Rotation test in the weightless phase of parabolic flight.

Human test-persons and pigs were subjected to pendular swing movements during parabolic flight. The rotary-induced nystagmus frequency in pigs increased during a G-load of more than 1.5 G. In the trajectory from zero G to 1.5 G the nystagmus SPV in pigs increased. In human subjects weightlessness suppressed the rotary-induced nystagmus, and gravitational conditions over 2 G increased the nystagmus amplitude. Nystagmus responses in experienced test-persons proved to be independent of changes in G-load. The differences in the results in man and pig support the assumption that rotary-induced nystagmus is not solely a response of the cupulae and the otoliths, but is also affected by tactile and somatosensory stimulation.