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.

许多涉及行人的致命事故发生在路口，其原因可归结为行人与驾驶员之间的沟通失效。因此，研究交通中的沟通形式（如眼神接触（eye contact））如何影响行人的过街决策至关重要。迄今为止，关于驾驶员的眼神接触对行人过街感知安全性的影响，相关研究信息仍较为匮乏。现有研究将眼神接触视为固定不变的——即整个互动过程中要么存在要么不存在——这种方法忽略了眼神接触时机的影响。为此，我们开展了一项在线众包研究（online crowdsourced study）以填补这一研究空白。1835名参与者以随机顺序两次观看了13段汽车驶近的视频，并在感到安全过街时按下按键。这些视频在以下方面有所不同：汽车是否让行、驾驶员是否有眼神接触，以及驾驶员做出眼神接触的时机。参与者还回答了关于驾驶员眼神接触行为感知直观性的问题。结果表明，与无眼神接触相比，眼神接触使人们感到过街安全得多（观察到按键比例从31%上升至50%）。此外，眼神接触的开始和结束分别比持续的眼神接触和完全没有眼神接触对过街感知安全性的影响更大。然而，汽车的运动状态是一个更主导的因素。此外，驾驶员在汽车刹车时的眼神接触被认为是直观的，而在汽车驶离时则被认为是非直观的。总而言之，本研究首次揭示了动态场景下驾驶员的眼神接触如何随时间影响行人的过街感知安全性，并对近期文献中关于道路互动中眼神接触并非必需的观点提出了质疑。这些发现可能对自动驾驶汽车（automated vehicles，AVs）的研发具有参考价值——在自动驾驶汽车中，驾驶员可能并不总是关注周围环境。