Otolith tilt-translation reinterpretation following prolonged weightlessness: implications for preflight training.

Observations with three astronauts yielded two major findings. First, perceived self-motion during sinusoidal roll differed immediately postflight from preflight. Between 70 and 150 min after landing, roll was perceived primarily as linear translation. Secondly, more horizontal eye movement was elicited by roll stimulation immediately postflight relative to both preflight and later postflight observations. These results support an "otolith tilt-translation reinterpretation" hypothesis, which has clear implications for understanding astronaut reports of space motion sickness during the early period of orbital flight. A proposal for "prophylactic adaptation training" which may provide preflight adaptation to weightlessness, derives from this research.