Most people hold unrealistic positive beliefs about their personal skills, their knowledge (Fischoff, Slovic, & Lichtenstein, 1977), and their possibilities to overcome the performance of other individuals (Weinstein, 1980). This general tendency, called overconfidence, is a stable and pervasive finding both in many real-life domains and in several experimental settings. People are overconfident about their driving skills (Svenson, 1981), about their ability as basketball players (McGraw, Mellers, & Ritov, 2004), about their competence in financial and managerial problems (Camerer & Lovallo, 1999; Mahajan, 1992), and about their general knowledge (Juslin, 1994; Harvey, 1997). This systematic overestimation of one's own capabilities and probabilities of success can have important consequences, and sometimes results in suboptimal decisions.