[Application of multistage evaluation scale in subjective assessment of mental workload]

The efficiency of multistage evaluation scale (MES) based on the fuzzy set theory as used in subjective assessment of mental workload was studied, and the results were compared with those of tracking performance and category scale (CS). It was found that error (ER) significantly increased when task became more difficult (P < 0.01) and the scalings of MES and CS also increased, but that of MES was significantly different in tasks of all the three difficulties (P<0.01) while those of CS was significant only between tasks 1 and 3 as well as tasks 2 and 3 (P <0.01), but not between tasks 1 and 2. These show that the result of MES is more agreeable with that of ER. So it might be a better subjective assessment measure of mental workload.