ABSTRACT
OBJECTIVE: The current study was designed to determine whether continuous, physiobehavioral monitoring via transcranial Doppler sonography (TCD) has negative effects on human performance or user state in a vigilance task. BACKGROUND: Physiobehavioral measures have been identified as a promising method of user state assessment, in part because they are thought to be relatively nonintrusive. The notion that physiobehavioral measures are nonintrusive should not be taken for granted and needs to be tested empirically. It is possible that, even though physiobehavioral measures do not require input from a user, they may still hinder performance by causing discomfort, distraction, or interfering with physical activities required for task performance. METHOD: The current study employed TCD, a common method of monitoring user vigilance. Participants completed a 40-min vigilance task. During the task, 50% wore TCD apparatus, while 50% did not. Intrusiveness was measured in terms of vigilance performance as well as workload, stress, and simulator sickness. RESULTS: Analyses revealed results that mirrored prototypical vigilance findings: performance declined over time, workload was high, distress and reported simulator sickness symptomology increased during the task, while engagement decreased. The presence or absence of TCD monitoring had no direct or interactive effects on performance or user state. CONCLUSION: TCD monitoring of user vigilance appears to be nonintrusive. APPLICATION: Findings support the recommendation that TCD should be used in research and operational settings where user vigilance is of paramount importance. More broadly, when developing and fielding physiobehavioral state measurement systems, intrusiveness should be considered and evaluated.
