Effects of Multimodal AR-HUD Navigation Prompt Mode and Timing on Driving Behavior.

Current research on multimodal AR-HUD navigation systems primarily focuses on the presentation forms of auditory and visual information, yet the effects of synchrony between auditory and visual prompts as well as prompt timing on driving behavior and attention mechanisms remain insufficiently explored. This study employed a 2 (prompt mode: synchronous vs. asynchronous) × 3 (prompt timing: -2000 m, -1000 m, -500 m) within-subject experimental design to assess the impact of multimodal prompt synchrony and prompt distance on drivers' reaction time, sustained attention, and eye movement behaviors, including average fixation duration and fixation count. Behavioral data demonstrated that both prompt mode and prompt timing significantly influenced drivers' response performance (indexed by reaction time) and attention stability, with synchronous prompts at -1000 m yielding optimal performance. Eye-tracking results further revealed that synchronous prompts significantly enhanced fixation stability and reduced visual load, indicating more efficient information integration. Therefore, prompt mode and prompt timing significantly affect drivers' perceptual processing and operational performance. Delivering synchronous auditory and visual prompts at -1000 m achieves an optimal balance between information timeliness and multimodal integration. This study recommends the following: (1) maintaining temporal consistency in multimodal prompts to facilitate perceptual integration and (2) controlling prompt distance within an intermediate range (-1000 m) to optimize the perception-action window, thereby improving the safety and efficiency of AR-HUD navigation systems.