MIT AgeLab and New England University Transportation Center researchers Bryan Reimer and Bruce Mehler recently published “The impact of cognitive workload on physiological arousal in young adult drivers: a field study and simulation validation” in the October 2011 edition of Ergonomics. The article addresses the use of physiological measures to characterize driver workload. Results show that heart rate and skin conductance are sensitive to changes in workload associated with a secondary cognitive task and the pattern of change in the physiological measures is highly consistent between the field and a driving simulator. This work highlights the growing complexity of assessing modern drivers’ attention and highlight the role physiological measures may provide in assessing cognitive workload.
Physiological measures provide a continuous and relatively non-invasive method of characterizing workload. The extent to which such measures provide sensitivity beyond that provided by driving performance metrics is more open to question. Heart rate and skin conductance were monitored during actual highway driving in response to systematically increased levels of cognitive demand using an auditory delayed digit recall task. The protocol was consistent with an earlier simulator study, providing an opportunity to assess the validity of physiological measures recorded during driving simulation. The pattern of change in heart rate with increased cognitive demand was highly consistent between field and simulator. The findings meet statistical criteria for both relative and absolute validity, although there was a trend for absolute levels to be higher under actual driving conditions. For skin conductance level, the pattern in both environments was also quite similar and a reasonable case for overall relative validity can be made.