Hormones and personality: Testosterone as a marker of individual differences

Recently, testosterone (T) has been linked to behaviors that are conceptually related to dominance as a personality characteristic. Although evidence for this association is growing, the psychometric properties of T as an individual difference variable have been largely neglected. For T to be considered a biological marker of dispositional dominance it is critical that it demonstrates high test–retest reliability and good convergent and discriminant validity. Two studies tested the temporal stability of salivary T in humans and the relationship between T and traditional measures of personality. Across both studies, test–retest reliability for T was high and comparable to the short-term stability of questionnaire-based and implicitly assessed personality assessment instruments. In being modestly correlated with self-reported dominance, T showed some evidence of convergent validity. In being statistically independent from conceptually unrelated personality constructs (such as Emotional Stability and Openness to Experience) it showed good evidence of discriminant validity. The findings strengthen the psychometric foundation for using T as a hormonal marker of individual differences.