Effects of mental workload and fatigue on the P300, alpha and theta band power during operation of an ERP (P300) brain–computer interface

• Mental workload and fatigue were manipulated during BCI operation.
• The study reveals electrophysiological indicators of high workload and fatigue.
• Differences in alpha power proved to be the most sensitive indicator of fatigue.
• High accuracies were achieved with the BCI despite constant distraction.

The study aimed at revealing electrophysiological indicators of mental workload and fatigue during prolonged usage of a P300 brain–computer interface (BCI). Mental workload was experimentally manipulated with dichotic listening tasks. Medium and high workload conditions alternated. Behavioral measures confirmed that the manipulation of mental workload was successful. Reduced P300 amplitude was found for the high workload condition. Along with lower performance and an increase in the subjective level of fatigue, an increase of power in the alpha band was found for the last as compared to the first run of both conditions. The study confirms that a combination of signals derived from the time and frequency domain of the electroencephalogram is promising for the online detection of workload and fatigue. It also demonstrates that satisfactory accuracies can be achieved by healthy participants with the P300 speller, despite constant distraction and when pursuing the task for a long time.