Virtual co-embodiment enables two users to share a single avatar in Virtual Reality (VR). During such experiences, the illusion of shared motion control can break during joint-action activities, highlighting the need for position-aware feedback mechanisms. Drawing on the perceptual crossing paradigm, we explore how haptics can enable non-verbal coordination between co-embodied participants. In a within-subjects study (20 participant pairs), we examined the effects of vibrotactile haptic feedback (None, Present) and avatar control distribution (25-75%, 50-50%, 75-25%) across two VR reaching tasks (Targeted, Free-choice) on participants' Sense of Agency (SoA), co-presence, body ownership, and motion synchrony. We found (a) lower SoA in the free-choice with haptics than without, (b) higher SoA during the shared targeted task, (c) co-presence and body ownership were significantly higher in the free-choice task, (d) players' hand motions synchronized more in the targeted task. We provide cautionary considerations when including haptic feedback mechanisms for avatar co-embodiment experiences.

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CHI Conference on Human Factors in Computing Sytems, CHI 2024
Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands

Venkatraj, K., Meijer, W., Perusquía-Hernández, M., Huisman, G., & El Ali, A. (2024). ShareYourReality: Investigating haptic feedback and agency in virtual avatar co-embodiment. In Proceedings of the Conference on Human Factors in Computing Systems (pp. 1–15). doi:10.1145/3613904.3642425