A Physical Measure of Subjective Workload

Abstract

This investigation compared a physical measure of subjective workload (i.e., hand dynamometer) with traditional verbal scaling techniques. There were four subjective rating groups. One group employed the Subjective Workload Assessment Technique (SWAT) which required three separate ratings of time stress, mental effort, and psychological stress. A second group used verbal magnitude estimation (ME). Two physical measure groups estimated the magnitude of workload by squeezing a dynamometer in accordance with the magnitude of workload experienced. The DYNA1 group made one overall rating of workload similar to the ME group. The DYNA3 group made three workload ratings along the same dimensions as SWAT. All groups rated the workload associated with the performance of a continuous memory task under twelve levels of task difficulty. The physical measure of subjective workload most closely corresponded to actual task performance differences. The results suggest future development of a physical measure of subjective workload which can be utilized on a continuous basis, thus avoiding a major shortcoming of typical verbal measures of subjective workload.