The use of autonomic components to improve cardiovascular assessment of mental workload in flight simulation

Principal components analysis of multiple psychophysiological measures of cardiovascular activity was used to derive the underlying sympathetic and parasympathetic information needed to represent the autonomic space for heart period. This method was applied to cardiac data that were previously collected during a full-mission flight simulation from volunteer commercial pilots (Corwin et al., 1989). Pilots flew both low- and high-workload mission scenarios in 2 separate test sessions. The autonomic components provided increased diagnosticity regarding the autonomic mode of control for heart period change between scenarios and across flight phases. Heart period was shorter (faster heart rate) during the high- than low-workload scenario because of uncoupled sympathetic activation. Heart period change across flight phases was due primarily to coupled reciprocal modes of autonomic control during the low-workload scenario. However, heart period change across phases was due to multiple modes of control, including coactivation, during the high-workload scenario. Further, heart period and the Sympathetic component score were significantly reliable across test sessions.