Effects of Proprioceptive Attenuation with Noisy Tendon Electrical Stimulation on Adaptation to Beyond-Real Interaction

Virtual reality (VR) enables beyond-real interactions (BRI) that transcend physical constraints, offering effective user experiences like extending a hand to grasp distant objects. However, adapting to novel mappings of BRI often reduces performance and the sense of embodiment. To address this, we propose using noisy tendon electrical stimulation (n-TES) to decrease proprioceptive precision. Previous studies have suggested that attenuating proprioceptive precision is crucial for sensory-motor adaptations. Thus, we hypothesize that n-TES, which has been shown to reduce proprioceptive precision and induce visual-dependent perception in VR, can enhance user adaptation to BRI. We conducted a user study using go-go interaction, a BRI technique for interacting with distant objects, to assess the effects of n-TES. Given the individual variability in n-TES response, participants first underwent a proprioceptive precision test to determine the optimal stimulation intensity to lower the proprioceptive precision from 5 levels $(\sigma=0.25-125\text{mA})$. Reaching tasks using a 2x2 within-participants design evaluated the effects of go-go interaction and n-TES on performance, subjective task load, and embodiment. Results from 24 participants showed that go-go interaction increased reaching time and task load while decreasing the sense of embodiment. Contrary to our hypothesis, n-TES did not significantly mitigate most of these negative effects of go-go interaction, except that perceived agency was higher with n-TES during go-go interaction. The limited effectiveness of n-TES may be due to participants' habituation or sensory adaptation during the tasks. Future research should consider the adaptation process to BRI and investigate different BRI scenarios.