ABSTRACT
Research in social and cognitive psychology has revealed a number of biases and shortcomings in everyday judgement and information processing (Kahneman, Slovic, & Tversky, 1982; Nisbett & Ross, 1980). One such bias is the “knew-it-all-along” effect, which refers to the tendency to overestimate how predictable the outcome of an event had been before one had experienced the now familiar outcome. This hindsight bias has the effect of making the past seem less uncertain than it was. It has been demonstrated across a range of predictions, subjects, and methodologies, in both laboratory and field settings (for reviews, see Christensen-Szalanski & Willham, 1991; Hawkins & Hastie, 1990). The phenomenon has been observed in domains as diverse as general knowledge (Fischhoff, 1977), scientific findings (Davies, 1987), football results (Leary, 1981), election outcomes (Blank & Fischer, 2000), and the location of cities on a map (Pohl & Eisenhauer, 1995). It has been obtained using both memory instructions and hypothetical instructions. With memory instructions, individuals first respond without feedback. They are subsequently told the correct answers and asked to recall their previous judgements as accurately as possible. In the hypothetical design, participants are given outcome information and are then asked to respond as they (or others) would have answered, had they not been told the correct answers (e.g., Fischhoff, 1975; Wood, 1978). In both cases, participants usually show an overestimation in the direction of the correct answer, either as compared to control participants who respond without
feedback (hypothetical condition) or as compared to their own pre-outcome estimates (memory condition). An important area of research on the hindsight bias phenomenon considers how the effect is linked to the laws of information processing and storage (e.g., Erdfelder & Buchner, 1998; Fischhoff, 1975; Hell, 1993; Hertwig, Fanselow, & Hoffrage, 2003-
Requests for reprints should be sent to Jochen Musch, Department of Psychology, Lehrstuhl Psychologie III, SchlossEhrenhof Ost, University of Mannheim, D-68131 Mannheim, Germany, Email: musch@psychologie.uni-mannheim.deI am very grateful to Robert Mischke for his help in collecting and analysing the data. I ani also indebted to Johanna Louda, Yvonne Mertens, Ursula Pryczak, and Romy Reyentanz for their help in collecting the data as part of their course work in a seminar on experimental psychology. Thanks are due to Hartmut Blank, Arndt Bröder, Katja Ehrenberg, Markus Eisenhauer, Edgar Erdfelder, Ulrich Hoffrage, Delroy Paulhus, Rüdiger Pohl, Anders Winman, and an anonymous reviewer for their many helpful comments and constructive suggestions on previous drafts of this article.
