Football hooligans
Abstract of:
Adang, O.M.J. (1999) Systematic observations of violent interactions between football hooligans.
In: In-group/ Out-group behaviour in modern societies. An evolutionary perspective (K. Thienpont & R. Cliquet, eds.) Brussel, Vlaamse Gemeenschap

Recently in the Netherlands a football hooligan was killed in a pre-planned confrontation between two rival hooligan groups. In this paper results of an observational study of interactions between football hooligans is presented. The observations made clear that most notions (both popular and mass-psychological notions) on the behaviour of people in crowds  are false and that the behaviour of people in crowds seems to be influenced by the same factors that influence the 'normal' everyday behaviour of humans.

It was not possible in the course of the research to establish the nature of the relationships or social ties between the participants. However, it was clear that many individuals that were most actively involved in the use of violence knew one another and formed part of loose 'groups'. These 'groups' were characterised by a shared tradition, common goals and attitudes and different forms of task division. They tended to react aggressively towards so-called 'spies' or 'traitors'.

The behaviour of football hooligans in many ways resembles other in-group/ out-group hostile interactions. However, in the case of football hooligans, kin selection mechanisms cannot adequately account for their behaviour, as the fans belonging to hooligan groups are unrelated and are composed of individuals from different etnies.
Young men in groups?
Abstract of:
Adang, O.M.J. (2000) Jonge mannen in groepen. Een geweldige combinatie? Justitiele Verkenningen 1, p 72 -80

Young males often behave provocatively or violently in the presence of other young males. We do not know why some young males seem to be more aggressive than others in this respect. However, it is clear that status seeking plays a role. In spite of the fact that often all of the ingredients for violent confrontations are at hand (a lot of young males, use of alcohol, presence of weapons, presence of different groups etc.), in most cases violence does not occur. There is no simple group process that leads almost automatically to irrational behaviour and violence. Processes present in everyday social behaviour provide the best clues. In spite of a lot of attention in the media and in politics, there is relatively little research into aggression and violence. Fundamental research is limited and fragmentary, there is little research aimed at a better understanding of violent interactions. As a result, there are few substantiated findings on the effectiveness of different interventions by the police or others. Research should not only focus on aggression and violence, but also on tolerance, tension regulation and reconciliation.
Research programme Managing Dangerous Situations