A Comparison of Heart Rate and Heart Rate Variability Indices in Distinguishing Single-Task Driving and Driving Under Secondary Cognitive Workload

Heart rate and heart rate variability (HRV) measures collected under actual highway driving from 25 young adults were compared to assess the relative sensitivity of each for distinguishing between a period of single task driving and periods of low and high additional cognitive workload. Basic heart rate, skin conductance and most, but not all, of the HRV indices were significantly different between single task driving and the high secondary demand period. Heart rate and skin conductance were also robust at distinguishing between single task driving and the low added demand period; however, several HRV measures did not show statistically significant differences between these two periods and the remaining HRV measures that did were less robust than basic heart rate as assessed by effect size and observed power. Rather than attempting to argue for the inherent superiority of any one physiological measure, these findings are presented with the intent of encouraging a broader discussion around the conditions under which particular physiological measures may be most useful and/or complementary for detecting different aspects of workload and operator state