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Perception Sep 2023A novel geometrical optical illusion is reported in this article: the horizontal distances of the contextual structures distort the perceived vertical positions of...
A novel geometrical optical illusion is reported in this article: the horizontal distances of the contextual structures distort the perceived vertical positions of observed objects. Specifically, the illusion manifests in the form of connected boxes of varying widths but equal heights, each containing a circle at the center. Despite identical vertical positioning of the circles, they appear misaligned. The illusion diminishes when the boxes are removed. Potential underlying mechanisms are discussed.
Topics: Humans; Orientation; Optical Illusions
PubMed: 37427447
DOI: 10.1177/03010066231186557 -
Journal of Vision Aug 2020We recently found only weak correlations between the susceptibility to various visual illusions. However, we observed strong correlations among different variants of an...
We recently found only weak correlations between the susceptibility to various visual illusions. However, we observed strong correlations among different variants of an illusion, suggesting that the visual space of illusions includes several illusion-specific factors. Here, we specifically examined how factors for the vertical-horizontal, Müller-Lyer, and Ponzo illusions relate to each other. We measured the susceptibility to each illusion separately and to combinations of two illusions, which we refer to as a merged illusion; for example, we tested the Müller-Lyer illusion and the vertical-horizontal illusion, as well as a merged version of both illusions. We used an adjustment procedure in two experiments with 306 and 98 participants, respectively. Using path analyses, correlations, and exploratory factor analyses, we found that the susceptibility to a merged illusion is well predicted from the susceptibilities to the individual illusions. We suggest that there are illusion-specific factors that, by independent combinations, represent the whole visual structure underlying illusions.
Topics: Adult; Female; Humans; Illusions; Male; Optical Illusions; Visual Perception; Young Adult
PubMed: 32766743
DOI: 10.1167/jov.20.8.12 -
Vision Research Nov 2014The 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... (Review)
Review
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.
Topics: Humans; Optical Illusions; Pattern Recognition, Visual; Psychophysics; Schizophrenia; Visual Cortex; Visual Perception
PubMed: 24995379
DOI: 10.1016/j.visres.2014.06.009 -
Saudi Journal of Gastroenterology :... 2019
Topics: Colonic Polyps; Endoscopy; Humans; Image Enhancement; Optical Illusions
PubMed: 30900612
DOI: 10.4103/sjg.SJG_159_19 -
Philosophical Transactions of the Royal... Aug 1997Following Hermann von Helmholtz, who described visual perceptions as unconscious inferences from sensory data and knowledge derived from the past, perceptions are... (Review)
Review
Following Hermann von Helmholtz, who described visual perceptions as unconscious inferences from sensory data and knowledge derived from the past, perceptions are regarded as similar to predictive hypotheses of science, but are psychologically projected into external space and accepted as our most immediate reality. There are increasing discrepancies between perceptions and conceptions with science's advances, which makes it hard to define 'illusion'. Visual illusions can provide evidence of object knowledge and working rules for vision, but only when the phenomena are explained and classified. A tentative classification is presented, in terms of appearances and kinds of causes. The large contribution of knowledge from the past for vision raises the issue: how do we recognize the present, without confusion from the past. This danger is generally avoided as the present is signalled by real-time sensory inputs-perhaps flagged by qualia of consciousness.
Topics: Cognition; Consciousness; Humans; Optical Illusions; Visual Perception
PubMed: 9304679
DOI: 10.1098/rstb.1997.0095 -
Perception 2003
Topics: Animals; Attention; Cognition; Delusions; Humans; Optical Illusions; Psychophysics; Rotation; Visual Perception
PubMed: 12729377
DOI: 10.1068/p3203ed -
Journal of Vision May 2014In 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...
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.
Topics: Adult; Computer Simulation; Form Perception; Humans; Light; Motion Perception; Optical Illusions; Pattern Recognition, Visual; Young Adult
PubMed: 24784030
DOI: 10.1167/14.5.1 -
Perception 2000
Topics: Humans; Optical Illusions; Perception; Semantics
PubMed: 11220206
DOI: 10.1068/p2910ed -
Proceedings. Biological Sciences Aug 2011Procedures for three-dimensional image reconstruction that are based on the optical and neural apparatus of human stereoscopic vision have to be designed to work in... (Review)
Review
Procedures for three-dimensional image reconstruction that are based on the optical and neural apparatus of human stereoscopic vision have to be designed to work in conjunction with it. The principal methods of implementing stereo displays are described. Properties of the human visual system are outlined as they relate to depth discrimination capabilities and achieving optimal performance in stereo tasks. The concept of depth rendition is introduced to define the change in the parameters of three-dimensional configurations for cases in which the physical disposition of the stereo camera with respect to the viewed object differs from that of the observer's eyes.
Topics: Depth Perception; Humans; Imaging, Three-Dimensional; Optical Illusions; Vision Tests
PubMed: 21490023
DOI: 10.1098/rspb.2010.2777 -
Perception 2009
Topics: Depth Perception; History, 19th Century; Humans; Optical Illusions; Paintings; Vision Disparity
PubMed: 19662939
DOI: 10.1068/p3805ed