In the field of autonomous driving research, the use of immersive virtual reality (VR) techniques is widespread to enable a variety of studies under safe and controlled conditions. However, this methodology is only valid and consistent if the conduct of participants in the simulated setting mirrors their actions in an actual environment. In this paper, we present a first and innovative approach to evaluating what we term the behavioural gap, a concept that captures the disparity in a participant's conduct when engaging in a VR experiment compared to an equivalent real-world situation. To this end, we developed a digital twin of a pre-existed crosswalk and carried out a field experiment (N=18) to investigate pedestrian-autonomous vehicle interaction in both real and simulated driving conditions. In the experiment, the pedestrian attempts to cross the road in the presence of different driving styles and an external Human-Machine Interface (eHMI). By combining survey-based and behavioural analysis methodologies, we develop a quantitative approach to empirically assess the behavioural gap, as a mechanism to validate data obtained from real subjects interacting in a simulated VR-based environment. Results show that participants are more cautious and curious in VR, affecting their speed and decisions, and that VR interfaces significantly influence their actions.

翻译：在自动驾驶研究领域，沉浸式虚拟现实（VR）技术被广泛用于在安全受控条件下开展各类研究。然而，只有当参与者在模拟环境中的行为能真实反映其在现实环境中的行动时，该方法才具备有效性与一致性。本文提出了一种创新性方法，首次对我们称之为"行为差异"的概念进行评估——该概念用于描述参与者在VR实验场景与等效现实场景中行为表现的差距。为此，我们构建了一个既有斑马线的数字孪生模型，并开展实地实验（样本量N=18），以研究真实与模拟驾驶条件下行人-自动驾驶车辆的交互行为。实验中，行人在不同驾驶风格及外部人机界面（eHMI）存在的情况下尝试横穿道路。通过结合问卷调查与行为分析方法，我们开发了一种量化方法来实证评估行为差异，以此验证从模拟VR环境中真实受试者交互所获数据的有效性。结果表明：参与者在VR环境中表现出更强的谨慎性与好奇心，这影响了他们的移动速度与决策过程，且VR界面会显著改变其行为模式。