Temporal Dynamics of Ocular and Physiological Responses to Multisensory Stimulation Across Different Driving Modes and Stimulation Durations

Prolonged driving can reduce vigilance, especially when advanced driver-assistance systems lower drivers’ active engagement. This study examines how drivers’ ocular and physiological responses change before, during, and after in-vehicle multisensory stimulation. Forty drivers completed on-road drives in manual and SAE Level 2 assisted modes. The stimulation integrated music, seat vibration, cool airflow, blue ambient lighting, and scent, and lasted 240 and 480 s. Eye-tracking and heart rate data were segmented into 30-s windows and analyzed using a sharp-change point method. Results showed early onset effects across driving modes, with decreases in blink duration and heart rate after stimulation began. Longer stimulation was associated with fewer abrupt temporal changes. Manual driving showed more changes in blink rate and heart rate after stimulation, whereas assisted driving showed greater fluctuations in blink duration during stimulation. Findings highlight the importance of timing, duration, and driving context when designing adaptive multisensory interventions for driver vigilance.