Psychological and Psychophysiological Effects of Confinement in a High-pressure Helium-oxygen-nitrogen Atmosphere for 284 Hours. Rep No. 441.

Three submariners were confined in a chamber for 284 hours in a heliumoxygen-nitrogen environment at 7 atmospheres pressure. Electrodermal conductance (EDC) levels, changes and recoverability prior to and following hyperventilation and breathholding were obtained before, three times during, and once at the termination of the pressurization phase of the experiment. In addition, breathholding time, time-span estimation and indices of spatial perception were obtained during the same measurement sessions. The results suggested individual differences in general excitability (EDC level), in autonomic reactivity (change in EDC during hyperventilation), in recoverability (rate of EDC recovery during breathholding), in breathholding time and in time estimation. Some of these change patterns, particularly in autonomic indices, may be useful predictors of individual differences in capacities to adjust to confinement in an exotic gaseous atmosphere at high pressure. The subject sample was too sparse (N=3) to suggest definite group autonomic or other effects of these conditions.