THE EFFECTS OF VECTION AND OPTOKINETIC NYSTAGMUS ON VISUALLY INDUCED MOTION SICKNESS DURING EXPOSURE TO OPTOKINETIC STIMULI

Objective: This study investigates isolated effects of vection and optokinetic nystagmus (OKN) on visually induced motion sickness (VIMS) provoked by rotating optokinetic drum patterns. Background: VIMS was the subject of recent standardization activities (ISO IWA3, 2005) but the effects of OKN have not been studied in the absence of vection. Method: Experiment one suppressed OKN by eye fixation and examined VIMS severity (both ordinal and ratio scale) and time spent in saturated vection at four pattern rotating velocities of 0, 2, 14, and 34 degrees per second (dps). Experiment two suppressed vection by adding a peripheral visual field rotating in the opposite direction to the rotating patterns. VIMS severity and OKN slow-phase velocity were studied at four rotating velocities of 0, 30, 60, and 90 dps. Results: Results from Experiment one indicated that VIMS severity increased as the pattern velocity increased from 0 dps to 34 dps. Results from Experiment two indicated that as the velocity of the rotating pattern increased, the slow-phase velocity (SPV) of OKN and the severity of VIMS increased and peaked in the 60 dps condition. In both experiments, ratio-scaled nausea data significantly correlated with ordinal-scaled nausea ratings. Conclusion: VIMS can still occur in the absence of either vection or OKN. Interestingly, the profile of the summed This is the Pre-Published Version