A Bystander Behavior Model in bullying situations

Proceedings of ‏The 10th International Conference on Humanities, Psychology and Social Sciences

Year: 2020

DOI: https://www.doi.org/10.33422/10th.hps.2020.03.75

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A Bystander Behaviour Model in bullying situations

Yuriko Isada, Nobuko Igaki and Aiko Shibata



In this paper, the behaviour of bystanders is analysed. It is said that the structure of bullying consists of three parties, namely “bullies”, “victims” and “bystanders” and that it is important to control bullying by changing bystanders’ behaviour.  In general, bystanders may act like they don’t see bullying even if they witness it. However, an individual bystander may take action if more bystanders take action to stop bullying. Conversely, when most bystanders act to prevent bullying, some may think that they don’t have to act. A mathematical model is formulated assuming that the action timings are different for each person. In more concrete, we suppose that each bystander is influenced by the ratio of members who take action to stop bullying. We call this ratio the active rate. Each bystander has his/her own lower threshold and his/her own upper threshold, then, if the active rate is between these two thresholds he/she takes action to stop bullying. That is, each bystander knows the active rate every day and decides whether to act or not to act on the following day. Simulations are performed for this model. As a result, it is found that the existence of highly motivated members has a positive effect on the entire bystanders. On the other hand, even if there are no highly motivated members, it could be quite effective to continue educating members with low motivation.

Keywords: bystander, bullying, collective behaviour, mathematical model, simulation.