what proportion of possible stability they show. Dividing stability coeffi -
cients by short-term retest reliabilities gives an estimate of the stability
of the true score , the actual level of the traits that we try to infer from
our tests.
This procedure—called disattenuating correlations —leads to con -
siderably higher estimates of stability . When corrected for attenuation
resulting from unreliability , 12-year stability estimates for the GZTSscales shown in Table 11 (in Chapter 6) ranged from .80 to 1.00 (Costaet al., 1980); the 6-year stability estimates for N, E, and O scales for theNEO-PI were .95, .90, and .97, respectively (Costa & McCrae, 1988b).Such analyses suggest that if we had perfect measures we would findnear-perfect stability of personality traits. The 50% of variance not pre -
dictable from earlier scores is not true change; it is mostly error of mea -
surement.
RETROSPECTION AND SELF-PERCEIVED CHANGE
In Chapter 6 we mentioned that retrospection—asking individuals to
recall how they were and how they have changed—was a simple butsuspect method of examining stability or change in personality . We saidthat we could not be sure whether the reports would be accurate reflec-tions of reality or distortions of memory . By now , however, we have areasonable idea of what reality must have been like for most people: Weknow that stability rather than change predominates when prospectivelongitudinal studies are conducted. So is there any reason to reconsiderretrospective reports?
In fact, there is. They serve, to begin with, as one more source of
data, one more way to bolster or cast doubt on our findings of con -
stancy . But equally importantly , they let us know something about how
individuals view their own lives. If most individuals were to claim thatthey had changed dramatically when all the evidence points to the op -
posite conclusion, this would suggest that memory does indeed play
tricks on us, and the function of these tricks would be of considerableinterest. It might also explain why critics find the notion of stability inpersonality so counterintuitive.
Most people, in fact, can point to aspects of themselves that have
changed in the past few years, and the reader may have been protestingon the basis of these exceptions throughout this book. But three thingsshould be borne in mind in considering this kind of evidence:124 PERSONALITY IN ADULTHOOD