sectional because they take a slice at one time of individuals of various
ages. Note that this strategy has a number of advantages. For example,if we measure enough people, we can look not only at young versus oldbut at much finer groupings: We can contrast people 38–43 years oldwith people 44–49 years old to see if the former are showing signs of amidlife crisis. We can search for a curve of growth and decline by de -
cade or year to say at exactly what point there is a peak in creativity or
productivity or depression. In a matter of weeks or months a researchercan estimate effects of age on whatever variable he or she is interested instudying.
By this method, thousands of studies on age and personality have
been conducted and hundreds published in the scientific literature. In1977, Neugarten reviewed the findings that had been reported: ego -
centrism, dependency , introversion, dogmatism, rigidity , cautiousness,
conformity , ego strength, risk taking, need for achievement, locus ofcontrol, creativity , hope, the self-concept, social responsibility , morale,dreaming, and attitudes toward aging were all found to be different indifferent groups. However, the studies rarely agreed with each other:Some researchers found that older people are more dogmatic, some thatthey are less. (Doubtless other researchers have found no age differ-ences at all, but it is sometimes difficult to find a journal that will pub-lish such “uninteresting” results.) Only introversion, according toNeugarten, seems to show a consistent pattern of increase in the latterhalf of life.
In updating Neugarten’s review we can take advantage of the Five-
Factor Model (FFM) to organize results, and we can test the replica -
bility of findings by comparing age effects for different scales that mea -
sure each of the five domains. We will begin with three large-scale
studies that use instruments that cover all or most of the five domains.Siegler, George, and Okun (1979) studied a sample of 331 men andwomen initially aged 54–70 who completed the 16PF . Douglas andArenberg (1978) examined age differences on the GZTS among twogroups of men in BLSA: 605 men tested between 1958 and 1968, and310 men tested between 1968 and 1974. Subjects ranged in age from 17to 98, so age differences anywhere in adulthood should be apparent. Inour study of the PRF (Costa & McCrae, 1988a) we examined age corre -
lates in a sample of 296 men and women aged 22–90 who were friends
and neighbors of BLSA participants. (A significant positive correlation60 PERSONALITY IN ADULTHOOD