A role for the striatum in regret-related choice repetition.

"Regret aversion" is proposed to explain a tendency to avoid future choices that have induced past regret. However, regret might also motivate us to repeat previous regret-related choices to make up for their previous selection, a behavior resembling "chasing" in the context of gambling. In the current experiment, we acquired fMRI brain data while participants placed monetary bets on repeated gambles. Behaviorally, participants showed a tendency to repeat previously regret-related choices (operationalized as those leading to an outcome worse than what might have been), an effect restricted to early runs of the task. At gamble outcome, we show a reduction in ventral striatal activity for regret-related relative to relief-related outcomes. Critically, this modulation was only seen when subjects were responsible for the bet choice. Activity in dorsal striatum was associated with an influence of previous regret on participants' subsequent choices, which is evident in increased activity when regret-related choices were repeated, relative to avoided, on the next trial. Our findings indicate that regret can lead to choice repetition as if seeking to make up for our mistakes and in so doing may lead to subsequent chasing behavior.