Whereas a large literature traditionally focuses on predicting collective action to achieve social change (e.g., strikes, demonstrations, petitions), we propose the very first experimental research on its potential psychological consequences. This is important because this research has the unique potential to discover how undertaking collective action activates psychological processes that increase the likelihood of social change (e.g., emancipation, equalization). Moving beyond existing models, three sets of studies unravel how ?action changes actors? through a novel and integrative focus on empowerment and politicization. A better understanding of these psychological processes greatly improves our ability to predict, explain, and achieve social change.

This research investigates group growth, in particular the transition from small to large groups. We focus on processes in small groups that enable such transition. Small groups are formed ?organically? around interactions and interdependencies. We aim to show that bystanders can get psychologically involved in this, even without participating actively. Through emotional ?contagion? and empathy, organic bonds can extend to bystanders. Psychologically, bystanders thus become part of an in-group. This process may, at a fundamental level, underpin a broad range of group growth phenomena and alter our understanding of large group formation.

When facing mental health problems and domestic violence, people with non-Western backgrounds seek less psychosocial help. We propose this is because different cultural worldviews of agency and fate create a mismatch between perceptions on help seeking and acceptance. In experimental and field studies, a new model is developed and tested.

In this international project, we investigate the psychological mechanisms explaining radical group behaviour. Perpetrators of group-based violence like hooligans, rioters, or terrorists are often portrayed as either mad or bad. However we argue that any group has the potential to resort to radical behaviour under the “right” conditions. We propose two key factors in this regard. Firstly, a sense of low group efficacy or political power in combination with local social support can promote radicalization. Secondly, threats to the group’s standing in the social hierarchy can evoke contempt, also prompting radical action. Finally we consider interventions designed to defuse radicalization.

Antisocial behaviour, such as aggression or ethnocentrism, is still common. Why do people engage in such behavior? Recent research suggests that such behavior is more effective than previously thought because it may restore a sense of “agency” or control after experiencing failure or other forms of control loss. We suggest that the motivation that drives antisocial behavior can be converted to prosocial behavior if it also restores agency. This research will focus on prosocial compensation for loss of agency, at both individual and group levels, and will examine whether such compensation is more effective within or between these identity levels.