The effects of exogenous testosterone on economic decision making and executive functioning

A small body of correlational work suggests that the steroid hormone testosterone may play an important role in economic decision-making, although mixed findings have raised questions about the nature of these relationships. Very few studies have featured the experimental control of testosterone that would be needed to establish causal relationships between testosterone and decision-making, and it remains unknown whether causal effects are modulated by important contextual or individual difference variables. A further gap exists in understanding if, and how, testosterone influences executive functions—the higher order cognitive mechanisms that are germane to purposeful behaviour, including economic choice. This dissertation sought to address these gaps in three experiments that employed double-blind, placebo-controlled, testosterone administration paradigms. Experiment 1 examined the effects of testosterone on economic decisions in a one-shot public goods game, with participants randomized to make their decision under time-pressure or after time-delay. Results from Experiment 1 indicated that testosterone (1) abolished a prosocial time-pressure effect among men low in a personality risk factor for testosterone-induced antisociality, and (2) fully reversed a prosocial time-delay effect among men high in personality risk. Replicating and extending this work, results from Experiment 2 indicated that (1) testosterone reduced prosocial economic decisions among high risk (but not low risk) men when there was no game observer; (2) when the game observer was a man perceived as relatively more (vs. less) attractive, testosterone increased prosocial economic contributions among participants with restricted sociosexualities (long-term mating orientations) but decreased contributions among those with unrestricted sociosexualities (short-term mating orientations); and (3) when the game observer was a woman perceived as relatively less (vs. more) attractive, testosterone reduced prosocial contributions most prominently for participants with unrestricted sociosexualities. Experiment 3 examined the effects of testosterone on executive functioning, and economic decision-making on the Iowa Gambling Task (IGT). Results from Experiment 3 indicated that testosterone (1) down-regulated task planning ability and inhibition, and (2) produced null effects for economic decisions on the IGT. The experiments herein are discussed within the context of evolving theoretical models that link rapid increases in testosterone to context-dependent, reproductively-relevant behaviours.