| Research Abstract |
We, human beings, have been adapted to the gravity environment on the earth and our motor behavior supported by sensory system has been tuned up for the gravity specific form. (Yves, Koga et al., 1993) Moving a leg to walk, pointing outside somewhere by the finger, turning a neck to the sound source, and looking for something with eyes by controlling extraocular muscles, are all well organized under the 1G condition. When humans are exposed to an environment with altered gravity conditions, this programmed behavior must be change ; that is, it is reprogramming. Unusual induced gravity situations, such as rotation, linear acceleration, and parallel swinging, (Guedry, 1965, Lackner, 1977) have also been investigated. Visually induced motion sensation or distorted perception has been evaluated with respect to visual stability by many investigators (Rock & Halper, 1968, Lackner & Ashton, 1981, Allison et al.1998, Howard, 1986, Yves, 1993, Young et al.1983, Koga, 1992, 1998, 2000, Higashiya
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ma & Koga, 1998, 2002). These studies are all concerned with the effect of gravity and the induction motion sickness through human visual perception. Direct investigations under microgravity, such as parabolic flight, Skylab., and Spacelab, have been conducted. (Young et al.1986) These studies not only focused on how human visual stability is established through various sensory afferent in specific gravity conditions but also related with the SAS (Space Adaptation Syndrome). The interaction of visual, vestibular and somatosensory perception is smoothly coordinated under the normal gravitational condition of Earth in our daily life. Another difficulty to keep our healthy life under the microgravity should be noted here. SAS(Space Adaptation Syndrome) is the one which human beings suffers under the micro-gravity environments. Visual environments including human body axis changed in both exocentric and egocentric axis. The acute change of input caused by altered gravity causes non-adaptive syndrome when human reaches micro-gravity environment which is called SAS. The chapter has no aim to describe the subject in detail here, but it should be taken into account to consider entire human adaptive behavior in space. Less
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