Individual versus group use of base-rate and individuating information

Abstract This study compared individual and group use of base-rate and individuating information. Individuals and five-person groups were presented with base-rate information and with individuating information and were asked to judge probabilities. Results indicate that groups report relying on the individuating information significantly more and on the base rate significantly less than individuals. The probability judgments of groups are more sensitive to subjects' beliefs about what the individuating information sounds like than the judgments of individuals. There is some evidence that the probability judgments of groups are more extreme than those of individuals. Group discussion appears to amplify the tendency of individuals to judge by representativeness when assessing category membership.

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