The Facial Width-to-Height Ratio Predicts Sex Drive, Sociosexuality, and Intended Infidelity.

Previous research has linked the facial width-to-height ratio (FWHR) to a host of psychological and behavioral characteristics, primarily in men. In two studies, we examined novel links between FWHR and sex drive. In Study 1, a sample of 145 undergraduate students revealed that FWHR positively predicted sex drive. There were no significant FWHR × sex interactions, suggesting that FWHR is linked to sexuality among both men and women. Study 2 replicated and extended these findings in a sample of 314 students collected from a different Canadian city, which again demonstrated links between the FWHR and sex drive (also in both men and women), as well as sociosexuality and intended infidelity (men only). Internal meta-analytic results confirm the link between FWHR and sex drive among both men and women. These results suggest that FWHR may be an important morphological index of human sexuality.

Preliminary evidence that testosterone's association with aggression depends on self-construal.

A contribution to a special issue on Hormones and Human Competition. Previous research and theory suggest testosterone is an important hormone for modulating aggression and self-regulation. We propose that self-construal, a culturally-relevant difference in how individuals define the self in relation to others, may be an important moderator of the relationship between testosterone and behaviors linked to aggression. Within two studies (Study 1 N=80; Study 2 N=237) and an integrated data analysis, we find evidence suggesting that acute testosterone changes in men are positively associated with aggressive behavior for those with more independent self-construals, whereas basal testosterone is negatively associated with aggression when individuals have more interdependent self-construals. Although preliminary, these findings suggest that self-construal moderates the association between testosterone and aggression, thereby paving the way toward future work examining the potential cultural moderation of the behavioral effects of testosterone.

Effects of exogenous testosterone and mating context on men's preferences for female facial femininity.

Correlational research suggests that men show greater attraction to feminine female faces when their testosterone (T) levels are high. Men's preferences for feminine faces also seem to vary as a function of relationship context (short versus long-term). However, the relationship between T and preferences for female facial femininity has yet to be tested experimentally. In the current paper, we report the results of two experiments examining the causal role of T in modulating preferences for facial femininity across both short and long-term mating contexts. Results of Experiment 1 (within-subject design, n=24) showed that participants significantly preferred feminized versus masculinized versions of women's faces. Further, participants showed a stronger preference for feminine faces in the short versus the long-term context after they received T, but not after they received placebo. Post-hoc analyses suggested that this effect was driven by a lower preference for feminine faces in the long-term context when on T relative to placebo, and this effect was found exclusively for men who received placebo on the first day of testing, and T on the second day of testing (i.e., Order x Drug x Mating context interaction). In Experiment 2 (between-subject design, n=93), men demonstrated a significant preference for feminized female faces in the short versus the long-term context after T, but not after placebo administration. Collectively, these findings provide the first causal evidence that T modulates men's preferences for facial femininity as a function of mating context.

Exogenous testosterone increases men's perceptions of their own physical dominance.

Men's testosterone is associated with several constructs that are linked to dominance rank, such as risk-taking, mating success, and aggression. However, no study has directly tested the relationship between men's self-perceived dominance and testosterone using an experimental design. We employed a within-subjects, double-blind, placebo-controlled paradigm to assess whether testosterone influences men's self-perceived dominance. Exogenous testosterone or a placebo was administered to healthy adult men and self-perceptions of physical dominance were subsequently assessed by having participants select what they believed to be their true face from an array of images digitally manipulated in masculinity. Men picked a more masculine version of their own face after testosterone versus placebo--an effect that was particularly pronounced among men with relatively low baseline testosterone. These findings indicate that a single administration of testosterone can rapidly modulate men's perceptions of their own physical dominance, which may explain links between testosterone and dominance-related behaviors.

Digit ratio (2D:4D) and psychopathic traits moderate the effect of exogenous testosterone on socio-cognitive processes in men.

Recent evidence suggests that testosterone is negatively correlated with empathic processes in both men and women. Also, administration of testosterone to young women impairs socio-cognitive performance as assessed using the "Reading the Mind in the Eyes Task", especially among those exposed to elevated testosterone concentrations prenatally. However, the extent to which testosterone plays a similar causal role in socio-cognitive abilities in men is currently unknown. Here, using a crossover, double-blind, placebo-controlled, within-subject design, we investigated the extent to which a single administration of testosterone to healthy young men (N=30) would impair socio-cognitive abilities assessed using the "Reading the Mind in the Eyes Task" (RMET). Also, we investigated whether individual differences in 2D:4D ratio and psychopathic traits would moderate the effect of testosterone on task performance. Results indicated that testosterone administration on its own did not impair RMET performance. However, variability in both 2D:4D ratio and psychopathic traits moderated the effect of testosterone on task performance. Specifically, testosterone impaired RMET performance among individuals with relatively low (i.e., masculinized) 2D:4D ratio and among individuals scoring relatively low on the interpersonal/affective facet (i.e., Factor 1) of psychopathy. Our findings highlight the importance of considering theoretically- and empirically-based individual difference factors when attempting to characterize the neuroendocrine mechanisms underlying socio-cognitive processes.