How the Ventromedial Prefrontal Cortex (VMPFC) Facilitates Welfare Maximization in Social Contexts

Social decision-making is a fundamental aspect of human behavior. Utilitarian philosophy, as articulated by Hume (2003), posits that social decision-makers should opt for choices that maximize the overall welfare of the group. This approach necessitates comparing individual preferences on a common scale—meaning that each person's welfare must be measured in a way that allows meaningful comparisons across individuals. However, the legitimacy and possibility of such interpersonal utility comparisons has been the subject of significant debate. Roberts (1997) rigorously shows that combining different individuals’ utility judgments into a single, objective scale is only feasible under very strong assumptions; otherwise, the process leads to extreme outcomes, such as relying solely on one person's perspective. Despite these theoretical difficulties, humans routinely engage in informal forms of such comparisons in everyday life. From choosing a restaurant with friends to formulating national policies, we constantly face the challenge of balancing diverse preferences to maximize collective welfare. This cognitive ability is crucial for preventing social discord. The neural mechanisms underpinning our ability to maximize collective welfare have been a subject of increasing interest in neuroscience, as researchers seek to bridge the gap between abstract philosophical concepts and concrete biological mechanisms. A key component of this ability is the generation of neural representations of value associated with stimuli, actions, or decisions for each individual in the group. Previous research has identified several brain regions involved in value representation and social decision-making. The orbitofrontal cortex (OFC), ventromedial prefrontal cortex (VMPFC), and striatum can all encode subjective values (Padoa-Schioppa and Assad, 2006; Bartra et al., 2013; Clithero and Rangel, 2014). The VMPFC and striatum are also implicated in processing vicarious rewards … Correspondence should be addressed to Manning Zhang at manningzhang{at}g.ucla.edu.