Cognitive performance during simulated deep-sea diving

Abstract

Psychological observations were reported on men during a number of simulated (pressure chamber) dives. Cognitive performance was investigated during a dive to 540 m of sea water (MSW) in oxyhelium (HeO2) and allowed a direct comparison with earlier results in trimix (HeN2O2). Impairments were detected at depths exceeding 300 MSW and these increased with depth. The decrements were not as great as those obtained at similar depths in trimix. The 2nd dive to 61 MSW used a mixture of O2 and N to determine the role of N in the trimix dive. Impairments were small, suggesting that effects with trimix were due to an interaction between the presence of N and overall pressure. This dive also provided an assessment of the sensitivity of the tests at the maximum recommended depth for diving in air (50 MSW). The absence of effects at depths greater than this recommended maximum suggested that results with the deeper dives were not attributed to an oversensitive test battery. A 3rd dive investigated the effects of caging in the restricted chamber environment with a 10 day exposure to 6 MSW in oxhelium. No impairments were detected, indicating that previous results did not result from lengthy periods of confinement in a pressure chamber. The implications of these results are discussed with regard to practical applications and suggestions for future research.