Cognitive impairment during 5 m water immersion

Area of Science:

• Human physiology
• Cognitive psychology
• Environmental medicine

Background:

• Previous research indicated intact human cognition at 6m water immersion, conflicting with divers' reports of cognitive impairment.
• Discrepancies may stem from testing abstract skills (e.g., mental arithmetic) instead of performance-related skills and not controlling for water viscosity.

Purpose of the Study:

• To investigate the impact of shallow water immersion on performance-related cognitive skills.
• To assess the effects of 5m water immersion on reaction time, tracking, and sustained attention.
• To determine if cognitive deficits are linked to increased ambient pressure.

Main Methods:

• Forty-eight subjects performed multiple choice reaction tasks, a tracking task, and combined tasks in 5m water and on dry land.
• Isometric responses were used to evaluate performance-related cognitive skills.
• Sustained attention and subjective workload were also measured.

Main Results:

• Cognitive performance degraded by 9% under water, irrespective of task type or dual-task conditions.
• Sustained attention decreased by 11% and tracking performance by 48% under water.
• Observed deficits were uncorrelated, suggesting multiple independent effects of immersion.

Conclusions:

• Shallow water immersion significantly impairs performance-related cognitive skills, including sustained attention and tracking.
• Findings support the hypothesis that cognitive functions sensitive to performance demands are affected by water immersion.
• The observed deficits, not present just below the surface, are likely attributable to increased ambient pressure.