Cognitive Efficiency of Divers Working in Cold Water

The cognitive efficiency of 14 divers was studied during 1-hour exposure to water of 40°F (4.4°C) and 78°F (25.6°C). Reasoning ability was tested using a sentence comprehension task presented at the beginning and end of each test session. Vigilance was tested by requiring subjects to detect the onset of a faint peripheral light during the performance of a two-man pipe assembly task. Memory was tested by requiring subjects to learn a number of “facts” during the dive, with retention tested by recall and recognition on land, after a 40-min delay. Despite a mean drop in rectal temperature of 1.3°F (0.72°C), neither reasoning nor vigilance was impaired. Memory performance did deteriorate, though it is suggested that this may reflect a peripheral context-dependent memory effect. It is concluded that a well-motivated subject may be cognitively unimpaired despite a marked drop in deep body temperature.