A sudden-stop vestibulovisual test for rapid assessment of motion sickness manifestations.

The test made use of a rotating chair mounted in a striped cylindrical enclosure, 4.6 m in diameter. The subject was exposed to the following motion profile: With eyes covered he was accelebrated at 15 degrees/s2 to clockwise volocity of 300 degrees/s and maintained at that velocity for 30 s. The chair was then decelerated to a stop within 1.5 s and maintained at rest for 30 s while physiological parameters and motion sickness symptoms were recorded. This procedure was repeated until a pre-selected motion sickness endpoint was reached or 20 stops had been made. If the endpoint was not reached, testing continued without the blindfold while the subject passively viewed the striped enclosure; if the endpoint was still not reached after 20 stops, the direction of rotation was reversed. The subject's score represented one-half the number of stops with eyes covered plus the number of stops with eyes open plus twice the number of stops after reversal of direction of rotation. Fourteen subjects were each assessed four times; the average interval between tests was 3 d. The first test was usually a poor indicator of alter performance. The second test provided a satisfactory ranking of susceptibility to motion sickness, and the results of the four sessions provided an indication of the rates of acquisition and decay of adaptation. Some advantages and uses of this new test are summarized.