Revealing risky mistakes through revisions

We argue that a choice that is modified, absent any informational change, is revealed to have been a mistake. In an experiment, we allow subjects to choose from budgets over binary lotteries. To identify mistakes, which we interpret as deviations from an underlying “true” preference, we allow subjects to revise a subset of their initial choices. The set of revised decisions improves under several standard definitions of optimality. These mistakes are prevalent: subjects modify over 75% of their initial choices when given the chance. Subjects make larger mistakes when inexperienced and when choosing over lotteries with small probabilities of winning.