BACKGROUND: The most commonly cited hypotheses for motion sickness (MS) focus on inconsistent sensory inputs. Visual/vestibular conflicts may lead to MS, but visual input from retinal regions/neural pathways that are sensitive to motion might bear more weight in MS etiology. We hypothesized that inducing blurred vision in an optokinetic drum would attenuate the influence of foveal (parvocellular) input, but not peripheral (magnocellular) input that is sensitive to motion. Increased relative influence of peripheral visual input was predicted to subsequently lead to more visual/vestibular conflict and subsequently more severe MS symptoms.METHODS: Through goggles that were either clear or frosted, 15 subjects (5 men, 10 women, mean age = 24.9 yr, range = 18-49) viewed the interior of a rotating (60° · s⁻¹) optokinetic drum for 10 min. Subjects completed the Simulator Sickness Questionnaire (SSQ) before and after viewing. Overall subjective sickness ratings (0-10) and visually induced self-motion perception (vection) ratings (0-10) were also recorded.RESULTS: Postexposure SSQ scores obtained in the blur condition (total - 52.9, oculomotor - 38.9, disorientation - 69.6) were significantly higher than those obtained in the control condition (total - 30.4, oculomotor - 21.7, disorientation - 37.8). Overall sickness ratings and vection ratings were also significantly higher in the blur condition.CONCLUSIONS: These results suggest that visual blur can exacerbate MS, perhaps because of differential influences of visual pathways. Although these results were obtained with an optokinetic drum, possible effects of visual blurring in motion provocative environments such aircraft, watercraft, spacecraft, and land vehicles should be considered.Bonato F, Bubka A, Thornton W. Visual blur and motion sickness in an optokinetic drum. Aerosp Med Hum Perform. 2015; 86(5):440–444.