Face-to-face spatial orientation fine-tunes the brain for neurocognitive processing in conversation.

We here demonstrate that face-to-face spatial orientation induces a special 'social mode' for neurocognitive processing during conversation, even in the absence of visibility. Participants conversed face to face, face to face but visually occluded, and back to back to tease apart effects caused by seeing visual communicative signals and by spatial orientation. Using dual EEG, we found that (1) listeners' brains engaged more strongly while conversing face to face than back to back, irrespective of the visibility of communicative signals, (2) listeners attended to speech more strongly in a back-to-back compared to a face-to-face spatial orientation without visibility; visual signals further reduced the attention needed; (3) the brains of interlocutors were more in sync in a face-to-face compared to a back-to-back spatial orientation, even when they could not see each other; visual signals further enhanced this pattern. Communicating in face-to-face spatial orientation is thus sufficient to induce a special 'social mode' which fine-tunes the brain for neurocognitive processing in conversation.