The Effects of Exogenous Testosterone on Men’s Moral Decision-Making

Correlational research has linked testosterone (T) to moral reasoning, such that individuals high in T respond to moral dilemmas in a more utilitarian manner (Carney and Mason 2010). In the present study, 30 male undergraduates completed baseline measures of T, psychopathic traits, and digit-ratio (2D:4D) and were subsequently administered 150 mg of testosterone or placebo in a double-blind within-subjects experiment meant to explore a potential causal influence of T on moral decision-making. Following drug administration, participants rated their agreement with a set of incidental and instrumental moral dilemmas, the total of which provided an index of the participant’s utilitarian decision-making on that testing day. Results revealed a significant drug × type of dilemma interaction. Post-hoc analyses revealed that T administration was associated with increased utilitarian behavior within incidental moral dilemmas, but with decreased utilitarian decision-making in instrumental dilemmas, although neither trend was statistically-significant. The interpersonal/affective facet (i.e., Factor 1) of psychopathy was positively correlated with utilitarian responses. No effects were found for baseline testosterone or digit ratio. Potential reasons underlying the effect of T decreasing utilitarianism in incidental dilemmas, as well as future directions for research in this area, are discussed. © 2016, Springer International Publishing.