The Bourdon illusion in subjective contours

Walker, James T.; Shank, Matthew D.

doi:10.3758/bf03211509

Cited by 14 publications

(49 citation statements)

References 24 publications

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“…Rozvany and Day (1980) showed that the Bourdon illusion is markedly weaker in outline figures than in solid figures of the same dimensions. This observation was confirmed by both Walker and Shank (1987) and Wenderoth and O'Connor (1987a). The illusion in Figure 3C is again clearly visible-the two aligned edges apparently point in different directions.…”

Section: Discussionsupporting

confidence: 56%

“…The tangent points would have to be averaged for the direction (or profile) of an edge to be evident. The point of interest is that these "pointaveraged" edges appear to produce the same illusory effects as real edges and, as Walker and Shank (1987, 1988a, 1988b have shown, as illusory edges. If the perception of a particular edge derives from an averaging of points that delineate it, the illusion described here conceivably arises because points along adjacent edges are included in the averaging process.…”

Section: Discussionmentioning

confidence: 92%

“…The Bourdon illusion has been investigated in greater detail by Walker and Shank (1987, 1988a, 1988b and Wenderoth and O'Connor (1986, 1987a, 1987b. The former showed that it occurs more strongly when the figure is delineated by illusory contours and that the bent edge of the figure (DBE in Figure 1) appears to be straighter than it is.…”

mentioning

confidence: 99%

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The bourdon illusion occurs with straight-, right-angle-, and parallel-edge figures

Day

Mitchell

Stecher

1990

Perception & Psychophysics

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Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 92%

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The bourdon illusion occurs with straight-, right-angle-, and parallel-edge figures

Day

Mitchell

Stecher

1990

Perception & Psychophysics

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“…A number of researchers have employed illusory contour versions of classical illusions involving impaired estimations of orientations. It appears that illusory contours facilitate the Bourdon illusion (Walker & Shank, 1987, 1988a, 1988bWenderoth, Criss, & van der Zwan, 1990) but slightly decrease the effect of the Poggendorff illusion (Day, Dickinson, & lory, 1977;Goldstein & Weintraub, 1972;Meyer & Garges, 1979). General equivalence in orientation estimation is a strong, though not unequivocal, argument for early representation of illusory contours, Time course studies.…”

Section: Psychophysical Similarities Between Real and Illusory Contoursmentioning

confidence: 98%

Illusory contours: Toward a neurally based perceptual theory

Lesher

1995

Psychon Bull Rev

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Although illusory contours were first described nearly a century ago, researchers have only recently begun to approach a consensus on the processes underlying their formation. Neurophysiological and psychophysical evidence indicate that neural mechanisms of the early visual cortex subserve illusory contour generation, although cognitive factors play important roles in determining the fmal percept. I summarize experiments concerning the determinants of illusory contour strength and form, concentrating on findings particularly relevant to modeling. After establishing arguments for the early generation of illusory contours, I provide an overview of formation theories, culminating with descriptions of neural models. The constraints that experimental data place on models are outlined, and neural models are evaluated with respect to these constraints. Throughout the review,I indicate where further experimental and modeling research are critical.Schumann introduced the first illusory contour, depicted in Figure 1a, in 1900, noting that a central "white rectangle with sharply defined contours appears, which objectively are not there." Schumann had discovered and noted two salient features of illusory figures: sharp edges in regions of homogeneous luminance, and a brightening within the figure. Perhaps because this stimulus failed to yield particularly convincing illusory contours, it was not until more than 50 years later that illusory contours became a topic for activeresearch. Although Ehrenstein (1941) demonstrated stimuli with salient illusory contours, it is remarkable that he failed to note their existence in the text of his article explicitly, commenting instead only on illusory brightening effects. Kanizsa's (1955) stunning figures, examples of which are depicted in Figures Iband 1c, produced extremely sharp, salient contours along with obvious brightening, initiating a wave of research.Although there have been a number ofexcellent illusory contour review papers Meyer & Petry, 1987;Parks, 1984), research advances in the psychophysical, neurophysiological, and modeling domains have been more than sufficient to mandate a new summary ofthe literature. Inthis review, I will not only present more recent data, but also employ an approach to the summaries that is markedly different from those previously taken. At the time of the earlier reviews, determination of the locus of formation of illusory contours was the central issue in illusory contour research, a fact reflected in the structure of the review papers. Experimental results were presented primarily in the historical context of supporting or refut-I would like to thank Ennio Mmgolla of Boston University for generously providing many helpful comments and suggestions during the development ofthis review.

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“…Under most conditions, the colinear test contours, A and B in Figure IG, appear displaced toward the bent induction contours (C and D). In addition, the objectively bent induction contours appear displaced-partially unbent-in the direction of the colinear test edges (Walker & Shank, 1987).…”

mentioning

confidence: 99%

Interactions between real and subjective contours in the Bourdon illusion

Walker

Shank

1988

Perception & Psychophysics

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The Bourdon illusion is a contour-attraction effect in which two colinear test edges of a plane figure appear displaced toward a bent induction edge located nearby. This illusion and related effects are stronger in subjective contours than in real contours. In Bourdon figures combining both varieties of contours, real induction contours produced a strong illusion in subjective test contours, but subjective induction contours produced no illusion in real test contours. Thus, interactions between real and subjective contours were asymmetrical. Luminance contrast between real and subjective contours weakened the Bourdon illusion.

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The Bourdon illusion in subjective contours

Cited by 14 publications

References 24 publications

The bourdon illusion occurs with straight-, right-angle-, and parallel-edge figures

The bourdon illusion occurs with straight-, right-angle-, and parallel-edge figures

Illusory contours: Toward a neurally based perceptual theory

Interactions between real and subjective contours in the Bourdon illusion

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