An Integrative Assessment of Cognitive-Motor Processes Underlying Mental Workload and Performance Under Varying Levels of Controllability.

A study of mental workload is essential to understanding the intrinsic limitations of the human information processing system and the resultant cognitive-motor behavior, the results of which hold great importance for any discipline connected to human operators in the context of safety-critical behavior. Mental workload and the quality of cognitive-motor performance are known to be impacted by task demand. However, one feature of task demand far less understood is the controllability of a system (e.g., the responsiveness of a flight platform and its handling qualities). In the realm of Human-Machine Interface, the assessment of system controllability has typically been conducted through subjective measurements, such as the Cooper-Harper Rating Scale (CHR) [ 9 ], Bedford Workload Scale (BWS) [ 43 ], or the NASA Task Load Index (NASA-TLX) [ 21 ]. A fundamental element of the decision-making process for handling qualities associated with operator workload includes the reporting of the control compensation required to overcome deficiencies and errors that could impact and inhibit the successful completion of a task. However, subjective ratings suffer reduced sensitivity to dynamic changes in operator workload, and are solely dependent on subjective estimates of effort to control compensation within a system, despite such wide usage in the field. Conversely, objective metrics, such as power spectra derived from the electroencephalogram (EEG) paired with behavioral performance measures exist as an attractive alternative. Thus, the purpose of the present study was to assess brain dynamics explicitly related to mental workload and subjective ratings as reported during compensatory tracking tasks of varying complexity while also challenged with progressively increasing levels of difficulty.