Congruency of Information Rather Than Body Ownership Enhances Motor Performance in Highly Embodied Virtual Reality.

Ingrid A Odermatt,Tobias Nef,Laura Marchal-Crespo,Özhan Özen,Karin A Buetler,Joaquin Penalver-Andres,Fred W Mast,Nicolas Wenk

doi:10.3389/fnins.2021.678909

Abstract

In immersive virtual reality, the own body is often visually represented by an avatar. This may induce a feeling of body ownership over the virtual limbs. Importantly, body ownership and the motor system share neural correlates. Yet, evidence on the functionality of this neuroanatomical coupling is still inconclusive. Findings from previous studies may be confounded by the congruent vs. incongruent multisensory stimulation used to modulate body ownership. This study aimed to investigate the effect of body ownership and congruency of information on motor performance in immersive virtual reality. We aimed to modulate body ownership by providing congruent vs. incongruent visuo-tactile stimulation (i.e., participants felt a brush stroking their real fingers while seeing a virtual brush stroking the same vs. different virtual fingers). To control for congruency effects, unimodal stimulation conditions (i.e., only visual or tactile) with hypothesized low body ownership were included. Fifty healthy participants performed a decision-making (pressing a button as fast as possible) and a motor task (following a defined path). Body ownership was assessed subjectively with established questionnaires and objectively with galvanic skin response (GSR) when exposed to a virtual threat. Our results suggest that congruency of information may decrease reaction times and completion time of motor tasks in immersive virtual reality. Moreover, subjective body ownership is associated with faster reaction times, whereas its benefit on motor task performance needs further investigation. Therefore, it might be beneficial to provide congruent information in immersive virtual environments, especially during the training of motor tasks, e.g., in neurorehabilitation interventions.

Highlights

In neurorehabilitation therapy, movements are often trained — e.g., with robotic support (Marchal-Crespo and Reinkensmeyer, 2009) — by visualizing the task in virtual reality (VR)
We investigated in 50 healthy participants the potential benefits of virtual body ownership on motor performance in a simple sensorimotor decision-making task with the non-embodied hand (Task 1) and a complex motor task performed with the virtual hand (Task 2)
Subjective body ownership Regarding the reported body ownership (BO) values before the Baseline task (BO-Baseline), one-way ANOVA revealed a significant effect of Condition [F(4,45) = 2.59, p = 0.05], whereby pairwise comparisons of conditions did not differ significantly

Summary

Introduction

Movements are often trained — e.g., with robotic support (Marchal-Crespo and Reinkensmeyer, 2009) — by visualizing the task in virtual reality (VR). During conventional VRbased neurorehabilitation practice, the virtual environment (VE) is usually displayed on a computer screen. Within this twodimensionally represented VE, patients interact via a symbolic virtual representation of their limbs (e.g., a cursor), drawing patients’ attention away from their real limbs (Wenk et al, 2019). In VR, a sense of embodiment is experienced if the avatar’s body is — at least partly — processed like one’s own (artificial) body (Kilteni et al, 2012). Embodiment comprises three subcomponents: body ownership, agency, and self-location (Longo et al, 2008; Kilteni et al, 2012). Agency indicates the sense of initiating and being in control of one’s own actions (Braun et al, 2018)

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Conclusion