In full-touch HMI mode: How does car-following pressure, task complexity, and speed affect driver's visual...

With the development of vehicle intelligence and automation, full-touch Human-Machine Interaction (HMI) is becoming a vital bridge for transferring substantial information between the driver and the system. Prior research suggests that the full-touch HMI mode may consume more visual resources from the driver, yielding in potential visual distraction. This study aims to investigate the effects of interaction tasks and traffic situations on drivers' visual distraction characteristics in full-touch HMI mode. Under safe conditions, a novel method was employed to create a visually realistic car-following situation. A total of 50 distinct participants were recruited: 30 took part in a real-road experiment, and 30 participated in a driving simulator experiment. Ten participants took part in both experiments, contributing to a total of 60 participant-sessions. Air volume control, temperature control, and call a contact are selected as typical tasks in each experiment. Total off-road glance duration, the number of off-road glances, and the mean off-road glance duration are selected as indicators for visual distraction characteristics. The results show that the mean off-road glance duration is influenced by the car-following pressure but not by the task. The mean glance duration is lower when the driver is following a vehicle, with an average decrease of 21.3%. Complex interaction tasks consume more of the driver's visual attention. Furthermore, higher speeds lead to a decrease in the total off-road glance duration, where participants tend to reduce the duration of each off-road glance while increasing the number of glances to compensate for the increased risk. The study findings can differentiate the visual demands of various HMI tasks and clarify how drivers adapt their gaze behaviors as driving demands change (e.g., car-following pressure), offering safety-related recommendations for drivers.