The effects of perceptual set on the shape and apparent depth of subjective contours

Coren, Stanley; Porac, Clare; Theodor, Leonard H.

doi:10.3758/bf03202999

Cited by 17 publications

(8 citation statements)

References 42 publications

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“…When the white form was referred to as "figure," the result was 20 drawings of a circular outline, 2 of a square, and 4 amorphous outlines by 51 subjects; when it was referred to as a circle, the result was 39 circular outlines from the 58 subjects; and when it was called a square, the result was 5 circular and 20 square outlines from 52 subjects. Coren et al (1986) found these results "consistent with cognitive explanations of subjective-contour formation" and compatible with several theoretical positions: Subjective contours may be "a form of problem solving, ... a form of Gestalt closure," or arise from a "reorganization of the configuration on the basis of implicit depth cues" (p. 332). Our experiments, on the other hand, support the view that subjective figures are manifestations of memorial representations coming into play and being part of the form process.…”

Section: Summary and Discussionsupporting

confidence: 71%

“…Coren, Porac, and Theodor (1986) published two experiments that demonstrated the effectiveness of set. Their Experiment 2 demonstrated a general set produced by prior exposure to subjective-eontour-inducing patterns.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…This is comparable to the general set that operated in our Experiment 1, in which subjects were first made acquainted with a subjective-contour-producing pattern and were under instruction to report subjective contours when they saw them. Coren et al 's (1986) Experiment 1 is more relevant to this discussion. Their test figure consisted of four thin lines forming an upright cross with a gap where the crossing point would have been.…”

Section: Summary and Discussionmentioning

confidence: 99%

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The role of memory in perceiving subjective contours

Wallach

Slaughter

1988

Perception & Psychophysics

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Section: Summary and Discussionsupporting

confidence: 71%

Section: Summary and Discussionmentioning

confidence: 99%

Section: Summary and Discussionmentioning

confidence: 99%

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The role of memory in perceiving subjective contours

Wallach

Slaughter

1988

Perception & Psychophysics

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“…In both edge and line-end induced contours, completion in the form of a smooth curve is apparently preferred to completion with curvature discontinuities (Gregory, 1972;Shipley & Kellman, I992a). However, in rare cases, illusory contours with unsupported corners or discontinuities may be observed (Coren, Porac, & Theodor, 1986). For example, some observers report a square illusory figure in the Ehrenstein stimulus of Figure 2b, rather than a circle.…”

Section: Low-level Determinantsmentioning

confidence: 99%

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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“…Thus, it should be pointed out that although this view is accepted by many investigators of subjective contours (see Coren, Porac, & Theodor, 1986;Parks, 1984;and Pritchard & Warm, 1983, for recent examples of this position), it is not universal. Some investigators, most notably Becker and Knopp (1978), Ginsburg (1975), and Smith and Over (1975, 1976, 1977, have argued that subjective contours are based on peripheral, physiological mechanisms.…”

mentioning

confidence: 98%

Illusion decrement and transfer of illusion decrement in real- and subjective-contour Poggendorff figures

Beckett

1989

Perception & Psychophysics

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The reduction in illusion magnitude with visual inspection and the transfer of such illusion decrement to a noninspected figure were examined in real-and subjective-contour Poggendorff figures. For both types of figures, illusion magnitude decreased significantly, and in a similar manner, during a 5-min inspection period. Postinspection tests showed that inspecting either a real-or subjective-contour figure resulted in a reduction in illusion magnitude for the other, noninspected figure. These findings suggest that real-and subjective-contour Poggendorfffigures share a similar global organization and are thus probably processed in a similar manner. These characteristics make subjective-contour figures a useful tool for separating illusion-producing mechanisms into structural and strategy components.

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The effects of perceptual set on the shape and apparent depth of subjective contours

Cited by 17 publications

References 42 publications

The role of memory in perceiving subjective contours

The role of memory in perceiving subjective contours

Illusory contours: Toward a neurally based perceptual theory

Illusion decrement and transfer of illusion decrement in real- and subjective-contour Poggendorff figures

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