Individual Differences in Audio-Visual Binding Can Predict the Varied Severity of Motion Sickness

Abstract

In neuroscience, research often focuses on the group, while ignoring large individual differences, which are left poorly understood. One such example is the large individual variability in the susceptibility to motion-sickness (MS), the feeling of sickness that typically occurs during travel or movement. Current explanations of MS focus on the sensory conflict in the perception of motion, primarily between the vestibular and the visual systems, e.g., when feeling motion but not seeing it. To account for the large individual differences in MS, we hypothesized that people feel motion sickness only when the conflicting stimuli are perceived as bound together, and their tendency to bind conflicting multi-sensory information is an individual trait. To test this hypothesis, we measured the persistence of audio-visual binding using the McGurk effect in which watching a moving mouth alters the auditory perception of phonemes. We used a temporal audio-visual mismatch to probe the persistence of binding and computed a temporal binding window for each individual (n=21) in 3 tasks: syllable Identification (McGurk), simultaneity judgement, and syllable synchronization judgement. To assess the severity of MS, we used 2 subjective symptom questionnaires. We found that the temporal binding window of the McGurk stimuli in two of the tasks varied across individuals and was positively correlated (R>0.8) with the MS questionnaire severity scores. These results support our hypothesis and shed new light on the enigmatic differences between individuals regarding their susceptibility to motion-sickness. They also highlight the potential strength of studies focusing on individual differences and neurological diversity. Significance StatementMotion sickness is the feeling of sickness that typically occurs during travel or movement. Although it is commonly linked to a sensory mismatch, the large differences in its susceptibility across people remains poorly understood. In the current study, we link these individual differences to a multi-modal temporal binding window, which measures the persistence of perceiving multi-modal stimuli as coming from the same source despite temporal discrepancies. We demonstrated this link by finding a high correlation between the temporal binding window of an audio-visual illusion (the McGurk effect) and the subjective reports of the susceptibility to motion sickness. These results shed new light on the enigmatic differences between individuals regarding their susceptibility to motion sickness and highlight the potential strength of studies focusing on individual differences and neurological diversity.