Comparing heart rate and pupil size as objective measures of workload in the driving context

Historically detection of workload has been done through the use of subjective measures but new demands in research are driving interests to objective and immediate physiological measures. This paper is a look at some initial data from a study comparing the commonly used measure of heart rate (HR) to that of pupil size (PS), in detecting changes in workload in a driving environment. Participants drove a simulator and performed the n-back task while having their HR and PS tracked. Initial results show both measures have the expected trends; but significant differences between n-back levels found in the PS data suggest that PS may be more sensitive to differences in workload. The results and considerations are discussed.