Decision for self and other modulates risk attitude and electrophysiological processing: evidence from a behavioral and electrophysiological experiment

Understanding how people make risky decisions for others compared to themselves is central to decision neuroscience. However, the cognitive and neural underpinnings of such self-other shifts in risk preference-and the mechanisms driving individual differences-remain unclear. To address this, we employed a mixed gambling task with feedback in which participants made risky decisions for themselves and for others while electroencephalography was recorded. Although individuals generally exhibited similar patterns across agents, decisions made for others were associated with a higher degree of risk-taking compared to those made for oneself. In terms of individual heterogeneity, predispositions and decision weights derived from the drift-diffusion model accounted for individual differences and agent-specific shifts in risk preferences. The event-related potential (ERP) component P300 was significantly modulated by the agent, valence, and risk attitude. Critically, risk-averse individuals showed larger P300 deflections and greater amplitude differences between the self and other conditions, whereas risk-seeking individuals exhibited smaller and more uniform P300 responses across agents. Together, these findings highlight both shared and distinct behavioral and neural mechanisms underlying risky decision-making for self and others and underscore the potential of ERP components as neural markers of decision-making under risk in social contexts.