The Availability Explanation of Excessive Plausibility Assessments
Abstract
The assessment of hypotheses in hypothesis generation involves a comparison between those hypotheses that have been generated (specified) and those that are not generated (unspecified). This study investigated the 'availability explanation' (Tversky and Kahneman, 1973) for subjects' overconfidence in estimating the probability of specified hypotheses. The conjecture is that subjects have difficulty retrieving unspecified hypotheses; a complete set of candidate unspecified hypotheses is unavailable during assessment. Therefore, the underpopulated set of unspecified hypotheses is regarded as less probable and the specified set is regarded as more probable. A control group in this study replicated previous findings of overconfidence for specified hypotheses. Two manipulations to increase the availability of unspecified hypotheses were investigated. One manipulation involved explicitly requesting subjects to populate the unspecified set. The other manipulation consisted of computer presentation of candidate unspecified hypotheses. Although in a normative sense, neither manipulation should have affected judgements, results indicated that assessment overconfidence for both experimental groups was reduced. These results support our conjecture that the availability heuristic is at least partially responsible for subjects excessive behavior in evaluating specified hypotheses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 30, 1979
- Accession Number
- ADA072678
Entities
People
- Carol Manning
- Charles Gettys
- Stanley Fisher
- Suzanne Baca
- Thomas Mehle
Organizations
- University of Oklahoma