Processing of visual illusions in the frequency and spatial domains

Becker, Michael F.; Knopp, Jerome

doi:10.3758/bf03199529

Cited by 22 publications

(14 citation statements)

References 16 publications

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“…Theories that postulate that anomalous contours derive from various forms of local contrast effects which somehow spread across regions that are marked by real edge fragments, line ends, and other features may encounter difficulties in these situations because contrast enhancements of opposite sign, on the one hand, must somehow interact to produce the illusion but, on the other hand, must not simply average out. The opposite-contrast displays also argue against a form of a physiologically based theory (Becker & Knopp, 1978;Ginsburg, 1975), which suggests that anomalous contours are not completely illusory in the sense that they are physically present in the low spatial frequency components of a Fourier transform of the inducing stimuli. Figure 1b illustrates why such an explanation is bound to fail in the displays containing inducing forms of opposite contrast: any (brightness domain) filtering of such stimuli will necessarily produce edges lying perpendicular to the perceived illusory contours.…”

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confidence: 98%

On the nature of inducing forms generating perceptions of illusory contours

Prazdny

1985

Perception & Psychophysics

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confidence: 98%

On the nature of inducing forms generating perceptions of illusory contours

Prazdny

1985

Perception & Psychophysics

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“…Ginsburg (1975Ginsburg ( , 1987 and Becker and Knopp (1978) proposed that stimuli inducing illusory contours actually contained the illusory form information in their spatial frequency spectrum-that the illusory forms were not, in fact, illusory if one considered only the low-frequency information ofthe inducer configuration. If the early stages of visual processing had various frequency bands, these low-frequency illusory forms could easily be perceived directly.…”

Section: Spatial Frequency Theoriesmentioning

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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“…Most subjective-contour figures show systematic brightness effects; therefore, the same mechanisms that account for brightness contrast have been used to explain the emergence of these figures (Brigner & Gallagher, 1974;Coren & Theodor, 1977;Day & Jory, 1978Frisby & Clatsworthy, 1975;Jory & Day, 1979). Other investigators have suggested that subjective contours arise from the interactions among the receptive fields of orientation-specific cortical cells (Jung;1973;Jung & Spillman, 1970;Kennedy, 1979;Smith & Over, 1975, 1979 or that they are due to Fourier analysis processes in the visual system (Becker & Knopp, 1978;Ginsburg, 1975). In general, these structural theories have not fared well against recent findings.…”

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confidence: 99%