自动驾驶车辆外部人机交互界面（external human-machine interfaces, eHMI）的呈现方式与时机会影响行人的过街决策，因此研究过街行人对自动驾驶车辆的意图理解具有重要意义。利用Unity 3D建立仿真模型，依据车辆意图呈现方式与时机的不同进而生成16段自动驾驶车辆驶来视频，将视频乱序向参试者播放，收集参试者在面对不同视频时做出的反应时间与过街决策，基于此来探究eHMI呈现方式和时机对行人过街决策的影响。结果表明：在呈现方式方面，相比于中性颜色，显著的文本颜色往往更可以影响行人的过街决策，可以大大缩短行人的反应时间，帮助行人做出更准确、更安全的过街决策；在呈现时机方面，当自动驾驶车辆车速处于35 ~ 40 km/h时，激活距离越近越会对行人的过街决策产生积极的影响。

The presentation and timing of external human-machine interfaces (eHMI) for autonomous vehicles were found to significantly influence pedestrians' crossing decisions. Therefore, understanding pedestrians' interpretations of autonomous vehicles' intentions is of great importance. A simulation model was constructed using Unity 3D, and 16 videos depicting approaching autonomous vehicles with varying presentations and timings of vehicle intentions were generated. These videos were presented to participants in a randomized order to gather data on their reaction times and crossing decisions in response to the different scenarios. The results show that in terms of presentation, prominent text colors, as opposed to neutral colors, tend to significantly impact pedestrians' crossing decisions. This effect notably reduces pedestrians' reaction times and assists in making more accurate and safer crossing decisions. Regarding the timing of presentation, it is observed that a closer activation distance positively influences pedestrians' crossing decisions when autonomous vehicles' speeds are between 35 ~ 40 km/h. The closer the activation distance, the more positive the impact on pedestrians' crossing decisions.