bility of individual differences. Table 13 presents stability coefficients
for men and women subdivided into two age groups, as well as for thetotal for all NEO-PI scales. (Note that the stability coefficients for A andC are based on a 3-year retest interval, because A and C were not mea -
sured until 1983.) These correlations, ranging from .55 to .87, are all
significant and all testify to extraordinary stability of personality , in menand women, in early and late adulthood.
The results in Tables 11–13 provide consistent evidence of high
1evels of stability over intervals of up to 30 years. Consider what thatmeans. In the course of 30 years, most adults will have undergone radi -
cal changes in their life structures. They may have married, divorced,
remarried. They have probably moved their residence several times.Many people will have experienced job changes, layoffs, promotions,and retirement. Close friends and confidants will have died or movedaway or become alienated. Children will have been born, grown up,married, and begun a family of their own. Individuals will have aged bi-ologically , with changes in appearance, health, vigor, memory , and sen-sory abilities. Wars, depressions, and social movements will have comeand gone. Most people will have read dozens of books, seen hundreds ofmovies, watched thousands of hours of television. And yet, most will not
have changed appreciably in their standing on any of the five dimensions ofpersonality.
The Time Course of Stability
Although the generalization that individual differences are preservedacross time is supported by a rich body of evidence, we cannot claimthat there are no changes. Quite aside from unusual cases, such as sus -
tained traumatic experiences and effective psychotherapy , there is a cer -
tain degree of instability in the course of normal aging. The degree of
stability seen is a function both of the retest interval and the initial agefrom which it is reckoned.
When people complete the same personality measure twice over an
interval of a few days, it is not usually considered a measure of stabilityat all, but rather a way to assess the retest reliability of the measure, be -
cause it can be assumed that personality has not changed in so short a
time. Good measures have high retest reliability , although it is neverperfect, and retest unreliability sets an upper limit to the stability thatcan be observed.112 PERSONALITY IN ADULTHOOD