Causal evidence of right temporal parietal junction involvement in implicit Theory of Mind processing

The ability to represent the internal thoughts, beliefs and desires of others, and recognise that these might be distinct from one's own, is crucial for adaptive social interaction. Such operations are thought to tap Theory of Mind (ToM), with its importance underscored by the link between ToM impairment and a range of neurodevelopmental disorders (e.g., Autism and Schizophrenia). Extensive investigations into the neural substrates of ToM, when individuals have to make overt/explicit judgments concerning others, have highlighted a link with a network of regions including the temporal parietal junction (TPJ), particularly in the right hemisphere. Recently, evidence has emerged that ToM can also operate implicitly and that this may be particularly impaired in Autism. However, very few studies have examined the neural basis of implicit ToM and none have employed methods allowing casual inferences to be made. Here, using brain stimulation, a Sally-Anne false-belief task, and eye-tracking we show that right TPJ is causally involved in ToM judgments that are made implicitly. These findings have implications for characterising the neural substrates of a key executive function, determining the extent to which implicit and explicit ToM draw on overlapping neural architecture and, potentially, better understanding of disorders tied to ToM impairment.