EFFECTS OF SPATIAL-FREQUENCY OF A VERTICALLY STRIPED ROTATING DRUM ONVECTION-INDUCED MOTION SICKNESS

Purpose: The present study investigated the effects of differential sp atial frequencies of a vertically striped, horizontally rotating drum on the observer's frequency of eye nystagmus, perceived velocity of se lf-motion, and symptoms of motion sickness. Methods and Results: Two e xperiments were conducted. In Experiment 1, each of 10 subjects viewed 1 min of an optokinetic relating drum at the speed of 10 rpm covered with 6, 12, 24, 48, and 96 pairs of black and white stripes, presented in counterbalanced order. The results indicated that subjects perceiv ed significantly stronger circular vection (p < 0.05) and generated si gnificantly higher frequencies of eye nystagmus (p < 0.05) when they w ere viewing 24 pairs of black and white stripes than when they were vi ewing any of the other combinations of 6, 12, 48, or 96 black and whit e stripes. In Experiment 2, 100 highly susceptible subjects viewed 16 min of an optokinetic rotating drum covered with one of the five diffe rent numbers of black and white stripe pairs: 6, 12, 24, 48, and 96. T he results indicated that subjects in the group viewing 24 moving cont rasts perceived significantly stronger circular vection (p < 0.001), r eported significantly more severe symptoms of motion sickness (p < 0.0 01), and showed significantly greater ratios of ECC 4-9 cycles per min ute spectral intensity between drum rotation and baseline periods (p < 0.004) than those in the groups of viewing 6, or 96 moving contrasts. Conclusion: These results demonstrated that the severity of vection-i nduced motion sickness is affected by differential spatial frequencies of the stripes of the rotating drum and may be affected by number of horizontal eye movements.