chapter  23
Hindsight bias
ByRüdiger F. Pohl, Edgar Erdfelder
Pages 22

Whenever in hindsight, we tend to exaggerate what we knew in foresight. For example, after being told that “absinthe” is not a precious stone but rather a liquor, we are likely to express inflated confidence that we knew the solution all along (Fischhoff, 1975). This effect has been termed “hindsight bias” or “knew-it-along effect” (Fischhoff, 1975) and has been observed in numerous studies up to date. Hindsight bias was the focus of two meta-analyses (Christensen-Szalanski & Willham, 1991; Guilbault, Bryant, Brockway, & Posavac, 2004) and several overviews (e.g., Bernstein, Aßfalg, Kumar, & Ackerman, 2016; Hawkins & Hastie, 1990; Pezzo, 2011; Pohl, 2004; Roese & Vohs, 2012). Common to all studies is that participants initially are in a state of uncertainty (which is necessary in order to observe the effect); usually accomplished by using rather difficult knowledge questions or uncertain events. The results of these studies showed that after knowing the solution or outcome, respectively, participants are quite often simply unable to access their uncontaminated foresight knowledge state (Erdfelder, Brandt, & Bröder, 2007; Pohl & Hell, 1996) so that they are left to reconstruct their earlier given estimate in a biased manner. Moreover, participants are generally unaware of the biasing process itself, that is, of how the solution or outcome might have influenced reconstruction.