inspection of Table 8 shows very little consistent evidence of maturational
effect—indeed, not a single scale shows unequivocal evidence of change.Total Neuroticism, for example appears to decline in cross-sectionalanalyses of both self-reports and spouse ratings. It also declines overtime in self-reports. But according to husbands and wives, rated Neurot -
icism actually increased over the 6-year period! No effect was seen in
the cross-sequential analyses.
All the other studies we have discussed—and most in the litera -
ture—are based on self-reports, and systematic biases in self-reports
might account for the general lack of age changes reported. It could beargued that external observers may more accurately perceive and reporttrue aging effects. The analyses of spouse ratings summarized in Table8, however, confirm the absence of strong and clear maturational effectsfor the three domains of Neuroticism, Extraversion, and Openness.
For a look at all five factors, consider a 7-year study of peer ratings
(Costa & McCrae, 1992b). In 1983 we had asked BLSA participants tonominate friends or neighbors who knew them well, and then askedthese peers to provide personality ratings of the BLSA participants. In1990 we recontacted peer raters; we also recruited a new group of ratersfor new BLSA participants (recall that an independent sample is neededfor cross-sequential analyses). Cross-sectional analyses showed verysmall effects: N, E, and O declined with age; A and C increased (al-though the effect for C was not significant). Longitudinal analysesshowed no changes for men but a small increase in Conscientiousnessfor women. Finally , cross-sequential analyses showed no significant ef -
fects for any of the factors. It appears that personality as judged by
friends and neighbors changes little over 7 years of adulthood.
It is worth considering what different conclusions would be drawn
if the different analyses summarized in Table 8 had been done in sepa -
rate studies. The researchers who conducted cross-sectional studies
would have reported decreases in N, E, and O and increases in A and C;the researchers who conducted the cross-sequential analyses wouldhave found increases in E and O and declines in A and C! Neither set ofconclusions would have been replicated by the longitudinal researchers.The moral seems to be that so many factors—sampling, cohort differ -
ences, practice effects, time-of-measurement artifacts, selective mortal -
ity—affect results that most so-called aging effects are probably spuri -
ous. Only when several types of evidence are considered together can
reasonable conclusions be drawn.Growth or Decline in Personality 77