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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 -
Journal of Experimental Psychology.... Feb 2024The Ponzo illusion is a famous optical illusion that is not well understood so far. Here we suggest that its origin is closely linked to distribution of spatial...
The Ponzo illusion is a famous optical illusion that is not well understood so far. Here we suggest that its origin is closely linked to distribution of spatial attention. In essence, it arises because the size of the attentional field varies between different parts of the stimulus layout, which comes with different spatial resolution and, as a consequence, different apparent sizes of the objects in the stimulus display. We report four experiments (conducted in 2022 and 2023), which support this approach. The illusion substantially decreases when the stimulus layout is modified so that the size of the supposed attentional field is equalized for the crucial parts (Experiment 1). Moreover, we induce a Ponzo-like illusion by means of attentional cues only (Experiment 2). The perceived spatial frequency differs for different parts of the stimulus layout consistent with predicted changes in spatial resolution (Experiment 3). Attentional cuing exerts an analogous influence on the apparent spatial frequency (Experiment 4). The presented approach provides a novel look at the origin of the Ponzo illusion and related phenomena. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
Topics: Humans; Optical Illusions; Cues
PubMed: 38376934
DOI: 10.1037/xhp0001171 -
Perception 2015This paper is about the Poggendorff illusion in pictorial artworks. In particular, it deals with the role played by the Poggendorff illusion in the making of the...
This paper is about the Poggendorff illusion in pictorial artworks. In particular, it deals with the role played by the Poggendorff illusion in the making of the geometrical misalignments in the mosaic known as Lunetta di San Lorenzo in Ravenna (Italy) and in Rubens's oil on panel Descent from the Cross in Antwerp (Belgium). Three experiments are presented. Experiment 1 tested the role of viewing distance in perceived collinearity in the mosaic by asking participants to adjust two ends of a cross in silhouette renderings of the saint projected so to mimic its original size. Results confirm an effect of viewing distance and support the hypothesis that the author of the mosaic became aware of the illusion and attempted to 'fix' it. Experiment 2 aimed at verifying perceived collinearity in a book-size version of Rubens's Descentfrom the Cross by employing a similar adjustment method. Results demonstrate that the Poggendorff illusion affects perceived collinearity in the painting, but perceptual collinearity does not agree with the actual geometrical misalignment in book-size reproductions of the masterpiece. Experiment 3 tested the role of viewing distance in a classic Poggendorff illusion configuration by employing the same setup as in experiment 1. Contrary to what was found in experiment 1, viewing distance did not modulate the magnitude of the illusion in the classic display, suggesting that the outcome of perceived collinearity is sensitive to the complexity of the visual scene. The difference in results between experiments 1 and 3 underscore the necessity of new tests before any reasonable conclusion can be drawn about the whys and wherefores of Rubens's misalignment.
Topics: Adult; Female; Humans; Male; Optical Illusions; Pattern Recognition, Visual; Space Perception
PubMed: 26492724
DOI: 10.1068/p7788 -
Vision Research Dec 2019Perception of local properties of the visual field is influenced by aftereffects of adaptation. The tilt aftereffect describes repulsion of the perceived orientation of...
Perception of local properties of the visual field is influenced by aftereffects of adaptation. The tilt aftereffect describes repulsion of the perceived orientation of a line from the orientation of an adapting line. Analogous effects of spatial context are often called illusions. Repulsion of the perceived orientation of a grating from the orientation of a surrounding grating is referred to as the tilt illusion. In the same manner, the size aftereffect and Ebbinghaus illusion form a complementary pair of temporal and spatial context effects of size. Here we report psychophysical evidence for a previously unknown aspect-ratio illusion which causes the perceived aspect-ratio of a rectangle to be repelled from the aspect-ratio of rectangles surrounding it. This illusion provides a spatial analogue to the aspect-ratio aftereffect.
Topics: Form Perception; Humans; Optical Illusions; Orientation, Spatial; Photic Stimulation; Psychophysics; Visual Fields
PubMed: 31678618
DOI: 10.1016/j.visres.2019.10.003 -
Brain and Nerve = Shinkei Kenkyu No... Nov 2021An optical illusion represents a perception that deviates from the actual visual information of the visualized scene and is considered to be generated by an error in... (Review)
Review
An optical illusion represents a perception that deviates from the actual visual information of the visualized scene and is considered to be generated by an error in visual processing in the brain. The mechanisms by which optical illusions are generated have attracted the interest of scientists for many years. In this review, I focus on a vertebrate model, the zebrafish, and discuss how research using zebrafish has uncovered the mechanisms underlying optical illusions, and how optical illusions serve as a tool to help us understand how normal visual processing works in the brain.
