Investigating the Effects of Haptic Illusions in Collaborative Virtual Reality

Our sense of touch plays a crucial role in physical collaboration, yet rendering realistic haptic feedback in collaborative extended reality (XR) remains a challenge. Co-located XR systems predominantly rely on prefabricated passive props that provide high-fidelity interaction but offer limited adaptability. Haptic Illusions (HIs), which leverage multisensory integration, have proven effective in expanding haptic experiences in single-user contexts. However, their role in XR collaboration has not been explored. To examine the applicability of HIs in multi-user scenarios, we conducted an experimental user study (N=30) investigating their effect on a collaborative object handover task in virtual reality. We manipulated visual shape and size individually and analyzed their impact on users' performance, experience, and behavior. Results show that while participants adapted to the illusions by shifting sensory reliance and employing specific sensorimotor strategies, visuo-haptic mismatches reduced both performance and experience. Moreover, mismatched visualizations in asymmetric user roles negatively impacted performance. Drawing from these findings, we provide practical guidelines for incorporating HIs into collaborative XR, marking a first step toward richer haptic interactions in shared virtual spaces.