Subjective Contour: Apparent Depth or Simultaneous Brightness Contrast?

Brigner, Willard L.; Gallagher, Maria

doi:10.2466/pms.1974.38.3c.1047

Cited by 91 publications

(43 citation statements)

References 10 publications

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“…There are no examples of illusory contours induction collinear to thin lines, as would be required for contour formation in the first two examples of Figure 14, although there have been examples ofcollinear lines in noninductive roles, such as the short line anchors employed by Minguzzi (1987). If one considers collinear lines as extremely thin edges, it appears that the thickness of the inducer (in the direction perpendicular to the support region) plays an important role in illusory contour formation, as has been supported by several parametric investigations (Brigner & Gallagher, 1974;Purghe, 1991;Sambin, 1981). Purghe (1991) found contour strength to be an increasing function ofthis inducer thickness.…”

Section: Low-level Determinantsmentioning

confidence: 80%

“…The most noticeable of illusory contour characteristics in such common figures as Kanizsa's and Ehren-LESHER stein's, illusory brightness received a great deal ofearly attention and was often invoked as the causal factor in illusory contour formation, as opposed to a consequence of illusory figure formation. Indeed, researchers have demonstrated a high degree ofcorrelation between simultaneous brightness contrast and illusory brightening in edgeinduced illusory figures (Brigner & Gallagher, 1974;Dresp, 1992;Dresp, Lorenceau, & Bonnet, 1990), although brightness contrast alone is insufficient to explain the phenomenon (Coren & Theodor, 1975;Frisby & Clatworthy, 1975).…”

Section: Characteristics Of Illusory Figuresmentioning

confidence: 99%

“…Coren (1972) claimed that perceived differences in depth drove illusory contour formation and thus determined brightness and clarity. Others claimed that brightness drove the formation and thus determined depth and clarity (Brigner & Gallagher, 1974;Brussel et aI., 1977;Frisby & Clatworthy, 1975). Cognitivists and Gestaltists made the claim that boundaries were formed first, followed by depth and brightness (Gregory, 1972;Kanizsa, 1955;Rock & Anson, 1979).…”

Section: Characteristics Of Illusory Figuresmentioning

confidence: 99%

“…Ultimately, the actual perception ofillusory contours is not only a cognitive process, but doubtless a process that also manifests itself in lower level neural representations. Brigner and Gallagher (1974) first examined the link between conventional brightness contrast and illusory contour brightness and strength. Recent studies have shown that the degree of illusory darkening in a Kanizsa square with light-on-dark inducing elements is proportional to the degree ofconventional brightness contrast in similar control stimuli (which do not result in illusory figures) under variations of spatial and luminance characteristics of the inducing elements (Dresp, 1992;Dresp et aI., 1990).…”

Section: Cognitive Theoriesmentioning

confidence: 99%

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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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Section: Low-level Determinantsmentioning

confidence: 80%

Section: Characteristics Of Illusory Figuresmentioning

confidence: 99%

Section: Characteristics Of Illusory Figuresmentioning

confidence: 99%

Section: Cognitive Theoriesmentioning

confidence: 99%

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Illusory contours: Toward a neurally based perceptual theory

Lesher

1995

Psychon Bull Rev

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“…Although these theories account for the perception of an apparent border, they do not directly address the apparent increase in brightness of the subjectively bounded figure. A second theoretical approach proposes neural explanations of the perceived brightness difference between the subjective figure and its background. Brigner andGallagher (1974) andlory andDay (1979) suggest that lateral inhibitory mechanisms can account for the difference in brightness and offer a simultaneous brightness-contrast explanation of the phenomenon. Brigner and Gallagher also emphasize the importance of the interior angle of the inducing elements; lory and Day also discuss assimilation and end-of-line contrast.…”

mentioning

confidence: 99%