The Determinants of Illusory-Contour Perception

The term ‘illusory contours' refers to contours perceived where none physically exist. Three hypotheses that have been successful in their ability to account for this phenomenon invoke: (i) apparent depth; (ii) brightness contrast; and (iii) use of figural cues. An experiment has been designed to determine the extent to which each hypothesis accounts for the overall variation in subjects' responses to illusory contours when all three hypotheses are considered simultaneously. Experimental results suggest that different processes may assume a primary role in the perception of illusory contours depending upon the type of inducing area and the configuration. The results highlight the multifaceted nature of the processes involved, and indicate that no single theory can explain the perception of illusory contours.

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The Multiple Determination of Illusory Contours: 1. A Review

Perception ◽

10.1068/p120281 ◽

1983 ◽

Vol 12 (3) ◽

pp. 281-291 ◽

Cited By ~ 21

Author(s):

Diane F Halpern ◽

Billie Salzman

Keyword(s):

Illusory Contour ◽

Brightness Contrast ◽

Simultaneous Contrast ◽

Illusory Contours ◽

Contour Perception ◽

Partial Activation ◽

Multiple Determination

Four theories of illusory-contour perception are reviewed—brightness contrast (simultaneous contrast, assimilation, and dissimilation), depth/completion, partial activation of neural feature analyzers, and the diffuse—sharp dichotomy. It is concluded that the processes and mechanisms involved in illusory-contour perception most likely depend upon the stimulus elements used in the illusory-contour display.

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The Multiple Determination of Illusory Contours: 2. An Empirical Investigation

Perception ◽

10.1068/p120293 ◽

1983 ◽

Vol 12 (3) ◽

pp. 293-303 ◽

Cited By ~ 18

Author(s):

Diane F Halpern ◽

Billie Salzman ◽

Wayne Harrison ◽

Keith Widaman

Keyword(s):

Illusory Contour ◽

Factor Model ◽

Illusory Contours ◽

Contour Perception ◽

Confirmatory Factor ◽

Linear Effects ◽

Explained Variance ◽

Taxonomic Approach ◽

Contour Strength

Judgments of contour strength or saliency for twenty-four illusory-contour configurations were subjected to a confirmatory factor analysis. A four-factor model that posited the involvement of simultaneous contrast, linear effects (assimilation and dissimilation), depth/completion cues, and feature analyzers accounted for a substantial proportion of the variance in judgments of illusory-contour strength. The hierarchical addition of a fifth factor, diffuse illusory contours, significantly improved the overall fit of the model, but added little to the proportion of explained variance. The taxonomic approach adopted provides support for a multiprocess model of illusory-contour perception.

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Illusory Contours in Line Patterns with Apparent Depth Due to Either Perspective or Overlay

Perception ◽

10.1068/p120485 ◽

1983 ◽

Vol 12 (4) ◽

pp. 485-490 ◽

Cited By ~ 7

Author(s):

Ross H Day ◽

Richard T Kasperczyk

Keyword(s):

Illusory Contour ◽

Apparent Depth ◽

Illusory Contours ◽

Line Patterns

An illusory contour along a partially delineated border in the form of an apparent ‘outside’ corner due to perspective was as strong as one along a similarly delineated border in the form of an edge due to overlay. An illusory contour along a border in the form of an apparent ‘inside’ corner, due probably to both perspective and overlay, was stronger than either. These outcomes suggest that apparent stratification from overlay is not necessary for the occurrence of illusory contours. They also accord with the view that apparent depth due to overlay or to perspective is equally effective in rendering partially delineated borders more prominent and, in consequence, the illusory contours that form along them stronger.

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The Generic-Viewpoint Assumption and Illusory Contours

Perception ◽

10.1068/p3016 ◽

2000 ◽

Vol 29 (3) ◽

pp. 303-312

Author(s):

Marc K Albert ◽

Donald D Hoffman

Keyword(s):

Machine Vision ◽

Infinite Number ◽

Illusory Contour ◽

Human Vision ◽

Visual Images ◽

Illusory Contours ◽

Contour Perception ◽

The World

Visual images are ambiguous. Any image, or collection of images, is consistent with an infinite number of possible scenes in the world. Yet we are generally unaware of this ambiguity. During ordinary perception we are generally aware of only one, or perhaps a few of these possibilities. Human vision evidently exploits certain constraints—assumptions about the world and images formed of it—in order to generate its perceptions. One constraint that has been widely studied by researchers in human and machine vision is the generic-viewpoint assumption. We show that this assumption can help to explain the widely discussed fact that outlines of blobs are ineffective inducers of illusory contours. We also present a number of novel effects and report an experiment suggesting that the generic-viewpoint assumption strongly influences illusory-contour perception.

