A perceptual mechanism of cybersickness in virtual reality systems

Abstract

Exposure to virtual reality systems often leads to nausegenic side effects known as cybersickness. Three widely cited hypotheses are often used to explain the aetiology of this malady. Yet, the underlying perceptual mechanism of cybersickness remains largely unknown. This thesis compares and examines the perceptual mechanism of the hypotheses related to cybersickness in detail with the objective to develop a theoretical model to explain cybersickness for VR users. Three major studies are undertaken in this thesis.

Study 1 examined the sensory conflict hypothesis using a seated motion-coupled VR system. It was found that a synchronised visual-physical signal in VR could reduce visual-vestibular sensory conflict and mitigate cybersickness symptoms. Results suggest that the absence of multisensory synchronisation, visual-vestibular at least, plays a key role in the mechanism of cybersickness elicitation.

Study 2 examined the sensory conflict hypothesis and the postural instability hypothesis using a standing motion-coupled VR system. While previous research found that postural instability is the prerequisite of cybersickness, it was found that postural instability induced by external horizontal physical oscillation may not necessarily lead to the onset of cybersickness. This suggests that postural instability may only be a contributing factor to the immediate cause of cybersickness.

Study 3 examined the eye movement hypothesis and the differences between central and peripheral visual field. It was found that manipulating involuntary eye movements via viewpoint fixation may be more effective in reducing cybersickness discomfort than a peripheral field of view restriction. Yet, other factors, such as motions of visual images projected on the peripheral retina, were found to interact with the eye movement mechanism of cybersickness. This suggests that the eye movement mechanism could also be a contributing factor to the aetiology of cybersickness.

Results of the three studies confirmed that the sensory conflict hypothesis may take a predominant role in the perceptual mechanism of cybersickness. This thesis concludes by examining the three hypotheses in a perceptual framework of cybersickness. The results of the studies are synthesised with previous literatures and explained by a theoretical model developed in this research for future studies to explore the aetiology of cybersickness in VR systems.