skilled professionals who create very special circumstances. We will re -
turn later to the issue of personality change associated with the use of
therapeutic drugs like Prozac.
When Does Adulthood Begin?
The claim that personality is stable in adulthood needs some clarifica -
tion. Who, after all, is an adult? Legal definitions of adulthood vary
widely , not only by state but by function. A woman is legally of an ageto marry at 14 in many states; the driver’s license is withheld until age16, voting until 18, and drinking until 21. Insurance companies, withactuarial wisdom, charge higher rates for drivers under 25. WilliamJames and a subsequent generation of hippies set age 30 as the dividingpoint between youth and settled adulthood.
Most psychologists probably consider college students—at least by
the time of graduation—full-fledged adults; and in many respects, ofcourse, they are. There is reason to think, however, that personality de-velopment continues, at least for some individuals, for several moreyears (K. M. White, Spiesman, & Costos, 1983). Studies that trace indi-viduals from college age into later adulthood almost invariably reportsome changes in the average levels of personality traits and more fluctu-ations for individuals than are found in studies of individuals who areinitially older (Finn, 1986; Helson & Moane, 1987; Jessor, 1983;Mortimer, Finch, & Kumka, 1981; McGue, Bacon, & Lykken, 1993).Haan, Millsap, and Hartka (1986) concluded from their study of per -
sonality that important changes may occur after high school:
Great shifts in personality organization are ordinarily thought to occur
during adolescence, but these findings suggest that more marked shifts oc -
cur, not during adolescence, but at its end when most people make the
profound role shifts entailed by entry into full-time work and marriage.(p. 225; emphasis in original)
That somewhat surprising conclusion is bolstered by recent longitudi -
nal data showing that there are few changes in the mean levels of per -
sonality traits in the age range from 12 to 16 (Costa, Parker, & McCrae,
2000).
What is the nature of the changes seen in the decade of the 20s?
When we compare the personality scores of college students to those of10 PERSONALITY IN ADULTHOOD