Zhang Zhi-jun

Multiple measures of monitoring mental workload

This study explored the possibility of developing a technique combining multiple measures of mental workload. Dual task technique was applied. Twenty subjects were asked to perform computer-simulated monitoring tasks with three different levels of difficulties. A reaction time performance with digital stimuli was added as subsidiary task. The four indexes, accurate reaction time of primary task, variation rate of accurate reaction time of subsidiary task, weighted subjective workload rating and variation rate of heart rate variance, were used and tested. The correlation matrix of the four indexes was examined with principal component analysis technique, and two mathematical models of comprehensive mental workload indexes (CMWIA, CMWIB) were then advanced. It is verified that these two comprehensive indexes were far more sensitive for monitoring mental workload as compared with any one of the preceding four indexes. It was concluded that it was useful to construct some comprehensive mental workload indexes for practical industrial purposes.