Abstract
Introduction: Despite improvement in the computational capabilities of visual displays in flight simulators, intersensory visual-vestibular confl ict remains the leading cause of simulator sickness (SS). By using galvanic vestibular stimulation (GVS), the vestibular system can be synchronized with a moving visual fi eld in order to lessen the mismatch of sensory inputs thought to result in SS. Methods: A multisite electrode array was used to deliver combinations of GVS in 21 normal subjects. Optimal electrode combinations were identifi ed and used to establish GVS dose-response predictions for the perception of roll, pitch, and yaw. Based on these data, an algorithm was then implemented in fl ight simulator hardware in order to synchronize visual and GVS-induced vestibular sensations (oculo-vestibular-recoupled or OVR simulation). Subjects were then randomly exposed to fl ight simulation either with or without OVR simulation. A self-report SS checklist was administered to all subjects after each session. An overall SS score was calculated for each category of symptoms for both groups. Results: The analysis of GVS stimulation data yielded six unique combinations of electrode positions inducing motion perceptions in the three rotational axes. This provided the algorithm used for OVR simulation. The overall SS scores for gastrointestinal, central, and peripheral categories were 17%, 22.4%, and 20% for the Control group and 6.3%, 20%, and 8% for the OVR group, respectively. Conclusions: When virtual head signals produced by GVS are synchronized to the speed and direction of a moving visual fi eld, manifestations of induced SS in a cockpit fl ight simulator are signifi -cantly reduced. © by the Aerospace Medical Association, Alexandria, VA.