brief essay is to focus on the relation between the meaning of reality and illusion in the movie La Grande Illusion (1937 by Jean Renoir and therefore to find how these ideas of the author may be productive in a thought about the imaginary. After a short look on the movies made at that time on the First World War, there is an overview of the French director poetics, which redefines the conception of the realism, contextualizing its work at the point of convergence of two imaginary “technological lines”, the cinema and the aviation. It follows the analysis of the movie and the illusions, as social largely shared imaginaries, described by the author. In the end it is showed the importance and the of illusion in Renoir’s poetics. Beyond the relationship realityfiction, he thought a dynamic reciprocity among illusion and reality: so that the reality is as “illusion” (a ruled horizon in which it is possible to enjoy a world of play and the illusion as an activity creating contents of “reality”.

  15. Seeing size and feeling weight: the size-weight illusion in natural and virtual reality.

    Science.gov (United States)

    Heineken, Edgar; Schulte, Frank P

    2007-02-01

    We experimentally tested the degree that the size-weight illusion depends on perceptual conditions allowing the observer to assume that both the visual and the kinesthetic stimuli of a weight seen and lifted emanate from the same object. We expected that the degree of the illusion depended on the "realism" provided by different kinds of virtual reality (VR) used when the weights are seen in virtual reality and at the same time lifted in natural reality. Welch and Warren (1980) reported that an intermodal influence can be expected only if perceptual information of different modalities is compellingly related to only one object. Objects of different sizes and weights were presented to 50 participants in natural reality or in four virtual realities: two immersive head-mounted display VRs (with or without head tracking) and two nonimmersive desktop VRs (with or without screening from input of the natural environment using a visor). The objects' heaviness was scaled using the magnitude estimation method. Data show that the degree of the illusion is largest in immersive and lowest in nonimmersive virtual realities. The higher the degree of the illusion is, the more compelling the situation is perceived and the more the observed data are in correspondence with the data predicted for the illusion in natural reality. This shows that the kind of mediating technology used strongly influences the presence experienced. The size-weight illusion's sensitivity to conditions that affect the sense of presence makes it a promising objective presence measure.

  16. The Muller-Lyer Illusion in a computational model of biological object recognition.

    Directory of Open Access Journals (Sweden)

    Astrid Zeman

    Full Text Available Studying illusions provides insight into the way the brain processes information. The Müller-Lyer Illusion (MLI is a classical geometrical illusion of size, in which perceived line length is decreased by arrowheads and increased by arrowtails. Many theories have been put forward to explain the MLI, such as misapplied size constancy scaling, the statistics of image-source relationships and the filtering properties of signal processing in primary visual areas. Artificial models of the ventral visual processing stream allow us to isolate factors hypothesised to cause the illusion and test how these affect classification performance. We trained a feed-forward feature hierarchical model, HMAX, to perform a dual category line length judgment task (short versus long with over 90% accuracy. We then tested the system in its ability to judge relative line lengths for images in a control set versus images that induce the MLI in humans. Results from the computational model show an overall illusory effect similar to that experienced by human subjects. No natural images were used for training, implying that misapplied size constancy and image-source statistics are not necessary factors for generating the illusion. A post-hoc analysis of response weights within a representative trained network ruled out the possibility that the illusion is caused by a reliance on information at low spatial frequencies. Our results suggest that the MLI can be produced using only feed-forward, neurophysiological connections.

  17. Sad mood increases pain sensitivity upon thermal grill illusion stimulation: implications for central pain processing.

    Science.gov (United States)

    Boettger, Michael Karl; Schwier, Christiane; Bär, Karl-Jürgen

    2011-01-01

    In different fields of neuroscience research, illusions have successfully been used to unravel underlying mechanisms of stimulus processing. One such illusion existing for the field of pain research is the so-called thermal grill illusion. Here, painful sensations are elicited by interlacing warm and cold bars, with stimulus intensities (temperatures) of these bars being below the respective heat pain or cold pain thresholds. To date, the underlying mechanisms of this phenomenon are not completely understood. There is some agreement, however, that the sensation evoked by this stimulation is generated by central nervous interactions. Therefore, we followed two approaches in this study: firstly, we aimed at developing and validating a water-driven device which might be used in fMRI scanners in future studies - subject to minor adaptations. Secondly, we aimed to interfere with this illusion by induction of a sad mood state, a procedure which is suggested to influence central nervous structures that are also involved in pain processing. The newly developed device induced thermal grill sensations similar to those reported in the literature. Induction of sad, but not neutral mood states, resulted in higher pain and unpleasantness ratings of the painful illusion. These findings might be of importance for the understanding of pain processing in healthy volunteers, but putatively even more so in patients with major depressive disorder. Moreover, our results might indicate that central nervous structures involved in the affective domain or cognitive domain of pain processing might be involved in the perception of the illusion.

  18. Rotating Snakes Illusion-Quantitative Analysis Reveals a Region in Luminance Space With Opposite Illusory Rotation.

    Science.gov (United States)

    Atala-Gérard, Lea; Bach, Michael

    2017-01-01

    The Rotating Snakes Illusion employs patterns with repetitive asymmetric luminance steps forming a "snake wheel." In the underlying luminance sequence {black, dark grey, white, light grey}, coded as {0, g1, 100, g2}, we varied g1 and g2 and measured illusion strength via nulling: Saccades were performed next to a "snake wheel" that rotated physically; observers adjusted rotation until a stationary percept obtained. Observers performed the perceptual nulling of the seeming rotation reliably. Typical settings for (g1, g2), measured from images by Kitaoka, are around (20%, 60%). Indeed, we found a marked illusion in the region (g1≈{0%-25%}, g2≈{20%-75%}) with a rotation speed of ≈1°/s. Surprisingly, we detected a second "island" around (70%, 95%) with opposite direction of the illusory rotation and weaker illusion. Our quantitative measurements of illusion strength confirmed the optimal luminance choices of the standard snake wheel and, unexpectedly, revealed an opposite rotation illusion.

  19. The Müller-Lyer Illusion in a computational model of biological object recognition.

    Science.gov (United States)

    Zeman, Astrid; Obst, Oliver; Brooks, Kevin R; Rich, Anina N

    2013-01-01

    Studying illusions provides insight into the way the brain processes information. The Müller-Lyer Illusion (MLI) is a classical geometrical illusion of size, in which perceived line length is decreased by arrowheads and increased by arrowtails. Many theories have been put forward to explain the MLI, such as misapplied size constancy scaling, the statistics of image-source relationships and the filtering properties of signal processing in primary visual areas. Artificial models of the ventral visual processing stream allow us to isolate factors hypothesised to cause the illusion and test how these affect classification performance. We trained a feed-forward feature hierarchical model, HMAX, to perform a dual category line length judgment task (short versus long) with over 90% accuracy. We then tested the system in its ability to judge relative line lengths for images in a control set versus images that induce the MLI in humans. Results from the computational model show an overall illusory effect similar to that experienced by human subjects. No natural images were used for training, implying that misapplied size constancy and image-source statistics are not necessary factors for generating the illusion. A post-hoc analysis of response weights within a representative trained network ruled out the possibility that the illusion is caused by a reliance on information at low spatial frequencies. Our results suggest that the MLI can be produced using only feed-forward, neurophysiological connections.

  20. Do rhesus monkeys (Macaca mulatta) perceive the Zöllner illusion?

    Science.gov (United States)

    Agrillo, Christian; Parrish, Audrey E; Beran, Michael J

    2014-08-01

    A long-standing debate surrounds the issue of whether human and nonhuman animals share the same perceptual mechanisms. In humans, the Zöllner illusion occurs when two parallel lines appear to be convergent when oblique crosshatching lines are superimposed. Although one baboon study suggests that they too might perceive this illusion, the results of that study were unclear, whereas two recent studies suggest that birds see this illusion in the opposite direction from humans. It is currently unclear whether these mixed results are an artifact of the experimental design or reflect a peculiarity of birds' visual system or, instead, a wider phenomenon shared among nonhuman mammals. Here, we trained 6 monkeys to select the narrower of two gaps at the end of two convergent lines. Three different conditions were set up: control (no crosshatches), perpendicular (crosshatches not inducing the illusion), and Zöllner (crosshatches inducing the illusion in humans). During training, the degrees of convergence between the two lines ranged from 15° to 12°. Monkeys that reached the training criterion were tested with more difficult discriminations (11°-1°), including probe trials with parallel lines (0°). The results showed that monkeys perceived the Zöllner illusion in the same direction as humans. Comparison of these data with the data from bird studies points toward the existence of different orientation-tuned mechanisms between primate and nonprimate species.

  1. An auditory illusion reveals the role of streaming in the temporal misallocation of perceptual objects.

    Science.gov (United States)

    Mehta, Anahita H; Jacoby, Nori; Yasin, Ifat; Oxenham, Andrew J; Shamma, Shihab A

    2017-02-19

    This study investigates the neural correlates and processes underlying the ambiguous percept produced by a stimulus similar to Deutsch's 'octave illusion', in which each ear is presented with a sequence of alternating pure tones of low and high frequencies. The same sequence is presented to each ear, but in opposite phase, such that the left and right ears receive a high-low-high … and a low-high-low … pattern, respectively. Listeners generally report hearing the illusion of an alternating pattern of low and high tones, with all the low tones lateralized to one side and all the high tones lateralized to the other side. The current explanation of the illusion is that it reflects an illusory feature conjunction of pitch and perceived location. Using psychophysics and electroencephalogram measures, we test this and an alternative hypothesis involving synchronous and sequential stream segregation, and investigate potential neural correlates of the illusion. We find that the illusion of alternating tones arises from the synchronous tone pairs across ears rather than sequential tones in one ear, suggesting that the illusion involves a misattribution of time across perceptual streams, rather than a misattribution of location within a stream. The results provide new insights into the mechanisms of binaural streaming and synchronous sound segregation.This article is part of the themed issue 'Auditory and visual scene analysis'.

  2. Tuning and disrupting the brain – modulating the McGurk illusion with electrical stimulation

    Directory of Open Access Journals (Sweden)

    Lucas M Marques

    2014-08-01

    Full Text Available In the so-called McGurk illusion, when the synchronized presentation of the visual stimulus /ga/ is paired with the auditory stimulus /ba/, people in general hear it as /da/. Multisensory integration processing underlying this illusion seems to occur within the Superior Temporal Sulcus (STS. Herein, we present evidence demonstrating that bilateral cathodal transcranial direct current stimulation (tDCS of this area can decrease the McGurk illusion-type responses. Additionally, we show that the manipulation of this audio-visual integrated output occurs irrespective of the number of eye-fixations on the mouth of the speaker. Bilateral anodal tDCS of the Parietal Cortex also modulates the illusion, but in the opposite manner, inducing more illusion-type responses. This is the first demonstration of using non-invasive brain stimulation to modulate multisensory speech perception in an illusory context (i.e., both increasing and decreasing illusion-type responses to a verbal audio-visual integration task. These findings provide clear evidence that both the superior temporal and parietal areas contribute to multisensory integration processing related to speech perception. Specifically, STS seems fundamental for the temporal synchronization and integration of auditory and visual inputs. For its part, PPC may adjust the arrival of incoming audio and visual information to STS thereby enhancing their interaction in this latter area.

