Evaluation of physiological responses to mental workload in n-back and arithmetic tasks

Area of Science:

• Cognitive Psychology
• Human Factors Engineering
• Neuroscience

Background:

• Mental workload assessment is crucial for understanding cognitive load and performance.
• N-back and arithmetic tasks are standard tools for inducing and measuring mental workload.
• Identifying sensitive physiological correlates of mental workload is essential for objective evaluation.

Purpose of the Study:

• To compare the sensitivity of various physiological measures to different mental workload levels.
• To evaluate the efficacy of n-back and arithmetic tasks in modulating physiological responses.
• To determine which physiological indicators best reflect changes in cognitive demand.

Main Methods:

• Participants performed n-back and arithmetic tasks at three distinct difficulty levels.
• Physiological data including pupil diameter, fixation duration, blink rate/duration, heart rate (HR), and electrodermal activity (Galvanic Skin Response - GSR) were recorded.
• Statistical analyses were employed to compare physiological responses across task difficulties.

Main Results:

• Significant differences in fixation duration and pupil diameter were observed across difficulty levels for both tasks.
• Pupil diameter increased with mental workload, while fixation duration decreased.
• Heart rate and blink duration increased with difficulty in n-back tasks; RMSSD and SDNN decreased in arithmetic tasks.
• Blink rate and GSR showed limited sensitivity to task difficulty variations.

Conclusions:

• Pupil diameter and fixation duration are sensitive and reliable physiological measures for assessing mental workload in n-back and arithmetic tasks.
• Most tested physiological indices can detect significant changes in mental workload, particularly at extreme difficulty levels.
• Pupil diameter emerges as a highly sensitive indicator across different cognitive tasks.