Endogenous estradiol levels are associated with attachment avoidance and implicit intimacy motivation

Estradiol has been linked with attachment and caregiving processes in humans and other mammals; however, relations between estradiol and personality constructs relevant to intimate relationships have not yet been explored. In the present sample of 100 adult participants (52 men, 48 women), we examined endogenous estradiol levels in relation to two personality constructs that predict comfort with and desire for close, intimate relationships—attachment style and implicit intimacy motivation. In both men and women, estradiol levels were predicted by an interaction between a dimension of attachment style—attachment avoidance—and implicit intimacy motivation. Specifically, the highest estradiol levels were observed among participants whose explicit traits support the expression of their implicit motives, that is, those characterized by both low avoidance and high intimacy motivation. Our findings provide novel evidence that endogenous estradiol levels are associated with relationship-relevant personality constructs in theoretically meaningful ways. These findings also highlight the importance of considering interactions between implicit and explicit personality constructs in the study of the biological bases of personality.