Turning Perceptions into Design Recommendations: Exploring the Implications of Multisensory Stimuli on Alertness and Mood in Manual and Partially Automated Vehicles

Driver alertness and mood are critical for driving safety and experience. Despite interests in multisensory interventions to elevate alertness and mood, few studies have combined multisensory modalities and evaluated their joint impact in real-world driving. This study introduces and evaluates a novel in-vehicle multisensory experience that synchronizes sound, vibration, light, scent, and airflow to enhance driver engagement. Using a 2×2 within-subject design, we conducted a naturalistic study with 45 participants to examine the effect of driving mode (manual vs. assisted-driving) and experience duration (one song vs. two songs) on the driver's perceptions and responses. Self-reported alertness and mood were collected alongside qualitative user feedback. Overall, alertness and arousal were significantly increased following the onset of the experience. Arousal remained elevated throughout the experience, while alertness diminished at the end. The positive effect was more pronounced during manual driving. These findings offer insights for future development of adaptive, user-centered in-vehicle systems.