Future automated vehicles may be equipped with external Human-Machine Interfaces (eHMIs). Currently, little is known about the effect of the perspective of the eHMI message on crossing decisions of pedestrians. We performed an experiment to examine the effects of images depicting eHMI messages of different perspectives (egocentric from the pedestrian’s point of view: WALK, DON’T WALK, allocentric: BRAKING, DRIVING, and ambiguous: GO, STOP) on participants’ (N = 103) crossing decisions, response times, and eye movements. Considering that crossing the road can be cognitively demanding, we added a memory task in two-thirds of the trials. The results showed that egocentric messages yielded higher subjective clarity ratings than the other messages as well as higher objective clarity scores (i.e., more uniform crossing decisions) and faster response times than the allocentric BRAKING and the ambiguous STOP. When participants were subjected to the memory task, pupil diameter increased, and crossing decisions were reached faster as compared to trials without memory task. Regarding the ambiguous messages, most participants crossed for the GO message and did not cross for the STOP message, which points towards an egocentric perspective taken by the participant. More lengthy text messages (e.g., DON’T WALK) yielded a higher number of saccades but did not cause slower response times. We conclude that pedestrians find egocentric eHMI messages clearer than allocentric ones, and take an egocentric perspective if the message is ambiguous. Our results may have important implications, as the consensus among eHMI researchers appears to be that egocentric text-based eHMIs should not be used in traffic.

未来的自动驾驶汽车可能会配备外部人机界面（eHMI）。目前，关于eHMI消息的视角对行人穿越决策的影响知之甚少。我们进行了一项实验，研究了描绘不同角度的eHMI消息的图像（从行人的角度以自我为中心：行走，不行走，同心为中心：制动，驾驶和模糊不清：开始，停止）对参与者的影响（N = 103）越过决策，响应时间和眼球运动。考虑到过马路可能需要认知上的要求，我们在三分之二的试验中增加了记忆任务。结果表明，以自我为中心的信息比其他信息产生的主观清晰度等级更高，并且具有更高的客观清晰度得分（即，更一致的穿越决策）和更快的响应时间，这比同心异味的制动和含糊的停止要快。与没有记忆任务的试验相比，当参与者接受记忆任务时，瞳孔直径增加，并且做出交叉决定的速度更快。关于模棱两可的消息，大多数参与者越过GO消息而没有越过STOP消息，这表明参与者采取了以自我为中心的观点。较长的短信（例如，不要走动）产生的扫视次数更多，但不会导致响应时间变慢。我们得出的结论是，行人发现以自我为中心的eHMI消息比同素为中心的消息更清晰，如果该消息不明确，则采取以自我为中心的观点。我们的结果可能具有重要意义，因为eHMI研究人员之间的共识似乎是，不应在流量中使用基于自我中心的基于文本的eHMI。