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visual illusion

Nicholas J Smeeton, Matyas Varga, Joe Causer, A Mark Williams
The ability to disguise and deceive action outcomes was examined by manipulating sports garments. In Experiment 1, those with higher and lower skill levels in anticipation predicted the throw direction of an opponent who wore a garment designed to disguise kinetic-chain information. Higher skill anticipators were more adversely affected by the disguise garment than the lower skill anticipators, demonstrating that disguise removed the anticipation advantage. In Experiment 2, using the same occlusion methodology, the effect of deception was examined using 2 garments designed to create visual illusions of motion across the proximal-to-distal sequence of the thrower's action and compared with a white-garment control...
June 17, 2018: Journal of Sport & Exercise Psychology
Victor J Barranca, George Zhu
The center-surround receptive field structure, ubiquitous in the visual system, is hypothesized to be evolutionarily advantageous in image processing tasks. We address the potential functional benefits and shortcomings of spatial localization and center-surround antagonism in the context of an integrate-and-fire neuronal network model with image-based forcing. Utilizing the sparsity of natural scenes, we derive a compressive-sensing framework for input image reconstruction utilizing evoked neuronal firing rates...
June 13, 2018: Journal of Theoretical Biology
Yoshiyuki Nishio, Kayoko Yokoi, Kazumi Hirayama, Toshiyuki Ishioka, Yoshiyuki Hosokai, Miyeong Gang, Makoto Uchiyama, Toru Baba, Kyoko Suzuki, Atsushi Takeda, Etsuro Mori
OBJECTIVE: To identify the phenomenological features and neural correlates of visual illusions in Parkinson's disease (PD). METHODS: Ninety-three patients with PD were assessed via questionnaires regarding visual illusions and behavioral symptoms, and neuropsychological tests, motor assessments and 18-F fluorodeoxyglucose-positron emission tomography (FDG-PET) were performed. The relationship between visual illusions or hallucinations and regional cerebral glucose metabolism was investigated using partial least squares (PLS) correlation and conventional mass-univariate analyses...
May 28, 2018: Parkinsonism & related Disorders
Maria Ruiz, Alfonso Arias, Ernesto Sánchez-Llanos, Maria Pilar Gil, Ricard López-Ortega, Faridé Dakterzada, Francisco Purroy, Gerard Piñol-Ripoll
BACKGROUND: Hallucinations may have a broad spectrum and include so-called minor hallucinations (MHs). MH includes passage hallucinations (PHs), visual illusions, and presence hallucinations (PrHs). OBJECTIVE: To determine the prevalence and characteristics of MH in Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) patients, and to describe their potential relationship with cognition, behavioral symptoms, and use of psychoactive drugs. METHODS: We have recruited prospectively and consecutively 268 subjects (90 AD mild-moderate drug-naïve patients, 78 aMCI, and 100 controls)...
June 4, 2018: Journal of Alzheimer's Disease: JAD
Bruce Bridgeman, Paul Dassonville, Benjamin D Lester
The visual image provides important cues for an observer's sense of location and orientation within the world. Occasionally, though, these cues can be misleading, resulting in illusions. In the Roelofs and induced Roelofs effects, for example, a large illuminated frame, offset from the observer's midline in otherwise complete darkness, tends to bias the observer's judgment of straight ahead, causing the position of the frame, and anything contained within it, to be misperceived. Studies of these illusions have provided much insight into the processes that establish an observer's egocentric reference frame, and the manner in which object locations are encoded relative to this frame for perception and action...
June 6, 2018: Consciousness and Cognition
Noa Zitron-Emanuel, Tzvi Ganel
Hunger, caused by mild amount of food deprivation, is an everyday physiological state familiar to us all. Ongoing research has pinpointed the way hunger affects peoples' physiological functions as well as their attitudes and allocation of attention toward domain-specific, food-related objects. Yet, little is known about the way food deprivation affects basic perceptual abilities. Here, we utilized size-contrast visual illusions commonly associated with food to explore the way deprivation affects relative processing of food size...
