Summary

The challenge for a psychology of crowds and collective behavior is to explain how large numbers of people are, spontaneously, able to act together in patterned and socially meaningful ways and, at the same time, how crowd events can bring about social and psychological change.

Classical theories, which treat crowd psychology as pathological, deny any meaning to crowd action. More recent normative and rationalist models begin to explain the coherence of crowd action but are unable to explain how that links to broader social systems of meaning. In both cases, the explanatory impasse derives from an individualistic conception of selfhood that denies any social basis to behavioral control. Such a basis is provided by the social identity approach. This proposes that crowd formation is underpinned by the development of shared social identity whereby people see themselves and others in terms of membership of a common category. This leads to three psychological transformations: members perceive the world in terms of collective values and belief systems; they coordinate themselves effectively; and hence they are empowered to realize their collective goals. These transformations explain the social form of crowd action. At the same time, crowd events are intergroup phenomena. It is through the intergroup dynamics between the crowd and an out-group (typically the police)—more specifically the way the social position of crowd members can change through the way police officers understand and respond to their actions—that change can occur. The social identity framework helps make sense of a range of phenomena beyond conflict crowds, including behavior in emergencies and disasters and the psychology of mass gatherings. The practical adequacy of the social identity approach is demonstrated by its use in a number of applied fields, including “public order” policing, crowd and emergency management, mass gatherings, health, and pedestrian modeling.