Shared Avatar for Hand Movement Imitation: Subjective and Behavioral Analyses

Virtual co-embodiment enables sharing avatars with others in virtual environments and can be applied for training motor skills by allowing teachers to share movements with learners in first-person perspective. We conducted a task where participants were asked to imitate pre-recorded hand movements of a teacher as accurately as possible. The participant’s virtual hand movements were averaged in real-time with those of the teacher (shared avatar hand). We compared their usability ratings and behavior against a controlled condition with full control of the hand (solo avatar hand). The teacher’s hand was displayed facing the same or the opposite direction as the participant’s hand. We hypothesized that using the shared avatar hand would improve imitation over using the solo hand, and the teacher’s hand presented in the same direction is better than that in the opposite direction. Subjective ratings showed that the shared hand was easier to use than the solo hand, and the teacher’s hand when presented in the same direction was easier to imitate than when presented in the opposite direction. Spatial error was less with the opposite-direction presentation than the same-direction presentation of the teacher’s hand, irrespective of movement sharing. Time delay was less when the participants used the shared hand compared to when they used the solo hand, irrespective of the teacher’s hand direction. These results suggest that sharing movements enhances usability and matching speed during movement imitation, and the same-direction presentation of the teacher’s hand improves usability while the opposite-direction presentation improves spatial accuracy of motor imitation.