Supplementary data for the paper 'Crowdsourced assessment of 227 text-based eHMIs for a crossing scenario'

Future automated vehicles may be equipped with external human-machine interfaces (eHMIs) capable of signaling whether pedestrians can cross the road. Industry and academia have proposed a variety of eHMIs featuring a text message. An eHMI message can refer to the action to be performed by the pedestrian (egocentric message) or the automated vehicle (allocentric message). Currently, there is no consensus on the correct phrasing of the text message. We created 227 eHMIs based on text-based eHMIs observed in the literature. A crowdsourcing experiment (<i>N</i> = 1241) was performed with images depicting an automated vehicle equipped with an eHMI on the front bumper. The participants indicated whether they would (not) cross the road, and response times were recorded. Egocentric messages were found to be more compelling for participants to (not) cross than allocentric messages. Furthermore, Spanish-speaking participants found Spanish eHMIs more compelling than English eHMIs. Finally, it was established that some eHMI texts should be avoided, as signified by compellingness, long responses, and high inter-subject variability.

未来的自动驾驶车辆可配备外部人机交互界面（external human-machine interfaces，简称eHMIs），用于向行人传递是否可横穿道路的信号。当前，工业界与学术界已提出多种搭载文本信息的eHMIs设计方案。eHMI文本信息可分为两类：一类指向行人需执行的动作（以自我为中心的提示，egocentric message），另一类指向自动驾驶车辆需执行的动作（以他者为中心的提示，allocentric message）。目前，学界与工业界尚未就eHMI文本信息的规范措辞达成共识。本研究基于已发表文献中记载的文本型eHMIs，共构建227组eHMI方案，并开展了一项众包实验（有效样本量N=1241）。实验所用材料为搭载前保险杠eHMI的自动驾驶车辆图像，要求参与者判断自身是否会横穿道路，并记录其反应时。实验结果显示，以自我为中心的提示相较于以他者为中心的提示，对参与者是否横穿道路的决策更具说服力。此外，以西班牙语为母语的参与者认为西班牙语eHMI比英语eHMI更具说服力。最后，本研究明确了部分应避免使用的eHMI文本，该结论可通过文本的说服力水平、参与者的较长反应时以及较高的被试间变异性得以佐证。