THE BODILY APPEARANCE OF A VIRTUAL PARTNER AFFECTS THE ACTIVITY OF THE ACTION OBSERVATION AND ACTION MONITORING SYSTEMS IN A MINIMALLY INTERACTIVE TASK

One pending question in social neuroscience is whether interpersonal interactions are processed differently by the brain depending on the bodily characteristics of the interactor, i.e., their physical appearance. To address this issue, we engaged participants in a minimally interactive task with an avatar either showing bodily features or not while recording their brain activity using Electroencephalography (EEG) in order to investigate indices of action observation and action monitoring processing. Multivariate results showed that bodily compared to non-bodily appearance modulated parieto-occipital neural patterns throughout the entire duration of the observed movement and that, importantly, such patterns differ from the ones related to initial shape processing. Furthermore, among the electrocortical indices of action monitoring, only the early observational Positivity (oPe) was responsive to the bodily appearance of the observed agent under the specific task requirement to predict the partner movement. Taken together, these findings broaden the understanding of how bodily appearance shapes the spatiotemporal processing of an interactor's movements. This holds particular relevance in our modern society, where human-artificial (virtual or robotic) agent interactions are rapidly becoming ubiquitous. Significance statement During interpersonal motor interactions, the observation and monitoring of other's actions are essential mechanisms depending on two interconnected brain networks. Whether the neurophysiological signatures of action observation and monitoring are modulated by the appearance of an interacting partner remains an open question of particular relevance in order to tackle how the brain interfaces with artificial agents. In the present study we used highly ecological virtual stimuli in a minimally interacting scenario as well as univariate and multivariate EEG analyses to broaden our understanding of the influence of bodily appearance on the spatiotemporal processing of biological movements in the AON and in the action monitoring system.