we do not yet know whether or how often that happens. It seems likely
that some aspects of the life narrative—like optimistic or pessimistictone—are tied to personality traits and thus might be expected to bestable. Other aspects, such as the choice of critical events, probablychange.
STUDYING LIFE STRUCTURE AND LIFE COURSE
In view of the evidence of trait stability in adulthood, there would seemto be two directions in which the study of adult development mightproceed: It might focus on samples where substantial change would beexpected, including individuals undergoing psychotherapy or thoseunder age 30; or it might redefine the field as the psychology of adult -
hood, in which enduring dispositions would be viewed as a foundation
for adaptation to the changing demands of life.
We believe both of these approaches are useful: Researchers should
study change where it occurs and stability where it does not. There hasbeen a renewed interest in personality changes during the college years(R. W . Robins et al., 2001; Neyer & Asendorpf, 2001), studies that canprofitably be extended at least through the decade of the 20s. (Studiesof personality change prior to college are surprisingly few; they suggestthat there is considerable individual change but relatively little meanlevel change between 12 and 18; Costa, Parker, & McCrae, 2000).
Psychotherapy remains an area in which much remains to be done.
Longitudinal studies are observational, not experimental; they tell uswhat happens to a sample of people during the normal course of events.The fact that most people do not change much does not necessarilymean that they could not change given the right set of circumstances.Although interest in psychotherapy research waxes and wanes (VandenBos,1986), we still do not have long-term, large-scale studies of the effectsof different forms of therapy on personality traits.
Equally exciting to us is the research agenda that flows from a re -
versal of the conventional approach to adult development. Students of
age and personality have traditionally asked, “How does aging affectpersonality?” The complementary question—“How does personality af -
fect the aging process?”—is still new. In the first version of this book
(McCrae & Costa, 1984), we lamented the scarcity of research on thistopic. In the intervening years, things have begun to change (Costa &216 PERSONALITY IN ADULTHOOD