People often hesitate to evacuate their homes even when facing imminent danger from natural disasters. In particular, flash flood is one of most difficult disasters for people to evacuate because of its rapid onset and destructive features. This study proposed two public interventions to encourage early evacuation decisions from flash floods by changing environmental or social situations at the time recommended for evacuation. The first intervention involves designing a river cross section for signaling flash flood risk in the landscape. The second intervention requires predetermined members of the community to initiate an evacuation at a recommended time when in danger of a flash flood. These interventions were designed to rely on people's intuitive judgement rather than deliberative thinking. To examine the effects of these interventions, we conducted randomized controlled trials using virtual reality (VR) where each participant was randomly assigned to one of the five scenarios: two control scenarios and three treatment scenarios that include the first, second, and combined interventions, respectively. In the VR experiment, time of evacuation decision was measured under each scenario. The participants of this study were 103 students recruited from Kumamoto University in Japan. The results revealed that the participants reacted to the environmental and social cues provided using VR. The interventions were effective in promoting early evacuation decisions. These findings suggest that effective interventions can be designed and empirically examined using VR experiments to promote evacuation during natural disasters.

即使面对自然灾害迫在眉睫的危险，人们也常常不愿撤离房屋。尤其是，山洪暴发迅速且具有破坏性，是人们撤离最困难的灾难之一。这项研究提出了两种公共干预措施，以通过建议撤离时改变环境或社会状况来鼓励从山洪暴发中尽早撤离的决定。第一项干预措施是设计河流断面，以表示景观中的山洪暴发风险。第二种干预措施要求社区中预定的成员在遇到山洪暴发的危险时，在建议的时间开始疏散。这些干预措施旨在依靠人们的直觉判断而非审议性思维。为了检查这些干预措施的效果，我们使用虚拟现实（VR）进行了随机对照试验，其中将每个参与者随机分配到以下五个方案中的一个：两个控制方案和三个治疗方案，分别包括第一，第二和联合干预措施。在VR实验中，在每种情况下都测量了疏散决策的时间。这项研究的参与者是从日本熊本大学招募的103名学生。结果显示，参与者对使用虚拟现实提供的环境和社交线索有反应。干预措施有效地促进了早期疏散决策。这些发现表明，可以使用VR实验设计有效的干预措施并进行经验检验，以促进自然灾害期间的疏散。