Cerebral Blood Flow Velocity and Subjective State as Indices of Resource Utilization during Sustained Driving

Recent studies from our laboratory have shown that the vigilance decrement, the decline in signal detection over time that typifies vigilance performance, is accompanied by a decline in Cerebral Blood Flow Velocity (CBFV) measured by transcranial Doppler ultrasonography and by an increase in stress measured by the Dundee Stress State Questionnaire (DSSQ). These studies were restricted to single vigilance tasks. In operational settings, such as driving, vigilance is often combined with other task components. Therefore, the aim for the present study was to generalize the findings from the earlier studies to a simulated driving task. As in the earlier studies, temporal declines in performance efficiency, indexed in this case by variability in lateral position, were accompanied by declines in CBFV and increased feelings of distress and task disengagment on the DSSQ. The results suggest that resource utilization patterns found with single vigilance tasks may extend to dynamic performance situations in which vigilance is one of several task elements.