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perceptual illusion

Michael Kometer, Franz X Vollenweider
Serotonergic hallucinogens, such as lysergic acid diethylamide (LSD), psilocybin, and N,N-dimethyltryptamine (DMT), are famous for their capacity to temporally and profoundly alter an individual's visual experiences. These visual alterations show consistent attributes despite large inter- and intra-individual variances. Many reports document a common perception of colors as more saturated, with increased brightness and contrast in the environment ("Visual Intensifications"). Environmental objects might be altered in size ("Visual illusions") or take on a modified and special meaning for the subject ("Altered self-reference")...
November 30, 2016: Current Topics in Behavioral Neurosciences
Woong Choi, Liang Li, Satoru Satoh, Kozaburo Hachimura
Improving the sense of immersion is one of the core issues in virtual reality. Perceptual illusions of ownership can be perceived over a virtual body in a multisensory virtual reality environment. Rubber Hand and Virtual Hand Illusions showed that body ownership can be manipulated by applying suitable visual and tactile stimulation. In this study, we investigate the effects of multisensory integration in the Virtual Hand Illusion with active movement. A virtual xylophone playing system which can interactively provide synchronous visual, tactile, and auditory stimulation was constructed...
2016: BioMed Research International
Pablo R Grassi, Natalia Zaretskaya, Andreas Bartels
A growing body of literature suggests that feedback modulation of early visual processing is ubiquitous and central to cortical computation. In particular stimuli with high-level content that invariably activate ventral object responsive regions have been shown to suppress early visual cortex. This suppression was typically interpreted in the framework of predictive coding and feedback from ventral regions. Here we examined early visual modulation during perception of a bistable Gestalt illusion that has previously been shown to be mediated by dorsal parietal cortex rather than by ventral regions that were not activated...
November 12, 2016: NeuroImage
Toyomi Matsuno, Masaki Tomonaga
Extracting a cause-and-effect structure from the physical world is an important demand for animals living in dynamically changing environments. Human perceptual and cognitive mechanisms are known to be sensitive and tuned to detect and interpret such causal structures. In contrast to rigorous investigations of human causal perception, the phylogenetic roots of this perception are not well understood. In the present study, we aimed to investigate the susceptibility of nonhuman animals to mechanical causality by testing whether chimpanzees perceived an illusion called causal capture (Scholl & Nakayama, 2002)...
November 8, 2016: Cognition
Christian Agrillo, Audrey E Parrish, Michael J Beran
The Solitaire illusion occurs when the spatial arrangement of items influences the subjective estimation of their quantity. Unlike other illusory phenomena frequently reported in humans and often also in non-human animals, evidence of the Solitaire illusion in species other than humans remains weak. However, before concluding that this perceptual bias affects quantity judgments differently in human and non-human animals, further investigations on the strength of the Solitaire illusion is required. To date, no study has assessed the exact misperception of numerosity generated by the Solitaire arrangement, and the possibility exists that the numerical effects generated by the illusion are too subtle to be detected by non-human animals...
2016: Frontiers in Psychology
Na Sang, Lijie Zhang, Lei Hao, Yongchao Wang, Xiaogang Wang, Fan Zhang, Hui Huang, Xin Hou, Yu Mao, Taiyong Bi, Jiang Qiu
Bistable perception is a type of subjective perception that spontaneously alternates between two perceptual interpretations of an ambiguous sensory input. Past functional magnetic resonance imaging (fMRI) studies have examined the activation patterns underlying bistable perception, yet the variability between individuals in the alternations is not well understood. Therefore, voxel-based morphometry (VBM) was introduced in this study to correlate the GM of the sensory cortex with the alternations of Rubin face-vase illusion in a large group of young adults...
October 31, 2016: Neuroscience Letters
Jiehui Qian, Yury Petrov
Perceptual constancy refers to the ability to stabilize the representation of an object even though the retinal image of the object undergoes variations. In previous studies, we proposed a General Object Constancy (GOC) hypothesis to demonstrate a common stabilization mechanism for perception of an object's features, such as size, contrast and depth, as the perceived distance varies. In the present study, we report another depth illusion supporting the GOC model. The stimuli comprised pairs of disks moving in a pattern of radial optic flow...