June 6, 2018: Appetite
Laurie Geers, Mauro Pesenti, Michael Andres
How does the eye guide the hand in an ever-changing world? The perception-action model posits that visually-guided actions rely on object size estimates that are computed from an egocentric perspective independently of the visual context. Accordingly, adjusting grip aperture to object size should be resistant to illusions emerging from the contrast between a target and surrounding elements. However, experimental studies gave discrepant results that have remained difficult to explain so far. Visual and proprioceptive information of the acting hand are potential sources of ambiguity in previous studies because the on-line corrections they allow may contribute to masking the illusory effect...
June 5, 2018: Neuropsychologia
Cassandra J Brooks, Yu Man Chan, Andrew J Anderson, Allison M McKendrick
Within each sensory modality, age-related deficits in temporal perception contribute to the difficulties older adults experience when performing everyday tasks. Since perceptual experience is inherently multisensory, older adults also face the added challenge of appropriately integrating or segregating the auditory and visual cues present in our dynamic environment into coherent representations of distinct objects. As such, many studies have investigated how older adults perform when integrating temporal information across audition and vision...
2018: Frontiers in Human Neuroscience
Tyler Bernadyn, Keith A Feigenson
Individuals use data gathering methods to inform judgments and behaviors. Effective interaction with the environment depends on these having high accuracy and low noise, but when they become abnormal, aberrant thoughts and perceptions can occur. In this study, we examined if data gathering methods were consistent across tasks that relied on different cognitive abilities, specifically visual perception and probabilistic reasoning. Thirty-four non-clinical participants engaged in the Ebbinghaus Illusion and the Jumping to Conclusions tasks, while also completing questionnaires concerning aspects of delusion formation...
March 2018: Heliyon
Julian De Freitas, George A Alvarez
To what extent are people's moral judgments susceptible to subtle factors of which they are unaware? Here we show that we can change people's moral judgments outside of their awareness by subtly biasing perceived causality. Specifically, we used subtle visual manipulations to create visual illusions of causality in morally relevant scenarios, and this systematically changed people's moral judgments. After demonstrating the basic effect using simple displays involving an ambiguous car collision that ends up injuring a person (E1), we show that the effect is sensitive on the millisecond timescale to manipulations of task-irrelevant factors that are known to affect perceived causality, including the duration (E2a) and asynchrony (E2b) of specific task-irrelevant contextual factors in the display...
May 28, 2018: Cognition
Sander Wessel Keemink, Clemens Boucsein, Mark C W van Rossum
Neurons in the primary visual cortex respond to oriented stimuli placed in the center of their receptive field, yet their response is modulated by stimuli outside the receptive field (the surround). Classically, this surround modulation is assumed to be strongest if the orientation of the surround stimulus aligns with the neuron's preferred orientation - irrespective of the actual center stimulus. This neuron-dependent surround modulation has been used to explain a wide range of psychophysical phenomena, such as biased tilt perception and saliency of stimuli with contrasting orientation...
May 30, 2018: Journal of Neurophysiology
Tal Makovski
In many daily activities, we need to form and retain temporary representations of an object's size. Typically, such visual short-term memory (VSTM) representations follow perception and are considered reliable. Here, participants were asked to hold in mind a single simple object for a short duration and to reproduce its size by adjusting the length and width of a test probe. Experiment 1 revealed two powerful findings: First, similar to a recently reported perceptual illusion, participants greatly overestimated the size of open objects - ones with missing boundaries - relative to the same-size fully closed objects...
