Learning to Simulate Others' Decisions

A fundamental challenge in social cognition is how humans learn another person@s values to predict their decision-making behavior. This form of learning is often assumed to require simulation of the . other by direct recruitment of one@s own valuation process to model the other@s process. However, the cognitive and neural mechanism of simulation learning is not known. Using behavior, modeling, and fMRI, we show that simulation involves two learning signals in a hierarchical arrangement. A simulated-other@s reward prediction error processed in ventromedial prefrontal cortex mediated simulation by direct recruitment, being identical for valuation of the self and simulated-other. However, direct recruitment was insufficient for learning, and also required observation of the other@s choices to generate a simulated-other@s action prediction error encoded in dorsomedial/dorsolateral prefrontal cortex. These findings show that simulation uses a core prefrontal circuit for modeling the other@s valuation to generate prediction and an adjunct circuit for tracking behavioral variation to refine prediction.