Delineating testosterone's impact on model-based and model-free decision-making processes

Testosterone is believed to increase impulsive behaviour in men, sparking an ongoing debate about whether testosterone biases decision-making towards intuitive choices that necessitate less cognitive effort. In this study, we administered testosterone to 216 healthy men and employed a sequential decision-making paradigm complemented by computational modelling to assess the impact of testosterone on the arbitration between goal-directed ('model-based') and reflexive ('model-free') decision-making. We found no evidence that testosterone affects the weight on model-based valuation when making choices, either in absolute terms or relative to the model-free weighting. Instead, testosterone administration reduced the absolute weight on model-free valuation and led to a decrease in points earned in trials of the task that did not require keeping the mapping between stages in mind. These findings provide evidence against the hypothesis that testosterone supports intuitive decision-making by reducing the willingness to exert cognitive effort.