Human reliability and confinement

Problems inherent in the modifiability of circadian periodicity and in impoverished sensory environments were explored for the purpose of appraising attenuative effects upon human reliability. Accordingly, highly selected subjects were confined within a one-man altitude chamber for prolonged periods of time and under a variety of designed conditions. The findings relative to the modifiability of biological rhythm indicate that adjustment to a drastic revision of the 24-hour biological day was accomplished to a significant and practical extent by certain subjects, the extent of adjustment was directly related to the maintenance of high initial levels of proficiency, and just as subjects differ greatly in their adjustment to revised biological time, they differ to an equal extent in the degree of synchronization manifested by the apparent periodicities of the different physiological systems. In the investigation of impoverished sensory environments, it was found that the joint effects of impoverished sensory conditions and continuous work at an operator system drastically degraded the reliability of certain subjects. Further, neither prior experience nor knowledge acted to mitigate the degree of aberrancy experienced which in the case of one subject was so extreme as to necessitate his removal from the chamber prior to the termination of confinement period. Finally, management of certain aberrant behavior, specifically hallucinatory experiences, could be successfully achieved by those subjects who continuously attempted to maintain a diversity of sensory input.