Some Measurement and Methodological Considerations in the Application of Subjective Workload Measurement Techniques

Previous research with the NASA Task Load Index (TLX) and the Subjective Workload Assessment Technique (SWAT) has demonstrated their sensitivity to variations in workload under flight and other complex work conditions but has not addressed some important measurement and methodological issues regarding their application. This article reviews data that address several such issues including the effects of delayed workload ratings, the effects of previous workload levels on ratings, and procedures used to combine subscale ratings into one overall estimate of subjective workload.