Our daily lives are shaped by a series of decision processes, ranging from very unimportant choices to life-changing judgments. The complexity of the decision processes increases tremendously when the decision-making takes place in a social context, i.e., when other human beings are directly involved in the decision. In such conditions the decision-maker not only tries to maximize his own utility, but also needs to take into account the interdependent nature of the situation. Information about others’ preferences, characteristics, and actions play an important role, and need to be thoroughly evaluated and predicted before making a decision. In this thesis we explore the neural correlates of two different types of social decision-making.

In the first experiment we investigate economic decision-making in the context of a two-player social exchange game. In order to maximize their overall and personal earnings, players need to cooperate and build up a trust relationship with their partner. Synchronized neural data is recorded from the two interacting brains using functional magnetic resonance imaging. In this thesis we present four main findings: (i) the neural correlates of strategic uncertainty and how it can be used to predict a player’s future strategic choice; (ii) the dynamic interaction of the brains of two interacting players; (iii) the neural correlates of trust and its development over the course of the game; and (iv) how the brain distinguishes between one’s own actions and those of another person.