December 2016: Vision Research
Shunsuke Aoki, Akitoshi Kawano, Masahiko Terao, Ikuya Murakami
Although it is known that a moving stimulus appears to dilate in duration compared to a stationary stimulus, whether subjective motion devoid of stimulus motion is sufficient remains unknown. To elucidate this, we used a motion illusion in which an actually static stimulus clearly appears to move, a useful dissociation between actual and subjective motions. We used the jitter aftereffect resulting from adaptation to dynamic noise as such a tool and measured subjective durations of a static random-dot pattern in which illusory jitter was seen, an actually oscillating pattern mimicking the illusory jitter, and a static pattern without illusory jitter...
November 1, 2016: Journal of Vision
Anahita H Mehta, Ifat Yasin, Andrew J Oxenham, Shihab Shamma
In a complex acoustic environment, acoustic cues and attention interact in the formation of streams within the auditory scene. In this study, a variant of the "octave illusion" [Deutsch (1974). Nature 251, 307-309] was used to investigate the neural correlates of auditory streaming, and to elucidate the effects of attention on the interaction between sequential and concurrent sound segregation in humans. By directing subjects' attention to different frequencies and ears, it was possible to elicit several different illusory percepts with the identical stimulus...
October 2016: Journal of the Acoustical Society of America
Francesca Ferri, Marcello Costantini
No abstract text is available yet for this article.
2016: Frontiers in Human Neuroscience
Alessandro Soranzo, Michelle Newberry
This paper discusses how the 'Uncatchable Smile' illusion in Leonardo da Vinci's La Bella Principessa portrait was discovered. Kemp and Cotte(1) described the expression of the Princess as ambiguous and "subtle to an inexpressible degree". A combination of three methods was used (inter-observation, structured interviews, and psychophysical experiments) to identify what may underlie this 'ambiguity'. The inter-observation and the structured interview methods were firstly applied to generate experimental hypotheses that were successively tested by a series of psychophysical experiments...
October 4, 2016: Journal of Visualized Experiments: JoVE
Kyriaki Mikellidou, André D Gouws, Hannah Clawson, Peter Thompson, Antony B Morland, Bruce D Keefe
We use the simple, but prominent Helmholtz's squares illusion in which a vertically striped square appears wider than a horizontally striped square of identical physical dimensions to determine whether functional magnetic resonance imaging (fMRI) BOLD responses in V1 underpin illusions of size. We report that these simple stimuli which differ in only one parameter, orientation, to which V1 neurons are highly selective elicited activity in V1 that followed their physical, not perceived size. To further probe the role of V1 in the illusion and investigate plausible extrastriate visual areas responsible for eliciting the Helmholtz squares illusion, we performed a follow-up transcranial magnetic stimulation (TMS) experiment in which we compared perceptual judgments about the aspect ratio of perceptually identical Helmholtz squares when no TMS was applied against selective stimulation of V1, LO1, or LO2...
September 2016: I-Perception
Catherine Preston, H Henrik Ehrsson
In today's Western society, concerns regarding body size and negative feelings toward one's body are all too common. However, little is known about the neural mechanisms underlying negative feelings toward the body and how they relate to body perception and eating-disorder pathology. Here, we used multisensory illusions to elicit illusory ownership of obese and slim bodies during functional magnetic resonance imaging. The results implicate the anterior insula and the anterior cingulate cortex in the development of negative feelings toward the body through functional interactions with the posterior parietal cortex, which mediates perceived obesity...
