Does a surprising outcome reinforce or reverse the hindsight bias?

There are conflicting hypotheses regarding the effect of a surprising outcome on hindsight judgment. According to the hypothesis presented in this paper, high levels of surprise will lead to the elimination or reversal of hindsight bias. The feeling of surprise serves as a cue to subjects making them aware of the fact that outcome information is largely different from whatever they knew about the event. Subjects under these conditions seek explanations to the outcome and ''effortless assimilation,'' the most accepted theoretical account for the hindsight bias, is less likely. The alternative hypothesis postulates that surprising outcomes will lead to reinforcement of hindsight bias. The results of three experiments conducted in the framework of the present study indicate that when surprise levels are moderate or low, judgments are consistent with the hindsight bias, whereas highly surprising outcomes lead to the reversal of the bias. (C) 1997 Academic Press.