intensely they act and react in relevant situations. A very gregarious in -
dividual really likes to be around people, and frequently is. Frequency
and intensity of the appropriate acts and feelings are the major signsfrom which we infer the level of a trait.
The word tendencies in our definition emphasizes the fact that traits
are only dispositions, not absolute determinants. A great number ofother factors go into the choice of a particular action or the occurrenceof a particular experience. Gregarious people like to talk, but they nor -
mally do not chatter on during moments of silent prayer. Well-adjusted
people may not worry much, but even they are likely to be anxiouswhen awaiting the results of a job interview or a medical procedure.The requirements of the social roles we play , the facts of the current sit -
uation, the mood of the moment, and acquired habits all join in shaping
the choice of a particular act, word, or emotional reaction.
This is a crucial point, because it was once considered a reason to
discard the trait approach altogether. In 1968, Mischel published anenormously influential summary of the literature in which he arguedthat personality traits account for only about 5–10% of individual differ-ences in actual behavior in any specific instance. This disappointinglysmall contribution seemed to suggest that the whole enterprise of traittheory and assessment was a fool’s errand.
But, in fact, that finding is just what a thoughtful trait theorist
would expect. Suppose we use the trait of warmth to predict whether anindividual will smile at a stranger (Costa & McCrae, 1998b). We knowthat traits operate on a probabilistic basis and that people vary from lowto high, with most in the middle of a bell curve. So we might predictthat only 10% of the coldest research subjects would smile when webring a stranger into the laboratory whereas 90% of the warmest sub -
jects would; others would fall somewhere in between, perhaps as shown
in Table 2. If these are the numbers we actually observed in the labora -
tory , we would be overjoyed at how well trait theory had predicted
behavior. And yet, in this instance, the correlation between warmth andsmiling is only .41, meaning that only about 16% of smiling behaviorcan be predicted from knowing the subject’s trait level.
If traits are such weak predictors of behaviors even when they work
perfectly , what is their attraction? As Epstein (1979) famously showed,the answer is that we are rarely interested in predicting a single behav -
ior. We usually want to know how people act in general, and if we aver -
age behaviors across many instances, we can predict the average with26 PERSONALITY IN ADULTHOOD