Affiliation as a Social Tension Buffer in the Aftermath of Street Fights.

Naturalistic observations of conflict events documented that, similarly to nonhuman primates, human bystanders take an active role in managing the negative consequences of the conflict. However, although in nonhuman primates it has been suggested that bystanders affiliate with each other to decrease the social tension generated by the conflict, in humans affiliation as a stress-response in naturally occurring conflicts has not been documented yet. By applying observational methods from primatology, we conducted video analysis of streets fights recorded by surveillance cameras in public spaces of Amsterdam in order to evaluate whether conflicts promote bystanders’ affiliation as a tension-reduction mechanism. We found that witnessing a street fight increased the expression of anxiety-related behaviours in bystanders and their propensity to engage in non-physical and physical affiliative interactions with other bystanders and the conflict parties. The occurrence of physical affiliation improves in turn the emotional state of bystanders by reducing the expression of anxiety-related behaviours. By offering a behavioural-based analysis of the role of social affiliation in the post-conflict context, our approach allows to reveal that some mechanisms to cope with social tension observed in nonhuman primates can lead to similar management dynamics in human bystanders.