October 12, 2016: Cerebral Cortex
Daniel J King, Joanne Hodgekins, Philippe A Chouinard, Virginie-Anne Chouinard, Irene Sperandio
Specific abnormalities of vision in schizophrenia have been observed to affect high-level and some low-level integration mechanisms, suggesting that people with schizophrenia may experience anomalies across different stages in the visual system affecting either early or late processing or both. Here, we review the research into visual illusion perception in schizophrenia and the issues which previous research has faced. One general finding that emerged from the literature is that those with schizophrenia are mostly immune to the effects of high-level illusory displays, but this effect is not consistent across all low-level illusions...
October 11, 2016: Psychonomic Bulletin & Review
Anouk J de Brouwer, Jeroen B J Smeets, Myrthe A Plaisier
The perception of object properties, such as size and weight, can be subject to illusions. Could a visual size illusion influence perceived weight? Here, we tested whether the size-weight illusion occurs when lifting two physically identical but perceptually different objects, by using an illusion of size. Participants judged the weight and length of 11 to 17 cm brass bars with equal density to which cardboard arrowheads were attached to create a Müller-Lyer illusion. We found that these stimuli induced an illusion in which the bar that was visually perceived as being shorter was also perceived as feeling heavier...
September 2016: I-Perception
Claus-Christian Carbon
The folded paper-size illusion is as easy to demonstrate as it is powerful in generating insights into perceptual processing: First take two A4 sheets of paper, one original sized, another halved by folding, then compare them in terms of area size by centering the halved sheet on the center of the original one! We perceive the larger sheet as far less than double (i.e., 100%) the size of the small one, typically only being about two thirds larger-this illusion is preserved by rotating the inner sheet and even by aligning it to one or two sides, but is dissolved by aligning both sheets to three sides, here documented by 88 participants' data...
July 2016: I-Perception
Solaiman Shokur, Simone Gallo, Renan C Moioli, Ana Rita C Donati, Edgard Morya, Hannes Bleuler, Miguel A L Nicolelis
Spinal cord injuries disrupt bidirectional communication between the patient's brain and body. Here, we demonstrate a new approach for reproducing lower limb somatosensory feedback in paraplegics by remapping missing leg/foot tactile sensations onto the skin of patients' forearms. A portable haptic display was tested in eight patients in a setup where the lower limbs were simulated using immersive virtual reality (VR). For six out of eight patients, the haptic display induced the realistic illusion of walking on three different types of floor surfaces: beach sand, a paved street or grass...
2016: Scientific Reports
Jan B Deręgowski, Benjamin W Tatler
Monocular depth cues can lead not only to illusory depth in two-dimensional patterns but also to perspective reversals in three-dimensional objects. When a viewer perceptually inverts (reverses) a three-dimensional object, stimuli on the inner surfaces of that object also invert. However, the perceptual fate of anything occurring within the space that is enclosed by the walls of a perceptually reversible object is unknown. In the present study, perceptions of the relative vertical heights of stimuli within a truncated pyramidal chute were compared for stimuli placed laterally, on the inner surface of the chute, or centrally, suspended within the volume enclosed by the chute...
September 10, 2016: Perception
Nicholaus P Brosowsky, Todd A Mondor
Whereas visual demonstrations of multistability are ubiquitous, there are few auditory examples. The purpose of the current study was to determine whether simultaneously presented melodies, such as underlie the scale illusion [Deutsch (1975). J. Acoust. Soc. Am. 57(5), 1156-1160], can elicit multiple mutually exclusive percepts, and whether reported perceptions are mediated by musical expertise. Participants listened to target melodies and reported whether the target was embedded in subsequent test melodies...
August 2016: Journal of the Acoustical Society of America
M E Jacobsen, M Barros, R S Maior
The Müller-Lyer's illusion (MLI) is a visual illusion in which the presence of contextual cues (i.e., the orientation of arrowheads) changes the perception of the length of straight lines. An altered sensitivity to the MLI has been proposed as a marker for the progression of perceptual deficits in schizophrenia. Since dizocilpine (MK-801), a noncompetitive antagonist of the NMDA glutamate receptor, induces schizophrenic-like sensory impairments, it may have potential value for investigating the neurochemical basis of the perceptual changes in schizophrenia...
January 1, 2017: Behavioural Brain Research
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