Peak shift revisited: a test of alternative interpretations.
In Experiment 1, 2 groups of human subjects were trained to respond to 1 of 2 light intensity stimuli, S2 or S4, and then were tested for generalization with a randomized series of increasing values from S1 to S11. Both groups, including the group trained to respond to dimmer value, showed peak shifts to a brighter more centrally located test stimulus. In Experiment 2, which used line angle stimuli, both the size of the difference between S+ and S- and the range of test stimuli that extended beyond S+ were varied. The larger the S(+)-S- separation and the larger the range, the greater was the peak shift obtained. In Experiment 3, training involved an S- (line angle) surrounded by 2 S+ values with testing symmetrical about the training values and covering either a narrow or a wide range. The wide range produced greater peak shifts in both directions from S-. All 3 experiments support an adaptation-level interpretation of intradimensional discrimination learning and generalization test performance in human subjects. Related work with animals suggests the presence of similar processes.
Thomas
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Department of Psychology, University of Colorado, Boulder 80309-0345.
Mood
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Morrison
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Wiertelak
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D000328:Adult; D000818:Animals; D001288:Attention; D003662:Decision Theory; D004193:Discrimination Learning; D005260:Female; D005795:Generalization, Stimulus; D006801:Humans; D008027:Light; D008297:Male; D011597:Psychomotor Performance; D014796:Visual Perception