Computational and Motivational Mechanisms of Human Social Decision Making Involving Close Others

Abstract

Every day, human beings make decisions with social consequences. These social consequences matter most when they impact those closest to us. Recent research has shown that humans exhibit reliable preferences when deciding between conflicting outcomes involving close others -for example, prioritizing the interests of one's family member over one's friend. However, virtually nothing is known about the mechanisms that drive these preferences. We conducted a pre-registered study in a large (N = 375) sample to quantify the computational and motivational mechanisms of human social decision making preferences involving close others. By pairing assessment techniques from behavioral economics and psychological science with computational modeling and random coefficient regression, we show that value-based cognitive computations (e.g., risk and loss aversion) drive social decision making preferences involving financial outcomes, whereas socioemotional motivations (e.g., relationship quality) underlie preferences involving social outcomes. These results imply mechanistic heterogeneity, underscoring a need for greater attention to contextual specificity in social decision making. Significance StatementAs social creatures, humans frequently make decisions that affect our loved ones. However, relatively little work has examined the factors that govern social decision making involving those closest to us. Here we sought to uncover the computational and motivational architecture of social decision making preferences involving two important close others, parents and friends. We demonstrated that individuals favored parents over friends in decision making with financial outcomes, whereas no clear preference emerged for decisions with social outcomes. Value-based computations drove decisions with financial outcomes whereas socioemotional motivations guided decisions with social outcomes. Our results illuminate how and why individuals make decisions they do involving those closest to them.