May 29, 2018: Memory & Cognition
Bruno Laeng, Fredrik Svartdal Færevaag, Stine Tanggaard, Stephen von Tetzchner
Previous studies indicate that individuals with autism spectrum disorder (ASD) do not experience optical illusions in the same manner as individuals with typical development. This study uses pupillary responses as an objective measure of perception of visual illusions, with the hypothesis that adults with ASD will show weaker pupillary constrictions to the illusions than adults without ASD. An eye-tracker was used to investigate the spontaneous pupillary changes to brightness illusions in adults diagnosed with ASD ( N  = 11) and in a control group ( N  = 24)...
May 2018: I-Perception
Stephen Palmisano, Bernhard E Riecke
Typically it takes up to 10 seconds or more to induce a visual illusion of self-motion ("vection"). However, for this vection to be most useful in virtual reality and vehicle simulation, it needs to be induced quickly, if not immediately. This study examined whether vection onset latency could be reduced towards zero using visual display manipulations alone. In the main experiments, visual self-motion simulations were presented to observers via either a large external display or a head-mounted display (HMD)...
2018: PloS One
Lynn Shi, Linus D Sun, Jeffrey G Odel
Purpose: Since its report in one patient more than 70 years ago, digitalis-induced colored muscae volitantes have not surfaced again in the literature. We report here a case of digoxin induced colored floaters. Observations: An 89-year-old man on 0.25 mg digoxin daily developed visual hallucinations and colored floaters. He had floaters in the past but now they were in various colors including yellow, green, blue and red, though predominantly in yellow. These "weirdly" shaped little particles wiggled around as if in a viscous solution and casted shadows in his vision...
June 2018: American Journal of Ophthalmology Case Reports
Vilayanur Ramachandran, Chaipat Chunharas, Zeve Marcus, Timothy Furnish, Albert Lin
AL's leg was amputated resulting in phantom-limb pain (PLP). (1) When a volunteer placed her foot on or near the phantom - touching it evoked organized sensations in corresponding locations on AL's phantom. (2) Mirror-visual-feedback (MVF) relieved PLP, as did, "phantom massage". (3) Psilocybin-MVF pairing produced synergistic effects, complete elimination of PLP, and reduction in paroxysmal episodes. (4) Touching the volunteer's leg where AL previously had external fixators, evoked sensation of nails boring through the leg...
April 2018: Neurocase
Sofia Lavrenteva, Ikuya Murakami
In the retinal image of the natural world, edges and shapes can be defined by first-order attributes, such as luminance, and second-order attributes, such as contrast and texture. Previous studies have suggested that, in the human visual system, these attributes are initially detected separately and integrated later. Thus, comparing the strength of different geometrical optical illusions in stimuli, in which different elements are defined by the same or different attributes, is helpful to investigate at which stage the underlying mechanism of the illusion is located...
May 11, 2018: Vision Research
Jessica L Parker, Christopher W Robinson
The study examined individual contributions of visual and auditory information on multisensory integration across the life span. In the experiment, children, young adults, and older adults participated in a variant of the Sound-Induced Flash Illusion where participants had to either ignore beeps and report how many flashes they saw or ignore flashes and report how many beeps they heard. Collapsed across age, auditory input had a stronger effect on visual processing than vice versa. However, relative contributions of auditory and visual information interacted with age, with young adults showing evidence of auditory dominance (only auditory input affected visual processing), whereas, multisensory integration effects were more symmetrical in children and older adults...
May 2018: Psychology and Aging
Alberta Ipser, Maayan Karlinski, Elliot D Freeman
Sight and sound are out of synch in different people by different amounts for different tasks. But surprisingly, different concurrent measures of perceptual asynchrony correlate negatively (Freeman et al., 2013). Thus, if vision subjectively leads audition in one individual, the same individual might show a visual lag in other measures of audiovisual integration (e.g., McGurk illusion, Stream-Bounce illusion). This curious negative correlation was first observed between explicit temporal order judgments and implicit phoneme identification tasks, performed concurrently as a dual task, using incongruent McGurk stimuli...
May 7, 2018: Journal of Experimental Psychology. Human Perception and Performance
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