  3. Voluntary self-touch increases body ownership

    Directory of Open Access Journals (Sweden)

    Masayuki eHara

    2015-10-01

    Full Text Available Experimental manipulations of body ownership have indicated that multisensory integration is central to forming bodily self-representation. Voluntary self-touch is a unique multisensory situation involving corresponding motor, tactile and proprioceptive signals. Yet, even though self-touch is frequent in everyday life, its contribution to the formation of body ownership is not well understood. Here we investigated the role of voluntary self-touch in body ownership using a novel adaptation of the rubber hand illusion (RHI, in which a robotic system and virtual reality allowed participants self-touch of real and virtual hands. In the first experiment, active and passive self-touch were applied in the absence of visual feedback. In the second experiment, we tested the role of visual feedback in this bodily illusion. Finally, in the third experiment, we compared active and passive self-touch to the classical RHI in which the touch is administered by the experimenter. We hypothesized that active self-touch would increase ownership over the virtual hand through the addition of motor signals strengthening the bodily illusion. The results indicated that active self-touch elicited stronger illusory ownership compared to passive self-touch and sensory only stimulation, and indicate an important role of active self-touch in the formation of bodily self.

  4. "I Feel Contaminated in My Fake Hand": Obsessive-Compulsive-Disorder like Disgust Sensations Arise from Dummy during Rubber Hand Illusion.

    Science.gov (United States)

    Jalal, Baland; Krishnakumar, Divya; Ramachandran, Vilayanur S

    2015-01-01

    Despite its theoretical and clinical interest, there are no experimental studies exploring obsessive-compulsive disorder (OCD)-like disgust sensations through using somatosensory illusions. Such illusions provide important clues to the nature and limits of multisensory integration and how the brain constructs body image; and may potentially inform novel therapies. One such effect is the rubber hand illusion (RHI) in which tactile sensations are referred to a rubber hand; if the experimenter simultaneously strokes a subject's occluded hand together with a visible fake hand, the subject starts experiencing the touch sensations as arising from the dummy. In this study, we explore whether OCD-like disgust may result from contamination of a dummy hand during the RHI; suggesting a possible integration of somatosensory and limbic inputs in the construction of body image. We predicted that participants would experience sensations of disgust, when placing a disgust stimulus (fake feces, vomit or blood) on the dummy hand after establishing the RHI. We found that 9 out of 11 participants experienced greater disgust during the synchronous condition (real hidden hand and fake hand are stroked in synchrony) compared to the asynchronous control condition (real hidden hand and fake hand are stroked in asynchrony); and on average such disgust was significantly greater during the synchronous condition compared to the asynchronous control condition, Z = 2.7, p = .008. These results argue against a strictly hierarchical modular approach to brain function and suggest that a four-way multisensory interaction occurs between vision, touch, proprioception on the one hand and primal emotions like disgust on the other. These findings may inform novel clinical approaches for OCD; that is, contaminating a dummy during the RHI could possibly be used as part of an in-vivo exposure-intervention for OCD.

  5. "I Feel Contaminated in My Fake Hand": Obsessive-Compulsive-Disorder like Disgust Sensations Arise from Dummy during Rubber Hand Illusion.

    Directory of Open Access Journals (Sweden)

    Baland Jalal

    Full Text Available Despite its theoretical and clinical interest, there are no experimental studies exploring obsessive-compulsive disorder (OCD-like disgust sensations through using somatosensory illusions. Such illusions provide important clues to the nature and limits of multisensory integration and how the brain constructs body image; and may potentially inform novel therapies. One such effect is the rubber hand illusion (RHI in which tactile sensations are referred to a rubber hand; if the experimenter simultaneously strokes a subject's occluded hand together with a visible fake hand, the subject starts experiencing the touch sensations as arising from the dummy. In this study, we explore whether OCD-like disgust may result from contamination of a dummy hand during the RHI; suggesting a possible integration of somatosensory and limbic inputs in the construction of body image. We predicted that participants would experience sensations of disgust, when placing a disgust stimulus (fake feces, vomit or blood on the dummy hand after establishing the RHI. We found that 9 out of 11 participants experienced greater disgust during the synchronous condition (real hidden hand and fake hand are stroked in synchrony compared to the asynchronous control condition (real hidden hand and fake hand are stroked in asynchrony; and on average such disgust was significantly greater during the synchronous condition compared to the asynchronous control condition, Z = 2.7, p = .008. These results argue against a strictly hierarchical modular approach to brain function and suggest that a four-way multisensory interaction occurs between vision, touch, proprioception on the one hand and primal emotions like disgust on the other. These findings may inform novel clinical approaches for OCD; that is, contaminating a dummy during the RHI could possibly be used as part of an in-vivo exposure-intervention for OCD.

  6. Is lidocaine patch as effective as intravenous lidocaine in pain and illus reduction after laparoscopic colorectal surgery? A randomized clinical trial

    Science.gov (United States)

    Elhafz, Ahmed Ali Abd; Elgebaly, Ahmed Said; Bassuoni, Ahmed Sobhy; El Dabaa, Ahmed Ali

    2012-01-01

    Objective: To evaluate the efficacy of lidocaine patch applied around wound in laparoscopic colorectal surgery in reduction of postoperative pain and illus compared to intravenous lidocaine infusion and placebo. Background: Postoperative illus and pain after colorectal surgery is a challenging problem associated with increased morbidity and cost. Inflammatory response to surgery plays crucial rule in inducing postoperative illus. Systemic local anesthetics proved to have anti-inflammatory properties that may be beneficial in preventing ileus added to its analgesic actions. The lidocaine patch evaluated in many types of pain with promising results. We try to evaluate the patch in perioperative field as a more simple and safe technique than the intravenous route. Materials and Methods: Prospective, randomized, controlled study was conducted, comparing three groups. Group 1 (placebo) received saline infusion, group 2 received i.v. lidocaine infusion after induction of anesthesia, 2 mg/min if body weight >70 kg or 1 mg/min if body weight lidocaine patch 5%, three patches each one divided into two equal parts and applied around the three wounds just before induction. Data collected were, pain scores (VAS), morphine consumption, return of bowel function, pro-inflammatory cytokines plasma levels and plasma lidocaine level. Results: Pain intensity (VAS) scores at rest and during coughing were significantly lower during the first 72 h postoperative in i.v. lidocaine group and patch group compared to the placebo group. Mean morphine consumption were significantly lower in the i.v. lidocaine group and patch group compared to placebo group. Return of the bowel function was significantly earlier in i.v. lidocaine group in comparison to the other groups. Proinflammatory cytokines (IL6, IL8, and C3a) were significantly lower in i.v. lidocaine group compared to the other two groups. Conclusion: The lidocaine patch was equal to i.v. lidocaine infusion in decreasing pain scores and

  7. The effect of age on the haptic horizontal-vertical curvature illusion with raised-line shapes.

    Science.gov (United States)

    Ballesteros, Soledad; Mayas, Julia; Reales, José Manuel; Heller, Morton

    2012-01-01

    In the present study, we investigated the effect of age in the haptic horizontal-vertical curvature illusion from adolescence to old age. Blindfolded participants explored raised-line convex curves with one finger and two fingers (Experiment 1). They judged the size of the curves (horizontal/vertical), using two sliding rulers. The results suggest that young and older haptic explorers overestimated the vertical. Adolescents did not show the haptic illusion. In Experiment 2, adolescents performed the task visually showing a stronger horizontal-vertical illusion. The findings suggest that the illusion develops later in touch than in vision. The theoretical implications of the results are discussed.

  8. Visual illusions, delayed grasping, and memory: no shift from dorsal to ventral control.

    Science.gov (United States)

    Franz, V H; Hesse, C; Kollath, S

    2009-05-01

    We tested whether a delay between stimulus presentation and grasping leads to a shift from dorsal to ventral control of the movement, as suggested by the perception-action theory of Milner and Goodale (Milner, A.D., & Goodale, M.A. (1995). The visual brain in action. Oxford: Oxford University Press.). In this theory the dorsal cortical stream has a short memory, such that after a few seconds the dorsal information is decayed and the action is guided by the ventral stream. Accordingly, grasping should become responsive to certain visual illusions after a delay (because only the ventral stream is assumed to be deceived by these illusions). We used the Müller-Lyer illusion, the typical illusion in this area of research, and replicated the increase of the motor illusion after a delay. However, we found that this increase is not due to memory demands but to the availability of visual feedback during movement execution which leads to online corrections of the movement. Because such online corrections are to be expected if the movement is guided by one single representation of object size, we conclude that there is no evidence for a shift from dorsal to ventral control in delayed grasping of the Müller-Lyer illusion. We also performed the first empirical test of a critique Goodale (Goodale, M.A. (2006, October 27). Visual duplicity: Action without perception in the human visual system. The XIV. Kanizsa lecture, Triest, Italy.) raised against studies finding illusion effects in grasping: Goodale argued that these studies used methods that lead to unnatural grasping which is guided by the ventral stream. Therefore, these studies might never have measured the dorsal stream, but always the ventral stream. We found clear evidence against this conjecture.

  9. 墙体传湿对内表面温度的影响关系研究%Influence of moisture transferring on inner surface temperature wall bodies

    Institute of Scientific and Technical Information of China (English)

    王莹莹; 刘艳峰; 王登甲; 刘加平

    2012-01-01

    A dynamic mathematical model of coupled heat and moisture transfer through a wall body was proposed,choosing the relative humidity and temperature as the driving potentials.The model accuracy was verified by the experimental data.Taking pine wood and brick for examples,their heat transfer process under different hot wet environment were calculated using the mathematical model.The results show that in the steady-state condition,the inner surface temperatures of pine wood and brick are lower 1.4 ℃ and 0.7 ℃ or so than those without considering the moisture transfer process respectively.In the periodic boundary conditions,taking the moisture transfer process into account,the inner surface temperatures of pine wood and brick are lower than indoor air temperature in a period of time coincides with the working hours,which is beneficial to improve the indoor thermal environment.When the moisture transfer process is not taken into account,the wall inner surface temperature is always higher than indoor air temperature.The pine board is recommended as wall material in humid or dry areas with larger variation range of indoor air moisture content,and the brick is recommended as wall material in dry areas with smaller variation range of indoor air moisture content.%建立了以相对湿度和温度为驱动势的热湿耦合传递数学模型,并对模型准确性进行了验证.以松木板墙和砖墙为例,利用所建数学模型对其在不同热湿环境下进行计算分析,结果发现:在稳态条件下,松木板墙内表面温度比未考虑传湿情况最多低1.4℃,砖墙内表面温度比未考虑传湿情况最多低0.7℃;在周期性边界条件下且不考虑传湿时,松木板墙和砖墙内表面温度始终高于室内空气温度,考虑墙体传湿时,墙体在白天有部分时间段内表面温度低于室内空气温度,有利于室内热环境的改善;松木板适合在室内空气含湿量变化幅度较大的地区作墙体材料,而砖适合

  10. Sleep dissolves illusion: sleep withstands learning of visuo-tactile-proprioceptive integration induced by repeated days of rubber hand illusion training.

    Directory of Open Access Journals (Sweden)

    Motoyasu Honma

    Full Text Available Multisensory integration is a key factor in establishing bodily self-consciousness and in adapting humans to novel environments. The rubber hand illusion paradigm, in which humans can immediately perceive illusory ownership to an artificial hand, is a traditional technique for investigating multisensory integration and the feeling of illusory ownership. However, the long-term learning properties of the rubber hand illusion have not been previously investigated. Moreover, although sleep contributes to various aspects of cognition, including learning and memory, its influence on illusory learning of the artificial hand has not yet been assessed. We determined the effects of daily repetitive training and sleep on learning visuo-tactile-proprioceptive sensory integration and illusory ownership in healthy adult participants by using the traditional rubber hand illusion paradigm. Subjective ownership of the rubber hand, proprioceptive drift, and galvanic skin response were measured to assess learning indexes. Subjective ownership was maintained and proprioceptive drift increased with daily training. Proprioceptive drift, but not subjective ownership, was significantly attenuated after sleep. A significantly greater reduction in galvanic skin response was observed after wakefulness compared to after sleep. Our results suggest that although repetitive rubber hand illusion training facilitates multisensory integration and physiological habituation of a multisensory incongruent environment, sleep corrects illusional integration and habituation based on experiences in a multisensory incongruent environment. These findings may increase our understanding of adaptive neural processes to novel environments, specifically, bodily self-consciousness and sleep-dependent neuroplasticity.

