MIT AgeLab will present three papers at the Sixth International Driving Symposium on Human Factors in Driver Assessment, Training, and vehicle Design in Lake Tahoe, California. Below are titles and abstracts. Full citations can be found here.
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.
The effect of age and gender on visual search during lane changing.
This study examined visual search behavior relative to three regions of interest (ROI) (side mirror, rear view mirror, and blind spot) for self-initiated lane changes in a sample of 108 drivers under actual highway conditions. As has been observed previously, few drivers scan all three of the ROI prior to executing a lane change, with turning around to inspect the blind spot being the lowest frequency behavior. Age, gender and direction (left or right lane change) were found to influence visual search behaviors. For lane changes to the right, blind spot checking occurred less than 32% of the time in females and less than 15% of the time in males. This low level of blind spot checking to the right was consistent across younger and older age groupings. Interestingly, the most notable age discrepancy was in checking the left blind spot. Younger drivers checked their left blind spot 53.3% of the time compared to a rate of 23.9% for drivers in their 60s. Implications of these findings for both driver remediation programs and the increasing availability of blind spot identification systems are considered.
Impact of cognitive workload on physiological arousal and performance in younger and older drivers.
Two groups, aged 25-35 and 60-69, engaged in 3 levels of a delayed auditory recall task while driving a simulated highway. Heart rate and skin conductance increased with each level of demand, demonstrating that these indices can correctly rank order cognitive workload. Effects were also observed on speed and SD of lane position, but they were subtle, nonlinear, and did not effectively differentiate. Patterns were quite consistent across age groups. These findings on the sensitivity of physiological measures replicate those from an onroad study using a similar protocol. Together, the results support the validity of using these physiological measures of workload in a simulated environment to model differences likely to be present under actual driving conditions.