INTRODUCTION: Habituation to motion has therapeutic applications for motion sickness desensitization and rehabilitation of patients with vestibular disease. Less attention has been devoted to the opposite process: sensitization. METHODS: Subjects (N = 50) were randomly allocated to four sequences: Baseline visual stimulus; then 15 min of time gap; cross-coupled motion (C-C) or a Control condition; then a time gap of 15 min or 2 h; then a retest visual stimulus. Motion exposures were for 10 min or until moderate nausea, whichever was sooner. The visual stimulus was a scene rotating in yaw at 0.2 Hz with superimposed "wobble". C-C was whole-body rotation on a turntable with eight 45° head tilts during each 30-s period. Control was head tilt without rotation. Rotational velocity was incremented in staircase steps of 3° · s−1 every 30 s. 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 retest of visual stimulus. For the retest visual stimulus, Total Symptoms were higher following C-C (15.1 ± 9.0) than following Control (8.3 ± 7.1) for both the 15 min and 2 h retests. Sickness ratings (SR) mirrored these effects of C-C. DISCUSSION: C-C motion sensitized subsequent responses to visual stimulation up to 2 h later. Sensitization 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 retest. The results have implications for the use of visual technologies within hours of exposure to provocative motion. Golding JF, Alund D, Gresty MA, Flynn MB. Sensitization of visually induced motion sickness by prior provocative physical motion. Aerosp Med Hum Perform. 2024; 95(10):741–748.
Schematic flowchart of the experimental design where the following abbreviations are used: Vis Stim = visual stimulus (optokinetic); C-C = cross-coupled (Coriolis) motion; Control = sham cross-coupled motion without rotation; SSQ = Simulator Sickness Questionnaire (Total Symptom score). In addition, sickness ratings (SR) were measured repeatedly throughout.
A) Schematic of the visual stimulus: rotating scene of a complete 360° panorama; frequency 0.2 Hz (72° · s−1); "wobble" 18° axial tilt; and field of view with mask of 83.5° with circular restriction. B) Schematic of the cross-coupled (Coriolis) stimulus (enclosed cabin removed for clarity) showing the head when pitched down during whole-body rotation on a turntable with eight head tilts of 45° during each 30-s period. Rotational velocity incremented as a staircase profile in steps of 3° · s−1 step every 30 s.
Mean sickness ratings (1 = OK; 2 = initial symptoms; 3 = mild nausea; 4 = moderate nausea) are shown over time (not to scale) for the four experimental groups. V = visual stimulus (optokinetic); C-C = cross-coupled (Coriolis) whole body motion; cntrl = sham cross-coupled motion without rotation.
Mean Total Symptom scores (Simulator Sickness Questionnaire; SSQ) are shown over time (not to scale) for the four experimental groups. V = visual stimulus (optokinetic); C-C = cross-coupled (Coriolis) whole body motion; cntrl = sham cross-coupled motion without rotation.
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