08 | Exploring motion sickness reduction using incongruent vestibular and visual stimuli based on a computational model

Motion sickness often occurs in environments involving both vestibular and visual inputs, such as when passengers engage in visual tasks. Typical countermeasures are based on the sensory conflict theory1 and involve presenting visual stimuli matching vehicle motion, assuming congruent visual-vestibular input is optimal. Given recent developments in computational models, this study explores whether incongruent visual stimuli can reduce symptoms based on model predictions. We used a motion sickness model based on the Subjective Vertical Conflict (SVC) theory,2 which accepts vestibular and visual inputs.3 Assuming vehicle motion cannot be changed, we proposed a method to compute visual stimuli minimizing model-predicted sickness in real time and present via VR. A within-subject design was used with two conditions: (A) stimuli optimized by the method and (B) stimuli consistent with vehicle motion. Seven participants wore a VR headset while riding an automated electric wheelchair under both conditions. MISC scores4 were used to assess sickness. The study was approved by the NAIST ethics committee. The proposed method generated visual stimuli within 1 ms. Although motion was limited to fore-aft translation, optimized stimuli included pitch-direction angular velocity. In 6 of 7 participants, the peak MISC score was reduced or delayed under incongruent stimulation. These findings suggest that deliberately incongruent visual stimuli may offer an effective countermeasure.