[Psychological adaptation and work capacity during simulated weightlessness].

In two-head-down tilt studies of 7 and 8 days in duration variations in the work capacity of 24 test subjects were examined and the following stages were distinguished: habituation, stable work capacity, and unstable compensation. Among the test subjects two groups were discriminated: those with plastic and those with inert types of adaptation to a changed environment. It is concluded that the plastic-type people can better and faster adapt to head-down tilt and therefore can work more efficiently during an acute stage of adaptation to weightlessness.