Conservative cutoff placement in a numerical decision task

概要

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Conservative placement of a criterion was investigated in a numerical decision task where the subjects were required to make binary decisions on five-digit numbers drawn from two overlapping normal distributions. In Experiment 1 (subjects were 32 graduates and undergraduates), there were two conditions of discriminability determined by the degree of the overlap of distributions. Although observed cutoff locations for uneven prior probabilities of stimulus distributions were conservative in both conditions, the subjects in the low discriminative condition changed their cutoff placement less than those in the high discriminative condition. In both conditions, subjects' response probabilities were close to the prior probabilities. In Experiment 2 (subjects were eight graduates and undergraduates), the verbal protocol during the task showed that ambiguous impressions were used for judgments and that responses were made as accurately as possible to both stimulus distributions. It was concluded that the heuristics the subjects used in the task could account for the conservative cutoff placement and that the heuristics confirmed their judgments.
公益社団法人日本心理学会の論文