An Investigation of Judgments of Category Frequency
Technical rept. Jul 1982-Jun 1983
ARMY RESEARCH INST FOR THE BEHAVIORAL AND SOCIAL SCIENCES ALEXANDRIA VA
Pagination or Media Count:
Two experiments investigated the kinds of frequency information that people can remember and individual differences in accuracy of reporting frequency. The task involved presenting individual instances of natural categories and requiring subjects to give absolute estimated of the number of times each category had occurred. In the first experiment, the variability of items was manipulated to assess whether subjects base their estimates on a direct memory access or on a retrieval and mental count of individual instances. A second experiment evaluated subjects capability to report category frequency at two levels of conceptual organization and whether the accuracy of either type of judgement was related to learning style. Data from both experiments suggested that frequency is encoded directly with the memory representation for the concept. The second experiment revealed a sensitivity for frequency of both higher and lower categories, although the former were substantially underestimated. Learning style was not related to either frequency judgement task. The observed underestimation of high frequencies implies a need to take this fundamental judgement bias into account when training persons to make frequency judgements as part of analytical tasks such as risk assessment.