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Journal of Vision Jun 2020Vision scientists have attempted to classify visual illusions according to certain aspects, such as brightness or spatial features. For example, Piaget proposed that...
Vision scientists have attempted to classify visual illusions according to certain aspects, such as brightness or spatial features. For example, Piaget proposed that visual illusion magnitudes either decrease or increase with age. Subsequently, it was suggested that illusions are segregated according to their context: real-world contexts enhance and abstract contexts inhibit illusion magnitudes with age. We tested the effects of context on the Müller-Lyer and Ponzo illusions with a standard condition (no additional context), a line-drawing perspective condition, and a real-world perspective condition. A mixed-effects model analysis, based on data from 76 observers with ages ranging from 6 to 66 years, did not reveal any significant interaction between context and age. Although we found strong intra-illusion correlations for both illusions, we found only weak inter-illusion correlations, suggesting that the structure underlying these two spatial illusions includes several specific factors.
Topics: Adolescent; Adult; Aged; Child; Ependymoglial Cells; Female; Humans; Illusions; Individuality; Male; Middle Aged; Optical Illusions; Young Adult
PubMed: 32511665
DOI: 10.1167/jov.20.6.4 -
Vision Research Jan 2009There is evidence that global visual context affects orientation perception in later stages of processing than local context. We measured the relative time courses of... (Randomized Controlled Trial)
Randomized Controlled Trial
There is evidence that global visual context affects orientation perception in later stages of processing than local context. We measured the relative time courses of two orientation illusions: The Tilt Illusion (TI) involves dense gratings in close proximity; the Rod and Frame Illusion (RFI) involves a solitary bar surrounded by a distant frame. We also varied whether the context was flashed briefly (Experiment 1) or remained visible (Experiment 2). Results showed that the TI (but not the RFI) occurs when the context is briefly flashed in advance of the test, that both illusions are strongest when the context and inducer appear simultaneously, and that the RFI frame must be visible for at least 800 ms to induce an illusion with asynchronous displays. Experiment 3 confirmed these patterns held for measures of illusion magnitude and discriminability. Results are consistent with an earlier effect of local spatial context and a later effect of global spatial context on orientation perception.
Topics: Adolescent; Adult; Cues; Discrimination, Psychological; Female; Form Perception; Humans; Male; Optical Illusions; Orientation; Psychophysics; Time Factors; Young Adult
PubMed: 18926844
DOI: 10.1016/j.visres.2008.09.020 -
Current Biology : CB Apr 2001It is well known that visual illusions can have a dramatic effect upon our visual perception of such properties as an object's size. It remains the subject of much... (Review)
Review
It is well known that visual illusions can have a dramatic effect upon our visual perception of such properties as an object's size. It remains the subject of much debate, however, whether visual illusions have a similar influence on visually guided actions. Recent studies have thrown new light on this debate.
Topics: Humans; Optical Illusions; Psychomotor Performance; Vision, Ocular; Visual Perception
PubMed: 11369219
DOI: 10.1016/s0960-9822(01)00170-1 -
Journal of Neurophysiology Nov 1950
Topics: Optical Illusions; Retina; Vision, Ocular
PubMed: 14784865
DOI: 10.1152/jn.1950.13.6.413 -
Acta Neurobiologiae Experimentalis 2012Subjective estimates of lengths or areas in the visual field depend on the visual contents of the estimated space (filled/empty or Oppel-Kundt illusion). We studied the...
Subjective estimates of lengths or areas in the visual field depend on the visual contents of the estimated space (filled/empty or Oppel-Kundt illusion). We studied the dependence of this phenomenon on the presentation mode (white on black vs. black on white background), and on the figure/ground contrast. We found, as expected, overestimation of the filled part of the figure for both contrast polarities. The expansion effect was found to be an increasing function of the absolute luminance contrast, and was consistently higher for the negative (luminant figures on a dark background) than for the positive polarity. The contrast factor contributes from one-fifth to one-third of the total effect. Possible interpretations in terms of known sensory phenomena (irradiation, lateral interactions) or higher, integrative functions are discussed.
Topics: Adolescent; Adult; Contrast Sensitivity; Female; Humans; Male; Optical Illusions; Photic Stimulation; Visual Fields; Young Adult
PubMed: 23377271
DOI: 10.55782/ane-2012-1912 -
Vision Research Jan 1996Two line gratings abutting each other with a phase shift of half a cycle elicit the perception of an illusory line running orthogonally between the two sets of grating... (Comparative Study)
Comparative Study
Two line gratings abutting each other with a phase shift of half a cycle elicit the perception of an illusory line running orthogonally between the two sets of grating lines. We found that rating strength increases with increasing number of lines, line length, and phase angle. In contrast, rating strength decreases with increasing spacing of lines, lateral misalignment, rotation of one grating relative to the other, and line width. There is a pronounced oblique effect at 45 deg when the orientation of the abutting gratings is changed from horizontal through diagonal to vertical. Findings are interpreted in terms of a neurophysiological model. We conclude that the end-stopped receptive fields activated by the grating lines are about 6 deg long and 2 deg wide. On the other hand, the "response fields" of the cells, integrating orthogonally across line ends, are assumed to be 5 deg long and less than 1 deg wide. The psychophysical data compare favorably with available neurophysiological data in Area V2 of the macaque suggesting that the perception of illusory contours in human observers may be based on cortical cell properties similar to those found in the monkey.
