Using Transcranial Doppler Sonography to Measure Cognitive Load in a Command and Control Task

Abstract

Previous work has explored the possibility of measuring the functional state of the operator to drive the implementation of physiological adaptive aiding. Transcranial Doppler Sonography (TCD), which has shown promise as an index of cognitive resource utilization in vigilance or sustained attention tasks, may provide a time and cost efficient alternative to traditional measures used to assess operator functional state. In the current study, participants performed a command and control simulation under varying levels of task load: a low task load condition in which enemy threats incurred at a steady pace, and a high workload trial in which the number of enemy threats increased unpredictably at two points within the scenario. Reaction time to engage and destroy enemies, and the efficiency of protection of a no-fly zone, were superior in the low than in the high load condition. Furthermore, an automated decision aid facilitated better performance in both task load conditions. As the demands of the task increased unpredictably in the high task load condition, cerebral blood flow velocity (CBFV) increased in a similar manner for the first task load transition, but not for the second. Results suggest that the TCD measure may be useful in monitoring the dynamic changes of operator workload in unpredictable environments, but additional studies are needed to validate its use for physiologically-driven adaptive automation.