Topics: Animals; Brain; Illusions; Motion Perception; Optical Illusions; Visual Perception; Zebrafish
PubMed: 34759061
DOI: 10.11477/mf.1416201923 -
Acta Neurobiologiae Experimentalis 2009The filled/empty illusion (Oppel-Kundt) is one of the oldest geometrical-optical illusions, but the determinants of the illusion are not yet sufficiently understood. We...
The filled/empty illusion (Oppel-Kundt) is one of the oldest geometrical-optical illusions, but the determinants of the illusion are not yet sufficiently understood. We studied magnitude of the illusory effect as a function of the height of vertical strokes subdividing a spatial extension of fixed length, using the psychophysical standard-variable matching paradigm. For vertical strokes shorter than, or of the same height as strokes delimiting the standard, the length was over-reproduced consistently with earlier studies of the illusion. However, for vertical strokes three times longer than the delimiters, the illusory effect paradoxically decreased, and attained negative values in two of six subjects. The magnitude of the effect thus depends on the patterning of the space between the delimiters, not merely on the number of subdividing elements.
Topics: Adult; Female; Form Perception; Humans; Male; Optical Illusions; Photic Stimulation; Psychophysics; Reaction Time; Space Perception; Young Adult
PubMed: 20048771
DOI: 10.55782/ane-2009-1765 -
Journal of Experimental Psychology.... Apr 2022A Müller-Lyer figure consists only of a line and arrowheads located at both ends of the line. Many comparative studies have reported that animals perceive Müller-Lyer...
A Müller-Lyer figure consists only of a line and arrowheads located at both ends of the line. Many comparative studies have reported that animals perceive Müller-Lyer illusion as humans, but few have used appropriate experimental designs to verify whether animal subjects actually respond to line length alone. The present study investigated whether budgerigars (Melopsittacus undulatus) can perceive the Müller-Lyer illusion by using a method that addresses this problem. Four budgerigars were trained to select a long or short line (counterbalanced across subjects) from two horizontal lines. Next, the same task was conducted using two lines, one of which was situated between arrowheads pointing either right (>>) or left (<<). In the final training phase, the arrowheads were replaced with those pointing inward (><) or outward (<>). The performance of each subject toward each stimulus set of these trainings suggested that they did not determine the length of the line by including the arrowheads. In the test phase, response tendencies to the four figures were compared. Results suggested that budgerigars perceive the Müller-Lyer illusion in the same direction as humans; however, its magnitude is larger than that of humans. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Topics: Animals; Humans; Melopsittacus; Optical Illusions
PubMed: 35533105
DOI: 10.1037/xan0000321 -
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 -
Canadian Journal of Surgery. Journal... Apr 2021
Topics: Cholecystectomy; Cholecystectomy, Laparoscopic; Humans; Length of Stay; Optical Illusions
PubMed: 33829741
DOI: 10.1503/cjs.2164209 -
Perception Sep 2018The new "eyes wide shut" illusion uses a standard enlarging (shaving or makeup) mirror. Close one eye and look at the closed eye in the mirror; the eye should take up...
The new "eyes wide shut" illusion uses a standard enlarging (shaving or makeup) mirror. Close one eye and look at the closed eye in the mirror; the eye should take up most of the mirror. Switch eyes to see the other closed eye. Switch back-and-forth a few times, then open both eyes. You see an open eye. Which eye is it? To find out, close one eye. Whichever you close, that's the eye you see. How can this be possible? The brain is fusing two images of the two eyes! The illusion depends on (a) binocular fusion: The brain combines two images to a single percept; (b) symmetry: Mirrors don't affect appearance of left-right symmetric objects and the eyes are sufficiently left-right symmetric for the brain to combine them. Why aren't the lingering asymmetries sufficient to prevent fusion? (c) Only vision with scrutiny affords conscious access to scene details. Consistent with reverse hierarchy theory, vision at a glance grants conscious perception of the gist of the scene, integrating images of nonperfectly symmetric eyes.
Topics: Adult; Eye; Humans; Optical Illusions; Vision, Binocular; Vision, Monocular; Visual Perception
PubMed: 30001678
DOI: 10.1177/0301006618786863