Third parties tend to take an active role and intervene in interpersonal
conflicts in public. Previous research has shown that the level of aggression
of these interventions determines how they influence the conflict. No
previous study has, however, systematically investigated whether the
aggression of third-party interventions is influenced by the development
of the conflict situation. The objective of this study is twofold. First, the
study determines the extent to which the aggression level of intervening
third parties changes during the course of interpersonal conflicts. Second,
the study identifies and investigates the factors that affect the aggression
levels displayed by intervening third parties. We systematically observed and
coded CCTV footage of 46 interpersonal conflicts in public space, recorded
by surveillance cameras in Amsterdam, the Netherlands. The data included
565 intervention behaviors by 125 third parties. We recorded the levels of aggression of the individuals involved in the conflict and conducted a
multinomial logistic regression analysis to investigate what influenced
the aggression level of the third-party interventions. We found that the
aggression levels of the preceding intervention behaviors by the third parties
predict aggression levels of their subsequent interventions. This shows a
consistency in third-party interventions over the course of a conflict. We also
found that the aggression levels of the conflict parties that are the targets of
the interventions influence the aggression levels of third-party intervention.
This finding demonstrates that the development of the conflict situation
influences how aggressive the third parties are. Our study emphasizes the
importance of taking the interactional dynamics of interpersonal conflicts
into consideration when explaining third-party behavior.