Adaptive changes in perception of body orientation and mental image rotation in microgravity.

The perception of the subjective body orientation with respect to a foot reference basis, and the adaptation of mental image rotation have been investigated before, during, and after a 7-d spaceflight. The findings show that the body is tilted forward in darkness and in stabilized vision, which indicates a predominant role of vision in such orientational tasks performed in microgravity. Furthermore, perception of head angular rotation in pitch and roll axes seems to be altered in microgravity, whereas head displacements in yaw are estimated correctly. Subjects' capability to rotate mentally the image of the visual environment increased during the flight. Memorized writing was affected in microgravity, especially concerning the layout of letters corresponding to the vertical direction.