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visual illusion

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
Tina Gupta, Steven M Silverstein, Jessica A Bernard, Brian P Keane, Thomas V Papathomas, Andrea Pelletier-Baldelli, Derek J Dean, Raeana E Newberry, Ivanka Ristanovic, Vijay A Mittal
Patients with psychosis exhibit a reduced susceptibility to depth inversion illusions (DII) in which a physically concave surface is perceived as convex (e.g., the hollow mask illusion). Here, we examined the extent to which lessened susceptibility to DII characterized youth at ultra high risk (UHR) for psychosis. In this study, 44 UHR participants and 29 healthy controls judged the apparent convexity of face-like human masks, two of which were concave and the other convex. One of the concave masks was painted with realistic texture to enhance the illusion; the other was shown without such texture...
2016: NeuroImage: Clinical
Elisha E Simpson, N Justin Marshall, Karen L Cheney
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...
October 17, 2016: Scientific Reports
Anne R Reuter, J Malte Bumb, Juliane K Mueller, Cathrin Rohleder, Franziska Pahlisch, Franziska Hanke, Elisabeth Arens, F Markus Leweke, Dagmar Koethe, Emanuel Schwarz
Objectives Binocular depth inversion illusion (BDII) represents an illusion of visual perception that involves higher-order visual and cognitive processes. Its impairment has been linked to psychotic conditions and identified as a marker for at risk mental states. The endogenous cannabinoid system (ECS) is involved in various neurophysiological processes. One of its key components, anandamide, is involved in the pathophysiology of schizophrenia. Little is known about its impact on BDII alterations. Therefore, we explored associations between BDII and anandamide levels...
October 13, 2016: World Journal of Biological Psychiatry
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
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
Dan Parker, Colin Phillips
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...
October 6, 2016: Cognition
Guohua Liang, Guomin Qian, Ye Wang, Zige Yi, Xiaolei Ru, Wei Ye
To determine which graphic and color combination for a three-dimensional visual illusion speed reduction marking present the best visual stimulus, five parameters were designed. According to the Balanced Incomplete Blocks-Law of Comparative Judgment, three schemes, which produce strong stereoscopic impressions, were screened from the twenty-five initial design schemes of different combinations of graphics and colors. Three-dimensional experimental simulation scenes of the three screened schemes were created to evaluate four different effects according to a semantic analysis...
October 10, 2016: International Journal of Occupational Safety and Ergonomics: JOSE
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
Björn van der Hoort, H Henrik Ehrsson
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 advantage of recent developments in body representation research...
October 6, 2016: Scientific Reports
Tess Armstrong, Matthew Rockloff, Nancy Greer, Phillip Donaldson
Automated gambling products are now a common feature on many casino floors. Despite their increasing prevalence, little research has considered the impact of converting games traditionally free from technological enhancements to automated versions. This review seeks to illustrate how automation is likely to change the way people engage and experience traditional games based around five prominent modifications: visual and auditory enhancements; illusions of control; cognitive complexity; expedited play; and social customisation...
October 4, 2016: Journal of Gambling Studies
Mihail I Todorov, Katalin A Kékesi, Zsolt Borhegyi, Robert Galambos, Gábor Juhász, Anthony G Hudetz
Long-range gamma band EEG oscillations mediate information transmission between distant brain regions. Gamma band-based coupling may not be restricted to cortex-to-cortex communication but may include extracortical parts of the visual system. The retinogram and visual event-related evoked potentials exhibit time-locked, forward propagating oscillations that are candidates of gamma oscillatory coupling between the retina and the visual cortex. In this study, we tested if this gamma coupling is present as indicated by the coherence of gamma-range (70-200 Hz) oscillatory potentials (OPs) recorded simultaneously from the retina and the primary visual cortex in freely moving, adult rats...
October 2016: Physiological Reports
Stefano Mastandrea, John M Kennedy
A new everyday visual size illusion is presented-the Pot/Lid illusion. Observers choose an unduly large lid for a pot. We ask whether the optic slant of the pot brim would increase its apparent size or if vision underestimates the size of tilted lids.
