Supplementary data for the paper 'Understanding cyclists’ perception of driverless vehicles through eye-tracking and interviews'

As automated vehicles (AVs) become increasingly popular, the question arises as to how cyclists will interact with such vehicles. This study investigated (1) whether cyclists spontaneously notice if a vehicle is driverless, (2) how well they perform a driver-detection task when explicitly instructed, and (3) how they carry out these tasks. Using a Wizard-of-Oz method, 37 participants cycled a designated route and encountered an AV multiple times in two experimental sessions. In Session 1, participants cycled the route uninstructed, while in Session 2, they were instructed to verbally report whether they detected the presence or absence of a driver. Additionally, we recorded participants’ gaze behaviour with eye-tracking and their responses in post-session interviews. The interviews revealed that 30% of the cyclists spontaneously mentioned the absence of a driver (Session 1), and when instructed (Session 2), they detected the absence and presence of the driver with 93% accuracy. The eye-tracking data showed that cyclists looked more frequently and for longer at the vehicle in Session 2 compared to Session 1. Additionally, participants exhibited intermittent sampling of the vehicle, and they looked at the area in front of the vehicle when it was far away and towards the windshield region when it was closer. The post-session interviews also indicated that participants were curious, but felt safe, and reported a need to receive information about the AV’s driving state. In conclusion, cyclists can detect the absence of a driver in the AV, and this detection may influence their perception of safety. Further research is needed to explore these findings in real-world traffic conditions.

随着自动驾驶汽车（Automated Vehicles, AVs）日益普及，骑行者与这类车辆的交互方式已成为亟待探讨的问题。本研究围绕三个核心议题展开探究：（1）骑行者是否会自发察觉车辆处于无人驾驶状态；（2）在收到明确指令时，骑行者完成驾驶员检测任务的表现水平如何；（3）骑行者具体如何执行该类检测任务。本研究采用绿野仙踪（Wizard-of-Oz）实验法，招募37名参与者骑行指定路线，并在两次实验阶段中多次遭遇自动驾驶车辆。第一阶段实验中，参与者未被赋予额外检测指令即可完成骑行；第二阶段实验中，参与者被要求口头报告是否检测到驾驶员的存在或缺失。此外，本研究通过眼动追踪设备记录了参与者的注视行为，并在实验结束后开展访谈以收集补充数据。访谈结果显示，第一阶段实验中有30%的骑行者自发提及察觉到车辆无驾驶员；而在收到明确指令的第二阶段实验中，参与者对驾驶员存在与缺失的检测准确率达到93%。眼动追踪数据表明，相较于第一阶段，参与者在第二阶段会更频繁且更持久地注视目标车辆。进一步分析发现，参与者会间歇性采样观察目标车辆：当车辆距离较远时，他们的注视焦点集中于车辆前方区域；当车辆靠近时，则会将视线转向挡风玻璃区域。实验后访谈还反馈，参与者虽对无人驾驶车辆感到好奇，但同时认为该场景下自身处于安全状态，并表示需要获取自动驾驶车辆的行驶状态相关信息。综上，骑行者能够有效识别自动驾驶车辆的无人驾驶状态，且该检测结果可能会影响其对交通安全的感知。未来仍需开展进一步研究，在真实交通场景中验证本次研究的相关发现。