Do implicit and explicit belief processing share neural substrates?

Humans rely on their ability to infer another person's mental state to understand and predict others' behavior ("theory of mind," ToM). Multiple lines of research suggest that not only are humans able to consciously process another person's belief state, but also are able to do so implicitly. Here we explored how general implicit belief states are represented in the brain, compared to those substrates involved in explicit ToM processes. Previous work on this topic has yielded conflicting results, and thus, the extent to which the implicit and explicit ToM systems draw on common neural bases is unclear. Participants were presented with "Sally-Anne" type movies in which a protagonist was falsely led to believe a ball was in one location, only for a puppet to later move it to another location in their absence (false-belief condition). In other movies, the protagonist had their back turned the entire time the puppet moved the ball between the two locations, meaning that they had no opportunity to develop any pre-existing beliefs about the scenario (no-belief condition). Using a group of independently localized explicit ToM brain regions, we found greater activity for false-belief trials, relative to no-belief trials, in the right temporoparietal junction, right superior temporal sulcus, precuneus, and left middle prefrontal gyrus. These findings extend upon previous work on the neural bases of implicit ToM by showing substantial overlap between this system and the explicit ToM system, suggesting that both abilities might recruit a common set of mentalizing processes/functional brain regions. Hum Brain Mapp 38:4760-4772, 2017.