Effects of CO2 and N2 partial pressures on cognitive and psychomotor performance is a 1991 publication by Fothergill and colleagues addressing how two gases in a breathing environment relate to mental and motor function. The subject matters because divers must think clearly and act reliably while exposed to pressure and changing gas conditions.
Why examine gas partial pressures and performance?
Partial pressure is the share of a gas’s pressure within a mixture. As a diver descends, the surrounding pressure rises, and the partial pressures of gases in the breathing mix rise with it. The amount of each gas reaching the body therefore depends on both the mixture and the pressure at depth.
Performance underwater is not only a matter of strength or endurance. Divers may need to monitor instruments, interpret changing conditions, remember procedures and coordinate precise movements. Studying cognition alongside psychomotor performance helps frame how the breathing environment may intersect with tasks that require both sound judgement and controlled action.
What roles do carbon dioxide and nitrogen play?
Carbon dioxide is produced by the body’s metabolism and normally removed through breathing. If ventilation does not keep pace with production, carbon dioxide can accumulate. In diving, exertion, breathing resistance, equipment and other conditions can affect ventilation, making carbon dioxide an important consideration in the relationship between breathing and alertness.
Nitrogen is a major component of ordinary air and is also present in many diving gas mixtures. Its partial pressure increases as ambient pressure increases. Nitrogen’s effects under pressure are relevant to diving physiology because changes in gas pressure can influence the nervous system and, in turn, mental or motor performance.
The title brings these gases together in a question about cognitive and psychomotor function. That framing connects respiratory physiology with human performance: the issue is not simply what gases are present, but how their pressures in a breathing environment may relate to a diver’s ability to process information and respond.
Which kinds of performance matter underwater?
Cognitive performance includes mental processes such as attention, memory, decision-making and information processing. Psychomotor performance concerns the coordination of perception and movement—for example, carrying out a controlled action in response to a cue. These domains overlap during real diving tasks, even when researchers assess them separately.
- Gas partial pressure: the pressure contributed by an individual gas in a mixture, which changes with ambient pressure.
- Cognition: mental functions used to notice, interpret, remember and decide.
- Psychomotor function: the integration of mental processing with accurate, timely movement.
- Task conditions: workload, breathing circumstances and the demands of a task can all matter when interpreting performance.
These distinctions help readers understand why a study of performance may use more than one kind of task. A diver might recognise a problem yet respond slowly, or execute a movement accurately while overlooking other information. Considering both mental and motor dimensions gives a broader picture of operational capability.
How does this subject fit into diving research?
Diving research considers how pressure, breathing gases and the demands of underwater work interact with human physiology. Gas effects are part of a wider field that also examines breathing mechanics, workload, environmental stress and the reliability of performance. The publication’s subject sits at the boundary between gas physiology and human factors.
For diving physicians and hyperbaric clinicians, the general topic is relevant to understanding how the breathing environment can intersect with neurological function. For scientific divers and other underwater workers, it highlights why equipment and gas planning are considered alongside task demands rather than in isolation. The practical significance lies in recognising that safe performance depends on both physiological conditions and the ability to carry out required tasks.
Research on these questions is interpreted in context: a performance measure reflects the task being tested and the conditions under which it is performed. It should not be treated as a complete description of every diver’s response in every environment. Individual health concerns or fitness-to-dive questions call for assessment by a diving-medicine physician.
Frequently asked questions
What does partial pressure mean in diving?
What is the difference between cognitive and psychomotor performance?
Why is this topic relevant to diving medicine?
Citation details
- Title: Effects of CO2 and N2 partial pressures on cognitive and psychomotor performance
- Authors: Fothergill, DM; Hedges, D; Morrison, JB
- Year: 1991
- Published in: Undersea Biomedical Research 1991 Jan;18(1):1-19
- Identifiers: PMID 1902340
- Repository record: Rubicon Research Repository, handle 123456789/2576
This page is an original summary written by the Rubicon editors from the publication’s bibliographic record. It does not reproduce the paper, its abstract or its data; consult the publication itself for its methods and findings.
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