The coronavirus disease 2019 (COVID-19) outbreak is threatening not only health but also life worldwide. It is important to encourage citizens to voluntarily practise infection-prevention (IP) behaviours such as social distancing and self-restraint. Previous research on social cognition suggested that emphasizing self-identity is key to changing a person's behaviour. The present study investigated whether reminders that highlight self-identity would be effective in changing intention and behaviour related to the COVID-19 outbreak, and hypothesized that those who read reminders highlighting self-identity (Don't be a spreader) would change IP intention and behaviour better than those who read ‘Don't spread’ or no reminder. We conducted a two-wave survey of the same participants with a one-week interval, during which we assigned one of three reminder conditions to the participants: ‘Don't spread’ (spreading condition), ‘Don't be a spreader’ (spreader condition) and no reminder (control condition). Participants marked their responses to IP intentions and actual behaviours each week based on the Japanese Ministry of Health, Labour and Welfare guidelines. While the results did not show significant differences between the conditions, the post hoc analyses showed significant equivalence in either IP intentions or behavioural scores. We discussed the results from the perspective of the effect size, ceiling effects and ways of manipulation checks as future methods with more effective persuasive messaging. Following in-principle acceptance, the approved Stage 1 version of this manuscript was pre-registered on the OSF at https://doi.org/10.17605/OSF.IO/KZ5Y4. This pre-registration was performed prior to data collection and analysis.

2019 年冠状病毒病 (COVID-19) 的爆发不仅威胁着健康，还威胁着全世界的生命。鼓励公民自愿采取保持社交距离和自我克制等预防感染（IP）行为非常重要。先前关于社会认知的研究表明，强调自我认同是改变一个人行为的关键。本研究调查了强调自我认同的提醒是否能有效改变与 COVID-19 爆发相关的意图和行为，并假设那些阅读强调自我认同的提醒（不要成为传播者）的人会改变 IP 意图和行为比那些读到“不要传播”或没有提醒的人更好。我们对同一参与者进行了两轮调查，间隔一周，期间我们给参与者分配了三个提醒条件之一：“Don't spread”（传播条件）、“Don't be a spreader” （吊具条件）和无提醒（控制条件）。参与者根据日本厚生劳动省的指导方针，每周标记他们对知识产权意图和实际行为的反应。虽然结果没有显示条件之间存在显着差异，但事后分析显示知识产权意图或行为评分显着相同。我们从效应大小、上限效应和操纵检查方式的角度讨论了结果，作为未来更有效的说服性信息传递的方法。原则上接受后，经批准的本手稿第一阶段版本已在 OSF 上预先注册：https://doi.org/10.17605/OSF.IO/KZ5Y4。该预注册是在数据收集和分析之前进行的。