ABSTRACT
Perhaps one of the least controversial and most commonsense conclusions from psychology research is that expertise requires experience, and in many areas of expertise, acquisition of declarative, articulable knowledge is not sufficient to become a truly proficient expert (Chi, Glaser, & Farr, 1988; Ericsson & Smith, 1991). For example, many researchers agree that a minimum of 10 years of “active experience” is necessary to achieve true mastery in an area (the “10-year rule”; see Chase & Simon, 1973) and this specific minimum amount of experience applies to a surprisingly wide variety of domains, such as chess, musical composition, livestock judgment, mathematics, tennis, science, and interpretation of X-ray pictures (e.g., Chase & Simon, 1973; Chi et al., 1988; Gustin, 1985; Hayes, 1981; Krogius, 1976; Lehman, 1953; Lesgold, 1984; Sosniak, 1985).
