Bias and error in human judgment



Currently prevalent views of human inference are contrasted with an integrated theory of the epistemic process. The prevailing views are characterized by the following orienting assumptions: (1) There exist reliable criteria of inferential validity based on objectively veridical or optimal modes of information processing. (2) Motivational and cognitive factors bias inferences away from these criteria and thus enhance the likelihood of judgmental error. (3) The layperson's epistemic process is pluralistic; it consists of a diverse repertory of information-processing strategies (heuristics, schemas) selectively invoked under various circumstances. By contrast, the present analysis yields the following conclusions: (1) There exist no secure criteria of validity. (2) Psychological factors that bias inferences away from any currently accepted criteria need not enhance the likelihood of error. (3) The inference process may be considered unitary rather than pluralistic. The various strategies and biases discussed in the literature typically confound universal epistemic process with specific examples (or contents) of such processes. Empirical support for the present analysis is presented, including evidence refuting proposals that specific contents of inference are of universal applicability; evidence suggesting that people do not, because of a reliance on subnormative heuristics, underutilize nonnative statistical information—rather, people seem unlikely to utilize any information if it is nonsalient or (subjectively) irrelevant; and evidence demonstrating that the tendency of beliefs to persevere despite discrediting information can be heightened or lowered by introducting appropriate motivational orientations.