The reiteration effect in hindsight bias.

Repetition of an assertion increases the degree of belief in that assertion.This reiteration effect is used to explain two puzzling findings in research on hindsight bias.First, the reiteration effect explains the asymmetry in hindsight bias for true and false assertions.This striking asymmetry has often been observed in experimental studies, but no rationale has yet been found.Second, the reiteration effect predicts a novel finding: Recalled confidence will increase in hindsight bias studies even if no feedback is given.The authors have checked both predictions against results reported in the literature; with some exceptions, the evidence supports them.The aim of this article is to relate two hitherto unrelated phenomena in human confidence.These two phenomena are that (a) confidence in the truth of an assertion increases after the assertion is repeated, independent of its truth or falsity (e.g., Bacon, 1979; Hasher, Goldstein, & Toppino, 1977), and (b) recollection of confidence is systematically distorted after feedback about the actual truth or falsity has been received (known as "hindsight bias," e.g., Hawkins & Hastie, 1990).The effects of repetition and feedback on confidence are part of a group of puzzling phenomena related to human confidence that includes overconfidence, the hard-easy effect, and conservatism.Some two decades of research have yielded a rich phenomenology of these effects but have failed to produce theoretical models to describe the underlying cognitive processes.A consequence of this is that these phenomena are listed in textbooks side by side with little or no theoretical integration.This article seeks to provide a model for how two of these phenomena--the effect of repetition (which we term the reiteration effect) and the effect of feedback on confidence (the hindsight bias)--are linked.This article consists of three sections: a brief introduction of the reiteration effect and the hindsight bias; an exposition of the proposed model, including two predictions; and a test of these predictions.