Supplementary data for the paper 'The effect of an occlusion-induced delay on braking behavior in critical situations: A driving simulator study'

<b>Objective.</b> To share results of an experiment that used visual occlusion for a new purpose: inducing a waiting time. <b>Background.</b> Senders was a leading figure in human factors. In his research on the visual demands of driving, he used occlusion techniques. <b>Methods.</b> In a simulator experiment, we examined how drivers brake for different levels of urgency and different visual conditions. In three blocks (1 = brake lights, 2 = no brake lights, 3 = occlusion), drivers followed a vehicle at 13.4 or 33.4 m distance. At certain moments, the lead vehicle decelerated moderately (1.7 m/s²) or strongly (6.5 m/s²). In the occlusion condition, the screens blanked for 0.4 s (if 6.5 m/s²) or 2.0 s (if 1.7 m/s²) when the lead vehicle started to decelerate. Participants were instructed to brake only after the occlusion ended. <b>Results. </b>The lack of brake lights caused a delayed response. In the occlusion condition, drivers adapted to the instructed late braking by braking harder. However, adaptation was not always possible: In the most urgent condition, most participants collided with the lead vehicle because the ego-vehicle’s deceleration limits were reached. In non-urgent conditions, some drivers braked unnecessarily hard. Furthermore, while waiting until the occlusion cleared, some drivers lightly touched the brake pedal. <b>Conclusion.</b> This experimental design demonstrates how drivers (sometimes fail to) adjust their braking behavior to the criticality of the situation. <b>Application.</b> The phenomena of biomechanical readiness and (inappropriate) dosing of the brake pedal may be relevant to safety, traffic flow, and ADAS design.

**研究目的**：分享一项将视觉遮挡（visual occlusion）用于全新应用场景——即诱导等待时长——的实验结果。
**研究背景**：森德斯（Senders）是人机工程学领域的知名学者，其在驾驶视觉负荷相关研究中曾采用遮挡技术。
**研究方法**：本研究通过驾驶模拟器实验，探究驾驶员在不同紧急程度与视觉条件下的制动行为。实验分为三个区块：1. 制动灯组、2. 无制动灯组、3. 遮挡组。实验过程中，驾驶员分别以13.4米与33.4米的跟车距离跟随前车（lead vehicle）。当前车启动减速时，可分为中度减速（1.7 米每二次方秒）与高强度减速（6.5 米每二次方秒）两种场景。在遮挡组条件下，当前车开始减速时，驾驶模拟器屏幕将黑屏0.4秒（对应6.5 米每二次方秒减速场景）或2.0秒（对应1.7 米每二次方秒减速场景），且要求参与者仅在遮挡结束后再执行制动操作。
**实验结果**：无制动灯的场景会导致驾驶员制动响应延迟。在遮挡组条件下，驾驶员会通过加大制动力度来适应实验要求的延迟制动策略。但该适应能力并非总能达成：在最紧急的场景中，多数参与者因自车（ego-vehicle）的减速能力达到极限而与前车发生碰撞。在非紧急场景中，部分驾驶员出现了过度制动的情况。此外，部分驾驶员在等待遮挡结束的过程中，会轻微踩踏制动踏板。
**研究结论**：本实验设计清晰展现了驾驶员如何（有时无法）根据场景的临界程度调整自身制动行为。
**应用场景**：制动踏板的生物力学准备状态与（不恰当的）制动力度调控现象，对交通安全、交通流优化以及高级驾驶辅助系统（ADAS, Advanced Driver Assistance Systems）的设计均具有参考价值。