Preference reversal (Lichtenstein & Slovic, 1973) refers to a change in the relative frequency by which one option is favored over another in behavioral experiments, as evident in the less-is-better-effect or ratio bias, for example, or framing effects more generally. Preference reversals contradict the predictions of rational choice.
References
Lichtenstein, S., & Slovic, P. (1973). Reversals of preference between bids and choices in gambling decisions. Journal of Experimental Psychology, 89(1), 46-55.