Theory of Mind and the brain substrates of direct and indirect communicative action understanding

Grasping the speaker's communicative intention based on the verbal utterance and its context is one of the key aspects of human interaction. This ability relies on theory of mind (ToM), that is, the cognitive processing of mental states, beliefs and desires of others. We review evidence showing that brain regions ypically engaged in ToM processing, particularly the medial prefrontal cortex and bilateral temporo-parietal junction, are activated when listeners interpret indirect speech acts. However, other studies show a degree of variability of these 'ToM area activations' during indirect communication, while yet others demonstrate that the same areas are activated for specific communicative functions, such as requests, promises or questions per se, even when expressed directly. Furthermore, we show that studies on indirectness of communication raise questions about the role of different communicative function types in drawing upon 'ToM regions'. We attempt to relate cortical area activations to the commitments, assumptions and intentions that the interlocutors commit to when processing specific communicative function types. In essence, all communicative actions, including both direct and indirect ones, have in common that relevant knowledge about others' intentions and beliefs needs to be processed by the interlocutors.This article is part of the theme issue 'At the heart of human communication: new views on the complex relationship between pragmatics and Theory of Mind'.