With the benefit of feedback about the outcome of an event, people's recall
ed judgments are typically closer to the outcome of the event than their or
iginal judgments were. It has been suggested that this hindsight bias may b
e due to a reconstruction process of the prior judgment. A model of such a
process is proposed that assumes that knowledge is updated after feedback a
nd that reconstruction is based on the updated knowledge. Consistent with t
he model's predictions, the results of 2 studies show that knowledge after
feedback is systematically shifted toward feedback, and that assisting retr
ieval of the knowledge prior to feedback reduces hindsight bias. In additio
n, the model accounts for about 75% of cases in which either hindsight bias
or reversed hindsight bias occurred. The authors conclude that hindsight b
ias can be understood as a by-product of an adaptive process, namely the up
dating of knowledge after feedback.