Multiple axis rotation and cybersickness in a virtual environment

Introduction: Sensory conflict often arises in virtual reality (VR). Cybersickness refers to motion sickness that can result in VR when optic flow induces illusory self-motion (or vection) in a physically stationary observer. We compared cybersickness generated by displays simulating self-rotation about a single axis (pitch) or multiple axes (pitch and roll). We predicted that the dual axis condition would generate more salient sensory conflict, and subsequently, more cybersickness. Methods: Seated,

stationary subjects viewed the inside of a virtual cube via a stereo headmounted display. The cubeôs interior was covered with a black and white checkerboard pattern (which provided visual frame and motion, but not polarity information about the observerôs changing orientation with respect to gravity). Vection was produced by rotating the cube about the pitch axis or about both the pitch and roll axes. A simulator sickness questionnaire (SSQ) was used to assess symptoms prior to participation and after five

minutes of viewing. Results: Vection was reported by all subjects in both conditions although no significant differences were revealed. Mean post-treatment Total SSQ scores were significantly higher in the dual axis condition. Subscores for nausea, oculomotor symptoms, and disorientation were also significantly higher in the dual axis condition. Discussion: Since observers are normally presented with multisensory information during pitch and roll self-rotations (i.e. visual, semicircular canal and gravireceptor inputs), we expected sensory conflict to be generated by both conditions. That vection strength was similar in both conditions might suggest that sensory conflict had already saturated in single axis conditions. However, increased cybersickness in the dual axis condition was consistent with

our prediction that multiple-axis rotations generate more salient sensory conflicts. Our findings suggests that sensory conflict per se may not be a unifying explanation for all types of vection and motion sickness.

Learning Objectives: 1. To better understand how multiple axis rotation contributes to sensory conflict and cybersickness.