The monitoring system is attuned to others' actions during dyadic motor interactions

Abstract

Successful interpersonal motor interactions necessitate the simultaneous monitoring of our own and our partners actions. To characterize the dynamics of the action monitoring system for tracking self and other behaviors during dyadic synchronous interactions, we combined EEG recordings and immersive Virtual Reality in two tasks where participants were asked to coordinate their actions with those of a Virtual Partner (VP). The two tasks differed in the features to be monitored: the Goal task required participants to predict and monitor the VPs reaching goal; the Spatial task required participants to predict and monitor the VPs reaching trajectory. In both tasks, the VP performed unexpected movement corrections to which the participant needed to adapt. By comparing the neural activity locked to the detection of unexpected changes in the VP action (other-monitoring) or to the participants action-replanning (self-monitoring), we show that during interpersonal interactions the monitoring system is more attuned to others than to ones own actions. Additionally, distinctive neural responses to VPs unexpected goals and trajectory corrections were found: goal corrections were reflected both in early fronto-central and later posterior neural responses while trajectory deviations from the expected movement were reflected only in later and posterior responses. Since these responses were locked to the partners behavior and not to ones own, our results indicate that during interpersonal interactions the action monitoring system is dedicated to evaluating the partners movements. Hence, our results reveal an eminently social role of the monitoring system during motor interactions. Significance StatementNon-verbal synchronous interpersonal interactions require the monitoring of both our actions and those of our partners. Understanding the neural underpinnings of this ability with a focus on the dynamics between self- and other-monitoring is fundamental to the comprehension of social coordination. By combining EEG and immersive Virtual Reality we demonstrate that the monitoring system is more attuned to others actions than to our own. In two tasks, we show that the neural activity associated with unexpected corrections in the goal or the trajectory of an action are locked to the partners actions rather than to the participants subsequent adaptation. This pattern of results highlights a social mode adopted by the monitoring system to handle motor interactions.