Narcosis has additive rather than interactive effects on discrimination reaction time

Area of Science:

• Human Performance
• Neuroscience
• Diving Physiology

Background:

• Inert gas narcosis impairs diver performance, primarily by slowing reaction time (RT).
• Understanding the specific locus of this slowing is crucial for diver safety.
• Nitrous oxide serves as a model gas for studying narcosis effects.

Purpose of the Study:

• To investigate the underlying mechanism of reaction time slowing caused by inert gas narcosis.
• To determine if narcosis affects the speed of information processing or decision-making.
• To test the predictions of the slowed processing model.

Main Methods:

• Utilized 35% nitrous oxide to simulate inert gas narcosis.
• Employed Crossman's confusion function with line-length and weight discrimination tasks.
• Maintained constant accuracy levels to isolate reaction time effects.

Main Results:

• Narcosis significantly slowed reaction time (RT) in both discrimination tasks.
• The slowing was attributed to an increase in the intercept of Crossman's function.
• The slope of the function, representing processing speed, remained unaffected.

Conclusions:

• The findings support the slowed processing model of narcosis.
• Narcosis impairs performance by affecting decision-making processes, not the speed of stimulus evaluation.
• This research provides critical insights into the cognitive effects of gas narcosis on divers.