Exploring the feasibility of mitigating VR-HMD-induced cybersickness using cathodal transcranial direct current stimulation

Many head-mounted virtual reality display (VR-HMD) applications that involve moving visual environments (e.g., virtual rollercoaster, car and airplane driving) will trigger cybersickness (CS). Previous research Arshad et al. (2015) has explored the inhibitory effect of cathodal transcranial direct current stimulation (tDCS) on vestibular cortical excitability, applied to traditional motion sickness (MS), however its applicability to CS, as typically experienced in immersive VR, remains unknown. The presented double-blinded 2x2x3 mixed design experiment (independent variables: stimulation condition [cathodal/anodal]; timing of VR stimulus exposure [before/after tDCS]; sickness scenario [slight symptoms onset/moderate symptoms onset/recovery]) aims to investigate whether the tDCS protocol adapted from Arshad et al. (2015) is effective at delaying the onset of CS symptoms and/or accelerating recovery from them in healthy participants. Quantitative analysis revealed that the cathodal tDCS indeed delayed the onset of slight symptoms if compared to that in anodal condition. However, there are no significant differences in delaying the onset of moderate symptoms nor shortening time to recovery between the two stimulation types. Possible reasons for present findings are discussed and suggestions for future studies are proposed.

I. Introduction

Virtual reality (VR) environments are designed using three technologies: non-immersive VR [1], semi-immersive VR [2] and immersive VR (IVR) [3]. There are two commonly used forms of IVR [3]: cave automatic virtual environments (CAVEs) and head-mounted displays (HMDs). A CAVE is a specially designed room in which the walls, ceiling, and/or floor are covered with a screen that can project virtual images or videos. An HMD is a VR headset that positions two small screens in front of both eyes, completely blocking out the physical world including the user’s body, and allows users to turn their head to examine their surroundings, with the visual presentation moving in the opposition direction of head motion with low latency [3]–[5]. Although a CAVE has many immersive qualities, the current state-of-the-art consumerfriendly HMDs, including PC-powered HMDs (i.e., HTC Vive™), smartphone-based HMDs (i.e., Samsung Gear™), and all-in-one HMDs (i.e., Oculus Quest™), aim to achieve immersive effect in a manner that is both simple and inexpensive.