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ERIC Number: EJ859191
Record Type: Journal
Publication Date: 2009-Oct
Pages: 11
Abstractor: As Provided
Reference Count: 0
ISSN: ISSN-0010-0277
On the Provenance of Judgments of Conditional Probability
Zhao, Jiaying; Shah, Anuj; Osherson, Daniel
Cognition, v113 n1 p26-36 Oct 2009
In standard treatments of probability, Pr(A[vertical bar]B) is defined as the ratio of Pr(A[intersection]B) to Pr(B), provided that Pr(B) greater than 0. This account of conditional probability suggests a psychological question, namely, whether estimates of Pr(A[vertical bar]B) arise in the mind via implicit calculation of Pr(A[intersection]B)/Pr(B). We tested this hypothesis (Experiment 1) by presenting brief visual scenes composed of forms, and collecting estimates of relevant probabilities. Direct estimates of conditional probability were not well predicted by Pr(A[intersection]B)/Pr(B). Direct estimates were also closer to the objective probabilities defined by the stimuli, compared to estimates computed from the foregoing ratio. The hypothesis that Pr(A[vertical bar]B) arises from the ratio Pr(A[intersection]B)/[Pr(A[intersection]B)+Pr(A[vinculum][intersection]B)] fared better (Experiment 2). In a third experiment, the same hypotheses were evaluated in the context of subjective estimates of the chance of future events. (Contains 4 tables and 3 figures.)
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A