Supplementary data for the paper 'The effect of drivers’ eye contact on pedestrians’ perceived safety'

Many fatal accidents that involve pedestrians occur at road crossings, and are attributed to a breakdown of communication between pedestrians and drivers. Thus, it is important to investigate how forms of communication in traffic, such as eye contact, influencfe crossing decisions. Thus far, there is little information about the effect of drivers’ eye contact on pedestrians’ perceived safety to cross the road. Existing studies treat eye contact as immutable, i.e., it is either present or absent in the whole interaction, an approach that overlooks the effect of the timing of eye contact. We present an online crowdsourced study that addresses this research gap. 1835 participants viewed 13 videos of an approaching car twice, in random order, and held a key whenever they felt safe to cross. The videos differed in terms of whether the car yielded or not, whether the car driver made eye contact or not, and the times when the driver made eye contact. Participants also answered questions about their perceived intuitiveness of the driver’s eye contact behavior. The results showed that eye contact made people feel considerably safer to cross compared to no eye contact (an increase in keypress percentage from 31% to 50% was observed). In addition, the initiation and termination of eye contact affected perceived safety to cross more strongly than continuous eye contact and a lack of it, respectively. The car’s motion, however, was a more dominant factor. Additionally, the driver’s eye contact when the car braked was considered intuitive, and when it drove off, counterintuitive. In summary, this study demonstrates for the first time how drivers’ eye contact affects pedestrians’ perceived safety as a function of time in a dynamic scenario and questions the notion in recent literature that eye contact in road interactions is dispensable. These findings may be of interest in the development of automated vehicles (AVs), where the driver of the AV might not always be paying attention to the environment.

诸多涉及行人的致命交通事故均发生在道路交叉口，且多归因于行人与驾驶员之间的沟通失效。因此，探究诸如眼神交流这类交通沟通形式如何影响行人过街决策，具有重要意义。迄今为止，针对驾驶员眼神交流对行人过街感知安全感的影响，相关研究资料仍较为匮乏。现有研究均将眼神交流视为不可变的二元变量，即整个交互过程中要么存在眼神交流，要么完全不存在，这种研究范式忽略了眼神交流出现时机所带来的影响。本研究开展了一项线上众包实验，以填补这一研究空白。共有1835名参与者先后以随机顺序观看13段驶来车辆的视频各两次，并在自认为可安全过街时按下对应按键。这些视频在以下三个维度存在差异：车辆是否礼让行人、驾驶员是否与行人进行眼神交流，以及驾驶员进行眼神交流的具体时机。参与者还需回答关于驾驶员眼神交流行为的直观感知相关问题。实验结果显示，相较于无眼神交流的情况，眼神交流可显著提升行人的过街安全感：按键通过率从31%提升至50%。此外，眼神交流的起始与终止分别比持续眼神交流和完全无眼神交流，对行人过街安全感的影响更为显著。但车辆的运动状态仍是影响过街安全感的更主导性因素。此外，参与者认为驾驶员在车辆制动时进行眼神交流符合直观感知，而在车辆驶离时进行眼神交流则违背直观感知。综上，本研究首次在动态交通场景中，揭示了驾驶员眼神交流如何随时间变化影响行人的过街安全感，并对近期文献中提出的「道路交互中的眼神交流可有可无」这一观点提出了质疑。该研究结果对于自动驾驶汽车（Automated Vehicles, AVs）的研发具有参考价值——毕竟自动驾驶车辆的驾驶员（或系统）并非总能时刻关注周边环境。