Differences in driver takeover performance and physiological responses in conditionally automated driving: Links to emotional instability

When the automated driving system reaches its technical limit, drivers will have to take over control from the vehicle within a limited time. The drivers' emotional instability may affect whether they can safely control the vehicle during takeover transitions. Accordingly, this paper explores the association between emotional instability and physiological responses and driver takeover performance. 42 drivers engaged in negative emotion induced by movie clips were involved in a sequence of takeover events in a driving simulator. Personality questionnaires were used to assess the driver's level of emotional instability. Their physiological data before the takeover request (TOR) and operational behavior data fragments for the takeover process were extracted. The results demonstrated that integration of subjective evaluations with electroencephalogram (EEG) and electrocardiogram (ECG) signals allows for more objective measurement of drivers' level of emotional instability. The statistical analyses indicated that emotional instability has a significant effect on drivers' heartbeat interval, heart rate, the frequency bands of theta(4-8 Hz), alpha(8-12 Hz), beta(13-30 Hz), gamma (30-50 Hz) and lateral takeover performance. Those findings of differences in driver physiological responses and takeover performance under emotional instability may provide additional support for the design of driver state monitoring and adaptive warning systems.