Stimulus determinants of brightness and distinctness of subjective contours

Petry, Susan; Harbeck, Ardelle; Conway, Jane; Levey, Judy

doi:10.3758/bf03211344

Cited by 47 publications

(50 citation statements)

References 27 publications

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“…Although the data ofthe two research groups do not coincide perfectly, both indicate the same general trend for edge inducers: a monotonic increase in contour clarity as support ratio increases. The effect ofsupport ratio on line-end induced contour strength has been insufficiently studied, but the data of Petry et al (1983) indicate that it may also play an important role in determining contour strength in these cases as well. Employing stimuli similar to those of Figure 7, and excepting very thin lines, they found clarity to increase to a saturated plateau with increasing support ratio, defined for their Ehrenstein figures as the product of the number oflines and line width, divided by the illusory figure circumference.…”

Section: Low-level Determinantsmentioning

confidence: 99%

“…Watanabe and Oyama (1988) found that clarity and brightness decreased monotonically as they increased the separation between the sectored circle inducers in a Kanizsa figure without varying any other spatial parameters. By varying the width of inducing lines in an Ehrenstein figure, Petry et al (1983) and Sambin (1985) found that clarity was a monotonically increasing function of the width of the inducers, while brightness exhibited an inverted-U shape. Dresp (1992) investigated the effect of Kanizsa (edge) inducer separation and size on illusory brightness, finding that brightness was an inverse function of inducer proximity and a positive function of inducer size.…”

Section: Low-level Determinantsmentioning

confidence: 99%

“…Conversely, an edge inducer has two corners, the nonsupporting edges of which are often roughly perpendicular to the supporting edges, and thus provides something akin to line-end information. Gradually increasing the width ofa line results in a smooth progression from line end to edge inducer, with clear perception of an illusory contour throughout the entire transition (Lesher & Mingolla, 1993;Petry, Harbeck, Conway, & Levey, 1983). The role ofedges and line ends in illusory contour formation poses one of the fundamental questions in modeling these phenomena: Do the two types of inducers imply the existence of two completely separate mechanisms or extremes of the same mechanism?…”

Section: Line-end Induced Illusory Contoursmentioning

confidence: 99%

“…Although this has been the only explicit study of the effect of the number of edge inducers, there have been several investigations of the number of line-end inducers on clarity and brightness, using both thin and thick lines. As is indicated in Figure 7, Petry et al (1983) varied the number, as well as the widths, of inducing lines in Ehrenstein figures. They found that increasing the number of lines had very little effect on contour clarity but resulted in a monotonic increase in brightness.…”

Section: Low-level Determinantsmentioning

confidence: 99%

“…In the first study of illusory brightening, Ehrenstein (1941) noted qualitatively a number of stimulus variations that affected brightness. A wide range of quantitative brightness reports followed, including measurements by rating scale and magnitude estimation Halpern, 1981;Jory & Day, 1979;Petry et al, 1983), matching (Brussel, Stober, & Bodinger, 1977;Spillman, Fuld, & Neumeyer, 1984), nulling (Halpern, 1987;Spillman et al, 1984), and threshold increment levels (Coren & Theodor, 1975;Dresp, 1993;Dresp & Bonnet, 1991;Jory, 1987). Brightness measurements appear to be consistent across different types of measurement procedures (Dresp, 1992;Spillman et al, 1984).…”

Section: Characteristics Of Illusory Figuresmentioning

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: 99%

Section: Low-level Determinantsmentioning

confidence: 99%

Section: Line-end Induced Illusory Contoursmentioning

confidence: 99%

Section: Low-level Determinantsmentioning

confidence: 99%

Section: Characteristics Of Illusory Figuresmentioning

confidence: 99%

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Illusory contours: Toward a neurally based perceptual theory

Lesher

1995

Psychon Bull Rev

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A Neural Theory of Preattentive Visual Information Processing: Emergent Segmentation, Cooperative-Competitive Computation, and Parallel Memory Storage

Grossberg

Mingolla

1986

Structure and Dynamics of Nucleic Acids, Proteins, and Membranes

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Dogs (Canis lupus familiaris) are susceptible to the Kanizsa’s triangle illusion

et al. 2021

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The ability to complete partially missing contours is widespread across the animal kingdom, but whether this extends to dogs is still unknown. To address this gap in knowledge, we assessed dogs’ susceptibility to one of the most common contour illusions, the Kanizsa’s triangle. Six dogs were trained to discriminate a triangle from other geometrical figures using a two-alternative conditioned discrimination task. Once the learning criterion was reached, dogs were presented with the Kanizsa’s triangle and a control stimulus, where inducers were rotated around their centre, so as to disrupt what would be perceived as a triangle by a human observer. As a group, dogs chose the illusory triangle significantly more often than control stimuli. At the individual level, susceptibility to the illusion was shown by five out of six dogs. This is the first study where dogs as a group show susceptibility to a visual illusion in the same manner as humans. Moreover, the analyses revealed a negative effect of age on susceptibility, an effect that was also found in humans. Altogether, this suggests that the underling perceptual mechanisms are similar between dogs and humans, and in sharp contrast with other categories of visual illusions to which the susceptibility of dogs has been previously assessed.

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Stimulus determinants of brightness and distinctness of subjective contours

Cited by 47 publications

References 27 publications

Illusory contours: Toward a neurally based perceptual theory

Illusory contours: Toward a neurally based perceptual theory

A Neural Theory of Preattentive Visual Information Processing: Emergent Segmentation, Cooperative-Competitive Computation, and Parallel Memory Storage

Dogs (Canis lupus familiaris) are susceptible to the Kanizsa’s triangle illusion

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