Abstract
Two current notions concerning the etiology of motion sickness (the eye movement hypothesis and the perceptual conflict hypothesis) were evaluated under conditions that manipulated the degree of optokinetic nystagmus (OKN) and/or ego vection. These eye movement and perceptual responses were elicited with whole field stimulation in a vertically stripped drum and modulated with fixation and/or a restriction of the field of view. Measures of OKN, ego vection and motion sickness were recorded under the various conditions. Both visual field restriction and fixation diminished circular ego vection, while only fixation significantly reduced OKN. Conditions involving fixation resulted in greater reductions in motion sickness than did visual field restrictions. These finding lend considerable support to the eye movement hypothesis, but do not convincingly rule out the perceptual conflict idea. A model incorporating a synthesis of these two phenomena in the provocation of motion sickness will be discussed.