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Are Illusory Contours a Cause or a Consequence of Apparent Differences in Brightness and Depth in the Kanizsa Square?

Perception ◽

10.1068/p170513 ◽

1988 ◽

Vol 17 (4) ◽

pp. 513-521 ◽

Cited By ~ 31

Author(s):

Takeo Watanabe ◽

Tadasu Oyama

Keyword(s):

Causal Inference ◽

Path Analysis ◽

Illusory Contour ◽

Apparent Depth ◽

Inference Method ◽

Illusory Contours ◽

Partial Correlations

The causal flows between the processes responsible for illusory contour clarity, brightness, and apparent depth in the Kanizsa square were examined. The sixty-four stimuli used consisted of all possible combinations of eight disk luminances and eight centre-to-centre separations between nearest disks. Ten subjects were instructed to rate the clarity of the illusory contour and the brightness and apparent depth differences between the Kanizsa square and its surround in each stimulus. On the basis of results obtained with the causal inference method, using partial correlations and path analysis, it is suggested that clarity of illusory contour can be influenced directly by disk separation, and that the output from the process responsible for illusory contour clarity has some effect on the processes responsible for the apparent depth and brightness differences.

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Influence of Parallel and Orthogonal Real Lines on Illusory Contour Perception

Journal of Neurophysiology ◽

10.1152/jn.00001.2009 ◽

2010 ◽

Vol 103 (1) ◽

pp. 55-64 ◽

Cited By ~ 6

Author(s):

Barbara Dillenburger ◽

Anna W. Roe

Keyword(s):

Real Line ◽

Illusory Contour ◽

Contextual Effects ◽

Line Orientation ◽

The Other ◽

Imaging Data ◽

Illusory Contours ◽

Contour Perception ◽

Parallel Lines

Real lines and illusory contours (ICs) have been reported to either interfere with or facilitate the perception of the other, depending on real line orientation and contrast. Here we investigate contextual effects of real lines on illusory contour perception. Curvature discrimination thresholds of Kanizsa-contours were measured for superimposed real lines of different sub- and suprathreshold contrasts. We find that parallel lines interfere with curvature discrimination at suprathreshold, whereas orthogonal lines interfere at subthreshold contrasts. We did not find stable facilitating effects of lines in any orientation or contrast. These results are discussed in relation to existing physiological and imaging data.

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Affect from mere perception: Illusory contour perception feels good.

Emotion ◽

10.1037/emo0000293 ◽

2017 ◽

Vol 17 (5) ◽

pp. 856-866 ◽

Cited By ~ 7

Author(s):

Thorsten M. Erle ◽

Rolf Reber ◽

Sascha Topolinski

Keyword(s):

Illusory Contour ◽

Contour Perception

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Insect perception of illusory contours

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1992.0083 ◽

1992 ◽

Vol 337 (1279) ◽

pp. 59-64 ◽

Cited By ~ 27

Keyword(s):

Human Visual System ◽

Illusory Contour ◽

Optic Lobe ◽

Insect Vision ◽

Local Contrast ◽

Fault Line ◽

Illusory Contours ◽

Striped Pattern ◽

Processing Power ◽

As If

The human visual system sees an illusory contour where there is a fault line across a regular striped pattern. We demonstrate that bees respond as if they see the same illusory contour. There is also a type of neuron in the lobula of the dragonfly optic lobe which responds directionally to motion of the illusory contour as if to an edge or line. Apparently insects have a mechanism that sees illusory contours and therefore assists in the demarcation of edges and objects at places where local contrast falls to zero at an edge, or where one textured object partially obscures another. These results suggest that insect vision, although spatially crude and low in processing power, sees separate objects by similar mechanisms to our own.

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