Amodal completion, depth stratification, and illusory figures: a test of Kanizsa's explanation. 1992

F Purghé, and S Coren
Dipartimento di Psicologia, Università di Roma La Sapienza, Italy.

Subjective contours have been explained by Kanizsa as being a consequence of amodal completion of incomplete figures. According to the theory of amodal completion, figural incompleteness triggers the emergence of an illusory object superimposed on the gaps in the inducers, which in turn hide parts of the pattern, thus suggesting that the plane of the illusory object must always be seen to be above the plane of the inducers. A figure was created in which subjective contours are seen despite the fact that the perceived depth relationships run counter to that required by the theory of amodal completion. In four experiments, this depth relationship is confirmed by using direct and indirect measures which assess both registered and apprehended depth. By emphasizing a logical inconsistency in the explanation based on amodal completion, the results show that amodal completion, at least in Kanizsa-like patterns, cannot be considered as a causal factor for subjective contour figures.

UI MeSH Term Description Entries
D008297 Male Males
D009903 Optical Illusions An illusion of vision usually affecting spatial relations. Illusion, Optical,Illusions, Optical,Optical Illusion
D010364 Pattern Recognition, Visual Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs. Recognition, Visual Pattern,Visual Pattern Recognition
D003867 Depth Perception Perception of three-dimensionality. Stereopsis,Stereoscopic Vision,Depth Perceptions,Perception, Depth,Perceptions, Depth,Stereopses,Stereoscopic Visions,Vision, Stereoscopic,Visions, Stereoscopic
D005260 Female Females
D005556 Form Perception The sensory discrimination of a pattern, shape, or outline. Contour Perception,Contour Perceptions,Form Perceptions,Perception, Contour,Perception, Form,Perceptions, Contour,Perceptions, Form
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D015350 Contrast Sensitivity The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate VISUAL ACUITY and to detect eye disease. Visual Contrast Sensitivity,Sensitivity, Contrast,Sensitivity, Visual Contrast

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