Abstract

The term individual differences refers to how people differ with respect to a wide variety of factors such as personality, motives, and abilities. Conceptualizations of individual differences in human temperament can be traced from the ancient typologies of Hippocrates and Galen to the somatotypes of Kretschmer and Sheldon, the work of Galton on mental testing and Binet on intelligence, to the most contemporary multitrait personality inventories, such as the Big Five (Costa & McCrae, 1985; Digman, 1990). Individual differences can emerge from a large variety of heritable and non-heritable sources, and some of the innumerable ways in which individuals differ may be more adaptive than others (see Buss & Greiling, 1999, for a review).