Outcome Bias
An error made in evaluating the quality of a decision when the outcome of that decision is already known.
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Origin
Jonathan Baron and John C. Hershey named outcome bias in a 1988 paper published in the Journal of Personality and Social Psychology. Working at the University of Pennsylvania, they showed participants identical medical decisions differing only in outcome, finding that people consistently rated the reasoning as sounder when the patient survived — even when they acknowledged outcomes shouldn't matter.
Updated February 22, 2026