An embodied body morphology task for investigating self-avatar proportions perception in Virtual Reality

The perception of one's own body is subject to systematic distortions and can be influenced by exposure to visual stimuli showing distorted bodies. In Virtual Reality (VR), echoing such body judgment inaccuracies, avatars with strong appearance dissimilarities with respect to users' bodies can be successfully embodied. The present experimental work investigates, in the healthy population, the perception of the own body in immersive and embodied VR, as well as the impact of being co-present with virtual humans on such self-perception. Participants were successively presented with different avatars, corresponding to various upper- and lower-body proportions, and were asked to compare them with their perceived own body morphology. To investigate the influence of co-present virtual humans on this judgment, the task was performed in co-presence with virtual agents corresponding to various body appearances. Results show an overall overestimation of one's leg length and no influence of the co-present agent's appearance. Importantly, the embodiment scores reflect such body morphology judgment inaccuracy, with participants reporting lower levels of embodiment for avatars with very short legs than for avatars with very long legs. Our findings suggest specifics of embodied body judgment methods, likely resulting from the experience of embodying the avatar as compared to visual appreciation only.