On the nature of inducing forms generating perceptions of illusory contours

Prazdny, K.

doi:10.3758/bf03207570

Cited by 34 publications

(19 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, illusory contours induced in the stereo and kinetic domains have not typically been recognized as such. It has long been known that the strength of illusory contours induced by both edge and line-end stimuli can be enhanced by providing additional stereo or motion cues, such as to increase the salience of the perceptual boundary between illusory figure and inducing elements (Gregory & Harris, 1974;Lawson, Cowan, Gibbs, & Whitmore, 1974;Prazdny, 1985;Ramachandran, 1986aRamachandran, , 1987Ramachandran & Cavanagh, 1985;Whitmore, Lawson, & Kozora, 1976). In these examples, contours were already established in the monocular, luminance domainstereo and kinetic cues only mediated their strengths.…”

Section: Other Types Of Illusory Contoursmentioning

confidence: 99%

Illusory contours: Toward a neurally based perceptual theory

Lesher

1995

Psychon Bull Rev

View full text Add to dashboard Cite

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.

show abstract

Section: Other Types Of Illusory Contoursmentioning

confidence: 99%

Illusory contours: Toward a neurally based perceptual theory

Lesher

1995

Psychon Bull Rev

View full text Add to dashboard Cite

show abstract

“…Prazdny (1983Prazdny ( , 1985and Shapley and Gordon (1985) have also used reverse-contrast images in their discussions of form perception. Consider the vertical boundaries in the perceived Kanizsa square.…”

Section: Different Rules For Boundary Contours and Feature Contoursmentioning

confidence: 99%

Neural dynamics of perceptual grouping: Textures, boundaries, and emergent segmentations

Grossberg

Mingolla

1985

Perception & Psychophysics

760

172

View full text Add to dashboard Cite

A real-time visual processing theory is used to analyze and explain a wide variety of perceptual grouping and segmentation phenomena, including the grouping of textured images, randomly defined images, and images built up from periodic scenic elements. The theory explains how "local" feature processing and "emergent" features work together to segment a scene, how segmentations may arise across image regions that do not contain any luminance differences, how segmentations may override local image properties in favor of global statistical factors, and why segmentations that powerfully influence object recognition may be barely visible or totally invisible. Network interactions within a Boundary Contour (BC) System, a Feature Contour (FC) System, and an Object Recognition (OR) System are used to explain these phenomena. The BC System is defined by a hierarchy of orientationally tuned interactions, which can be divided into two successive subsystems called the OC filter and the CC loop. The OC filter contains two successive stages of oriented receptive fields which are sensitive to different properties of image contrasts. The OC filter generates inputs to the CC loop, which contains successive stages of spatially short-range competitive interactions and spatially long-range cooperative interactions. Feedback between the competitive and cooperative stages synthesizes a global context-sensitive segmentation from among the many possible groupings of local featural elements. The properties of the BC System provide a unified explanation of several ostensibly different Gestalt rules. The BC System also suggests explanations and predictions concerning the architecture of the striate and prestriate visual cortices. The BC System embodies new ideas concerning the foundations of geometry, on-line statistical decision theory, and the resolution of uncertainty in quantum measurement systems. Computer simulations establish the formal competence of the BC System as a perceptual grouping system. The properties of the BC System are compared with probabilistic and artificial intelligence models of segmentation. The total network suggests a new approach to the design of computer vision systems, and promises to provide a universal set of rules for perceptual grouping of scenic edges, textures, and smoothly shaded regions.

show abstract

“…(1) Von der Heydt, Peterhans, and Baumgartner (1984) have recently shown that certain cells in V2 (area 18) of the monkey respond quite strongly to illusory contours, and (2) illusory contours cannot be produced in the absence of luminance contrast between the disks and background texture. For example, if isoluminant color contours (Gregory, 1977), cyclopean targets (Prazdny, 1985), or texture boundaries (Cavanagh, personal communication, 1985) are used to define the cut sectors, then no illusory contours are seen. Also, as noted (a) (b) those in the interstripes are sensitive primarily to bar length ("form").…”

Section: •••••••mentioning

confidence: 99%

Capture of stereopsis and apparent motion by illusory contours

Ramachandran

1986

Perception & Psychophysics

132

View full text Add to dashboard Cite

The removal of right-angle sectors from four circular black disks created the impression of a white "subjective" square with its four corners occluding the disks ("illusory contours"). The display in one eye was identical to that in the other except that for one eye a horizontal disparity was introduced between the edges of the cut sectors so that an illusory white square floated out in front of the paper. When a "template" ofthis stereogram was superimposed on a vertical squarewave grating (6 cycles/deg) the illusory square pulled the corresponding lines of grating forward even though the grating was at zero disparity. (Capture was not observed if the template was superimposed on horizontal gratings; the grating remained flush with the background). Analogous effects were observed in apparent motion ("motion capture"). Removal of sectors from disks in an appropriately timed sequence generated apparent motion of an illusory square. When a template of this display was superimposed on a grating, the lines appeared to move vividly with the square even though they were physically stationary. It was concluded that segmentation of the visual scene into surfaces and objects can profoundly influence the early visual processing of stereopsis and apparent motion. However, there are interesting differences between stereo capture and motion capture, which probably reflect differences in natural constraints. The implications of these findings for computational models of vision are discussed.361 Figure I shows a square defined by illusory contours (Brady

show abstract

On the nature of inducing forms generating perceptions of illusory contours

Cited by 34 publications

References 19 publications

Illusory contours: Toward a neurally based perceptual theory

Illusory contours: Toward a neurally based perceptual theory

Neural dynamics of perceptual grouping: Textures, boundaries, and emergent segmentations

Capture of stereopsis and apparent motion by illusory contours

Contact Info

Product

Resources

About