Virtual Hand Realism Affects Object Size Perception in Body-Based Scaling

How does the representation of an embodied avatar influence the way in which one perceives the scale of a virtual environment? In virtual reality, it is common to embody avatars of various appearances, from abstract to realistic. It is known that changes in the realism of virtual hands affect the self-body perception, including body ownership. However, the influence of self-avatar realism on the perception of non-body objects has not been investigated. Considering the theory that the scale of the external environment is perceived relative to the size of one's body (body-based scaling), it can be hypothesized that the realism of an avatar affects not only body ownership but also the fidelity of the avatar with respect to our own body as a metric. Therefore, this study examines how avatar realism affects perceived object sizes as the size of the virtual hand changes. In the experiment, we manipulate the level of realism (realistic, iconic, and abstract) and size (veridical and enlarged) of the virtual hand and measure the perceived size of a cube. The results show that the size of the cube is perceived to be smaller when the virtual hand is enlarged compared to when it is veridical, indicating that the participants perceive the sizes of objects based on the size of the avatar, only in the case of a highly realistic hand. Our findings indicate that the more realistic the avatar, the stronger is the sense of embodiment including body ownership, which fosters scaling the size of objects using the size of the body as a fundamental metric. This provides evidence that self-avatar appearances affect how we perceive not only virtual bodies but also virtual spaces.

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