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Experimental Brain Research Mar 2001This research investigated the effects of an orientation illusion on action, as well as the ability of the motor system to adapt to the illusion. Subjects reached out...
This research investigated the effects of an orientation illusion on action, as well as the ability of the motor system to adapt to the illusion. Subjects reached out and picked up a small bar placed at various orientations. A background grating was used to induce an orientation illusion. When the direction of the illusion was reversed, the following seven trials revealed a large illusion effect in the early portion of the reach. In the subsequent seven trials, no effect of the illusion was present. This pattern of adaptation was similar to the pattern often obtained with displacing prisms, suggesting that the two types of visual distortions present the motor system with similar challenges that it meets in similar ways. These findings are consistent with a planning/control model that argues for separate visual representations underlying the planning and on-line control of reaching.
Topics: Adaptation, Physiological; Adolescent; Adult; Arm; Brain; Humans; Movement; Neuropsychological Tests; Optical Illusions; Orientation; Psychomotor Performance; Space Perception; Visual Pathways
PubMed: 11315556
DOI: 10.1007/s002210000651 -
Experimental Psychology Jul 2023An object appears to move at higher speed than another equally fast object when brief nonspatial tones coincide with its changes in motion direction. We refer to this...
An object appears to move at higher speed than another equally fast object when brief nonspatial tones coincide with its changes in motion direction. We refer to this phenomenon as the beep-speed illusion (Meyerhoff et al., 2022, , , 104978). The origin of this illusion is unclear; however, attentional explanations and potential biases in the response behavior appear to be plausible candidates. In this report, we test a simple bias explanation that emerges from the way the dependent variable is assessed. As the participants have to indicate the faster of the two objects, participants possibly always indicate the audio-visually synchronized object in situations of perceptual uncertainty. Such a response behavior potentially could explain the observed shift in perceived speed. We therefore probed the magnitude of the beep-speed illusion when the participants indicated either the object that appeared to move faster or the object that appeared to move slower. If a simple selection bias would explain the beep-speed illusion, the response pattern should be inverted with the instruction to indicate the slower object. However, contrary to this bias hypothesis, illusion emerged indistinguishably under both instructions. Therefore, simple selection biases cannot explain the beep-speed illusion.
Topics: Humans; Illusions; Optical Illusions; Selection Bias; Motion Perception; Attention; Cognition
PubMed: 38105748
DOI: 10.1027/1618-3169/a000594 -
Bio Systems 2016The Kanizsa triangle, wherein three Pac-Man configurations symmetrically face inwards, is a well-known illusion. By exposing foraging ants (Lasius niger) to...
The Kanizsa triangle, wherein three Pac-Man configurations symmetrically face inwards, is a well-known illusion. By exposing foraging ants (Lasius niger) to Kanizsa-shaped honeydew solutions, we studied the origin of this illusion. More specifically, we examined whether foraging ants showed different movement reactions to local honeydew patterns formed by nestmates. This novel phenomenon could serve as an abstract model of the Kanizsa triangle illusion under the assumption that such an illusion could arise through the sum of each agent's limited global cognitions, because each agent could not perceive the entire subjective contours. Even a subjective consciousness consists of some parts which have no identical perception and could be an illusion. We succeeded in inducing foragers to move along the sides of a Kanizsa triangle when Pac-Man-shaped inducers were introduced. Furthermore, foragers appeared to form Y-shaped trajectories when dot-shaped or inverse Kanizsa inducers were used. Based on our findings, we propose an agent-based ant model that compares modelled behaviour with experimental phenomena. Our abstract model could be used to explain such cognitive phenomena for bottom-up processes, because ants cannot perceive the given subjective contours, instead simply move along the edges.
Topics: Algorithms; Animals; Ants; Feeding Behavior; Locomotion; Male; Models, Biological; Optical Illusions; Pattern Recognition, Visual; Photic Stimulation
PubMed: 26930477
DOI: 10.1016/j.biosystems.2016.02.003 -
Journal of Vision Nov 2017In the classic tilt illusion, the perceived orientation of a center patch is shifted away from its oriented context. Additionally, a stronger illusion effect is yielded...
