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Conservatism in a simple probability inference task

Phillips, Lawrence D. and Edwards, Ward (1966) Conservatism in a simple probability inference task. Journal of Experimental Psychology, 72 (3). pp. 346-354. ISSN 0096-3445

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3 experiments investigated the effects on posterior probability estimates of: (1) prior probabilities, amount of data, and diagnostic impact of the data; (2) payoffs; and (3) response modes. Ss usually behaved conservatively, i.e., the difference between their prior and posterior probability estimates was less than that prescribed by Bayes' theorem. Conservatism was unaffected by prior probabilities, remained constant as the amount of data increased, and decreased as the diagnostic value of each datum decreased. More learning occurred under payoff than under nonpayoff conditions and between-S variance was less under payoff conditions. Estimates were most nearly Bayesian under the (formally inappropriate) linear payoff, but considerable overestimation resulted; the log payoff condition yielded less conservatism than the quadratic payoff. Estimates were most nearly Bayesian when Ss estimated odds on a logarithmic scale.

Item Type: Article
Official URL:
Additional Information: © 1966 American Psychological Association
Divisions: Management
Subjects: H Social Sciences > H Social Sciences (General)
H Social Sciences > HA Statistics
Date Deposited: 03 Mar 2010 15:34
Last Modified: 20 Nov 2019 05:53

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