  11. Sleep dissolves illusion: sleep withstands learning of visuo-tactile-proprioceptive integration induced by repeated days of rubber hand illusion training.

    Science.gov (United States)

    Honma, Motoyasu; Yoshiike, Takuya; Ikeda, Hiroki; Kim, Yoshiharu; Kuriyama, Kenichi

    2014-01-01

    Multisensory integration is a key factor in establishing bodily self-consciousness and in adapting humans to novel environments. The rubber hand illusion paradigm, in which humans can immediately perceive illusory ownership to an artificial hand, is a traditional technique for investigating multisensory integration and the feeling of illusory ownership. However, the long-term learning properties of the rubber hand illusion have not been previously investigated. Moreover, although sleep contributes to various aspects of cognition, including learning and memory, its influence on illusory learning of the artificial hand has not yet been assessed. We determined the effects of daily repetitive training and sleep on learning visuo-tactile-proprioceptive sensory integration and illusory ownership in healthy adult participants by using the traditional rubber hand illusion paradigm. Subjective ownership of the rubber hand, proprioceptive drift, and galvanic skin response were measured to assess learning indexes. Subjective ownership was maintained and proprioceptive drift increased with daily training. Proprioceptive drift, but not subjective ownership, was significantly attenuated after sleep. A significantly greater reduction in galvanic skin response was observed after wakefulness compared to after sleep. Our results suggest that although repetitive rubber hand illusion training facilitates multisensory integration and physiological habituation of a multisensory incongruent environment, sleep corrects illusional integration and habituation based on experiences in a multisensory incongruent environment. These findings may increase our understanding of adaptive neural processes to novel environments, specifically, bodily self-consciousness and sleep-dependent neuroplasticity.

  12. The Two-Wrongs model explains perception-action dissociations for illusions driven by distortions of the egocentric reference frame

    Directory of Open Access Journals (Sweden)

    Paul eDassonville

    2015-03-01

    Full Text Available Several studies have demonstrated a dissociation of the effects of illusion on perception and action, with perception generally reported to be susceptible to illusions, while actions are seemingly immune. These findings have been interpreted to support Milner and Goodale's Two Visual Systems model, which proposes the existence of separate visual processing streams for perception and action. However, an alternative interpretation suggests that this type of behavioral dissociation will occur for any illusion that is caused by a distortion of the observer's egocentric reference frame, without requiring the existence of separate perception and action systems that are differently affected by the illusion. In this scenario, movements aimed at illusory targets will be accurate if they are guided within the same distorted reference frame used for target encoding, since the error of motor guidance will cancel with the error of encoding (hence, for actions, two wrongs do make a right. We further test this Two-Wrongs model by examining two illusions for which the hypothesis makes very different predictions: the rod-and-frame illusion (which affects perception but not actions and the simultaneous-tilt illusion (which affects perception and actions equally. We demonstrate that the rod-and-frame illusion is caused by a distortion of the observer's egocentric reference frame suitable for the cancellation of errors predicted by the Two-Wrongs model. In contrast, the simultaneous-tilt illusion is caused by local interactions between stimulus elements within an undistorted reference frame, precluding the cancellation of errors associated with the Two-Wrongs model such that the illusion is reflected in both perception and actions. These results provide evidence for a class of illusions that lead to dissociations of perception and action through distortions of the observer's spatial reference frame, rather than through the actions of functionally separate visual

  13. Description of the 11Li(p,d)10Li transfer reaction using structure overlaps from a full three-body model

    Science.gov (United States)

    Casal, J.; Gómez-Ramos, M.; Moro, A. M.

    2017-04-01

    Recent data on the differential angular distribution for the transfer reaction 11Li(p , d)10Li at E / A = 5.7 MeV in inverse kinematics are analyzed within the DWBA reaction framework, using the overlap functions calculated within a three-body model of 11Li. The weight of the different 10Li configurations in the system's ground state is obtained from the structure calculations unambiguously. The effect of the 9Li spin in the calculated observables is also investigated. We find that, although all the considered models succeed in reproducing the shape of the data, the magnitude is very sensitive to the content of p1/2 wave in the 11Li ground-state wave function. Among the considered models, the best agreement with the data is obtained when the 11Li ground state contains a ∼31% of p1/2 wave in the n-9Li subsystem. Although this model takes into account explicitly the splitting of the 1+ and 2+ resonances due to the coupling of the p1/2 wave to the 3 /2- spin of the core, a similar degree of agreement can be achieved with a model in which the 9Li spin is ignored, provided that it contains a similar p-wave content.

  14. Interaction of cholesterol ester transfer protein polymo- rphisms, body mass index, and birth weight with the risk of dyslipidemia in children and adolescents: the CASPIAN-III study

    Directory of Open Access Journals (Sweden)

    Motahar Heidari-Beni

    2015-11-01

    Full Text Available Objective(s: This study aims to investigate joint association between cholesterol ester transfer protein (CETP polymorphisms and body mass index (BMI or birth weight with the risk of dyslipidemia in Iranian children and adolescents. Materials and Methods:This study was conducted as a sub-study of the “school-based nationwide health survey” (CASPIAN-III. We randomly selected 750 samples from the whole blood samples. Real-time PCR and high resolution melt (HRM analysis were performed to determine Taq1B (rs708272 and A373P (rs5880 polymorphisms. Results:Taq1B polymorphism increased HDL-C, and total cholesterol (TC as well as decreased triglyceride and LDL-C concentrations. LDL-C and triglyceride levels were significantly higher and HDL-C and TC levels were significantly lower among those with A373P polymorphism. CT/TT genotype in Taq1B polymorphism showed a protective effect on dyslipidemia (OR= 0.12, 95%CI: 0.07-0.20. G allele of A373P polymorphism increased the risk of dyslipidemia (OR=4.10, 95%CI: 2.14, 7.83 after adjusting the confounders. We observed interactive effects of CETP gene polymorphisms and BMI or birth weight on dyslipidemia. Conclusion:Findings showed Taq1B polymorphism might have a protective effect and A373P polymorphism had deleterious effect on dyslipidemia in Iranian children and adolescents. These associations interacted with BMI and birth weight.

  15. Description of the $^{11}$Li$(p,d){^{10}}$Li transfer reaction using structure overlaps from a full three-body model

    CERN Document Server

    Casal, J; Moro, A M

    2016-01-01

    Recent data on the differential angular distribution for the transfer reaction $^{11}$Li(p,d)$^{10}$Li at $E/A=5.7$~MeV in inverse kinematics are analysed within the DWBA reaction framework, using the overlap functions calculated within a three-body model of $^{11}$Li. The weight of the different $^{10}$Li configurations in the system's ground state is obtained from the structure calculations unambiguously. The effect of the $^{9}$Li spin in the calculated observables is also investigated. We find that, although all the considered models succeed in reproducing the shape of the data, the magnitude is very sensitive to the content of $p_{1/2}$ wave in the $^{11}$Li ground-state wave function. Among the considered models, the best agreement with the data is obtained when the $^{11}$Li ground state contains a $\\sim$31\\% of $p_{1/2}$ wave in the $n$-$^9$Li subsystem. Although this model takes into account explicitly the splitting of the $1^+$ and $2^+$ resonances due to the coupling of the $p_{1/2}$ wave to the $3...

  16. Belief in the unstructured interview: The persistence of an illusion

    Directory of Open Access Journals (Sweden)

    Jason Dana

    2013-09-01

    Full Text Available Unstructured interviews are a ubiquitous tool for making screening decisions despite a vast literature suggesting that they have little validity. We sought to establish reasons why people might persist in the illusion that unstructured interviews are valid and what features about them actually lead to poor predictive accuracy. In three studies, we investigated the propensity for ``sensemaking'' - the ability for interviewers to make sense of virtually anything the interviewee says---and ``dilution''---the tendency for available but non-diagnostic information to weaken the predictive value of quality information. In Study 1, participants predicted two fellow students' semester GPAs from valid background information like prior GPA and, for one of them, an unstructured interview. In one condition, the interview was essentially nonsense in that the interviewee was actually answering questions using a random response system. Consistent with sensemaking, participants formed interview impressions just as confidently after getting random responses as they did after real responses. Consistent with dilution, interviews actually led participants to make worse predictions. Study 2 showed that watching a random interview, rather than personally conducting it, did little to mitigate sensemaking. Study 3 showed that participants believe unstructured interviews will help accuracy, so much so that they would rather have random interviews than no interview. People form confident impressions even interviews are defined to be invalid, like our random interview, and these impressions can interfere with the use of valid information. Our simple recommendation for those making screening decisions is not to use them.

  17. New motion illusion caused by pictorial motion lines.

    Science.gov (United States)

    Kawabe, Takahiro; Miura, Kayo

    2008-01-01

    Motion lines (MLs) are a pictorial technique used to represent object movement in a still picture. This study explored how MLs contribute to motion perception. In Experiment 1, we reported the creation of a motion illusion caused by MLs: random displacements of objects with MLs on each frame were perceived as unidirectional global motion along the pictorial motion direction implied by MLs. In Experiment 2, we showed that the illusory global motion in the peripheral visual field captured the perceived motion direction of random displacement of objects without MLs in the central visual field, and confirmed that the results in Experiment 1 did not stem simply from response bias, but resulted from perceptual processing. In Experiment 3, we showed that the spatial arrangement of orientation information rather than ML length is important for the illusory global motion. Our results indicate that the ML effect is based on perceptual processing rather than response bias, and that comparison of neighboring orientation components may underlie the determination of pictorial motion direction with MLs.

  18. The Enfacement Illusion Is Not Affected by Negative Facial Expressions.

    Science.gov (United States)

    Beck, Brianna; Cardini, Flavia; Làdavas, Elisabetta; Bertini, Caterina

    2015-01-01

    Enfacement is an illusion wherein synchronous visual and tactile inputs update the mental representation of one's own face to assimilate another person's face. Emotional facial expressions, serving as communicative signals, may influence enfacement by increasing the observer's motivation to understand the mental state of the expresser. Fearful expressions, in particular, might increase enfacement because they are valuable for adaptive behavior and more strongly represented in somatosensory cortex than other emotions. In the present study, a face was seen being touched at the same time as the participant's own face. This face was either neutral, fearful, or angry. Anger was chosen as an emotional control condition for fear because it is similarly negative but induces less somatosensory resonance, and requires additional knowledge (i.e., contextual information and social contingencies) to effectively guide behavior. We hypothesized that seeing a fearful face (but not an angry one) would increase enfacement because of greater somatosensory resonance. Surprisingly, neither fearful nor angry expressions modulated the degree of enfacement relative to neutral expressions. Synchronous interpersonal visuo-tactile stimulation led to assimilation of the other's face, but this assimilation was not modulated by facial expression processing. This finding suggests that dynamic, multisensory processes of self-face identification operate independently of facial expression processing.

  19. Optical illusions and augmented graphics in guidance and control

    Science.gov (United States)

    Kelley, Robert S.; Tuggle, Francis D.

