eHMIs refers to a novel and explicit communication method for pedestrian-AV negotiation in interactions, such as in encounter scenarios. However, pedestrians with limited experience in negotiating with AVs could lack a comprehensive and correct understanding of the information on driving intentions' meaning as conveyed by AVs through eHMI, particularly in the current contexts where AV and eHMI are not yet mainstream. Consequently, pedestrians who misunderstand the driving intention of the AVs during the encounter may feel threatened and perform unpredictable behaviors. To solve this issue, this study proposes using the pre-instruction on the rationale of eHMI to help pedestrians correctly understand driving intentions and predict AV behavior. Consequently, this can improve their subjective feelings (ie. sense of danger, trust in AV, and sense of relief) and decision-making. In addition, this study suggests that the eHMI could better guide pedestrian behavior through the pre-instruction. The results of interaction experiments in the road crossing scene show that participants found it more difficult to recognize the situation when they encountered an AV without eHMI than when they encountered a manual driving vehicle (MV); in addition, participants' subjective feelings and hesitations while decision-making worsened significantly. After the pre-instruction, the participants could understand the driving intention of an AV with eHMI and predict driving behavior more easily. Furthermore, the participants' subjective feelings and hesitation to make decisions improved, reaching the same criteria used for MV. Moreover, this study found that the information guidance of using eHMI influenced the participants' walking speed, resulting in a small variation over the time horizon via multiple trials when they fully understood the principle of eHMI through the pre-instruction.

翻译：电子人机界面（eHMI）是指在人车交互（如相遇场景）中，行人与自动驾驶汽车（AV）进行协商的一种新颖且明确的通信方式。然而，在与AV协商方面经验有限的行人，可能无法全面且正确地理解AV通过eHMI传递的驾驶意图信息含义，尤其是在当前AV和eHMI尚未成为主流的背景下。因此，在相遇过程中误解AV驾驶意图的行人可能会感到威胁，并做出不可预测的行为。为解决这一问题，本研究提出使用关于eHMI原理的预说明，帮助行人正确理解驾驶意图并预测AV行为。这进而可改善其主观感受（即危险感、对AV的信任感和安全感）及决策。此外，本研究认为，通过预说明，eHMI能更好地引导行人行为。在道路横穿场景的交互实验结果表明，与遇到手动驾驶车辆（MV）相比，参与者在遇到无eHMI的AV时更难识别情境；同时，参与者的主观感受及决策时的犹豫程度显著恶化。经过预说明后，参与者能够更轻松地理解配备eHMI的AV的驾驶意图并预测驾驶行为。此外，参与者的主观感受和决策犹豫程度得到改善，达到与MV相同的标准。此外，本研究发现，使用eHMI的信息引导会影响参与者的步行速度，当参与者通过预说明完全理解eHMI原理后，其步行速度在多次试验中随时间的变化幅度较小。