In the classic tilt illusion, the perceived orientation of a center patch is shifted away from its oriented context. Additionally, a stronger illusion effect is yielded when the center patch is simultaneously rather than asynchronously presented with a constant context for a shorter duration. However, little is known about the temporal characteristic of the tilt illusion in a reverse situation in which a constant center patch is presented throughout while the contexts change. Therefore, we continuously alternated two opposite-oriented contexts and manipulated alternate speeds to examine how the tilt illusion would build up as a function of dynamic contextual alternation. Our results revealed that dynamic alternations between leftward- and rightward-oriented contexts caused a static vertical grating at the center to apparently sway from side to side. More importantly, the apparent sway illusion was modulated by the alternate speed of the oriented contexts (up to 8-10 Hz); the quicker the alternation is, the faster and weaker the apparent sway is. Intriguingly, the temporal characteristic of the "dynamic tilt illusion" suggests that, under a varying environment, the suppressions from temporally adjacent surrounds would be chunked into discrete epochs before affecting our percept.
Topics: Adult; Female; Humans; Male; Optical Illusions; Orientation; Perceptual Distortion; Photic Stimulation; Time Factors; Young Adult
PubMed: 29094146
DOI: 10.1167/17.13.1 -
Vision Research Apr 1997Disk-shaped luminance increments were added to the intersections of a Hermann grid consisting of medium grey bars on a black background. Illusory spots, darker than the...
Disk-shaped luminance increments were added to the intersections of a Hermann grid consisting of medium grey bars on a black background. Illusory spots, darker than the background, were perceived as flashing within the white disks with each flick of the eye. This striking phenomenon may be referred to as the scintillating grid illusion. We determined the conditions necessary for cancelling the Hermann grid illusion, as well as the luminance requirements and the size ratio between disks and bars that elicits the scintillation effect. The fact that scanning eye movements are necessary to produce the scintillation effect sets it apart from the Hermann grid illusion.
Topics: Eye Movements; Female; Humans; Lighting; Male; Neural Inhibition; Optical Illusions; Pattern Recognition, Visual; Photometry
PubMed: 9196721
DOI: 10.1016/s0042-6989(96)00255-6 -
Cortex; a Journal Devoted To the Study... Dec 2015Optical illusions have broadened our understanding of the brain's role in visual perception. A modern day optical illusion emerged from a posted photo of a striped...
Optical illusions have broadened our understanding of the brain's role in visual perception. A modern day optical illusion emerged from a posted photo of a striped dress, which some perceived as white and gold and others as blue and black. Here we show, using functional magnetic resonance imaging (fMRI), that those who perceive The Dress as white/gold have higher activation in response to the image of The Dress in brain regions critically involved in higher cognition (frontal and parietal brain areas). These results are consistent with theories of top-down modulation and present a neural signature associated with the differences in perceiving The Dress as white/gold or blue/black. Furthermore the results support recent psychophysiological data on this phenomenon and provide a fundamental building block to study interindividual differences in visual processing.
Topics: Adult; Brain; Brain Mapping; Cognition; Female; Humans; Magnetic Resonance Imaging; Male; Nerve Net; Optical Illusions; Visual Perception
PubMed: 26478963
DOI: 10.1016/j.cortex.2015.08.017 -
Tijdschrift Voor Psychiatrie 2020The name Maurits Escher is inextricably linked with the notion of 'optical illusion', a type of illusion evoked by his 'impossible figures'. Despite the sober style in...
The name Maurits Escher is inextricably linked with the notion of 'optical illusion', a type of illusion evoked by his 'impossible figures'. Despite the sober style in which he realised these figures, they go on to mesmerise generations of art lovers. It is unclear what causes this, and whether other factors than aesthetic ones are involved.