    1993-03-01

    Piloting and many related control activities, especially remote manipulation via teleoperations and robotics, stand to benefit substantially from better means of communication between controller and controlled. We have investigated one such approach: the use of augmented displays on a cathode ray terminal (CRT) for controlling simulation motion is microgravity. Such displays, which have been shown to be highly effective in a variety of applications, provide information to the operator which goes beyond that which is found in nature, and thereby emphasize important aspects of a task and minimize irrelevant ones. Using this approach, we attempted to develop stylized graphical displays, incorporating augmented feedback by distorting the background of the scene under display, for purposes of flight control and/or control of a robotic arm. Besides attempting to utilize transformations of the scene itself for informational purposes, the displays we developed represent significant departures from previous methods in two notable respects. First, we have attempted to design our instrumentation to make use of peripheral rather than exclusively foveal vision, thus broadening the bandwidth of perception by vision. Second, we attempted to incorporate optical illusions intended to enhance the perception of depth and apparent motion to provide better and more compelling feedback for the operator performing the task.

  20. Enhancing the mirror illusion with transcranial direct current stimulation.

    Science.gov (United States)

    Jax, Steven A; Rosa-Leyra, Diana L; Coslett, H Branch

    2015-05-01

    Visual feedback has a strong impact on upper-extremity movement production. One compelling example of this phenomena is the mirror illusion (MI), which has been used as a treatment for post-stroke movement deficits (mirror therapy). Previous research indicates that the MI increases primary motor cortex excitability, and this change in excitability is strongly correlated with the mirror's effects on behavioral performance of neurologically-intact controls. Based on evidence that primary motor cortex excitability can also be increased using transcranial direct current stimulation (tDCS), we tested whether bilateral tDCS to the primary motor cortices (anode right-cathode left and anode left-cathode right) would modify the MI. We measured the MI using a previously-developed task in which participants make reaching movements with the unseen arm behind a mirror while viewing the reflection of the other arm. When an offset in the positions of the two limbs relative to the mirror is introduced, reaching errors of the unseen arm are biased by the reflected arm's position. We found that active tDCS in the anode right-cathode left montage increased the magnitude of the MI relative to sham tDCS and anode left-cathode right tDCS. We take these data as a promising indication that tDCS could improve the effect of mirror therapy in patients with hemiparesis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. A phase mixing model for the frequency-doubling illusion.

    Science.gov (United States)

    Wielaard, James; Smith, R Theodore

    2013-10-01

    We introduce a temporal phase mixing model for a description of the frequency-doubling illusion (FDI). The model is generic in the sense that it can be set to refer to retinal ganglion cells, lateral geniculate cells, as well as simple cells in the primary visual cortex (V1). Model parameters, however, strongly suggest that the FDI originates in the cortex. The model shows how noise in the response phases of cells in V1, or in further processing of these phases, easily produces observed behavior of FDI onset as a function of spatiotemporal frequencies. It also shows how this noise can accommodate physiologically plausible spatial delays in comparing neural signals over a distance. The model offers an explanation for the disappearance of the FDI at sufficiently high spatial frequencies via increasingly correlated coding of neighboring grating stripes. Further, when the FDI is equated to vanishing perceptual discrimination between asynchronous contrast-reversal gratings, the model proposes the possibility that the FDI shows a resonance behavior at sufficiently high spatial frequencies, by which it is alternately perceived and not perceived in sequential temporal frequency bands.

  2. Do You Hear More Piano or Drum Sounds? An Auditory Version of the Solitaire Illusion.

    Science.gov (United States)

    Prpic, Valter; Luccio, Riccardo

    2016-10-03

    The solitaire illusion is an illusion of numerosity proposed by Frith and Frith. In the original version, an apparent number of elements was determined by the spatial arrangement of two kinds of elements (black and white marbles). In our study, an auditory version of the solitaire illusion was demonstrated. Participants were asked to judge if they perceived more drum or piano sounds. When half of the piano tones were perceived as lower in pitch than a drum sound and the other half higher, piano tones appeared to be arranged in small units, leading to numerosity underestimation. Conversely, when all piano tones were perceived to be higher in pitch than the drum sounds, they appeared to be arranged in a single large unit, leading to numerosity overestimation. Comparable to the visual version of the solitaire illusion, the clustering seems to be determined by Gestalt principles. In our auditory version, a clear reversal of the illusion (numerosity overestimation or underestimation) was observed when piano tones appeared to be arranged in a single large cluster or in several small clusters, respectively. © The Author(s) 2016.

  3. Does my step look big in this? A visual illusion leads to safer stepping behaviour.

    Directory of Open Access Journals (Sweden)

    David B Elliott

    Full Text Available BACKGROUND: Tripping is a common factor in falls and a typical safety strategy to avoid tripping on steps or stairs is to increase foot clearance over the step edge. In the present study we asked whether the perceived height of a step could be increased using a visual illusion and whether this would lead to the adoption of a safer stepping strategy, in terms of greater foot clearance over the step edge. The study also addressed the controversial question of whether motor actions are dissociated from visual perception. METHODOLOGY/PRINCIPAL FINDINGS: 21 young, healthy subjects perceived the step to be higher in a configuration of the horizontal-vertical illusion compared to a reverse configuration (p = 0.01. During a simple stepping task, maximum toe elevation changed by an amount corresponding to the size of the visual illusion (p<0.001. Linear regression analyses showed highly significant associations between perceived step height and maximum toe elevation for all conditions. CONCLUSIONS/SIGNIFICANCE: The perceived height of a step can be manipulated using a simple visual illusion, leading to the adoption of a safer stepping strategy in terms of greater foot clearance over a step edge. In addition, the strong link found between perception of a visual illusion and visuomotor action provides additional support to the view that the original, controversial proposal by Goodale and Milner (1992 of two separate and distinct visual streams for perception and visuomotor action should be re-evaluated.

  4. How the Thatcher illusion reveals evolutionary differences in the face processing of primates.

    Science.gov (United States)

    Weldon, Kimberly B; Taubert, Jessica; Smith, Carolynn L; Parr, Lisa A

    2013-09-01

    Face recognition in humans is a complex cognitive skill that requires sensitivity to unique configurations of eyes, mouth, and other facial features. The Thatcher illusion has been used to demonstrate the importance of orientation when processing configural information within faces. Transforming an upright face so that the eyes and mouth are inverted renders the face grotesque; however, when this "Thatcherized" face is inverted, the effect disappears. Due to the use of primate models in social cognition research, it is important to determine the extent to which specialized cognitive functions like face processing occur across species. To date, the Thatcher illusion has been explored in only a few species with mixed results. Here, we used computerized tasks to examine whether nonhuman primates perceive the Thatcher illusion. Chimpanzees and rhesus monkeys were required to discriminate between Thatcherized and unaltered faces presented upright and inverted. Our results confirm that chimpanzees perceived the Thatcher illusion, but rhesus monkeys did not, suggesting species differences in the importance of configural information in face processing. Three further experiments were conducted to understand why our results differed from previously published accounts of the Thatcher illusion in rhesus monkeys.

  5. Processing of the Müller-Lyer illusion by a Grey parrot (Psittacus erithacus).

    Science.gov (United States)

    Pepperberg, Irene M; Vicinay, Jennifer; Cavanagh, Patrick

    2008-01-01

    Alex, a Grey parrot (Psittacus erithacus) who identifies the bigger or smaller of two objects by reporting its color or matter using a vocal English label and who states "none" if they do not differ in size, was presented with two-dimensional Müller-Lyer figures (Brentano form) in which the central lines were of contrasting colors. His responses to "What color bigger/ smaller?" demonstrated that he saw the standard length illusion in the Müller-Lyer figures in 32 of 50 tests where human observers would also see the illusion and reported the reverse direction only twice. He did not report the illusion when (a) arrows on the shafts were perpendicular to the shafts or closely approached perpendicularity, (b) shafts were 6 times thicker than the arrows, or (c) after being tested with multiple exposures conditions that also lessen or eliminate the illusion for human observers. These data suggest that parrot and human visual systems process the Müller-Lyer figure in analogous ways despite a 175-fold difference in the respective sizes of their brain volumes. The similarity in results also indicates that parrots with vocal abilities like Alex's can be reliably tested on visual illusions with paradigms similar to those used on human subjects.

  6. Directional organization and shape formation: New illusions and Helmholtz’s Square

    Directory of Open Access Journals (Sweden)

    Baingio ePinna

    2015-03-01

    Full Text Available According to Helmholtz’s Square illusion, a square appears wider when it is filled with vertical lines and higher when filled with horizontal lines (Helmholtz, 1866. Recently, Pinna (2010a demonstrat- ed that the grouping of small squares on the basis of the similarity principle influences also percep- tion of their shape and of the whole emerging shapes. The direction imparted by grouping is the main attribute that influences the shape by polarizing it in the same direction both globally and locally. The rectangle illusion is opposite to what expected on the basis of Helmholtz’s Square illusion. Aim of this work is to solve the antinomy between the two sets of illusions and to demonstrate a common explanation based on the interaction between different sources of directional organization. This was accomplished by introducing some new phenomena and through phenomenological experiments proving the role played by the directional shape organization in shape formation. According to our results, Helmholtz’s square illusion shows at least two synergistic sources of directional organization: the direction of the grouping of the lines due to their similarity of the luminance contrast and the di- rection of the grouping of the lines due to the good continuation.

  7. Parietal disruption alters audiovisual binding in the sound-induced flash illusion.

    Science.gov (United States)

    Kamke, Marc R; Vieth, Harrison E; Cottrell, David; Mattingley, Jason B

    2012-09-01

    Selective attention and multisensory integration are fundamental to perception, but little is known about whether, or under what circumstances, these processes interact to shape conscious awareness. Here, we used transcranial magnetic stimulation (TMS) to investigate the causal role of attention-related brain networks in multisensory integration between visual and auditory stimuli in the sound-induced flash illusion. The flash illusion is a widely studied multisensory phenomenon in which a single flash of light is falsely perceived as multiple flashes in the presence of irrelevant sounds. We investigated the hypothesis that extrastriate regions involved in selective attention, specifically within the right parietal cortex, exert an influence on the multisensory integrative processes that cause the flash illusion. We found that disruption of the right angular gyrus, but not of the adjacent supramarginal gyrus or of a sensory control site, enhanced participants' veridical perception of the multisensory events, thereby reducing their susceptibility to the illusion. Our findings suggest that the same parietal networks that normally act to enhance perception of attended events also play a role in the binding of auditory and visual stimuli in the sound-induced flash illusion.

