The interaction effect between gain–loss framing and monetary amount on moral decision-making: evidence from behavioral and ERPs studies

Moral decision-making frequently requires individuals to navigate a conflict between their own self-interest and the imperative to prevent harm to others. When people choose to sacrifice their personal interests in favor of safeguarding the well-being of others, they are exhibiting altruistic behavior. However, existing research on the psychological motivations and neural mechanisms underlying such costly altruistic choices remains limited. To address the issue, the current research investigated how the cost of altruistic behavior influenced decision-making by considering the gain-loss framing effect. Behavioral results revealed that in the gain frame, participants were more likely to prevent harm to others in the small monetary condition than in the large. In the loss frame, they tended to prioritize protecting their self-interests in the large monetary condition more than in the small one. ERP results showed that the gain-loss frame and monetary amount jointly modulated N1 and P3 amplitudes. Specifically, there was no significant difference in N1 amplitudes in the gain frame; however, in the loss frame, large monetary amounts elicited more negative N1 amplitudes. P3 amplitudes were larger for large monetary amounts than for small ones in the gain frame, while small and large amounts evoked comparable P3 amplitudes in the loss frame. These findings suggest that the gain-loss framing effect and the monetary amount interact in a complex way to shape how individuals engage in altruistic behavior. This study deepens our understanding of moral decision-making and offers valuable empirical evidence that could help in promoting prosocial behavior.