39038$ SSS4 Hogrefe & Huber Publishers - EXPPSY 49/04/2002 - 3. Bel. - 01-10-02 09:54:37 - Rev 16.04x Hindsight Bias Around the World Riidiger F. Pohl, Michael Bender, and Gregor Lachmann Justus-Liebig University, Giessen, Germany Abstract. Hindsight bias refers to the tendency to overestimate in hindsight what one has known in foresight, Recently, two experiment:, extended the research to include samples from different cultures (Choi & Nisbett, 2000; Heine & Lehman,. 1996). Asking their participants what they would have guessed before they knew the outcome ("hypothetical design"), Choi and Nisbett (2000) found that Koreans, in comparison to North Americans, exhibited more hindsight bias. Heine; and Lehman (1996),: however, reported that Japanese people in comparison to Canadians showed marginally less hindsight bias. In: a second study, in which participants were asked to recall what they had estimated before they knew the outcome ("fnemory design"), the latter authors found no difference in hindsight bias between Japanese people and Canadians. We extended these studies with 225 Internet participants, in a hypothetical design, from four different continents (Asia, ; Aus- tralia, Europe, and North America).: Hindsight bias was large and similar for all samples except for (ierman and Dutch participants who showed no hindsight bias at all. While the latter effect may be based on peculiarities of the materia! and of the participants, the former underscores the worldwide stability of the phenomenon. In addition a follow-up surprise rating (paper and pencil) in China (35 participants) and Germany (20 participants) revealed that only less surprising items led to hindsight, bias while more surprising ones did not. We suggest that the basic cognitive processes leading: to hindsight bias are by-products of the evolutionary-evolved capacity of adaptive learning. On top of these basic processes, individual meta-eognitions (e.g., elicited by surprise) or motives (e.g., a self-serving motive) may further moderate the amount of bias, thus explaining the diverging results of Choi and Nisbett (2000), Heine and Lehman (1996), and ourown study. Key words: memory, judgment, hindsight bias, culture, surprise, self Hindsight bias describes the tendency to adjust one's memory about earlier given estimates towards inter- mediately presented outcome information (Fischhoff, 1975). If, for example, a person answered the ques- tion of "How many bones does a human have?" with an estimate of "450," but later received the correct solution, namely "214," he or she may then erro- neously recall to have given an estimate of "350." This would represent a shift of the original estimate towards the solution of 42.4% [= 100 x (450-350)/ (450-214)] and thus indicate hindsight bias (as de- fined by Hell, Gigerenzer, Gauggel, Mall, & Muller, 1988). The described procedure represents the Parts of this research were supported by a grant from the DFG (German Science Foundation) to the first author. We are very grateful to all colleagues who forwarded our experiment's Internet address to their students. Special thanks go to Michael M. Birnbaum for making available his "SurveyWiz" program, to Alfred Kohnert for program- ming the interface to receive the experimental protocols, and to Ursula Frost, Jens Frost, and Xiaodong Yue for ena- bling Michael Bender to conduct the follow-up survey in China. Martin Heydemann, Stefan Schwarz, U l f Reips, Jochen Musch, and Britta Renner provided very helpful comments on an earlier version of this paper. DOI: 10.1027//1618-3169.49.4.270 Experimental Psychology 2002; Vol. 49(4): 270-282 "memory" design, which is different from the "hypo- thetical" design in which the task is not to recall one's earlier given estimate, but rather to generate an estimate either in the presence of the solution (exper- imental group) or in its absence (control group). The experimental group in the hypothetical design is in- structed to answer the question as if they did not know the solution (hence the term "hypothetical"). Several researchers reported that hindsight bias was larger in the hypothetical than in the memory design (Campbell & Tesser, 1983; Davies, 1992; Fischhoff, 1977; Fischhoff & Beyth, 1975; Heine & Lehman, 1996; Hertwig, Gigerenzer, & Hoffrage 1997; Pow- ell, 1988; Wood, 1978, Exp. 2). The phenomenon of hindsight bias appears to be very robust (see Christensen-Szalanski & Willham, 1991, and Hawkins & Hastie, 1990, for reviews) and has been demonstrated in numerous studies over a period of more than 25 years (as examples for more recent studies, see Dehn & Erdfelder, 1998; Erd- felder & Buchner, 1998; Hardt & Pohl, in press; Hertwig et al., 1997; Hoffrage & Hertwig, 1999; Hoffrage, Hertwig, & Gigerenzer, 2000; Louie, 1999; Pohl, 1998, 2000; Pohl & Gawlik, 1995; Pohl & Hell, 1996; Schwarz & Reips, 2001; Stahl- © 2002 Hogrefe & Huber Publishers