The impact of cognitive workload on physiological arousal in young adult drivers: a field study and simulation validation

Abstract

Physiological measures provide a continuous and relatively non-invasive method of characterising 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.

Statement of Relevance: Growing complexity and multiple demands on modern drivers’ attention highlight the significance of determining whether physiological measures provide increased sensitivity in workload detection. Better understanding, including whether simulator assessments provide valid measures of real-world response patterns, has implications in evaluating and refining interface designs and for developing advanced workload managers.

Keywords:

• cognitive workload
• driver state
• heart rate
• skin conductance
• simulator validity

Acknowledgements

We gratefully acknowledge the support of the US Department of Transportation's Region I, New England University Transportation Centre at MIT, the Santos Family Foundation for support of further analysis and dissemination of findings, and Ford Motor Company for the development of the data sources. This article represents a significant extension of work that appeared in part in the proceedings of the Automotive User Interfaces and Interactive Vehicular Applications (AutomotiveUI 2009) conference (Reimer et al. 2009b). The artefact removal routine for the skin conductance signal was developed by Zach Tan.