pounds; imagine living for 40 years and gaining no more than 12
pounds!
Another Mystery
Recently T wenge (2000) reported a remarkable result: She collected allthe studies she could find of students given standard tests of anxiety orNeuroticism between 1952 and 1993, and plotted mean values by year.Her results suggested that each successive cohort has become more anx -
ious—by almost a full standard deviation. She suggested that the stress -
ors of modern life have induced these generational changes in personal -
ity . Most personality psychologists are puzzled by these findings, and it
may take some time to properly evaluate them.
As it happens, the earliest-born subjects in her meta-analyses corre -
spond to the youngest respondents (age 34–54) in the NHANES sample
(Costa, McCrae, et al., 1986). If each birth-year cohort is getting moreand more anxious, then when they are all tested at one time as adultsthe oldest (i.e., the earliest born) ought to be the best adjusted. Neuroti-cism in Figure 2 should show a steep decline with age, not the near-flatpattern we see. Why is that decline absent? Perhaps, as in the pessimis-tic scenario we envisioned earlier in this chapter, it is because with agepeople become increasingly neurotic and the birth-cohort effects arecanceled out by equal and opposite aging effects. But all the longitudi-nal evidence says that people actually decline a bit in Neuroticism with
age. The cross-sequential analyses T wenge (2000) reports for her stu -
dent samples are inconsistent with longitudinal and cross-sec tional
analyses of adults. Perhaps the stress-induced anxieties of childhoodsimply evaporate in adulthood. This curious set of findings awaits a fi -
nal explanation.
A Different Analysis
All the analyses we have discussed so far analyzed the mean values of
groups of people—different groups, or the same groups at differenttimes. In recent years methodologists have argued that there are muchmore powerful ways to examine longitudinal data, especially if peopleare assessed not twice but on multiple occasions. Then a curve can be fitto each individual’s data and these growth curves can be analyzed. Forexample, even when the group as a whole shows no change, it is likely80 PERSONALITY IN ADULTHOOD