A review of cognitive and perceptual-motor performance in space

Although a consensus developed early in the space program that complex oper ations could be performed successfully in space, it appears that humans are slower there than on Earth. Recent experiments aimed at determining the ca use of this slowing suggest that central cognitive operations are unaffecte d but that perceptual-motor performance is degraded under certain circumsta nces. Two hypotheses have been proposed to account for this degradation-the direct effects of microgravity on the central nervous system and the non-s pecific effects of multiple stressors. Present evidence can be interpreted as supporting either hypothesis and further experiments are required to set tle the question. This issue has practical implications since the counterme asures needed to ameliorate or prevent performance deficits will differ acc ording to which hypothesis is correct. Understanding and ameliorating perfo rmance deficits will help ensure safe operations aboard the International S pace Station and during a mission to Mars.