Human hippocampus and dorsomedial prefrontal cortex infer and update latent causes during social interaction

When an important event occurs, the observer should identify which features of the environment might have caused it. This is the latent cause inference problem, and it must be solved if observers are to understand their environments. The problem is acute in social settings where individuals may not make equal contributions to the outcomes they achieve together. Here, we designed a novel task in which participants inferred which of two characters was the more likely to have been responsible for outcomes achieved by working together. Using computational modelling, univariate and multivariate analysis of human fMRI, and continuous theta burst stimulation we identified two brain regions that solved the task. Notably, as each outcome occurred, it was possible to decode inference of its cause (the responsible character) from activity in hippocampus. Activity in dorsomedial prefrontal cortex updated estimates of association between cause -- the responsible character – and the outcome. ### Competing Interest Statement The authors have declared no competing interest.