Investigating the Relative Contributions of Unexpected Vection and Postural Instability to VR Cybersickness

This study tested unexpected vection and postural instability accounts of cybersickness by having 30 participants play a commercial virtual reality (VR) simulation ("Mission-ISS"), while wearing head-mounted displays (HMD) for up to 14 minutes, or until the first symptoms of sickness. Of these participants, 23 reported symptoms, while 7 did not. We found that the likelihood and severity of cybersickness increased when the vection experienced was unexpected. Spontaneous standing sway before entering VR was also found to differ depending on whether the participant became sick or remained well. In addition, the severity of their sickness appeared to be related to changes in their sway during VR. When these vection and sway-based predictors were examined together, unexpected vection emerged as the strongest predictor of cybersickness. Taken together with the findings of recent studies, the research shows that unexpected vection predicts experiences of cybersickness across a variety of different virtual environments, virtual navigation methods and types of simulated movement.