The Relationship between Stimulus-Oriented Changes in Heart Rate and Detection Efficiency in a Vigilance Task
Technical Report,01 Jun 1965,30 Jun 1967
AIR FORCE AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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The study was designed to assess the relationship between detection efficiency and beat-to-beat changes in heart rate around task stimuli in a vigilance task. Thirty-six subjects, instrumented for continuous recording of EKG and respiration, individually stood a 96 minute vigil. They monitored a light which flashed on stimulus event for 500ms. once every 6.0 seconds and were to report the occasional brighter flashes signals. Half of the subjects high signal density group received 240 signals the remaining 18 subjects low signal density group received but 16 signals. By urging the subjects to do their best, a motivational condition was induced in a six minute post-test. As expected, detection efficiency was higher and better sustained by the high signal density group. Detection efficiency of the low signal density group decayed appreciably over time. In the motivational post-test condition the performance of both groups improved significantly. Measures of changes in heart rate, analyzed both in terms of overall shifts in heart rate over the vigil and beat-to-beat changes in heart rate around each stimulus event, revealed 1 The median heart rate in succeeding quarters of the vigil, did not differ significantly between the two groups. 2 Heart rate preceding a stimulus event decelerated. 3 In the post-test the significant recovery in detection efficiency was accompanied by an increase in the magnitude of stimulus-oriented cardiac deceleration and by a decrease in overall heart rate.