Monitoring Seated Postural Responses to Assess Cognitive State

With recent advances in workstation technology, operators are often asked to perform complex tasks that require a tremendous amount of real-time information processing. In order to avoid poor task performance due to the operator's cognitive limitations, it would be advantageous to be able to probe an operator's cognitive state while performing such tasks. The current study investigates whether operators exhibit changes in seated posture as a result of changing cognitive task conditions. Furthermore, the current study presents means of quantifying such seated postural changes in real-time and uses these measures to construct an implicit cognitive state gauge. Fourteen subjects performed a simulated airspace monitoring task in which they tracked multiple 75.0 sec long waves of incoming aircraft with various levels of difficulty. Subjects were instructed to identify all incoming aircraft and to attend to them based on the level of threat that they posed. While performing the task, subjects' seated postural changes were monitored by tracking the distribution of pressure over the seat and back pads of the chair. This distribution of pressure was used to calculate changes in seated center of pressure, seat torsion, and the extent to which subjects used the back of the chair to brace themselves. Subjects demonstrated a significant decrease in seated postural changes over the course of more difficult waves (high number of aircraft on screen) in comparison to easier waves (low number of aircraft on screen). When subjects completed waves with 24 tracks on screen compared to waves with 6 tracks on screen, the distance traveled by the seated center of pressure decreased 40.3%, transverse-plane seat torsion decreased 32.2%, and the total change in distance between the left and right ischial tuberosities decreased 38.1% on average. The extent to which subjects' postural changes were correlated to the changing number of tracks on screen was consistently high while the number of tracks on screen was increasing and was consistently low after the maximum number of tracks on screen had been presented. It was concluded that monitoring seated posture is effective for gauging how subjects update their awareness of task conditions in real-time.

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