Factor Theories of Intelligence are All Right Almost

spects, but they have had in common their reliance on the factor as the unit in terms of which intelligence and individual differences in intelligence can be understood (Brody & Brody, 1976; Butcher, 1970; Sternberg, 1977). Although psychological interpretations of the meaning of factors differ from one investigator to another (Coan, 1964; Sternberg, 1977), the basic idea is usually that factors represent latent abilities of some kind that give rise to measured individual differences in performance on intelligence tests and in the real world. For example, observed individual differences in tests such as vocabulary, reading comprehension, and spelling might be understood primarily in terms of individual differences in an underlying verbal factor.