Chapter 29: Driving in States of Fatigue or Stress

Handbook of Driving Simulation for Engineering, Medicine, and Psychology

Driving in States of Fatigue or Stress

Authors
Gerald Matthews, University of Cincinnati
Dyani J. Saxby, University of Cincinnati
Gregory J. Funke, University of Cincinnati
Amanda K. Emo, Federal Highway Administration
Paula A. Desmond, Southwestern University


Abstract

The Problem. Fatigue is a serious safety problem for drivers. There are several separate sources of fatigue including sleep loss, circadian rhythm effects, and the intrinsic demands and workload of the driving task. It is important to understand both the processes that generate fatigue in the driver and the impact of fatigue states on information processing, performance, and safety. Fatigue effects involve a number of separate mechanisms and so a clear theoretical understanding of these mechanisms is needed in order to guide interventions to enhance safety. This chapter reviews methods for inducing fatigue during simulated driving, theoretical frameworks for interpreting fatigue data and practical applications. Role of Driving Simulators. The driving simulator affords the means for controlled experiments on the interplay between fatigue and driver performance. Fatigue states are readily induced on the simulator. They may be evaluated using subjective and psychophysiological measures. The simulator also affords measurement of fatigue-induced changes in vehicle control, attention, and risk-taking behaviors. Simulator methods are also pivotal for assessment of individual differences in fatigue vulnerability, investigation of clinical fatigue conditions, and evaluation of countermeasures for fatigue. Key Results of Driving Simulator Studies. One important contribution of simulator studies is to map how environmental factors such as monotony and workload elicit fatigue responses and to track the development of fatigue states over time. Fatigue responses may be understood within the transactional theory of stress; fatigue is the outcome of a self-regulative process of managing personal discomfort and tiredness. Simulator studies have also proved valuable in testing theories of performance decrement. Studies have explored how depletion of attentional resources and breakdown of effort-regulation may contribute to driver performance impairments. Scenarios and Dependent Variables. Scenarios for inducing fatigue typically involve some combination of monotony and extended drive duration. High workload is not directly tied to fatigue response, but may also contribute to fatigue. Several types of dependent variables may be assessed, including measures of subjective state, psychophysiological responses, and performance data logged by the simulator.

Keywords
Fatigue, Stress, Driver Behavior, Human Performance, Psychophysiology


Key Points

• Fatigue is a serious safety issue for drivers; simulator studies make an important contribution to investigating driver fatigue and stress.
• Driver simulators may be configured to induce qualitatively different fatigue states including sleepiness, passive fatigue (related to monotony and underload), and active fatigue (related to overload).
• Multidimensional assessments of fatigue response that may include both subjective and psychophysiological indices are recommended.
• Detrimental effects of fatigue may be observed in relation to a variety of performance indices, including measures of attention and psychomotor control, but different studies may show differing performance effects.
• Fatigue effects on driver performance may be moderated by workload factors; the passive fatigue that develops in underload conditions may be especially dangerous.
• Simulators may be used to investigate individual differences in fatigue vulnerability and clinical conditions associated with fatigue that may compromise safety.
• Simulators afford the systematic testing of countermeasures to fatigue and the evaluation of methods for detecting unsafe levels of fatigue, such as monitoring oculomotor behaviors.

Key Readings
Baulk, S. D., Biggs, S. N., Reid, K. J., van den Heuvel, C. J., and Dawson, D. (2008). Chasing the silver bullet: Measuring driver fatigue using simple and complex tasks. Accident Analysis and Prevention, 40, 396–402.

Desmond, P. A., and Hancock, P. A. (2001). Active and passive fatigue states. In P. A. Hancock and P. A. Desmond (Eds.), Stress, workload, and fatigue (pp. 455–465). Mahwah, NJ: Lawrence Erlbaum.

Fairclough, S. H. (2001). Mental effort regulation and the functional impairment of the driver. In P. A. Hancock and P. A. Desmond (Eds.), Stress, workload, and fatigue (pp. 479–502). Mahwah, NJ: Lawrence Erlbaum.

Lal, S. K. L., and Craig, A. (2001). A critical review of the psychophysiology of driver fatigue. Biological Psychology, 55, 173–194.

Matthews, G. (2002). Towards a transactional ergonomics for driver stress and fatigue. Theoretical Issues in Ergonomics Science, 3, 195–211.