Older Drivers' Physiological Responses during Last-Minute Braking in a Driving Simulator

The physiological stress and responses involved in last-minute braking situations are studied very little. The purpose of this study was to investigate older and younger drivers' physiological (central and autonomic nervous systems') responses and driving performance in two unexpected driving situations in a driving simulator. The subjects performed the test for two times, one for unexpected event while driving during 70 km/h and another driving during 90 km/h. An unexpected event described as while the lead-vehicle stops unexpectedly the subject vehicle needs to apply last minute braking. Nineteen healthy older (age: 65.6 ± 5.0 years) and nineteen healthy younger (age: 26.3 ± 2.0 years) drivers performed continuously simulated driving tasks with a simultaneous physiological parameters recording of each subject. The physiological parameters recorded were, Electroencephalogram (EEG) in the area of Fz and O₂, Electrocardiogram (ECG), Galvanic Skin Response (GSR), and Skin Temperature (SKT). The driving performance measured were accident rate, inter-vehicle distance, reaction time, full braking time and subject vehicle approaching velocity. The analysis of the EEG revealed the emotional states were classified by values of alpha and beta ratios and the autonomic nervous system responses, particularly the average of R-R interval, GSR and SKT. The results suggest that the values of EEG bands in the areas of Fz and O₂ and the average of R-R interval, GSR and SKT were significantly different between last-minute braking situations (p ≺ 0.05). In terms of accidents, the rate was higher for older driver's driving at 90 km/h than driving at 70 km/h in a driving simulator. In terms of response to the last minute braking, younger's reacted quicker than the elderly.