Recent developments in the psychology of crowds and collective behaviour.

Research on crowd behaviour has long transcended the narrow obsession with violence that marked its origins [1,2]. Today, studies are much more representative of the variety of crowd events and phenomena. The concern with understanding collective violence still remains a significant strand. Yet the emergence and development of the social identity approach has meant that the limiting assumptions of mindlessness that have hampered psychology in the past have given way to novel insights in the study of crowd conflict as well as in relation to numerous peaceful and less dramatic crowd events. This review of recent developments in research on the psychology of crowds and collective behaviour is divided into four areas. The first two sections cover the most well-established topics: crowd conflict and behaviour in mass emergencies. The second two sections cover topics where social psychology has only recently come together with other disciplines: pedestrian dynamics and mass gatherings. In each case, the social identity approach provides many of the concepts, research questions and hypotheses that have driven novel developments.