  8. Implementation and Assessment of an Intervention to Debias Adolescents against Causal Illusions

    Science.gov (United States)

    Barberia, Itxaso; Blanco, Fernando; Cubillas, Carmelo P.; Matute, Helena

    2013-01-01

    Researchers have warned that causal illusions are at the root of many superstitious beliefs and fuel many people’s faith in pseudoscience, thus generating significant suffering in modern society. Therefore, it is critical that we understand the mechanisms by which these illusions develop and persist. A vast amount of research in psychology has investigated these mechanisms, but little work has been done on the extent to which it is possible to debias individuals against causal illusions. We present an intervention in which a sample of adolescents was introduced to the concept of experimental control, focusing on the need to consider the base rate of the outcome variable in order to determine if a causal relationship exists. The effectiveness of the intervention was measured using a standard contingency learning task that involved fake medicines that typically produce causal illusions. Half of the participants performed the contingency learning task before participating in the educational intervention (the control group), and the other half performed the task after they had completed the intervention (the experimental group). The participants in the experimental group made more realistic causal judgments than did those in the control group, which served as a baseline. To the best of our knowledge, this is the first evidence-based educational intervention that could be easily implemented to reduce causal illusions and the many problems associated with them, such as superstitions and belief in pseudoscience. PMID:23967189

  9. Implementation and assessment of an intervention to debias adolescents against causal illusions.

    Directory of Open Access Journals (Sweden)

    Itxaso Barberia

    Full Text Available Researchers have warned that causal illusions are at the root of many superstitious beliefs and fuel many people's faith in pseudoscience, thus generating significant suffering in modern society. Therefore, it is critical that we understand the mechanisms by which these illusions develop and persist. A vast amount of research in psychology has investigated these mechanisms, but little work has been done on the extent to which it is possible to debias individuals against causal illusions. We present an intervention in which a sample of adolescents was introduced to the concept of experimental control, focusing on the need to consider the base rate of the outcome variable in order to determine if a causal relationship exists. The effectiveness of the intervention was measured using a standard contingency learning task that involved fake medicines that typically produce causal illusions. Half of the participants performed the contingency learning task before participating in the educational intervention (the control group, and the other half performed the task after they had completed the intervention (the experimental group. The participants in the experimental group made more realistic causal judgments than did those in the control group, which served as a baseline. To the best of our knowledge, this is the first evidence-based educational intervention that could be easily implemented to reduce causal illusions and the many problems associated with them, such as superstitions and belief in pseudoscience.

  10. The accentuation principle of visual organization and the illusion of musical suspension.

    Science.gov (United States)

    Pinna, Baingio; Sirigu, Luca

    2011-01-01

    The aim of this work is to demonstrate a new principle of grouping and shape formation that we called the accentuation principle, stating that, all else being equal, the elements tend to group in the same oriented direction of the element discontinuity placed within a whole set of continuous/homogeneous components. The discontinuous element is like an accent, i.e., a visual emphasis within a whole. We showed that this principle is independent from other gestalt principles. In fact, it shows vectorial properties not present in the other principles. It can be pitted against them. Furthermore, it is not only a grouping principle but it also influences shape formation, by inducing effects like the square/diamond and the rectangle illusions. Finally, the accentuation operates under stroboscopic conditions and manifests filling-in properties and long range effects. Through experimental phenomenology, it was shown that the accentuation principle can influence grouping and shape formation not only in space but also in time and, therefore, not only in vision but also in music perception. This was suggested by phenomenally linking visual and musical accents and by demonstrating a new illusion of musical suspension, related with its opposite effect, the downbeat illusion. This kind of illusions can be appreciated in two solo piano compositions respectively by Debussy and Chopin-Rêverie and Nocturne, op. 27 no. 1. Variations in the note where the accent is placed and in the kind of accent demonstrated their basic role in inducing the illusion of musical suspension.

  11. Mishaps, errors, and cognitive experiences: on the conceptualization of perceptual illusions

    Science.gov (United States)

    Zavagno, Daniele; Daneyko, Olga; Actis-Grosso, Rossana

    2015-01-01

    Although a visual illusion is often viewed as an amusing trick, for the vision scientist it is a question that demands an answer, which leads to even more questioning. All researchers hold their own chain of questions, the links of which depend on the very theory they adhere to. Perceptual theories are devoted to answering questions concerning sensation and perception, but in doing so they shape concepts such as reality and representation, which necessarily affect the concept of illusion. Here we consider the macroscopic aspects of such concepts in vision sciences from three classic viewpoints—Ecological, Cognitive, Gestalt approaches—as we see this a starting point to understand in which terms illusions can become a tool in the hand of the neuroscientist. In fact, illusions can be effective tools in studying the brain in reference to perception and also to cognition in a much broader sense. A theoretical debate is, however, mandatory, in particular with regards to concepts such as veridicality and representation. Whether a perceptual outcome is considered as veridical or illusory (and, consequently, whether a class of phenomena should be classified as perceptual illusions or not) depends on the meaning of such concepts. PMID:25918504

  12. Illusions and delusions: relating experimentally-induced false memories to anomalous experiences and ideas

    Directory of Open Access Journals (Sweden)

    Philip R Corlett

    2009-11-01

    Full Text Available The salience hypothesis of psychosis rests on a simple but profound observation that subtle alterations in the way that we perceive and experience stimuli have important consequences for how important these stimuli become for us, how much they draw our attention, how they embed themselves in our memory and, ultimately, how they shape our beliefs. We put forward the idea that a classical memory illusion – the Deese-Roediger-McDermott (DRM effect – offers a useful way of exploring processes related to such aberrant belief formation. The illusion occurs when, as a consequence of its relationship to previous stimuli, a stimulus is asserted to be remembered even when has not been previously presented. Such illusory familiarity is thought to be generated by the surprising fluency with which the stimulus is processed. In this respect, the illusion relates directly to the salience hypothesis and may share common cognitive underpinnings with aberrations of perception and attribution that are found in psychosis. In this paper, we explore the theoretical importance of this experimentally-induced illusion in relation to the salience model of psychosis. We present data showing that, in healthy volunteers, the illusion relates directly to self reported anomalies of experience and magical thinking. We discuss this finding in terms of the salience hypothesis and of a broader Bayesian framework of perception and cognition which emphasizes the salience both of predictable and unpredictable experiences..

  13. Mishaps, errors, and cognitive experiences: On the conceptualization of perceptual illusions

    Directory of Open Access Journals (Sweden)

    Daniele eZavagno

    2015-04-01

    Full Text Available Although a visual illusion is often viewed as an amusing trick, for the vision scientist it is a question that demands an answer, which leads to even more questioning. All researchers hold their own chain of questions, the links of which depend on the very theory they adhere to. Perceptual theories are devoted to answering questions concerning sensation and perception, but in doing so they shape concepts such as reality and representation, which necessarily affect the concept of illusion. Here we consider the macroscopic aspects of such concepts in vision sciences from three classic viewpoints – Ecological, Cognitive, Gestalt approaches – as we see this a starting point to understand in which terms illusions can become a tool in the hand of the neuroscientist. In fact, illusions can be effective tools in studying the brain in reference to perception and also to cognition in a much broader sense. A theoretical debate is, however, mandatory, in particular with regards to concepts such as veridicality and representation. Whether a perceptual outcome is considered as veridical or illusory (and, consequently, whether a class of phenomena should be classified as perceptual illusions or not depends on the meaning of such concepts.

  14. Field Dependence, Efficiency of Information Processing in Working Memory and Susceptibility to Orientation Illusions among Architects

    Directory of Open Access Journals (Sweden)

    Młyniec Agnieszka

    2016-04-01

    Full Text Available This study examined cognitive predictors of susceptibility to orientation illusions: Poggendorff, Ponzo, and Zöllner. It was assumed that lower efficiency of information processing in WM and higher field dependence are conducive to orientation illusions. 61 architects (30 women aged M = 29, +/- 1.6, and 49 university students (29 women aged M = 23.53, +/- 4.24, were tested with Witkin’s EFT to assess their field dependence; the SWATT method was used as a measure of WM efficiency, and susceptibility to visual illusions was verified with a series of computer tasks. We obtained a small range of the explained variance in the regression models including FDI and WM indicators. On the basis of WM efficiency indicators, we managed to confirm the existence of memory predictors of susceptibility to illusions (they are rather weak, as they explain from 6% to 14% of the variance of the dependent variable. Among the architects, lower efficiency of WM processing (weaker inhibition, task-switching and higher field dependence are responsible for greater susceptibility to orientation illusions.

  15. Mishaps, errors, and cognitive experiences: on the conceptualization of perceptual illusions.

    Science.gov (United States)

    Zavagno, Daniele; Daneyko, Olga; Actis-Grosso, Rossana

    2015-01-01

    Although a visual illusion is often viewed as an amusing trick, for the vision scientist it is a question that demands an answer, which leads to even more questioning. All researchers hold their own chain of questions, the links of which depend on the very theory they adhere to. Perceptual theories are devoted to answering questions concerning sensation and perception, but in doing so they shape concepts such as reality and representation, which necessarily affect the concept of illusion. Here we consider the macroscopic aspects of such concepts in vision sciences from three classic viewpoints-Ecological, Cognitive, Gestalt approaches-as we see this a starting point to understand in which terms illusions can become a tool in the hand of the neuroscientist. In fact, illusions can be effective tools in studying the brain in reference to perception and also to cognition in a much broader sense. A theoretical debate is, however, mandatory, in particular with regards to concepts such as veridicality and representation. Whether a perceptual outcome is considered as veridical or illusory (and, consequently, whether a class of phenomena should be classified as perceptual illusions or not) depends on the meaning of such concepts.

  16. Dentists make larger holes in teeth than they need to if the teeth present a visual illusion of size.

    Directory of Open Access Journals (Sweden)

    Robert P O'Shea

    Full Text Available BACKGROUND: Health care depends, in part, on the ability of a practitioner to see signs of disease and to see how to treat it. Visual illusions, therefore, could affect health care. Yet there is very little prospective evidence that illusions can influence treatment. We sought such evidence. METHODS AND RESULTS: We simulated treatment using dentistry as a model system. We supplied eight, practicing, specialist dentists, endodontists, with at least 21 isolated teeth each, randomly sampled from a much larger sample of teeth they were likely to encounter. Teeth contained holes and we asked the endodontists to cut cavities in preparation for filling. Each tooth presented a more or less potent version of a visual illusion of size, the Delboeuf illusion, that made the holes appear smaller than they were. Endodontists and the persons measuring the cavities were blind to the parameters of the illusion. We found that the size of cavity endodontists made was linearly related to the potency of the Delboeuf illusion (p<.01 with an effect size (Cohen's d of 1.41. When the illusion made the holes appear smaller, the endodontists made cavities larger than needed. CONCLUSIONS: The visual context in which treatment takes place can influence the treatment. Undesirable effects of visual illusions could be counteracted by a health practitioner's being aware of them and by using measurement.

  17. Comparing the effectiveness of different displays in enhancing illusions of self-movement (vection).

    Science.gov (United States)

    Riecke, Bernhard E; Jordan, Jacqueline D

    2015-01-01

    Illusions of self-movement (vection) can be used in virtual reality (VR) and other applications to give users the embodied sensation that they are moving when physical movement is unfeasible or too costly. Whereas a large body of vection literature studied how various parameters of the presented visual stimulus affect vection, little is known how different display types might affect vection. As a step toward addressing this gap, we conducted three experiments to compare vection and usability parameters between commonly used VR displays, ranging from stereoscopic projection and 3D TV to high-end head-mounted display (HMD, NVIS SX111) and recent low-cost HMD (Oculus Rift). The last experiment also compared these two HMDs in their native full field of view (FOV) and a reduced, matched FOV of 72° × 45°. Participants moved along linear and curvilinear paths in the virtual environment, reported vection onset time, and rated vection intensity at the end of each trial. In addition, user ratings on immersion, motion sickness, vection, and overall preference were recorded retrospectively and compared between displays. Unexpectedly, there were no significant effects of display on vection measures. Reducing the FOV for the HMDs (from full to 72° × 45°) decreased vection onset latencies, but did not affect vection intensity. As predicted, curvilinear paths yielded earlier and more intense vection. Although vection has often been proposed to predict or even cause motion sickness, we observed no correlation for any of the displays studied. In conclusion, perceived self-motion and other user experience measures proved surprisingly tolerant toward changes in display type as long as the FOV was roughly matched. This suggests that display choice for vection research and VR applications can be largely based on other considerations as long as the provided FOV is sufficiently large.

