Proprioceptive and Gaze Adaptations to Virtual Leg Length Asymmetry.

Abstract

Proprioception is the sense of perceiving and predicting body position and movement in space. Together with vision and touch, it plays a central role in shaping the body image. Virtual reality allows users to embody self-avatars with altered morphologies, thereby modifying the body representation. This study investigated how embodying an avatar with a leg twice its original length affects proprioception, embodiment, and visual scanning measured through state and transition gaze entropy. Congruent and incongruent visuotactile stimuli were used to induce high and low levels of embodiment. Across 26 participants, embodiment was preserved despite the deformation, regardless of whether the dominant or non-dominant leg was altered. A proprioceptive drift corresponding to 78% of the virtual leg length was observed, independent of visuotactile congruence. While leg deformation alone did not affect gaze entropy, incongruent visuotactile stimuli reduced embodiment and increased both state and transition gaze entropy, reflecting increased top-down modulation of gaze control. These findings show that deformations of the virtual lower limbs can be integrated into the body image without perturbing sensory integration, providing insights for developing rehabilitation strategies targeting proprioceptive deficits.