Keith E. Stanovich
University of Toronto, Canada
Richard F. West
James Madison University, Harrisonburg, Virginia, USA
An important research tradition in the cognitive psychology of reasoning-called the heuristics and biases approach-has firmly established that people's responses often deviate from the performance considered normative on many reasoning tasks. For example, people assess probabilities incorrectly, they display confirmation bias, they test hypotheses inefficiently, they violate the axioms of utility theory, they do not properly calibrate degrees of belief, they overproject their own opinions onto others, they display illogical framing effects, they uneconomically honour sunk costs, they allow prior knowledge to become implicated in deductive reasoning, and they display numerous other information processing biases (for summaries of the large literature, see Baron, 1998, 2000; Dawes, 1998; Evans, 1989; Evans & Over, 1996; Kahneman & Tversky, 1972, 1984, 2000; Kahneman, Slovic, & Tversky, 1982; Nickerson, 1998; Shafir & Tversky, 1995; Stanovich, 1999; Tversky, 1996).
It has been common for these empirical demonstrations of a gap between descriptive and normative models of reasoning and decision making to be taken as indications that systematic irrationalities characterize human cognition. However, over the last decade, an alternative interpretation of these findings has been championed by various evolutionary psychologists, adaptationist modellers, and ecological theorists (Anderson, 1990, 1991; Chater & Oaksford, 2000; Cosmides & Tooby, 1992, 1994b, 1996; Gigerenzer, 1996a; Oaksford & Chater, 1998, 2001; Rode, Cosmides, Hell, & Tooby, 1999; Todd & Gigerenzer, 2000). They have reinterpreted the modal response in most