Letting Go of Your Real Body: Noisy Electrical Stimulation Facilitates Body Schema Transformation in Virtual Reality

The use of beyond-real interactions (BRI) expands the possibilities of virtual reality (VR) experiences by enabling novel capabilities, such as extending the range of manipulation or employing unusual body configurations. However, such interactions require users to adapt to novel sensorimotor mappings, which can lead to decreased performance and a poorer quality of user experience. Recently, proprioceptive suppression with noisy tendon electrical stimulation (n-TES) has been proposed to promote adaptation to BRI, though its effects have been reported to be limited. This study investigated the effects of proprioceptive suppression via n-TES on the adaptation process to BRI and the consequent changes in body schema, which have remained unexplored in prior research. Using a between-subjects design with 24 participants, we examined the effects of n-TES on a reaching task with Go-Go interaction, which extends virtual hands to enable users to reach farther than physically possible. Body schema changes were measured using a pointing task without visual feedback of the hand after adaptation to the Go-Go interaction. The results revealed that n-TES significantly altered the adaptation process by facilitating early learning and also enhanced body schema changes and aftereffects of adaptation under certain conditions. However, parameter fitting of the learning curves also suggested that n-TES might lead to a deterioration in the final level of performance achieved through adaptation. Our findings provide initial evidence that proprioceptive suppression by n-TES can contribute to facilitating sensorimotor adaptation within VR applications, while its practical utility may require adjusting stimulation to prevent potential side effects in the later stages of adaptation, specifically in trajectory smoothness.