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Abstract

Experiences shape preferences. This is particularly the case when they deviate from our expectations and thus elicit prediction errors. Here we show that prediction errors do not only occur in response to actual events - they also arise endogenously in response to merely imagined events. Specifically, we show that people acquire a preference for acquaintances as they imagine interacting with them in unexpectedly pleasant situations. This learning can best be accounted for by a computational model that calculates prediction errors based on these rewarding experiences. Using functional MRI, we show that the prediction error is mediated via striatal activity. This activity, in turn, seems to update preferences about the individuals by updating their cortical representations. Our findings demonstrate that imaginings can violate our own expectations and thus drive endogenous learning by coopting a neural system that implements reinforcement learning. They reveal fundamental principles how we acquire knowledge devoid of actual experiences.