Distinction Bias
The tendency to view two options as more distinctive when evaluating them simultaneously than when evaluating them separately.
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Origin
Introduced by psychologist Christopher K. Hsee and Jiao Zhang of the University of Chicago in their 2004 paper "Distinction Bias: Misprediction and Mischoice Due to Joint Evaluation", published in the Journal of Personality and Social Psychology. They demonstrated that people over-predict the happiness differences between options when evaluating them jointly versus separately, leading to suboptimal choices.
Updated February 22, 2026