Effects of image scale and system time delay on simulator sickness within head-coupled virtual environments

Novel patterns of visual-vestibular intersensory stimulation often result in symptoms of simulator sickness, raising health and safety concerns regarding virtual environment exposure. Two experiments investigated the effect of conflicting visual-vestibular cues on subjective reports of simulator sickness during and after a 30-min exposure to a head-coupled virtual interface. Virtual image scale factors (0.5, 1.0, 2.0 magnification, generated by varying geometric field of view angle) were investigated in Experiment 1, and additional system time delays (125, 250 ms) were investigated in Experiment 2. Simulator sickness metrics included spoken self-reports during exposure and simulator sickness questionnaires (pre-exposure. immediate postexposure, and 20 min postexposure). Head yaw angular position data were also recorded. Reports of simulator sickness symptoms were significantly greater in the minification (0.5) and magnification (2.0) image scale factor conditions than in the neutral condition (1.0). Simulator sickness did not vary with changes in time delay, however. Furthermore, a comparison across experiments suggests no appreciable increase in simulator sickness with increasing time delays above the nominal value (48 ms). Head angular position data exhibited certain systematic variations across conditions. Actual or potential applications of this research include virtual environment training, simulation, and entertainment systems.