Abstract

Three experiments were conducted to examine the effects of base-rate on judgments upon characteristics of target person. In experiment 1, subjects read a manipulated base-rate information and four descriptions for each target persons, and judged his attitude for family planning campaign. Subjects judged the target person's altitude according to only the description about him regardless of base-rate information when a description comprised of consistent informations. And subjects in this condition more confided to their judgment than that of the other conditon. But subjects judged the target person's altitude according to base-rate when a description comprised of inconsistent informations. Experiment 2 and 3 were designed to test hypothesis that base-rate information impacts on subject's judgment only when subject has not a causal schema corresponding to the given information, but it cannot impact on judgment when subject has a causal schema. In exp. 2, subject's judgment and confidence were impacted by base-rate in judgment of moral act, but not in immoral act. In exp. 3, subject's judgment and confidence we impacted by base-rate in judgment of failure outcome, but not in success outcome. Differences both in the impacts of base-rate on social judgments and in the subject's confidence to their judgments were discussed in a hypothetical model.