Limitations of postural equilibrium tests for examining simulator sickness.

The psychometric properties of four ataxia tests and their sensitivities to disorientation were examined to assess their potential for measuring balance disturbances frequently reported with simulator sickness. The study was conducted in two parts. In the first, subjects practiced for 10 sessions to examine learning effects and to stabilize performance. In the second, the sensitivities of the four tests were examined by comparing performance before and after exposure to sensory conflict produced using a disorientation training flight simulator. Subjective measures of disorientation, including reports of postural disequilibrium, were also collected. The results indicated initial learning on all four ataxia measures. Two of the tests, the Stand on One Leg Eyes Closed and the Sharpened Romberg, exhibited acceptable levels of reliability. However, only the latter showed sufficient sensitivity to corroborate subjective reports of postural disequilibrium.