Correlative evidence suggests that testosterone promotes dominance and aggression. However, causal evidence is scarce and offers mixed results. To investigate this relationship, we administered testosterone for 48 h to 41 healthy young adult men in a within-subjects, double-blind placebo-controlled balanced crossover design. Subjects played the role of responders in an ultimatum game, where rejecting a low offer is costly, but serves to destroy the proposer's profit. Such action can hence be interpreted as non-physical aggression in response to social provocation. In addition, subjects completed a self-assessed mood questionnaire. As expected, self-reported aggressiveness was a key predictor of ultimatum game rejections. However, while testosterone affected subjective ratings of feeling energetic and interested, our evidence strongly suggests that testosterone had no effect on ultimatum game rejections or on aggressive mood. Our findings illustrate the importance of using causal interventions to assess correlative evidence.
Bibliographical noteFunding Information:
We thank Paul Fletcher, Emilio Fernandez-Egea, Ashley Grossman, Helen Gossage and Sheila Skidmore for their help during the project. This work was supported by the Economic and Social Research Council (grant ES/G005230/1 ). CC was supported by the Spanish Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional (FEDER) ECO2015-65820-P (MINECO/FEDER). PNT was supported by the Swiss National Science Foundation ( PP00P1_128574 PP00P1_150739 and CRSII3_141965 ). RER was supported by the UK Medical Research Council ( Mr/J004685/1 ).
- Sex hormones