Neuroimaging studies of human decision making have emphasized two distinct brain networks underlying choices in social contexts; on the one hand, reward-related regions and on the other, a set of regions active during mentalizing and perspective taking. However, the precise role of individual brain regions within these networks and their relationships during social choices are not well understood. The experimental studies described in this thesis aimed at answering these questions, by directly comparing decision making processes in private and social settings. More specifically, the goal of this work was to understand how emotions elicited by counterfactual and social comparisons (such as regret and envy, respectively) influence choice, and to compare the brain activity underlying these effects. Experimental results are presented from four studies, using an original monetary choice task in combination with diverse methodologies, including eye-tracking, physiological recordings, functional brain imaging and study of patients with brain injury. When participants were given the opportunity to compare their choice and outcome with that of a counterpart, they engaged in competitive behavior. They assigned a relatively larger weight to social gains than to social losses, strongly affecting economic choices. This result contrasts with current theories of decision making in private contexts.
Neural underpinnings of this behavioral effect involved the interaction between regions of the reward-related and mentalizing brain networks. The direct comparison of private and social settings revealed that different brain regions were involved in counterfactual and social comparison. This dissociation between regret and envy was confirmed by a study with brain-lesioned patients.
Decision making, emotions, regret, envy, gloating, ventromedial prefrontal cortex, striatum
Results of the behavioral study have been published (see the Publications Page)