Real world decisions are usually made within a social context. Many of our actions are chosen considering vicarious feelings of another’s reward or pain. However, there are times where this desire for another’s wellbeing is in conflict with self-interest, resulting in the need to rely upon strategic reasoning about the beliefs, desires, and goals of others to make our decisions.

To take a closer look at the neural mechanisms underlying such processes, we utilize a iterated game which allows interactive play between two players. We demonstrated that the primates, both human and non-human rely upon recursive reasoning to carry out gameplay. In the non-human primates, we obtained spiking activity in two brain areas, the primate homolog of the temporal-parietal junction (TPJ) which is implicated in mentalizing, and the anterior cingulate gyrus, an area connected to empathy and vicarious experience. We found that the neurons in TPJ were able to signal cooperative action, an abstract concept that is independent of realized reward and motor action. This suggests that the capacity to reason strategically is deeply rooted in the social behavior of primates.