Receipt of reward leads to altered estimation of effort

Significance Retrospective reevaluation of effort is a pervasive aspect of everyday life, such as when we assess our professional satisfaction after knowing the ensuing outcomes. Previous studies have focused on the interaction of effort and reward when a choice is to be made, whereas retrospective interactions have been largely ignored. Here we show that humans revise their estimation of effort after receiving a reward. When rewarded more than average, subjects tend to overestimate their effort, with a converse effect observed for low rewards. The size of this bias depends strongly on the contingency between reward magnitude and task difficulty and is dynamically adjusted when changes occur in these contingencies. These results reveal a sophisticated mechanism to cope with reward–effort inconsistencies.