Cortisol reactivity to psychosocial stress mediates the relationship between extraversion and unrestricted sociosexuality

a r t i c l e i n f o We investigated the hypotheses that extraversion is associated with unrestricted sociosexuality (operationalized as greater sexual experience and greater short-term mating orientation) and that this association is mediated by reduced cortisol reactivity to psychosocial stress. Study participants were heterosexual male college students (n = 109). Extraversion was assessed with the Big Five Inventory and sociosexuality was assessed with the Multidimensional Sociosexuality Orientation Inventory. Cortisol reactivity to psychosocial stress was assessed via three saliva samples collected immediately before, immediately after, and 15 min after the Trier Social Stress Test. Extraversion was associated with greater sexual experience but not with greater short-term mating orientation. As predicted, more extraverted individuals showed a lower increase in cortisol in response to psychosocial stress than less extraverted individuals. Previous sexual experience and short-term mating orientation were negatively correlated with cortisol reactivity to stress. Finally, mediation analyses confirmed our hypothesis that cortisol reactivity to psychosocial stress is a mechanism mediating the association between extraversion and unrestricted sociosexuality. These findings have implications for our understanding of the benefits and costs of different personality traits as well as for our understanding of the determinants or correlates of individual differences in sociosexuality. Evolutionary research on human personality has been concentrated in two main areas: the examination of the relative role of genetic poly-morphisms and facultative calibration in the maintenance of personality variation in human populations (e.g., Lukaszewski, 2011; Lukaszewski & von Rueden, 2015), and the study of the functional significance of personality variation to better understand the fitness costs and benefits associated with different personality traits (e.g., Nettle, 2005). In both areas of research, many studies have focused on extraversion The interpersonal dimension of ex-traversion, however, is heterogeneous and includes both a nurturance/ love component (expressed for example, in romantic or parent–child relationships) and a reward-seeking component, which leads extravert-ed individuals to compete for social attention and social success as well as pursue novelty-and sensation-seeking in sexual relationships (Lukaszewski & von Rueden, 2015). Extraverted individuals engage in social exchange with a large number of people, therefore potentially benefiting from cooperation but also exposing themselves to social exploitation. In contrast, introverted people are more inclined to invest in a smaller number of deep engagement relationships with close partners, as well as in solitary activities (Lukaszewski & von Rueden, 2015). Extraversion is also associated with status motivation (e.g., desire for attention, social …