How collective action produces psychological change and how that change endures over time: A case study of an environmental campaign.

Previous research on collective action has suggested that both intra- and intergroup interactions are important in producing psychological change. In this study, we examine how these two forms of interaction relate to each other over time. We present results from a longitudinal ethnographic study of participation in an environmental campaign, documenting endurance and prevalence of psychological change. Participants, locals (n = 14) and self-defined activists (n = 14), connected enduring psychological changes, such as changes in consumer behaviour and attitudes to their involvement in the environmental campaign. Thematic analysis of interviews suggested that participants linked the process of change to categorizing themselves in a new environmental-activist way that influenced their everyday lives beyond the immediate campaign. This recategorization was a result of a conflictual intergroup relationship with the police. The intergroup interaction produced supportive within-group relationships that facilitated the feasibility and sustainability of new world views that were maintained by staying active in the campaign. The data from the study support and extend previous research on collective action and are the basis of a model, suggesting that intragroup processes condition the effects of intergroup dynamics on sustained psychological change.