“Of heart and mind”: The role of reasoning and prosocial motives in social decision-making

According to economics and evolutionary biology, many social decisions are driven by the incentives at play, which can favour cooperation or competition. Experiments in behavioral economics and psychology have also shown that, in addition to cooperative and competitive incentives, such strategic decisions are shaped by individual differences in reasoning ability and prosocial dispositions. However, no study has simultaneously investigated how both factors contribute to social decision-making in cooperative and competitive environments. This study aims to fill this gap. We hypothesized that prosociality would increase cooperative and reduce competitive decision-making, and that reasoning would moderate this relationship only in competitive environments, as cooperative incentives alone are sufficient to drive cooperation without requiring high levels of reasoning. Reasoning abilities were measured using a matrix reasoning task (the MaRs-IB), and prosocial dispositions were assessed using the Social Value Orientation task. The social decision-making environment was manipulated with the use of two economic games that asked pairs of anonymous participants to maximize their gains by choosing between a low paying but safe option - whose value varied by trial - and a potentially higher paying but risky option, which depended on the choice of one’s counterpart. If both players choose the risky option, they both secure the maximum gain in the cooperative game, but they would both get zero in the competitive game, where one only gained the maximum by choosing the risky option alone. In the non-social control condition, the outcome of the risky option depended on the outcome of a lottery. A three-way interaction was found between prosociality, reasoning and game condition, as the effect of prosociality on risk was moderated by reasoning ability: in people with higher but not lower reasoning ability, prosocial motives were more likely to decrease risk taking in the competitive than in the cooperative environment. This was especially driven by the competitive environment, where prosocial participants with high levels of reasoning ability opted to take risks less frequently, thus favouring their counterpart to gain more. These findings add to the literature on prosociality and reasoning, suggesting that prosocial individuals with higher reasoning ability can use their cognitive resources to better guide their prosocial tendencies in competitive settings.