The Effect of Varying Task Difficulty on Subjective Workload

Abstract

The goal of the present study was to determine whether or not retrospective workload ratings would reflect the average demands of the entire block of trials or whether one segment within the block would have more weight in determining the magnitudes of ratings than another. Performance data within a block of trials almost perfectly reflected the different task difficulty manipulations: reaction times (but not movement times) reflected variations in the difficulty of the more cognitive response selection component whereas movement times (but not reaction times) reflected variations in the difficulty of the response execution component. Subjective ratings consistently reflected the combined demands of both task components averaged across levels of difficulty even when their levels of difficulty were varied within the block of trials. In every case, it appeared that all of the trials within a block were given equal weight in the composite subjective evaluation. These results suggest that subjective workload is not a specific retrieval of experiences heeded in working memory. Rather, it may reflect the experiences of an ongoing integration process.