Validity and Reliability of Rating Scale Mental Effort, Integrated Workload Scale, and Overall Workload Scale in Iran

Mental workload is an important issue in occupational health. This study aimed to determine the validity and reliability of the Rating Scale Mental Effort (RSME), Integrated Workload Scale (IWS), and Overall Workload Scale (OW) in Iran. This study was conducted on 100 male students of Iran University of Medical Sciences. The forwardbackward translation method was used to evaluate the linguistic validity of the scales. Then the scales were presented to six ergonomics and occupational health experts to assess the content validity of the scales. Internal validity of the scales was assessed by correlating mental workload scale scores with reaction times on a criterion task. Finally, multiple sessions of a hybrid memorysearch task were performed to determine the reliability of the scales. There was prefect agreement among the experts regarding of all three scales. Content Validity Index and Content Validity Ratio were 1 for each three scales. About the reliability of the scales, the Pearson correlation coefficients between the scale scores in the test and retest phases were 96, 88, and 84 for RSME, IWS, and OW, respectively. Finally, Validity and reliability of the scales were approved and It seems that these scales can be used for measuring selfreported mental workload.