Brent Roberts (personal communication, August 1, 2001) believes
the longitudinal literature contains a number of documented instancesof life experiences that caused meaningful changes in personality traits.We are not yet persuaded that these effects are robust and replicable orthat they really refer to changes in Basic Tendencies. Consider the accul -
turation study (McCrae, Yik, et al., 1998). Hong Kong Chinese scored
lower than Americans on measures of Altruism, because China is acollectivistic society in which individuals’ predominant loyalty is totheir family and business associates. So much is demanded of Chineseby these in-group members that little is left for out-group members. Inconsequence, Chinese respondents score low on the NEO-PI-R Altru -
ism scale, because it assesses altruism mainly by items like “I think of
myself as a charitable person.” Chinese who move to Canada may learnanother set of values (a Characteristic Adaptation) in which charity toout-group members is deemed appropriate. Thus, acculturation maysimply change the way in which Altruism is expressed.
We would not claim that we have convincingly demonstrated that
External Influences have no effect on Basic Tendencies, but we thinkthe burden of proof has shifted 180 degrees from the conventional wis-dom of psychologists: It is now incumbent on those who think the envi-ronment shapes personality to prove it. More realistically , since scienceis rarely a matter of either one principle or its opposite—either biologyorenvironment—what is needed is a specification of the particular con-
ditions and circumstances in which life experience can reshape person-ality and an explanation of how it does so. The great majority of lifeevents do not have lasting effects on personality traits; what is it aboutthose few events that do that sets them apart?
Trait Development and the FFT
Although FFT does not give a role to life experience in shaping person -
ality traits, it does acknowledge that trait levels change across the life -
span. As it was originally formulated in 1996, FFT claimed that traits
develop through childhood and reach mature form in adulthood; thereafterthey are stable in cognitively intact individuals . By 1999, we acknowl -
edged a need to modify that statement, because evidence suggested very
small but consistent changes in Neuroticism, Extraversion, and Open -
ness after age 30. We now have some idea of how traits develop from
adolescence on (Costa, Parker, & McCrae, 2000) but only hints aboutA Five-Factor Theory of Personality 197