The project has produced a testable mechanistic account of human mutual understanding abilities with implications for several academic fields (Stolk et al., TiCS 2016; Wheatley et al., Neuron 2019). This account makes predictions on the neuronal mechanisms supporting core interpersonal processes as well as how alterations of these mechanisms affect observable communicative behavior. Building bridges to the clinical domain, the project has tested some of the predictions by investigating social conduct deficits in medial prefrontal lesion patients (Stolk et al., Current Biology 2015) and sources of misunderstanding in individuals on the autism spectrum (Wadge et al., Cortex 2019). The project has also laid the groundwork for investigating the neuronal mechanisms supporting the creation of mutual understanding during social interaction. We have acquired scalp EEG simultaneously from interacting subjects and we have successfully developed a new methodological framework that improves the precision and reproducibility of intracranial EEG studies (Stolk et al., Nature Protocols 2018; Holdgraf et al., Nature Scientific Data 2019; Stolk et al., eLife 2019). The latter study types involve electrodes implanted in individuals undergoing presurgical monitoring for refractory epilepsy and provide rare but precise access to neurocognitive mechanisms underlying human mutual understanding.