Personality: Nomothetic or idiographic? A response to Kenrick and Stringfield.

Abstract

It is suggested, contrary to the interpretation presented by Kenrick and String- field, that substantial consistency can be observed in personality as reflected in both behavior and judges' ratings when the principle of aggregation is applied to traditional nomothetic assessment procedures and results are interpreted in terms of classical reliability theory. Moreover, it is demonstrated that conclusions by Kenrick and Stringfield about the supposed improvement in predictive power stemming from an idiographic analysis do not follow from their data because they confound trait consistency and trait extremity and fail to take account of restriction and inflation of range effects. Over the past 15 years, the traditional wisdom of the classical nomothetic approach to person- ality has come under repeated attack. The no- mothetic view is that the science of personality consists of a search for general laws having wide applicability to people in which consistent pat- terns of individual differences in behavior, some- times called traits, play a central role. Basic as- sumptions of this approach include substantial consistencies of people's behavior when reliably assessed and considerable predictive power of measures of traits in accounting for behavior. Critics have challenged assumptions about the predictive power of broad traits, arguing that when personality measures are used to predict a specific behavioral event, validity coefficients often fail to exceed .30.