  18. Comparing the effectiveness of different displays in enhancing illusions of self-movement (vection

    Directory of Open Access Journals (Sweden)

    Bernhard E. Riecke

    2015-06-01

    Full Text Available Illusions of self-movement (vection can be used in Virtual Reality (VR and other applications to give users the embodied sensation that they are moving when physical movement is unfeasible or too costly. Whereas a large body of vection literature studied how various parameters of the presented visual stimulus affect vection, little is known how different display types might affect vection. As a step towards addressing this gap, we conducted three experiments to compare vection and usability parameters between commonly used VR displays, ranging from stereoscopic projection and 3D TV to high-end head-mounted display (HMD, NVIS SX111 and recent low-cost HMD (Oculus Rift. The last experiment also compared these two HMDs in their native full field of view FOV and a reduced, matched FOV of 72×45°. Participants moved along linear and curvilinear paths in the virtual environment, reported vection onset time, and rated vection intensity at the end of each trial. In addition, user ratings on immersion, motion sickness, vection, and overall preference were recorded retrospectively and compared between displays. Unexpectedly, there were no significant effects of display on vection measures. Reducing the FOV for the HMDs (from full to 72×45° decreased vection onset latencies, but did not affect vection intensity. As predicted, curvilinear paths yielded earlier and more intense vection. Although vection has often been proposed to predict or even cause motion sickness, we observed no correlation for any of the displays studied. In conclusion, perceived self-motion and other user experience measures proved surprisingly tolerant towards changes in display type as long as the FOV was roughly matched. This suggests that display choice for vection research and VR applications can be largely based on other considerations as long as the provided FOV is sufficiently large.

  19. Sensory illusions: Common mistakes in physics regarding sound, light and radio waves

    Science.gov (United States)

    Briles, T. M.; Tabor-Morris, A. E.

    2013-03-01

    Optical illusions are well known as effects that we see that are not representative of reality. Sensory illusions are similar but can involve other senses than sight, such as hearing or touch. One mistake commonly noted among instructors is that students often mis-identify radio signals as sound waves and not as part of the electromagnetic spectrum. A survey of physics students from multiple high schools highlights the frequency of this common misconception, as well as other nuances on this misunderstanding. Many students appear to conclude that, since they experience radio broadcasts as sound, then sound waves are the actual transmission of radio signals and not, as is actually true, a representation of those waves as produced by the translator box, the radio. Steps to help students identify and correct sensory illusion misconceptions are discussed. School of Education

  20. Exterior optical cloaking and illusions by using active sources: A boundary element perspective

    Science.gov (United States)

    Zheng, H. H.; Xiao, J. J.; Lai, Y.; Chan, C. T.

    2010-05-01

    Recently, it was demonstrated that active sources can be used to cloak any objects that lie outside the cloaking devices [F. Guevara Vasquez, G. W. Milton, and D. Onofrei, Phys. Rev. Lett. 103, 073901 (2009)]. Here, we propose that active sources can create illusion effects so that an object outside the cloaking device can be made to look like another object. Invisibility is a special case in which the concealed object is transformed to a volume of air. From a boundary element perspective, we show that active sources can create a nearly “silent” domain which can conceal any objects inside and at the same time make the whole system look like an illusion of our choice outside a virtual boundary. The boundary element method gives the fields and field gradients, which can be related to monopoles and dipoles, on continuous curves which define the boundary of the active devices. Both the cloaking and illusion effects are confirmed by numerical simulations.

  1. The Wundt-Jastrow illusion in the study of spatial hemi-inattention.

    Science.gov (United States)

    Massironi, M; Antonucci, G; Pizzamiglio, L; Vitale, M V; Zoccolotti, P

    1988-01-01

    A new test to detect unilateral neglect was devised using a modified version of the Wundt-Jastrow area illusion. The test was given to three groups of subjects: left brain damaged (LBD), right brain damaged (RBD) patients and controls. Of RBD patients, 40.4% but no LBD patient or control, showed responses inconsistent with the visual illusion when the determinant features of the illusion pointed to the left visual field. These unexpected responses were highly related to a clinical evaluation of the severity of the hemi-inattention disorder. The sensitivity of this test and of other standard measures of hemi-neglect were compared. The possibility of identifying qualitatively different forms of hemi-neglect was also discussed.

  2. Multisensory integration in hemianopia and unilateral spatial neglect: Evidence from the sound induced flash illusion.

    Science.gov (United States)

    Bolognini, Nadia; Convento, Silvia; Casati, Carlotta; Mancini, Flavia; Brighina, Filippo; Vallar, Giuseppe

    2016-07-01

    Recent neuropsychological evidence suggests that acquired brain lesions can, in some instances, abolish the ability to integrate inputs from different sensory modalities, disrupting multisensory perception. We explored the ability to perceive multisensory events, in particular the integrity of audio-visual processing in the temporal domain, in brain-damaged patients with visual field defects (VFD), or with unilateral spatial neglect (USN), by assessing their sensitivity to the 'Sound-Induced Flash Illusion' (SIFI). The study yielded two key findings. Firstly, the 'fission' illusion (namely, seeing multiple flashes when a single flash is paired with multiple sounds) is reduced in both left- and right-brain-damaged patients with VFD, but not in right-brain-damaged patients with left USN. The disruption of the fission illusion is proportional to the extent of the occipital damage. Secondly, a reliable 'fusion' illusion (namely, seeing less flashes when a single sound is paired with multiple flashes) is evoked in USN patients, but neither in VFD patients nor in healthy participants. A control experiment showed that the fusion, but not the fission, illusion is lost in older participants (>50 year-old), as compared with younger healthy participants (illusions are dissociable multisensory phenomena, altered differently by impairments of visual perception (i.e. VFD) and spatial attention (i.e. USN). The occipital cortex represents a key cortical site for binding auditory and visual stimuli in the SIFI, while damage to right-hemisphere areas mediating spatial attention and awareness does not prevent the integration of audio-visual inputs in the temporal domain.

  3. Connectedness underlies the underestimation of the horizontal vertical illusion in L-shaped configurations.

    Science.gov (United States)

    Cai, Yongchun; Wang, Ci; Song, Chao; Li, Zhi

    2017-05-01

    L-shaped configuration is a commonly used stimulus configuration in studying horizontal vertical illusion. Here, we report that the horizontal vertical illusion is substantially underestimated when the L-shaped configuration is used for evaluating the illusion. Experiment 1 found that, in a length perception task, the perceived length of a vertical bar was about 10% longer than that of a horizontal bar with the same physical size. Similar amount of HVI was found in a length comparison task, in which the length of a horizontal bar was compared to that of a vertical bar and the two bars were presented separately in space or in time. In contrast, when the length comparison task was conducted with the two bars being arranged in a connected L-shape, the illusion was halved in strength. Experiment 2 and 3 studied what might be the cause of this L-shape induced HVI-underestimation. Two factors were investigated: the connectedness of the two lines, and the 45° absolute orientation or the 45° inner angle information embedded in the upright isosceles L-shape. The results showed that the HVI strength was not much affected when the 45° absolute orientation and the 45° angle information was made useless for the length comparison task. In contrast, the illusion was significantly reduced in strength whenever the two lines were separated as compared to when they were connected. These results suggested that the connectedness of the two lines must underlie the underestimation of the horizontal vertical illusion in the L-shaped configurations.

  4. The illusion of control and the importance of community in health care organizations.

    Science.gov (United States)

    Pitts, T

    1993-01-01

    The complexity of our health care environment and organizations requires a management style that moves beyond control to empowerment. Even though this complexity minimizes our ability to control events, many organizations are still preoccupied with the illusion of control. This restrains the performance of our health care organizations. Some of the contributing factors supporting this illusion are bureaucracy, scientific methodology, individualism, and our confusion of management with leadership. The concept of "community" is discussed from an organizational perspective. It is suggested that we can improve the performance of our organizations by rediscovering the values of community.

  5. Limitations of the Oriented Difference of Gaussian Filter in Special Cases of Brightness Perception Illusions.

    Science.gov (United States)

    Bakshi, Ashish; Roy, Sourya; Mallick, Arijit; Ghosh, Kuntal

    2016-03-01

    The Oriented Difference of Gaussian (ODOG) filter of Blakeslee and McCourt has been successfully employed to explain several brightness perception illusions which include illusions of both brightness-contrast type, for example, Simultaneous Brightness Contrast and Grating Induction and the brightness-assimilation type, for example, the White effect and the shifted White effect. Here, we demonstrate some limitations of the ODOG filter in predicting perceived brightness by comparing the ODOG responses to various stimuli (generated by varying two parameters, namely, test patch length and spatial frequency) with experimental observations of the same.

  6. Illusion and reality in the atmospheres of exoplanets

    Science.gov (United States)

    Deming, L. Drake; Seager, Sara

    2017-01-01

    The atmospheres of exoplanets reveal all their properties beyond mass, radius, and orbit. Based on bulk densities, we know that exoplanets larger than 1.5 Earth radii must have gaseous envelopes and, hence, atmospheres. We discuss contemporary techniques for characterization of exoplanetary atmospheres. The measurements are difficult, because—even in current favorable cases—the signals can be as small as 0.001% of the host star's flux. Consequently, some early results have been illusory and not confirmed by subsequent investigations. Prominent illusions to date include polarized scattered light, temperature inversions, and the existence of carbon planets. The field moves from the first tentative and often incorrect conclusions, converging to the reality of exoplanetary atmospheres. That reality is revealed using transits for close-in exoplanets and direct imaging for young or massive exoplanets in distant orbits. Several atomic and molecular constituents have now been robustly detected in exoplanets as small as Neptune. In our current observations, the effects of clouds and haze appear ubiquitous. Topics at the current frontier include the measurement of heavy element abundances in giant planets, detection of carbon-based molecules, measurement of atmospheric temperature profiles, definition of heat circulation efficiencies for tidally locked planets, and the push to detect and characterize the atmospheres of super-Earths. Future observatories for this quest include the James Webb Space Telescope and the new generation of extremely large telescopes on the ground. On a more distant horizon, NASA's study concepts for the Habitable Exoplanet Imaging Mission (HabEx) and the Large UV/Optical/Infrared Surveyor (LUVOIR) missions could extend the study of exoplanetary atmospheres to true twins of Earth.

  7. Neural substrate of body size: illusory feeling of shrinking of the waist.

    Directory of Open Access Journals (Sweden)

    2005-12-01

    Full Text Available The perception of the size and shape of one's body (body image is a fundamental aspect of how we experience ourselves. We studied the neural correlates underlying perceived changes in the relative size of body parts by using a perceptual illusion in which participants felt that their waist was shrinking. We scanned the brains of the participants using functional magnetic resonance imaging. We found that activity in the cortices lining the left postcentral sulcus and the anterior part of the intraparietal sulcus reflected the illusion of waist shrinking, and that this activity was correlated with the reported degree of shrinking. These results suggest that the perceived changes in the size and shape of body parts are mediated by hierarchically higher-order somatosensory areas in the parietal cortex. Based on this finding we suggest that relative size of body parts is computed by the integration of more elementary somatic signals from different body segments.

  8. Illusory Shrinkage and Growth: Body-Based Rescaling Affects the Perception of Size

    NARCIS (Netherlands)

    Linkenauger, S.A.; Ramenzoni, V.C.; Proffitt, D.R.

