The Dark Side of Mentalizing: Learning Signals in the Default Network During Social Exchanges Support Cooperation and Exploitation.

To navigate complex social lives, humans must learn from their interactions with others and adjust their own behavior accordingly. Here, we show that humans learn to predict the behavior of social counterparts by integrating reputational information with both observed and counterfactual feedback acquired during social experience. We find that superior learning during social interactions is related to empathy and compassion and associated with activity of the brain's default network. Paradoxically however, learning signals in the default network are also associated with manipulativeness and exploitativeness, suggesting that the ability to anticipate others' behavior can serve both the light and dark sides of human social behavior.