Document Type : Original Articles



Abstract Background: The mental workload and cognitive failures are among the factors affecting the human behavior, performance and efficiency, which are both effective on the human error and accidents of the drivers. This study was conducted to examine the relationship between cognitive failure and mental workload of taxi drivers in Shiraz.Methods: This descriptive-analytical and cross-sectional study was conducted on 200 taxi drivers in Shiraz in 2017. In order to measure the mental workload and cognitive failure, NASA-TLX mental workload questionnaire and CFQ cognitive failure questionnaire were used, respectively. Finally, statistical analysis was performed using SPSS version 21. Pearson correlation, T-test and one-way ANOVA tests were used to analyze the data statistically.Results: The taxi drivers' mental workload was reported relatively high in this study and the results showed that a significant relationship was found between mental and temporal workload and nominal memory error of drivers at 5% error level (p <0.05). Also, a significant relationship was observed between temporal pressure and performance and memory and attention, respectively (p<0.05). In general, a significant relationship was observed between total cognitive failure and total mental workload (p<0.05). Also, demographic factors as age had a significant effect on both mental workload and cognitive failure (p<0.05).Conclusion: The results of this study showed a significant relationship between the mental workload and cognitive failure, so that with increasing the mental workload, cognitive failure of taxi drivers also increased and the probability of the human error and consequently driving accidents increased. Therefore, reducing the mental workload with providing ergonomic solutions can greatly prevent the human error in driving as a major contributor to many accidents.


  1. Peden M, Scurfield R, Sleet D, et al. World report on road traffic injury prevention. World Health Organization Geneva; 2004.
  2. Nantulya VM, Reich MR. The neglected epidemic: road traffic injuries in developing countries. Bmj. 2002;324(7346):1139-1141.
  3. Allahyari T, Rangi NH, Khalkhali H, et al. Occupational cognitive failures and safety performance in the workplace. International journal of occupational safety and ergonomics. 2014;20(1):175-180.
  4. Wallace JC, Chen G. Development and validation of a work‐specific measure of cognitive failure: Implications for occupational safety. Journal of Occupational and Organizational Psychology. 2005;78(4):615-632.
  5. Wadsworth E, Simpson S, Moss S, et al. The Bristol Stress and Health Study: accidents, minor injuries and cognitive failures at work. Occupational Medicine. 2003;53(6):392-397.
  6. Wickens CM, Toplak ME, Wiesenthal DL. Cognitive failures as predictors of driving errors, lapses, and violations. Accident Analysis & Prevention. 2008;40(3):1223-1233.
  7. Brookhuis KA, de Waard D. Monitoring drivers’ mental workload in driving simulators using physiological measures. Accident Analysis & Prevention. 2010;42(3):898-903.
  8. Lim J, Wu W-c, Wang J, et al. Imaging brain fatigue from sustained mental workload: an ASL perfusion study of the time-on-task effect. Neuroimage. 2010;49(4):3426-3435.
  9. Berka C, Levendowski DJ, Lumicao MN, et al. EEG correlates of task engagement and mental workload in vigilance, learning, and memory tasks. Aviation, space, and environmental medicine. 2007;78(5):B231-B244.
  10. Rubio S, Diaz E, Martin J, et al. Evaluation of subjective mental workload: A comparison of SWAT, NASA‐TLX, and workload profile methods. Applied Psychology. 2004;53(1):61-86.
  11. Mohammadi M, Mazloumi, A.,. Developing and assessing the validity and reliability of a questionnaire toassess the mental workload among ICUs Nurses in one of the Tehran University of Medical Sciences hospitals, Tehran, Iran Scientific Journal of School of Public Health and Institute of Public Health Research 2013;11(2):78-96.
  12. Hart SG, editor NASA-task load index (NASA-TLX); 20 years later. Proceedings of the human factors and ergonomics society annual meeting; 2006: Sage Publications Sage CA: Los Angeles, CA.
  13. Mahdinia M, Mirzaei Aliabadi M, Darvishi E, et al. An investigation of cognitive failures and its related factors in industry employees in Qom Province, Iran, in 2016. Journal of Occupational Health and Epidemiology. 2017;6(3):157-164.
  14. Kompier MA, Di Martino V. Review of bus drivers' occupational stress and stress prevention. Stress medicine. 1995;11(1):253-262.
  15. Farshad N, Khosravi Y, Zare G. The survey of relationship between occupational cognitive failures and safety performance among bus drivers. Iran Occupational Health. 2013;10(6):13-23.
  16. Stenfors CU, Hanson LM, Oxenstierna G, et al. Psychosocial working conditions and cognitive complaints among Swedish employees. PloS one. 2013;8(4):e60637.