Systematic Review of the Convergence and Divergence of Cognitive Workload Measures

Cognitive workload, or the mental effort required to perform a task, has been used across many fields, yet variability in measurement and theoretical framing complicates the synthesis of findings. Within the same study, proxy measures for the term often find contradictory outcomes. This review examines empirical research on cognitive workload over the last 25 years in monitoring tasks. We categorize the incidence of multiple measures and measure types (i.e., subjective, performance-based, and physiological) and highlight patterns of convergence and divergence across studies. We also evaluate how the number and type of workload measures influence sensitivity and interpretability. We find that measure type has no detectable effect on convergence of measures, but that the number of measures increases the probability of convergence in our samples. Finally, we provide recommendations for future research to improve measurement consistency and enhance understanding of cognitive workload.