On the investigation of the neurophysiological correlates of knowledge worker mental fatigue using the EEG signal.

Technological trends and advances in automation have underscored the importance of task performance of certain jobs requiring mental functions such as information processing and decision analyses. Most experts agree that such work environments produce increased mental activities, with profound implications for mental fatigue and stress. Consequently, productivity measurement and improvement for white collar or 'knowledge worker' occupations remains a major challenge and concern. This investigation defines an experimental approach that examines the neurophysiological correlates of white collar worker mental fatigue using the EEG signal. A 6 h laboratory experiment was conducted to simulate work output. The methods of assessing fatigue employed were mental tests and physiological measurements. The experiment involved reading of standardized texts, finding solutions to arithmetic-logical problems and a combination of both task types. Two primary performance measures were obtained, work output and brain waves. Fast Fourier transform and correlation analyses are used to quantify the relationship between certain brain waves and mental fatigue. This research is a major step towards the development of a model that explores the relationship between mental fatigue and factors associated with output performance, optimal recuperation periods and related variables. Such a model would be useful in human reliability prediction based on task parameters and worker profiles.

System response time and method of pay: cardiovascular stress effects in computer-based tasks.

Psychophysiological effects of computer system response time (slow vs. rapid) and method of pay (incentive vs. nonincentive) were assessed in a computer-based data entry task among forty-five professional typists. Cardiovascular responses (i.e., heart rate and blood pressure) were monitored on a regular basis over four consecutive workdays. Heart rate and blood pressure did not vary significantly with slow or rapid response times. Incentive pay, however, significantly increased blood pressure and decreased heart rate variability across the workdays compared to nonincentive pay. Irrespective of response time or method of pay, performance of the data entry task for sustained periods of time was associated with reduced heart rate and increased heart rate variability. This temporal effect was indicative of reduced effort or increased mental fatigue. The results of this study suggest that incentive pay programmes in data entry work may produce stress-related physiological reactivity among healthy workers.