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.