An Empirical Validation of Subjective Workload Ratings

A correlational design was used to regress NASA TLX subjective workload ratings onto several potential independent variables (i.e., the number of concurrent tasks, task combination, task resource demands, and flight experience) to determine task characteristics that influence pilot subjective workload ratings. A part task simulator was used to present up to six concurrent tasks, in different combinations, to 27 cadets at the USAF Academy. The results indicated the number of concurrent tasks had the largest impact on subjective workload ratings. In terms of multiple resource theory, spatial, verbal, and visual demands (in that order) contributed the most variance. The implication for theoreticians and designers is that the number of concurrent tasks, mental resource demands, and time constraints seem to be key contributors to subjective workload ratings.