Comparing the neural basis of mixed-motive versus coordination games in people with different social preferences, an fMRI study

We use fMRI to investigate the neurological correlates of two factors that are known to enhance cooperative strategies in social dilemmas: the provision of extrinsic cooperative incentives, and the intrinsic motivation to cooperate. The former is achieved by changing the pay-off matrix of a mixed motive game (e.g., a Prisoner’s Dilemma, PD) to a coordination game (CG). The latter is achieved by comparing people who differ along the personality trait Social Value Orientation. Previous studies have indicated that proself oriented individuals (“hawks”) adopt a competitive strategy in a PD but switch to a cooperative strategy in a CG, while prosocial individuals (“doves”) maintain high levels of cooperation across games. A major aim of this study is to examine if there are fundamental neurological differences between prosocials and proselfs that substantiate these different behavioral strategies. Our imaging data of a full brain analysis contrasting PD and CG confirm that the PD poses a conflict (increased ACC activation) and induces subjects to think about the possible consequences for self and others (more prefrontal cortex activity). More importantly, a region of interest analysis contrasting prosocials and proselfs suggests that proselfs’ strategies are driven by calculation and self-interest. Increased activation was found in the precuneus, DLPFC, the posterior STS, and caudate nucleus. Prosocials’ strategies reflect norm compliance, morality, and social interaction. Increased activation was found in the lateral orbotifrontal cortex and the social brain network (including the ventromedial cortex, anterior STS, inferior parietal lobule, and amygdala).