September 2016: I-Perception
Shinji Nakamura, Stephen Palmisano, Juno Kim
Adding simulated viewpoint jitter or oscillation to displays enhances visually induced illusions of self-motion (vection). The cause of this enhancement is yet to be fully understood. Here, we conducted psychophysical experiments to investigate the effects of different types of simulated oscillation on vertical vection. Observers viewed horizontally oscillating and nonoscillating optic flow fields simulating downward self-motion through an aperture. The aperture was visually simulated to be nearer to the observer and was stationary or oscillating in-phase or counter-phase to the direction of background horizontal oscillations of optic flow...
July 2016: I-Perception
Valter Prpic, Riccardo Luccio
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...
October 3, 2016: Perception
Christian Ryan, Martina Stafford, Robert James King
Faces are one of the most socially significant visual stimuli encountered in the environment, whereas pareidolias are illusions of faces arising from ambiguous stimuli in the environment. Autism spectrum disorder (ASD) is characterised by deficits in response to social stimuli. We found that children with ASD (n = 60) identify significantly fewer pareidolic faces in a sequence of ambiguous stimuli than typically developing peers. The two groups did not differ in the number of objects identified, indicating that the children with ASD had a specific lack of attention to faces...
September 30, 2016: Journal of Autism and Developmental Disorders
Laura Aymerich-Franch, Damien Petit, Gowrishankar Ganesh, Abderrahmane Kheddar
Whole-body embodiment studies have shown that synchronized multi-sensory cues can trick a healthy human mind to perceive self-location outside the bodily borders, producing an illusion that resembles an out-of-body experience (OBE). But can a healthy mind also perceive the sense of self in more than one body at the same time? To answer this question, we created a novel artificial reduplication of one's body using a humanoid robot embodiment system. We first enabled individuals to embody the humanoid robot by providing them with audio-visual feedback and control of the robot head movements and walk, and then explored the self-location and self-identification perceived by them when they observed themselves through the embodied robot...
September 27, 2016: Consciousness and Cognition
Jasper H Fabius, Alessio Fracasso, Stefan Van der Stigchel
As the neural representation of visual information is initially coded in retinotopic coordinates, eye movements (saccades) pose a major problem for visual stability. If no visual information were maintained across saccades, retinotopic representations would have to be rebuilt after each saccade. It is currently strongly debated what kind of information (if any at all) is accumulated across saccades, and when this information becomes available after a saccade. Here, we use a motion illusion to examine the accumulation of visual information across saccades...
September 30, 2016: Scientific Reports
Brian L Day, Timothy Muller, Joanna Offord, Irene Di Giulio
KEY POINTS: When standing, the gain of the body-movement response to a sinusoidally moving visual scene has been shown to get smaller with faster stimuli, possibly through changes in the apportioning of visual flow to self-motion or environment motion. We investigated whether visual-flow speed similarly influences the postural response to a discrete, unidirectional rotation of the visual scene in the frontal plane. Contrary to expectation, the evoked postural response consisted of two sequential components with opposite relationships to visual motion speed...
October 1, 2016: Journal of Physiology
Jessie Barbin, Vanessa Seetha, Jean-Marie Casillas, Jean Paysant, Dominic Perennou
OBJECTIVE: Phantom limb pain (PLP) is a major problem after limb amputation. Mirror therapy (MT) is a non-pharmacological treatment using representations of movement, the efficacy of which in reducing PLP remains to be clarified. Here, we present the first systematic review on MT efficacy in phantom limb pain (PLP) and phantom limb movement (PLM) in amputees (lower or upper limb). MATERIAL/PATIENTS AND METHODS: A search on MEDLINE, COCHRANE DATABASE and EMBASE, crossing the key words "phantom limb" and "mirror therapy" found studies which were read and analyzed according the PRISMA statement...
September 2016: Annals of Physical and Rehabilitation Medicine
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