Parallel discrimination of subjective contours defined by offset gratings

Gurnsey, Rick; Humphrey, G. Keith; Kapitan, Paula

doi:10.3758/bf03209144

Cited by 52 publications

(54 citation statements)

References 44 publications

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“…High denotative regions were both more likely to be obtained as figure and more likely to be maintained as figure when the stimuli were upright rather than inverted. Subjective contours supported the operation ofprefigural recognition processes just as real contours did, which was expected, given the evidence that subjective contours are constructed early in visual processing (e.g., Gurnsey et al, 1992;.…”

Section: Resultsmentioning

confidence: 86%

“…Heydt, 1989; von der Heydt, Peterhans, & Baumgartner, 1984) found that a substantial proportion of cells in monkey V2 responded with short latencies to subjective contours as well as to real contours. In addition, behavioral evidence suggests that subjective contours produce some ofthe same consequences as real contours do--for example, tilt aftereffects (Paradiso, Shimojo, & Nakayama, 1989;Smith & Over, 1975); the Zollner illusion (Pastore, 1971); and parallel visual search functions (Gurnsey, Humphrey, & Kapitan, 1992). (See also theoretical proposals by Grossberg & Mingolla, 1985.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Object recognition contributions to figure-ground organization: Operations on outlines and subjective contours

Peterson

Gibson

1994

Perception & Psychophysics

143

114

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Section: Resultsmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Object recognition contributions to figure-ground organization: Operations on outlines and subjective contours

Peterson

Gibson

1994

Perception & Psychophysics

143

114

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“…They are generally believed to result from interactions among receptive fields at early stages of vision. Cells responsive to such lines have been found in cortical area V2 (von der Heydt & Peterhans, 1989;Peterhans & von der Heydt, 1989, 1991, and it has also been shown that rapid visual search can be based on their shape (Gurnsey, Humphrey, & Kapitan, 1992). To determine whether low-level grouping can operate on such lines, the first condition (A) replaced the lines of the stimuli of Experiment 1 by dot arrays in which dots were separated by 0.35 o .…”

Section: Methodsmentioning

confidence: 99%

Preemption effects in visual search: Evidence for low-level grouping.

Rensink¹,

Enns²

1995

Psychological Review

191

188

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Experiments are presented showing that visual search for Mueller-Lyer (ML) stimuli is based on complete configurations, rather than component segments. Segments easily detected in isolation were difficult to detect when embedded in a configuration, indicating preemption by low-level groups. This preemption-which caused stimulus components to become inaccessible to rapid search-was an all-ornothing effect, and so could serve as a powerful test of grouping. It is shown that these effects are unlikely to be due to blurring by simple spatial filters at early visual levels. It is proposed instead that they are due to more sophisticated processes that rapidly bind contour fragments into spatially-extended assemblies. These results support the view that rapid visual search cannot access the primitives formed at the earliest stages of visual processing; rather, it can access only higher-level, more ecologically-relevant structures.

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“…The high attentional demand indicated by these experiments has been used to argue for a cognitive theory of illusory contour formation. However, Gurnsey, Humphrey, and Kapitan (1992) have pointed out that edge type illusory figures were employed in all of these studies, and they reason that the attentional findings may be related to the low contrast between illusory figure and background, as opposed to the high contrast between the inducers and background. Eliminating contrast and other interfering factors by using fields oflines with lineend-induced illusory contours, Gurnsey et at.…”

Section: High-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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Parallel discrimination of subjective contours defined by offset gratings

Cited by 52 publications

References 44 publications

Object recognition contributions to figure-ground organization: Operations on outlines and subjective contours

Object recognition contributions to figure-ground organization: Operations on outlines and subjective contours

Preemption effects in visual search: Evidence for low-level grouping.

Illusory contours: Toward a neurally based perceptual theory

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