Dissociation of Performance and Subjective Measures of Workload

TLDR

The study proposes a theory to explain why performance and subjective workload can diverge. The model links performance to resource investment, efficiency, and competition, and links subjective workload to investment and working‑memory demands. The theory predicts dissociation when additional resources improve performance, when working‑memory demands increase, or when competition affects performance more than subjective load, and the authors discuss implications and future research.

Abstract

A theory is presented to identify sources that produce dissociations between performance and subjective measures of workload. The theory states that performance is determined by (1) amount of resources invested, (2) resource efficiency, and (3) degree of competition for common resources in a multidimensional space described in the multiple-resources model. Subjective perception of workload, multidimensional in nature, increases with greater amounts of resource investment and with greater demands on working memory. Performance and subjective workload measures dissociate when greater resources are invested to improve performance of a resource-limited task; when demands on working memory are increased by time-sharing between concurrent tasks or between display elements; and when performance is sensitive to resource competition and subjective measures are more sensitive to total investment. These dissociation findings and their implications are discussed and directions for future research are suggested.