Topics: Animals; Contrast Sensitivity; Haplorhini; Humans; Models, Biological; Optical Illusions; Pattern Recognition, Visual; Psychophysics; Rotation
PubMed: 8746248
DOI: 10.1016/0042-6989(95)00107-b -
Canadian Journal of Surgery. Journal... Jan 2021We sought to determine if lateral-inferior traction on the Hartmann pouch could produce bile duct kinking and subsequent misinterpretation of the space on the left side...
We sought to determine if lateral-inferior traction on the Hartmann pouch could produce bile duct kinking and subsequent misinterpretation of the space on the left side of the bile duct as the hepatobiliary triangle. Once traction was applied, we measured the angle between the cystic duct and inferior gallbladder wall hepatobiliary triangle) in 76 cases, and the angle between the common bile duct and common hepatic duct (porta hepatis "triangle") in 41 cases. The mean angles were significantly different (hepatobiliary triangle mean 68.2°, standard deviation [SD] 16.0°, range 23-109°; porta hepatis "triangle" mean 112.0°, SD 18.4°, range 72-170°; p < 0.01). The ranges, however, overlapped in 26 cases. In many cases, lateral-inferior traction on the Hartmann pouch produced substantial kinking of the bile duct that could easily elicit the illusion that it is the hepatobiliary triangle rather than the centre of the porta hepatis.
Topics: Bile Ducts; Biliary Tract Surgical Procedures; Humans; Intraoperative Complications; Optical Illusions
PubMed: 33411998
DOI: 10.1503/cjs.014019 -
Journal of Vision Dec 2016In this study, we report a new visual shape illusion, the eggs illusion, in which circular disks located at the midpoints between adjacent grid intersections are...
In this study, we report a new visual shape illusion, the eggs illusion, in which circular disks located at the midpoints between adjacent grid intersections are perceived as being deformed to ellipses. In Experiment 1, we examined the eggs illusion by using a matching method and found that grid luminance and patch size play a critical role in producing the illusory deformation. In Experiment 2, we employed several types of elliptic or circular patches to examine the conditions in which the illusory deformation was cancelled or weakened. We observed that the illusory deformation was dependent on local grid orientation. Based on these results, we found several common features between the eggs illusion and the scintillating grid illusion. This resemblance suggests a possibility that similar mechanisms underlie the two phenomena. In addition to the scintillating grid illusion, we also considered several known perceptual phenomena that might be related to the eggs illusion, i.e., the apparent size illusion, the shape-contrast effect, and the Orbison illusion. Finally, we discuss the role of orientation processing in generating the eggs illusion.
Topics: Adult; Female; Form Perception; Humans; Male; Optical Illusions; Orientation; Pattern Recognition, Visual
PubMed: 28006076
DOI: 10.1167/16.15.27 -
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 Dec 2016Perceptual constancy refers to the ability to stabilize the representation of an object even though the retinal image of the object undergoes variations. In previous...
Perceptual constancy refers to the ability to stabilize the representation of an object even though the retinal image of the object undergoes variations. In previous studies, we proposed a General Object Constancy (GOC) hypothesis to demonstrate a common stabilization mechanism for perception of an object's features, such as size, contrast and depth, as the perceived distance varies. In the present study, we report another depth illusion supporting the GOC model. The stimuli comprised pairs of disks moving in a pattern of radial optic flow. Each pair consisted of a white disk positioned upper left to a dark disk, creating a percept of the white disk casting a shadow. As the pairs contracted towards the center of the screen in accordance with motion away from the observer, the two disks in each pair appeared to increase in contrast and separate farther away from each other both in the fronto-parallel plane (angular separation illusion) and in depth (depth separation illusion). While the contrast illusion and the angular separation illusion, which is a variant of the size illusion, replicated our previous findings, the illusion of depth separation revealed a depth constancy phenomenon. We further confirmed that the size and depth perception were related, e.g., the depth separation and the angular separation illusions were highly correlated across observers. Whereas the illusory increase in the angular separation between a disk and its 'shadow' could not be canceled by modulation of depth, decreasing the angular separation could offset the illusory increase in depth separation. The results can be explained by the GOC hypothesis: the visual system uses the same scaling factor to account for contrast, size (angular separation), and depth variations with distance; additionally, the perceived size of the object is used to scale its depth and contrast signals in order to achieve constancy.
Topics: Adult; Awareness; Depth Perception; Distance Perception; Female; Humans; Male; Models, Theoretical; Optic Flow; Optical Illusions; Photic Stimulation; Size Perception
PubMed: 27810350
DOI: 10.1016/j.visres.2016.09.015