Abstract | INTRODUCTION Habituation to motion has therapeutic applications for motion sickness desensitisation, and rehabilitation of patients with vestibular disease. Less attention has been devoted to the opposite process: sensitisation. METHODS Subjects (n=50) were randomly allocated to four sequences: Baseline Visual stimulus; then 15min of time gap; Cross-Coupled motion (C-C) OR a Control condition; then a time gap of 15min OR 2h; Re-test Visual stimulus. Motion exposures were for 10min or until moderate nausea, whichever was sooner. The visual stimulus was a scene rotating in yaw at 0.2Hz with superimposed ‘wobble’. C-C was whole-body rotation on a turntable with eight 45° head tilts during each 30s period. Control was head tilt without rotation. Rotational velocity incremented in staircase steps of 3°/s every 30s. RESULTS Groups were equivalent for Total Motion Sickness Symptom scores elicited by the first visual stimulus (combined: mean+/-SD 10.8+/-8.4). C-C produced greater Total Symptoms (20.3+/-6.8) than Control (3.1+/-3.7). Subjects recovered subjectively from C-C before re-test of visual stimulus. For the re-test visual stimulus, Total Symptoms were higher following C-C (15.1+/-9.0) than following Control (8.3+/-7.1), for both the 15min and 2h re-tests. Sickness Ratings (SR) mirrored these effects of C-C. DISCUSSION C-C motion sensitised subsequent responses to visual stimulation up to 2h later. Sensitisation of visual stimulation crossed modalities, and appeared subconscious since it occurred despite subjective recovery from C-C. For some individuals, a previously relatively innocuous visual stimulus became nauseogenic on re-test. The results have implications for the use of visual technologies within hours of exposure to provocative motion. |
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