AIM: To gain insight into the genesis of optical illusions in Escher's work, and in the role of the perceptual system in that process.
METHOD: An explorative literature search in PubMed, Science.gov, Google Scholar, and the historical literature.
RESULTS: Since 'impossible figures' cannot be found in our natural environment, and therefore have a high novelty factor to the brain, they inevitably draw our attention. The reason that we remain captivated, is at least partly associated with the fact that the hippocampus and parahippocampal place area come into conflict with each other, and (in vain) accept the challenge to find a 'best fit'.
CONCLUSION: Fundamental research may benefit from Escher's 'impossible figures' to fathom the rules of our visual grammar. The optical illusions they evoke moreover constitute an ongoing source of inspiration for other artists, architects, and film makers.Topics: Art; Humans; Illusions; Male; Optical Illusions
PubMed: 32484566
DOI: No ID Found -
Vision Research 1985The orientation of a grating may be misperceived when that grating appears superimposed within one-dimensional visual noise of a different orientation. An adjustment...
The orientation of a grating may be misperceived when that grating appears superimposed within one-dimensional visual noise of a different orientation. An adjustment procedure was employed to measure the size of this tilt illusion and its dependence on noise orientation. The illusion is maximum when the noise and test differ by 20 to 40 deg, depending on the spatial frequency of the test grating. Noise composed of spatial frequencies several octaves removed from the test spatial frequency can still cause illusory tilt, although the degree of tilt under these conditions depends on test spatial frequency. This orientation illusion, like the tilt aftereffect, simultaneous tilt illusion and angle expansion illusion, may reflect inhibitory interactions between orientation selective neurons in human vision.
Topics: Female; Form Perception; Humans; Illusions; Male; Neural Inhibition; Optical Illusions; Pattern Recognition, Visual; Rotation
PubMed: 4090281
DOI: 10.1016/0042-6989(85)90225-1 -
Reviews in the Neurosciences 2008The perceptual deficit hypothesis for schizophrenia is based on more general models of normal human visual perception, which have traditionally postulated that objects... (Review)
Review
The perceptual deficit hypothesis for schizophrenia is based on more general models of normal human visual perception, which have traditionally postulated that objects must compete for attention and processing space in the visual system. Recent evidence suggests that susceptibility of schizophrenics to the Müller-Lyer (ML) illusion may be a marker of vulnerability, detectable in prodromic patients, but disappearing with the progression of the illness. This illusion consists of overestimating the length of a straight line with converging arrowheads at the ends, while underestimating those with diverging arrowheads. Although the ML illusion has been shown to occur in touch as well as vision, it is not known whether abnormal contextual suppression extends to other sensory modalities in schizophrenics. Another challenge consists in verifying whether different visual parameters of the illusion which favor the magnocellular and parvocellular systems would have diverse ML illusion effects in schizophrenia. In this review we present data showing the degree of illusion in capuchin monkeys (Cebus spp.), a possible animal model for schizophrenia. To this end, a computer program was developed to conduct experiments in humans and non-human primates, allowing the display of illusory figures, manipulation of the stimuli's exposure time, interval between stimuli and number of trials. In the non-primate experiments, the visual illusion test based on achromatic ML illusion figures indicated the presence of the ML illusory effect in 10 capuchin monkeys. These results suggest that Cebus might be a good model for the experimental study of schizophrenia.
Topics: Animals; Humans; Optical Illusions; Pattern Recognition, Visual; Schizophrenia
PubMed: 18751517
DOI: 10.1515/revneuro.2008.19.2-3.91 -
Plastic and Reconstructive Surgery Jan 1965
Topics: Ear Deformities, Acquired; Ear, External; Hand Deformities; Illusions; Optical Illusions; Plastic Surgery Procedures; Rhinoplasty; Surgery, Plastic
PubMed: 14231385
DOI: 10.1097/00006534-196501000-00011