Concavities as basic features in visual search : Evidence from search asymmetries

Concave cusps and negative curvature minima play an important role in many theories of visual shape perception. Cusps and minima are taken to be part boundaries, used to segment an object into parts. Because of their important role in determining object structure and because there is some evidence t...

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Bibliographic Details
Published in:Perception & psychophysics 2000, Vol.62 (1), p.162-174
Main Authors: HULLEMAN, J, TE WINKEL, W, BOSELIE, F
Format: Article
Language:English
Subjects:
Biological and medical sciences
Female
Form Perception
Fundamental and applied biological sciences. Psychology
Humans
Male
Perception
Psychology. Psychoanalysis. Psychiatry
Psychology. Psychophysiology
Vision
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Summary:Concave cusps and negative curvature minima play an important role in many theories of visual shape perception. Cusps and minima are taken to be part boundaries, used to segment an object into parts. Because of their important role in determining object structure and because there is some evidence that object structure is processed in parallel, it might be expected that concave cusps and negative curvature minima are processed preferentially. We tested this conjecture in several visual search experiments. Visual search for a target with a concave cusp among totally convex distractors yields nearly flat slopes (< 10 msec/item) for both present and absent trials. Reversing the roles of the target and the distractor results in inefficient search. The same asymmetry is found when the concave cusp is replaced by other types of concavity. We conclude, therefore, the concavities can serve as basic features in visual search experiments. This conclusion implies that the unit of selection in a visual search task is an object, rather than a location.
ISSN:0031-5117
1532-5962
DOI:10.3758/BF03212069