Analyzing the effect of a virtual avatar's geometric and motion fidelity on ego-centric spatial perception in immersive virtual environments

Previous work has shown that giving a user a first-person virtual avatar can increase the accuracy of their egocentric distance judgments in an immersive virtual environment (IVE). This result provides one of the rare examples of a manipulation that can enable improved spatial task performance in a virtual environment without potentially compromising the ability for accurate information transfer to the real world. However, many open questions about the scope and limitations of the effectiveness of IVE avatar self-embodiment remain. In this paper, we report the results of a series of four experiments, involving a total of 40 participants, that explore the importance, to the desired outcome of enabling enhanced spatial perception accuracy, of providing a high level of geometric and motion fidelity in the avatar representation. In these studies, we assess participants' abilities to estimate egocentric distances in a novel virtual environment under four different conditions of avatar self-embodiment: a) no avatar; b) a fully tracked, custom-fitted, high fidelity avatar, represented using a textured triangle mesh; c) the same avatar as in b) but implemented with single point rather than full body tracking; and d) a fully tracked but simplified avatar, represented by a collection of small spheres at the raw tracking marker locations. The goal of these investigations is to attain insight into what specific characteristics of a virtual avatar representation are most important to facilitating accurate spatial perception, and what cost-saving measures in the avatar implementation might be possible. Our results indicate that each of the simplified avatar implementations we tested is significantly less effective than the full avatar in facilitating accurate distance estimation; in fact, the participants who were given the simplified avatar representations performed only marginally (but not significantly) more accurately than the participants who were given no avatar at all. These findings suggest that the beneficial impact of providing users with a high fidelity avatar self-representation may stem less directly from the low-level size and motion cues that the avatar embodiment makes available to them than from the cognitive sense of presence that the self-embodiment supports.