Physiological workload reactions to increasing levels of task difficulty

Area of Science:

• Aerospace Medicine
• Human Factors Engineering
• Cognitive Psychology

Background:

• Assessing pilot mental workload is crucial for flight safety.
• Physiological measures offer objective indicators of cognitive load.
• Previous research has explored various physiological responses to workload, but sensitivity to varying difficulty levels requires further investigation.

Purpose of the Study:

• To investigate the sensitivity of physiological measures to mental workload in a flight simulator environment.
• To differentiate between mental effort and task difficulty using physiological data.
• To identify the most reliable physiological indicators of workload and difficulty.

Main Methods:

• Twelve pilots performed simulated flight tasks (tunnel, pursuit) with varying difficulty levels and an associated memory task.
• Physiological data including heart period, blood pressure, respiration, and eye blinks were recorded during tasks and rest periods.
• Analysis focused on respiratory parameters, heart rate variability, blood pressure variability, and the modulus between systolic blood pressure and heart period.

Main Results:

• All physiological measures differentiated between rest and flight conditions, and between pursuit and tunnel tasks.
• Heart period was the only measure sensitive to varying difficulty levels within the tunnel task.
• The modulus between systolic blood pressure and heart period showed less respiratory influence than heart rate variability, suggesting greater reliability.
• Blink interval and duration varied with visual processing demands, while memory task difficulty impacted blink interval, possibly due to subvocal rehearsal.

Conclusions:

• Physiological measures are sensitive to mental effort during flight simulation.
• Heart period and respiratory cycle duration appear most sensitive to workload intensity.
• The modulus measure offers a potentially more robust indicator of workload than heart rate variability.
• Physiological measures reflect mental effort, while subjective ratings capture both effort and perceived task difficulty.