Seeing Avatars during Social Interaction in VR May Enhance Inter-Brain Synchronization

Does seeing avatars during social interaction in virtual reality (VR) affect the neural synchrony of interacting people? To address this question, we assessed inter-brain synchronization (IBS), which reflects synchronization of brain activities among interacting people and is linked to interaction success. We designed a social interaction task in VR where participants' appearances were represented by virtual cursors only or additional human avatars on them. Participants performed a finger position tracking interaction under both conditions. We compared the IBS across interaction conditions by collecting electroencephalography (EEG), positional data, and virtual embodiment questionnaires. The results from 30 participants (15 pairs) show that seeing the avatars resulted in significantly higher virtual body ownership but comparable agency and positional synchronization compared to the virtual cursors-only condition. In the inter-brain analysis, we found a significant increase in IBS strength and an increasing trend in the number of IBS in the alpha band after interacting with avatarembodied virtual cursors. Correlation analyses further revealed a significant association between alpha-band IBS and subjective body ownership, and a trend with social inclusion scores. While the influence of visual complexity cannot be ruled out, these findings suggest that avatar-induced embodiment may contribute to enhanced inter-brain synchrony during VR-mediated social interaction.