Subjective contours and the Poggendorff illusion

Meyer, Glenn E.; Garges, Carol

doi:10.3758/bf03199884

Cited by 30 publications

(31 citation statements)

References 10 publications

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“…The low effect in the subjective condition is noteworthy in that it represents one of the few instances in which a subjective contour was relatively ineffective in comparison with its luminancedifference contour surrogate (e.g., Meyer & Garges, 1979;Smith & Over, 1979).…”

Section: /mentioning

confidence: 99%

Determinants of the rod-and-frame effect: Role of organization and subjective contour

Streibel

Barnes

Julness

et al. 1980

Perception & Psychophysics

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In Experiment I, performance on a conventional (full) rod and frame was compared with that on three other displays. These included a closure condition in which only the corners of a luminous frame were present, a subjective contour condition in which the rod was seen against a black square subjective surface, and a pattern condition in which four luminous disks were arranged to form the corners of a square pattern. In all cases, a square-like form was perceived. The rod-and-frame effect (RFE) was greatest on the full frame, which differed significantly from an the rest. Closure produced the next greatest influence, while the responses to subjective and pattern conditions did not differ from each other. Experiment 2 showed that a subjective frame was no more effective than the subjective surface of Experiment I, and verified the importance of 90-deg corner elements in the rod-and-frame display. The conclusion drawn was that equivalent form organizations are not sufficient to produce equivalent levels of the RFE, but certain luminance-difference contours appear to be essential. Figure I. All the display elements were made of electroluminescent panels and were shown with a luminance somewhat under I nit. The full frame was 101.6 cm in length and 2.5 cm wide. The rod dimensions were 96.5 x 2.5 cm and were identical in all conditions. In the closure condition (Figure 1b), the outer edge of each corner was 9.6 crn and this also was the dimension of one

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Section: /mentioning

confidence: 99%

Determinants of the rod-and-frame effect: Role of organization and subjective contour

Streibel

Barnes

Julness

et al. 1980

Perception & Psychophysics

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“…A number of researchers have employed illusory contour versions of classical illusions involving impaired estimations of orientations. It appears that illusory contours facilitate the Bourdon illusion (Walker & Shank, 1987, 1988a, 1988bWenderoth, Criss, & van der Zwan, 1990) but slightly decrease the effect of the Poggendorff illusion (Day, Dickinson, & lory, 1977;Goldstein & Weintraub, 1972;Meyer & Garges, 1979). General equivalence in orientation estimation is a strong, though not unequivocal, argument for early representation of illusory contours, Time course studies.…”

Section: Psychophysical Similarities Between Real and Illusory Contoursmentioning

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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“…The subjective contour, according to this explanation, represents the boundaries or edges of this plane. These apparent boundaries can also function as edges in the production of illusions (Bradley & Petry, 1977;Meyer & Garges, 1979). 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.…”

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confidence: 99%