    2010-01-01

    The notion that apparent sizes are perceived relative to the size of one's body is supported through the discovery of a new visual illusion. When graspable objects are magnified by magnifying goggles, they appear to shrink back to near-normal size when one's hand (also magnified) is placed next to t

  9. Digging up Von Békésy: Funneling of Touches around the Body

    Directory of Open Access Journals (Sweden)

    Lisa M Pritchett

    2011-10-01

    Full Text Available We investigated a technique that can be used to place tactile stimuli on a continuum between two points using two tactors placed several centimeters apart. As von Békésy first described in 1959, when two pieces of skin several centimeters apart are simultaneously stimulated, a single touch is perceived at an intermediate location. When the relative intensity of the vibration of the two tactors is slowly adjusted from 1:0 to 0:1 a sensation is created of a touch moving across the skin. This has come to be known as the funneling illusion. We have characterized the funneling illusion on a variety of body parts including the hand, arm, wrist, head, torso, and legs. We show that the illusion is robust to a variety of vibration parameters, and demonstrate how it may be used for within modality touch discrimination and adjustment procedures.

  10. Deficits in agency in schizophrenia, and additional deficits in body image, body schema and internal timing, in passivity symptoms.

    Directory of Open Access Journals (Sweden)

    Kyran Trent Graham

    2014-09-01

    Full Text Available Individuals with schizophrenia, particularly those with passivity symptoms, may not feel in control of their actions, believing them to be controlled by external agents. Cognitive operations that contribute to these symptoms may include abnormal processing in agency, as well as body representations that deal with body schema and body image. However, these operations in schizophrenia are not fully understood, and the questions of general versus specific deficits in individuals with different symptom profiles remain unanswered. Using the projected hand illusion (a digital video version of the rubber hand illusion with syn-chronous and asynchronous stroking (500 ms delay, and a hand laterality judgment task, we assessed sense of agency, body image and body schema in 53 people with clinically stable schizophrenia (with a current, past, and no history of passivity symptoms and 48 healthy controls. The results revealed a stable trait in schizophrenia with no difference be-tween clinical subgroups (sense of agency, and some quantitative (specific differences de-pending on the passivity symptom profile (body image and body schema. Specifically, a reduced sense of self-agency was a common feature of all clinical subgroups. However, subgroup comparisons showed that individuals with passivity symptoms (both current and past had significantly greater deficits on tasks assessing body image and body schema, relative to the other groups. In addition, patients with current passivity symptoms failed to demonstrate the normal reduction in body illusion typically seen with a 500 ms delay in visual feedback (asynchronous condition, suggesting internal timing problems. Altogether, the results underscore self-abnormalities in schizophrenia, provide evidence for both trait abnormalities and state changes specific to passivity symptoms, and point to a role for internal timing deficits as a mechanistic explanation for external cues becoming a possible source of self-body

  11. Size and direction of distortion in geometric-optical illusions: conciliation between the Müller-Lyer and Titchener configurations.

    Science.gov (United States)

    Nemati, Farshad

    2009-01-01

    Over the past few decades, different theories have been advanced to explain geometric-optical illusions based on various perceptual processes such as assimilation and/or contrast. Consistent with the contradictory effects of assimilation and contrast, Pressey's assimilation theory provided an explanation for the Müller-Lyer illusion, but failed to account for the Titchener (Ebbinghaus) illusion. A model that explains both Müller-Lyer and Titchener illusions according to a common underlying process may outline a unified explanation for a variety of geometric-optical illusions. In order to develop such a model, the concept of empty space is introduced as an area of the illusory figure that is not filled by line drawings. It was predicted that the magnitude of illusion would increase with the area of the empty space around the illusory figures. The effect of empty space on the magnitude of perceptual distortion was measured in Müller-Lyer figures, with outward arrowheads of different length. The results indicated an overestimation of the target stimulus in all of the figures. Nevertheless, consistent with the prediction of the present model, the horizontal line in the Müller-Lyer figure with the longest arrowheads appeared shorter than that with the shortest arrowheads, although the size contrast of these figures was the same. According to the analysis proposed in the present study, the area of empty space not only affects the magnitude of illusion but also serves as a contextual cue for the perceptual system to determine the direction of illusion (orientation). The functional relationships between the size contrast and empty space provide a common explanation for the Müller-Lyer, Titchener, and a variety of other geometric-optical illusions.

  12. Experimental Realization of a Circuit-Based Broadband Illusion-Optics Analogue

    Science.gov (United States)

    Li, Chao; Meng, Xiankun; Liu, Xiao; Li, Fang; Fang, Guangyou; Chen, Huanyang; Chan, C. T.

    2010-12-01

    We experimentally demonstrate the first metamaterial “illusion optics” device—an “invisible gateway” by using a transmission-line medium. The device contains an open channel that can block waves at a particular frequency range. We also demonstrate that such a device can work in a broad frequency range.

  13. Category Selectivity of Human Visual Cortex in Perception of Rubin Face–Vase Illusion

    Directory of Open Access Journals (Sweden)

    Xiaogang Wang

    2017-09-01

    Full Text Available When viewing the Rubin face–vase illusion, our conscious perception spontaneously alternates between the face and the vase; this illusion has been widely used to explore bistable perception. Previous functional magnetic resonance imaging (fMRI studies have studied the neural mechanisms underlying bistable perception through univariate and multivariate pattern analyses; however, no studies have investigated the issue of category selectivity. Here, we used fMRI to investigate the neural mechanisms underlying the Rubin face–vase illusion by introducing univariate amplitude and multivariate pattern analyses. The results from the amplitude analysis suggested that the activity in the fusiform face area was likely related to the subjective face perception. Furthermore, the pattern analysis results showed that the early visual cortex (EVC and the face-selective cortex could discriminate the activity patterns of the face and vase perceptions. However, further analysis of the activity patterns showed that only the face-selective cortex contains the face information. These findings indicated that although the EVC and face-selective cortex activities could discriminate the visual information, only the activity and activity pattern in the face-selective areas contained the category information of face perception in the Rubin face–vase illusion.

  14. Rumination and interoceptive accuracy predict the occurrence of the thermal grill illusion of pain

    OpenAIRE

    Scheuren, Raymonde; Sütterlin, Stefan; Anton, Fernand

    2014-01-01

    Background: While the neurophysiological mechanisms underlying the thermal grill illusion of pain (TGI) have been thoroughly studied, psychological determinants largely remain unknown. The present study aimed to investigate whether cognitive and affective personality traits encompassing rumination, interoception, and suggestibility may be identified as characteristics favouring the elicitation of paradoxical pain experiences. Methods: The dominant hand of 54 healthy volunteers was...

  15. Perceptual and Decisional Factors Influencing the Discrimination of Inversion in the Thatcher Illusion

    Science.gov (United States)

    Cornes, Katherine; Donnelly, Nick; Godwin, Hayward; Wenger, Michael J.

    2011-01-01

    The Thatcher illusion (Thompson, 1980) is considered to be a prototypical illustration of the notion that face perception is dependent on configural processes and representations. We explored this idea by examining the relative contributions of perceptual and decisional processes to the ability of observers to identify the orientation of two…

  16. The predictive power of dividend yields for future inflation: Money illusion or rational causes?

    DEFF Research Database (Denmark)

    Engsted, Tom; Pedersen, Thomas Quistgaard

    In long-term US data the stock market dividend yield is a strong predictor of long-horizon inflation with a negative slope coefficient. This finding is puzzling in light of the traditional Modigliani-Cohn money illusion hypothesis according to which the dividend yield varies positively with expec...

  17. Remembering Makes Evidence Compelling: Retrieval from Memory Can Give Rise to the Illusion of Truth

    Science.gov (United States)

    Ozubko, Jason D.; Fugelsang, Jonathan

    2011-01-01

    The "illusion of truth" is traditionally described as the increase in perceived validity of statements when they are repeated (Hasher, Goldstein, & Toppino, 1977). However, subsequent work has demonstrated that the effect can arise due to the increased familiarity or fluency afforded by repetition and not necessarily to repetition…

  18. Remembering Makes Evidence Compelling: Retrieval from Memory Can Give Rise to the Illusion of Truth

    Science.gov (United States)

    Ozubko, Jason D.; Fugelsang, Jonathan

    2011-01-01

    The "illusion of truth" is traditionally described as the increase in perceived validity of statements when they are repeated (Hasher, Goldstein, & Toppino, 1977). However, subsequent work has demonstrated that the effect can arise due to the increased familiarity or fluency afforded by repetition and not necessarily to repetition…

  19. The criminal profiling illusion : What’s Behind the Smoke and Mirrors?

    NARCIS (Netherlands)

    Snook, Brent; Cullen, Richard M.; Bennell, Craig; Taylor, Paul J.; Gendreau, Paul

    2008-01-01

    There is a belief that criminal profilers can predict a criminal's characteristics from crime scene evidence. In this article, the authors argue that this belief may be an illusion and explain how people may have been misled into believing that criminal profiling (CP) works despite no sound

  20. Assessment of Positive Illusions of the Physical Attractiveness of Romantic Partners

    NARCIS (Netherlands)

    Barelds, D.P.H.; Dijkstra, Pieternel; Koudenburg, N.; Swami, V.

    2011-01-01

    Positive illusions about a partner's physical attractiveness occur when individuals' ratings of their partner's attractiveness are more positive than more objective ratings. Ratings that may serve as a''reality benchmark' include ratings by the partner him/herself and observer ratings. The present

  1. Defining filled and empty space: reassessing the filled space illusion for active touch and vision.

    Science.gov (United States)

    Collier, Elizabeth S; Lawson, Rebecca

    2016-09-01

    In the filled space illusion, an extent filled with gratings is estimated as longer than an equivalent extent that is apparently empty. However, researchers do not seem to have carefully considered the terms filled and empty when describing this illusion. Specifically, for active touch, smooth, solid surfaces have typically been used to represent empty space. Thus, it is not known whether comparing gratings to truly empty space (air) during active exploration by touch elicits the same illusionary effect. In Experiments 1 and 2, gratings were estimated as longer if they were compared to smooth, solid surfaces rather than being compared to truly empty space. Consistent with this, Experiment 3 showed that empty space was perceived as longer than solid surfaces when the two were compared directly. Together these results are consistent with the hypothesis that, for touch, the standard filled space illusion only occurs if gratings are compared to smooth, solid surfaces and that it may reverse if gratings are compared to empty space. Finally, Experiment 4 showed that gratings were estimated as longer than both solid and empty extents in vision, so the direction of the filled space illusion in vision was not affected by the nature of the comparator. These results are discussed in relation to the dual nature of active touch.

  2. Charity donations and the Euro introduction: some quasi-experimental evidence on money illusion

    NARCIS (Netherlands)

    Kooreman, P.; Faber, R.; Hofmans, H.

    2004-01-01

    We compare the revenues of a house-to-house collection for a charity before and after the introduction of the euro in a ceteris paribus setting. We find strong evidence of money illusion, supplementing earlier econometric, experimental, and survey evidence on its existence.

  3. Coolness both underlies and protects against the painfulness of the thermal grill illusion.

    Science.gov (United States)

    Harper, Daniel E; Hollins, Mark

    2014-04-01

    We investigated the contributions of warm and cool signals in generating the thermal grill illusion (TGI), a phenomenon in which interlaced warm and cool bars generate an experience of burning, and under some conditions painful, heat. Each subject underwent 3 runs, 2 of which tested the effects of preadapting subjects to the grill's warm or cool bars (while the interlaced bars were thermally neutral) on the subsequent intensity of the illusion. In a control run, all bars were neutral during the adaptation phase. Thermal visual analogue scale ratings during the warm and cool adaptation periods revealed significant and equivalent adaptation to the 2 temperatures. Adaptation to the grill's cool bars significantly reduced pain and perceived thermal intensity of the TGI, compared to the control condition, while adaptation to the grill's warm bars had little effect. These results suggest that the cool stimulus triggers the pain signals that produce the illusion. The inability of warm adaptation to attenuate the TGI is at odds with theories suggesting that the illusion depends upon a simple addition of warm and cool signals. While the grill's cool bars are necessary for the TGI's painfulness, we also observed that the more often a participant reported feeling coolness or coldness, the less pain he or she experienced from the TGI. These results are consistent with research showing that cool temperatures generate activity in both thermoreceptive-specific, pain-inhibitory neurons and nociceptive dorsal horn neurons.

