Comparison of Mental Workload with N‑Back Test: A New Design for NASA‑Task Load Index Questionnaire

Aims: A most widely used tool for measuring the workload is the NASA‑task load index (TLX) questionnaire, in which various studies have reported numerous problems. The present study aimed to improve the NSAS‑TLX mental workload questionnaire using the fuzzy linguistic variables instead of the virtual rating scale, and multicriteria decision‑making Fuzzy Best‑Worst method (FBWM) instead of pair‑wise comparison. Materials and Methods: This cross‑sectional study was carried out among students of Shiraz University of Medical Sciences. In order to compare the traditional NASA‑TLX and FBWM NASA‑TLX questionnaire, participants performed a standard N‑Back task with three low, medium, and high workload, subsequently, they completed the two questionnaires. Finally, results were examined using the researcher‑made software and SPSS 16. Results: With regard to the reaction time to response the N‑Back test, the mean of correct responses were 107.43 and 85.86 responses at levels 1 and 3, respectively. The mean score of the subscales and the final score in the two questionnaires at different levels of the N‑Back test were independent as follows: the two questionnaires had a significant difference on mental demand at level 3 with a mean (standard deviation [SD]) of 18.09 (6.39) in the FBWM‑NASA‑TLX questionnaire and mean (SD) of 22.64 (8.15) in the NASA‑TLX questionnaire (P 0.05). Conclusion: In this study, the FBWM‑NASA‑TLX questionnaire was designed and studied with regard to the problems and limitations of the NASA‑TLX questionnaire. Results of this study showed that the FBWM‑NASA‑TLX questionnaire can estimate more realistic scores and decisions of workload in the studied task.