Can VR Robots Stand in for the Real Thing? Comparing a Physical Cobot and Its Virtual Twin for User Perceptions, Experimental Effects, and Study Costs

Researchers in Human-Robot Interaction (HRI) increasingly consider Virtual Reality (VR) for running user studies that would otherwise require physical robots. Yet it remains unclear when VR can serve as a valid proxy for real-world interaction. We present a preregistered comparison between two studies in which participants completed tasks with either a physically present cobot (N = 61) or its virtual twin (N = 39) in an immersive collaboration game. Procedures, game environment, task flow, and robot behavior were held constant across settings; the primary difference was the robot's embodiment. Our work delivers (1) a direct comparison of user perceptions and behavioral outcomes (e.g., attitudes, trust, presence, task completion time); (2) a replication test of an experimental manipulation (two different introductory tutorials); and (3) an analysis of study execution costs. Our results show no significant differences in any of the subjective self-reports between the virtual and physical robot, but task durations were longer with the physical robot, and tutorial effects replicated only partially across settings. Study costs were substantially lower for VR. Together, these findings provide a holistic assessment of VR's suitability as a complementary tool for HRI research, offering guidance for future study design and resource planning.