Bodily Self-Perception under Vestibular Galvanic Stimulation in Virtual Reality: A Replication and Extension of Karnath et al. (2019)

Virtual reality (VR) provides a tool for studying bodily self-perception by allowing the controlled manipulation of sensory inputs and body representations. Past studies produced inconclusive results regarding the impact of vestibular signals on body schema. For example, one study reported increased perceived hand sizes due to vestibular stimulation, while another study failed to show such an effect on perceived arm or leg length. We aimed to replicate the later study and added conditions to overcome potential shortcomings, particularly regarding the stimulation type and the stimulation intensity. Twenty participants engaged with an avatar seen from first person perspective in a VR setup, adjusting its arm to match their perceived arm length. Galvanic vestibular stimulation (GVS) was applied using both direct current (DC) GVS and alternating current (AC) GVS at intensities of 0.375 mA and 1 mA. VR allowed precise control over task conditions and immersive engagement with the virtual body, fostering a heightened sense of embodiment. Despite the immersive VR environment and novel stimulation methods, effects of DC-GVS and AC-GVS on avatars’ arm size were, as in the original study, absent. By highlighting the interaction between vestibular input and bodily representation within a VR framework, this study underscores the potential of immersive technologies to advance research on bodily self- perception. Future research should explore alternative VR paradigms and stimulation protocols to better capture subtle shifts in body schema. VR remains a promising avenue for disentangling the complex sensory processes underlying bodily self-awareness.