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

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.

Effect of immersive visualization technologies on cognitive load, motivation, usability, and embodiment

“…Importantly, neuroimaging studies have shown that brain areas linked with embodiment overlap with those involved in motor control (Ehrsson et al 2005;Wise 1985;Zeller et al 2016). Thus, increasing virtual embodiment through specialized displays-such as HMDs (Spanlang et al 2014)-might be an effective tool to promote brain plasticity and improve motor (re)learning (Grechuta et al 2017;Odermatt et al 2021;Shibuya et al 2018).…”

“…Although several studies have used HMDs to show beneficial effects of virtual embodiment on motor task performance (Grechuta et al 2017;Odermatt et al 2021;Shibuya et al 2018), they did not primarily aim at studying how different visualization technologies affect embodiment levels.…”

“Tricking the Brain” Using Immersive Virtual Reality: Modifying the Self-Perception Over Embodied Avatar Influences Motor Cortical Excitability and Action Initiation

“…Participants with relatively weak illusion effects likely experienced an enhanced sensory mismatch in the stone condition than participants with stronger illusion effects. Incongruency of information in virtual environments has previously shown to hamper reaction times and motor performance, independently of the experienced body ownership over the avatar ( Odermatt et al, 2021 ). The facilitated versus hampered feedforward movement depending on the illusion strength could explain why, across the whole group, marginal overall slowed movement initiations were found in the stone versus human avatar condition.…”

“…The rubber hand illusion has, for example, been replicated numerous times in VR –in the so-called “virtual hand illusion”– where congruent (e.g., haptic or tactile) feedback is provided to the real hand of the participant together with visual feedback in VR [i.e., on the hand of the avatar seen by the participant; ( Slater, 2008 ; Perez-Marcos et al, 2009 ; Sanchez-Vives et al, 2010 ; Pyasik et al, 2020 ; Jeong and Kim, 2021 ; Kanayama et al, 2021 )]. Further, the high visuo-motor or visuo-proprioceptive synchrony –i.e., the high spatial and temporal correlation between the performed movement and the visually perceived feedback on the display– in immersive VR has also been shown to induce strong embodiment over the avatar, without the need of additional tactile stimulation ( Sanchez-Vives et al, 2010 ; Carey et al, 2019 ; Odermatt et al, 2021 ). Notably, immersive VR, together with additional sensory feedback, can be used to induce embodiment over “unrealistic” avatars ( Kilteni et al, 2012b ; Preston and Newport, 2012 ).…”

“…To overcome this proprioceptive mismatch and to embody the rubber hand, the brain may be forced to disembody the own hand, lowering neural activity in the corresponding brain areas. Further, the experience of illusionary body ownership is commonly associated with congruent multisensory feedback (for example, applied to the participants real hand and a rubber hand), while the control condition (i.e., low body ownership) is associated with incongruent feedback, previously shown to introduce confounding congruency effects ( Rao and Kayser, 2017 ; Odermatt et al, 2021 ). Yet, immersive VR allows for congruent multisensory feedback with high visuo-proprioceptive congruency –i.e, the motor actions are spatially and temporally highly correlated with the visual feedback perceived through the HMD– and therefore, disembodiment of the own limb may not be necessary, allowing for a more naturalistic embodiment.…”