Abstract
Although patients with schizophrenia exhibit profound deficits in social cognition, studies into the neurobiological background of these deficits examined individuals in isolation, in single-person settings. We investigated the neurobiological basis of social cognitive deficits in a social setting, applying a novel approach using EEG-hyperscanning. Eighty subjects were included in the analyses, 49 healthy controls (HC) and 31 patients with schizophrenia. We recorded high-density EEG from pairs of participants, where one (the observer) watched their own screen while the other (the actor) actively performed a Go/NoGo task. The task was administered twice, with the participants switching roles. We focused on investigating the P300 event-related potential from the observer condition. The PANSS scale was used to characterize psychopathology. The Reading the Mind in the Eyes Test and the d-prime index were applied to characterize mentalization and signal detection ability. We found that patients with schizophrenia showed significant P300 reduction compared to the HC group at the first task exposure. They, however, exhibited augmented P300 with the repeated exposure, while HCs manifested a decrease. More severe positive symptoms were associated with larger P300 at both task-exposures. Moreover, poorer mentalization and signal detection performance were associated with decreased P300. Our findings provide evidence that P300 alterations in schizophrenia can be detected in social setting. The opposite changes in the two groups may be due to disparate reasons: habituation in HCs, whereas the alterations in patients may result from various factors, including deficient habituation and an aberrant processing of stimulus salience in a social setting.