The wide range of individual tolerances to the disturbing effects of vestibular stimulation has emphasized the importance of this factor in astronaut selection. At the same time, vestibular functions must be considered jointly with visual task performance, since both have special significance for such maneuvers as vehicle docking. Vestibular function in the weightless state remains almost completely unknown. Limited evidence from animal and manned space flights suggests that head turning, resulting from vestibular stimulation, may seriously interfere with visuomotor performance, but that susceptibility to these disturbances is significantly different between individuals and that partial adaptation occurs relatively quickly.

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