Maintaining Driver Arousal with Warning Sounds under Habituation: Effects of Sound Type, Novelty, and Conditioning-Based Learning

This study investigated methods to sustain driver arousal in driver-assist systems by considering habituation to repeated warning stimuli. Two experiments examined three approaches: using arousal-appropriate sound types, introducing novelty, and applying conditioning-based learning to form conditioned reflexes to warning sounds. In Experiment 1, we compared different sound types (monotone vs. warning sounds) and novelty-based methods (single repeated sound vs. randomized multiple-sound presentation). Warning sounds maintained higher arousal than monotone sounds, even with repetition. While the random presentation method did not significantly increase arousal compared to the repeated single-sound condition, randomized warning sounds preserved arousal longer despite habituation. Experiment 2 examined another novelty method—switching warning sounds near the session’s end—and conditioning-based learning. Sound switching maintained arousal better than no-switch conditions. While conditioning-based learning enhanced arousal under the switching condition, there was no main effect of learning overall. An age-based analysis revealed learning effects among participants in their 20s and 30s, but not in those aged 40–50, suggesting age-specific adjustments in stimuli or learning time may be needed. Furthermore, switching sounds without prior learning showed more habituation, indicating that combining learning and switching is more effective. These findings suggest that integrating effective warning sounds, novelty, and age-appropriate learning strategies can help sustain driver arousal, which is considered to potentially contribute to safer vehicle operation.