  4. Factors affecting the haptic filled-space illusion for dynamic touch

    NARCIS (Netherlands)

    Sanders, A.F.J.; Kappers, A.M.L.

    2009-01-01

    In the haptic filled-space illusion for active dynamic touch, observers move their fingertip across an unfilled extent or an extent filled with intermediate stimulations. Previous researchers have reported lengths of filled extents to be overestimated, but the parameters affecting the strength of th

  5. Visual Illusions and the Control of Ball Placement in Goal-Directed Hitting

    Science.gov (United States)

    Caljouw, Simone R.; Van der Kamp, John; Savelsbergh, Geert J. P.

    2010-01-01

    When hitting, kicking, or throwing balls at targets, online control in the target area is impossible. We assumed this lack of late corrections in the target area would induce an effect of a single-winged Muller-Lyer illusion on ball placement. After extensive practice in hitting balls to different landing locations, participants (N = 9) had to hit…

  6. Visual Illusions and the Control of Ball Placement in Goal-Directed Hitting

    NARCIS (Netherlands)

    Caljouw, Simone R.; Van der Kamp, John; Savelsbergh, Geert J. P.

    2010-01-01

    When hitting, kicking, or throwing balls at targets, online control in the target area is impossible We assumed this lack of late corrections in the target area would induce an effect of a single-winged Muller-Lyer illusion on ball placement After extensive practice in hitting balls to different lan

  7. The Vanishing Ball Illusion: A new perspective on the perception of dynamic events.

    Science.gov (United States)

    Kuhn, Gustav; Rensink, Ronald A

    2016-03-01

    Our perceptual experience is largely based on prediction, and as such can be influenced by knowledge of forthcoming events. This susceptibility is commonly exploited by magicians. In the Vanishing Ball Illusion, for example, a magician tosses a ball in the air a few times and then pretends to throw the ball again, whilst secretly concealing it in his hand. Most people claim to see the ball moving upwards and then vanishing, even though it did not leave the magician's hand (Kuhn & Land, 2006; Triplett, 1900). But what exactly can such illusions tell us? We investigated here whether seeing a real action before the pretend one was necessary for the Vanishing Ball Illusion. Participants either saw a real action immediately before the fake one, or only a fake action. Nearly one third of participants experienced the illusion with the fake action alone, while seeing the real action beforehand enhanced this effect even further. Our results therefore suggest that perceptual experience relies both on long-term knowledge of what an action should look like, as well as exemplars from the immediate past. In addition, whilst there was a forward displacement of perceived location in perceptual experience, this was not found for oculomotor responses, consistent with the proposal that two separate systems are involved in visual perception.

  8. Fooling the eyes: the influence of a sound-induced visual motion illusion on eye movements.

    Directory of Open Access Journals (Sweden)

    Alessio Fracasso

    Full Text Available The question of whether perceptual illusions influence eye movements is critical for the long-standing debate regarding the separation between action and perception. To test the role of auditory context on a visual illusion and on eye movements, we took advantage of the fact that the presence of an auditory cue can successfully modulate illusory motion perception of an otherwise static flickering object (sound-induced visual motion effect. We found that illusory motion perception modulated by an auditory context consistently affected saccadic eye movements. Specifically, the landing positions of saccades performed towards flickering static bars in the periphery were biased in the direction of illusory motion. Moreover, the magnitude of this bias was strongly correlated with the effect size of the perceptual illusion. These results show that both an audio-visual and a purely visual illusion can significantly affect visuo-motor behavior. Our findings are consistent with arguments for a tight link between perception and action in localization tasks.

  9. The Illusion of Transparency and Normative Beliefs about Anxiety during Public Speaking

    Science.gov (United States)

    MacInnis, Cara C.; Mackinnon, Sean P.; MacIntyre, Peter D.

    2010-01-01

    Public speakers believe their nervousness is more apparent to others than is actually the case, a phenomenon known as the illusion of transparency. Study 1, in which participants delivered a public speech to an audience, provided evidence of this phenomenon. Despite this, a substantial minority of participants (36%) thought that the audience would…

  10. Holistic Processing of Faces as Measured by the Thatcher Illusion Is Intact in Autism Spectrum Disorders

    Science.gov (United States)

    Cleary, Laura; Brady, Nuala; Fitzgerald, Michael; Gallagher, Louise

    2015-01-01

    Impaired face perception in autism spectrum disorders is thought to reflect a perceptual style characterized by componential rather than configural processing of faces. This study investigated face processing in adolescents with autism spectrum disorders using the Thatcher illusion, a perceptual phenomenon exhibiting "inversion effects"…

  11. Differential Effects of the Rod-and-Frame Illusion on the Timing of Forearm Rotations

    NARCIS (Netherlands)

    Lommertzen, J.; Zuijlen, A.M.J. van; Meulenbroek, R.G.J.; Lier, R.J. van

    2009-01-01

    The present study focused on the time course of the effects of the Rod-and-Frame Illusion (RFI) on the kinematics of targeted forearm rotations. Participants were asked to reproduce perceived rod orientations by propelling a hand-held cylinder forward while rotating it to the target orientation. Rod

  12. The "Illusion of Life" Rhetorical Perspective: An Integrated Approach to the Study of Music as Communication.

    Science.gov (United States)

    Sellnow, Deanna; Sellnow, Timothy

    2001-01-01

    Suggests the "illusion of life" rhetorical perspective increases understanding about how discursive linguistic symbols and non-discursive aesthetic symbols function together to communicate and persuade in didactic music. Argues that lyrics and music work together to offer messages comprised of both conceptual and emotional content through the…

  13. Here's Looking at You: Visual Similarity Exacerbates the Moses Illusion for Semantically Similar Celebrities

    Science.gov (United States)

    Davis, Danielle K.; Abrams, Lise

    2016-01-01

    When people read questions like "How many animals of each kind did Moses take on the ark?", many mistakenly answer "2" despite knowing that Noah sailed the ark. This "Moses illusion" occurs when names share semantic features. Two experiments examined whether shared "visual" concepts (facial features)…

  14. Remembering Makes Evidence Compelling: Retrieval from Memory Can Give Rise to the Illusion of Truth

    Science.gov (United States)

    Ozubko, Jason D.; Fugelsang, Jonathan

    2011-01-01

    The "illusion of truth" is traditionally described as the increase in perceived validity of statements when they are repeated (Hasher, Goldstein, & Toppino, 1977). However, subsequent work has demonstrated that the effect can arise due to the increased familiarity or fluency afforded by repetition and not necessarily to repetition per se. We…

  15. The Roles of Encoding and Retrieval Processes in Associative and Categorical Memory Illusions

    Science.gov (United States)

    Dewhurst, Stephen A.; Bould, Emma; Knott, Lauren M.; Thorley, Craig

    2009-01-01

    Four experiments investigated the origin of associative and categorical memory illusions by comparing the effects of study and test associations on Deese/Roediger-McDermott (DRM) and categorized lists. Experiments 1 and 2 found that levels of false recognition with both list types were increased by manipulations that facilitated the generation of…

  16. The Rubber Hand Illusion Reveals Proprioceptive and Sensorimotor Differences in Autism Spectrum Disorders

    Science.gov (United States)

    Paton, Bryan; Hohwy, Jakob; Enticott, Peter G.

    2012-01-01

    Autism spectrum disorder (ASD) is characterised by differences in unimodal and multimodal sensory and proprioceptive processing, with complex biases towards local over global processing. Many of these elements are implicated in versions of the rubber hand illusion (RHI), which were therefore studied in high-functioning individuals with ASD and a…

  17. Can walking motions improve visually induced rotational self-motion illusions in virtual reality?

    Science.gov (United States)

    Riecke, Bernhard E; Freiberg, Jacob B; Grechkin, Timofey Y

    2015-02-04

    Illusions of self-motion (vection) can provide compelling sensations of moving through virtual environments without the need for complex motion simulators or large tracked physical walking spaces. Here we explore the interaction between biomechanical cues (stepping along a rotating circular treadmill) and visual cues (viewing simulated self-rotation) for providing stationary users a compelling sensation of rotational self-motion (circular vection). When tested individually, biomechanical and visual cues were similarly effective in eliciting self-motion illusions. However, in combination they yielded significantly more intense self-motion illusions. These findings provide the first compelling evidence that walking motions can be used to significantly enhance visually induced rotational self-motion perception in virtual environments (and vice versa) without having to provide for physical self-motion or motion platforms. This is noteworthy, as linear treadmills have been found to actually impair visually induced translational self-motion perception (Ash, Palmisano, Apthorp, & Allison, 2013). Given the predominant focus on linear walking interfaces for virtual-reality locomotion, our findings suggest that investigating circular and curvilinear walking interfaces offers a promising direction for future research and development and can help to enhance self-motion illusions, presence and immersion in virtual-reality systems.

  18. Ice cream illusions - Bowls, spoons, and self-served portion sizes

    NARCIS (Netherlands)

    Wansink, Brian; van Ittersum, Koert; Painter, James E.

    2006-01-01

    Background: Because people eat most of what they serve themselves, any contextual cues that lead them to over-serve should lead them to over-eat. In building on the size-contrast illusion, this research examines whether the size of a bowl or serving spoon unknowingly biases how much a person serves

  19. Enlarged temporal integration window in schizophrenia indicated by the double-flash illusion

    NARCIS (Netherlands)

    Haß, Katharina; Sinke, Christopher; Reese, Tanya; Roy, Mandy; Wiswede, Daniel; Dillo, Wolfgang; Oranje, Bob; Szycik, Gregor R.

    2017-01-01

    Introduction: In the present study we were interested in the processing of audio-visual integration in schizophrenia compared to healthy controls. The amount of sound-induced double-flash illusions served as an indicator of audio-visual integration. We expected an altered integration as well as a

  20. Measurement of eye size illusion caused by eyeliner, mascara, and eye shadow.

    Science.gov (United States)

    Matsushita, Soyogu; Morikawa, Kazunori; Yamanami, Haruna

    2015-01-01

    Do eyeliner, mascara, and eye shadow actually make the eyes appear larger than they really are? If so, by what percentage? To answer these questions, we used psychophysical experiments. Experiment 1 manipulated the degree of eyeliner (four levels) and mascara (five levels), and measured perceived eye size using a psychophysical procedure called the staircase method. The results showed that both eyeliner and mascara make the eyes appear larger than they really are by up to 6% (13% in area), but their effects are not additive. Eyeliner increased perceived eye size only in the absence of mascara. In the presence of mascara, however, eyeliner has no additional effect. Experiment 2 measured perceived eye size with or without eye shadow and demonstrated that eye shadow increases perceived eye size by about 5% (10% in area). These findings indicate that one mechanism by which makeup and cosmetics alter facial appearances involves inducing visual illusions. In addition, it is suggested that the eye size illusion caused by eyeliner, mascara, and eye shadow uses the same mechanism as that of the Delboeuf illusion, a geometric illusion of assimilation.