The randomization procedure in the study of categorization of multidimensional stimuli by pigeons.
Pigeons categorized rectangles varying in both height and width in an adaptation of a method used by Ashby and colleagues for the cognitive and neuropsychological analysis of human decision bounds for ill-defined categories. Optimal decision bounds were defined in a stimulus space in which the point (x,y) corresponded to a rectangle with width x and height y. Four tasks defined the following 4 optimal bounds: x = y, x = c, x = y + d, and (x-a)2 + (y-b)2 = r2, where a, b, c, d, and r were constants given by a task. Estimated decision bounds for individual pigeons conformed approximately to the optimal decision bound in each of the 4 tasks. The new method suggests a way to (a) integrate the disparate literature on ill-defined visual concepts and on optimal performances in nonhuman animals; (b) compare how humans and nonhuman animals categorize ambiguous, multidimensional configural stimuli; (c) model how nonhuman animals categorize naturalistic stimuli; and (d) infer that pigeons' categorizations of naturalistic stimuli may be remarkably close to optimal.
Herbranson
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Department of Psychology, University of Utah, Salt Lake City 84112, USA.
Fremouw
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Shimp
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CP
D000818:Animals; D001288:Attention; D010856:Columbidae; D003210:Concept Formation; D003657:Decision Making; D004193:Discrimination Learning; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual; D011601:Psychophysics; D011897:Random Allocation; D012858:Size Perception; D013045:Species Specificity