EEG/ERP as a Measure of Mental Workload in a Simple Piloting Task

Abstract Operating an aircraft is cognitively challenging: pilots have to control the plane and must remain responsive to potential verbal-auditory stimuli (e.g. Air Traffic Control Communication) and auditory alerts (e.g. Terrain Awareness and Warning System). Fifteen participants had to control an aircraft in order to target one of three differently-colored aircrafts displayed on a computer screen. The name of the color (written in black ink) corresponding to the aircraft to target was displayed in the center of the screen. Simultaneously with the onset of the written name of the color, a spoken color name distractor that participants had to ignore was played. This auditory distractor was either congruent (10%, spoken color name matched the written color) or incongruent (10%, spoken color name did not match the written color). The task difficulty varied in terms of working memory load with an n-back-like sub-task. In the low load condition, participants had to target the aircraft corresponding to the currently presented written instruction (n = 0). In the high load condition, participants had to target the aircraft corresponding to the instruction presented two trials before (n = 2). Behavioral analysis showed that increased mental workload provoked a decrease in piloting performance, i.e. participants tended to forget the correct instruction. On the physiological level, EEG/ERP measurements related to instructions showed that increased mental workload was accompanied by lower P3b amplitude. We assume that the lower P3b amplitude reflects the depletion of the cognitive resources allocated to the processing of the instructions. These results suggest that P3b can be a relevant indicator of the openness of the system to sudden and unexpected critical stimuli such as auditory alerts.