People matter: Perceived sender identity modulates cerebral processing of socio-emotional language feedback.

How do human brains integrate content with social context in communication? Recent research demonstrates that the perceived communicative embedding of perceptually identical language messages alters their cortical processing. When emotional trait-adjectives are perceived as human-generated personality feedback, event-related brain potentials are considerably larger than when the same adjectives are perceived as random computer-generated feedback. Here, we investigate the unique role of ascribed sender humanness for the underlying neural mechanisms. Participants were told that they were going to receive written positive, negative, or neutral feedback from an unknown stranger or from a socially intelligent computer system while high-density EEG was recorded. In the event-related potential (ERP), feedback from the 'human sender' elicited larger P2, Early Posterior Negativity (EPN), P3, and Late Positive Potential (LPP) components. The sources of this activity were localized in extended visual cortex, but also in the right superior frontal gyri, related to mentalizing about others, and the bilateral postcentral gyri implicated in embodied language processing. For emotional feedback, larger EPN, P3 and LPP amplitudes were also observed, resulting from enhanced activity in visual and temporal regions. Finally, for the EPN an interaction between sender and emotion was found, showing substantially increased visual processing of human-generated emotional feedback. These data confirm visual amplification effects induced by motivated attention but crucially also reveal distinct effects of perceiving a communication partner as human that activate 'social brain' structures. Obviously who is perceived as saying something can be as relevant as what is said and induce specific brain activity.