Cyberbullying is a social problem in the digital age. Online social networks have been reported to be linked with cyberbullying, but the links remain unclear. Our research question is “Do social norms that allow cyberbullying spread via online social networks?” The objectives of our study are to answer this research question and clarify the effects of online social networks on cyberbullying from the perspective of a complex contagion model. Participants were 129,164 users in Pigg Party, which is a Japanese online chat platform with avatar. Their status of cyberbullying perpetrators and victims was estimated using a combination of questionnaire and machine learning methods. Results showed that both cyberbullying perpetrator and victim rates among their peers and among the peers of their peers increased participants' risk of becoming cyberbullying perpetrators. Similarly, these rates increased their risk of becoming cyberbullying victims. As their intimacy with cyberbullying perpetrators increased, their risks of perpetrating cyberbullying increased. However, as their intimacy with the perpetrators increased, their risks of becoming cyberbullying victims decreased. The social contagion of cyberbullying via online peer networks and the perpetrator's rational choice of cyberbullying victims are discussed.

网络欺凌是数字时代的社会问题。据报道，在线社交网络与网络欺凌有联系，但这些联系仍不清楚。我们的研究问题是“允许通过网上社交网络传播网络欺凌行为的社会规范吗？” 我们研究的目的是回答这一研究问题，并从复杂的传染模型的角度阐明在线社交网络对网络欺凌的影响。Pigg Party是一个具有化身的日语在线聊天平台，共有129,164位用户参加。通过问卷调查和机器学习方法的结合来估计他们的网络欺凌者和受害者的状况。结果显示，同龄人之间以及同龄人之间网络欺凌的犯罪者和受害者的比率都增加了参与者的 成为网络欺凌者的风险。同样，这些比率增加了成为网络欺凌受害者的风险。随着他们与网络欺凌者的亲密关系增加，他们进行网络欺凌的风险也随之增加。但是，随着他们与犯罪者之间的亲密关系增加，他们成为网络欺凌受害者的风险也有所降低。讨论了通过在线对等网络进行的网络欺凌的社会传播以及犯罪者对网络欺凌受害者的合理选择。