Cognitive activation and emotional regulation effects of olfactory intervention in the context of advanced driver...

Olfactory stimulation is an emerging sensory activation approach that can effectively mitigate passive distraction in advanced driver assistance systems (ADAS). Therefore, it is necessary to further determine its efficacy and to elucidate its differential effects within urban and highway driving environments.

A simulated vehicle cabin odor mixture served as the control baseline. Peppermint and bergamot were selected as intervention odors after screening. Thirty-four licensed drivers completed simulated driving under urban or highway conditions across three odor conditions, with physiological measures (EEG, EDA), task performance (RT, RTSD, accuracy), and subjective assessments (NASA-TLX, POMS Vigor and Confusion, SMS) recorded to systematically investigate the modulatory effects of olfactory interventions within ADAS. Parametric analyses were used when assumptions were met and aligned rank transform analyses were applied otherwise.

Relative to the simulated cabin baseline, olfactory stimulation improved driving attention performance and driver state. Peppermint produced the largest reduction in reaction time and increased beta-related alertness, with higher sympathetic activation. Bergamot yielded smaller speed gains but stronger stabilization of response rhythms and lower perceived workload with reduced confusion. Moreover, olfactory interventions exhibit significant context dependence across driving settings. In urban driving, characterized by high information density, bergamot more effectively suppressed low frequency electroencephalography indices and reduced variability, whereas peppermint sometimes increased variability. In highway driving, which is monotony prone, peppermint sustained vigilance and reduced attentional drift.

Olfactory benefits are context dependent and follow the Yerkes-Dodson law. Scenario matched deployment is recommended: peppermint for vigilance support in monotonous highway driving and bergamot for stabilization and stress relief in complex urban traffic. These findings provide novel insights into the development of context-adaptive olfactory systems for intelligent vehicle-cabin, facilitating safer human-machine co-driving environments.