Does Hand Size Matter? The Effect of Avatar Hand Size on Non-verbal Communication in Virtual Reality

Virtual reality (VR) has increasingly become a popular platform for socializing and collaborating remotely because it enables both verbal and nonverbal aspects of communication through the use of embodied avatars. However, such avatars are not typically adjusted to match the proportions of the user, leading to inaccuracies which might diminish experiences involving nonverbal communication. Therefore, in this paper, we investigated the impact that out-of-proportion avatar hands (relative to the user's hands) have on nonverbal communication and collaboration in VR. We designed an experiment based on the game "charades", wherein two users nonverbally interact with each other trying to communicate and guess words. In a within-subjects study with 72 participants (36 dyads), participants' avatar hands were scaled to be 25% smaller, the same size, and 25% larger than their own hands. We measured aspects related to task performance, avatar embodiment, communication satisfaction, workload, and user experience. We found that changes in hand size of 25% did not significantly impact any of our measurements when looking at all participants. Interestingly, despite the relatively obvious change in size, less than half of the participants noticed this change. On further inspection, we uncovered significant effects in two of our workload measures when focusing only on the participants who noticed the changes. We conclude that the effects of changes in hand size may be modest for the type of task and hand size manipulations investigated in this work.