No effect of glucocorticoid and noradrenergic activity on consistency in prosocial choice

Stress can alter the way people make decisions, affecting domains such as risk-taking and social interaction. Growing evidence suggests that this may be driven by distinct effects of the stress neuromodulators cortisol and noradrenaline. For example, stress-induced neuromodulatory changes can influence social decision-making, promoting either prosocial or antagonistic tendencies and consequently shifting underlying values and preferences. While choices are directly observable, preferences are not and must instead be inferred from observed choice patterns. This inference relies on the assumption that preferences remain stable throughout the observation period, as reflected in the internal consistency of choices. However, the effects of stress on social decision-making challenge this notion. This raises the question of whether choice consistency - the basis for inferring preferences from choices - remains robust across dynamic changes in neuromodulator activity. Therefore, we examined whether cortisol and noradrenaline affect prosocial decision-making and choice consistency. In a double-blind psychopharmacological study, we exogenously manipulated cortisol and/or noradrenaline activity by administering hydrocortisone, yohimbine, both hydrocortisone and yohimbine, or placebo to 129 participants. Prosocial decision-making was measured using a modified dictator game before and after drug administration, and choice consistency was quantified within the framework of the Generalized Axiom of Revealed Preferences. Our results indicate that neither cortisol nor noradrenergic activity affected prosocial decision-making or choice consistency, suggesting that social preferences remain stable despite changes in neurohormonal states. These findings underscore the robustness of choice consistency across neurohormonal fluctuations and illustrate the complexity of how stress neuromodulators shape (social) decision-making.