The Effects of Image Scale Factor on Vestibulo-Ocular Reflex Adaptation and Simulator Sickness in Head-Coupled Virtual Environments

Abstract

An experiment was conducted to determine the effects of virtual image scale factor on vestibulo-ocular reflex (VOR) adaptation and simulator sickness as a result of exposure to a head-coupled virtual interface. Subjects were exposed for 30 minutes, completing visual search tasks using active, unrestricted yaw head movement rotations. Three levels of image scale-factor changes (0.5X, 1.0X, 2.0X magnification) were explored. It was hypothesized that scale factors deviating from 1.0X magnification would cause VOR gain adaptation and increased simulator sickness. A secondary hypothesis predicted a moderate correlation between VOR gain adaptation and simulator sickness. Results demonstrated that significant VOR adaptation occurred only in the 0.5X and 2.0X scale conditions. VOR gain decreased an average of 15% in the 0.5X condition and increased an average of 6% in the 2.0X condition. Simulator sickness magnitudes in these two conditions were over twice that of the 1.0X condition. Only weak correlations were found between VOR gain adaptation and simulator sickness. Virtual interface design guidelines are suggested to minimize unwanted interface-generated effects on the user.