Social identification-building interventions to improve health: a systematic review and meta-analysis.

There is growing evidence that social identity processes play an important role in a range of health outcomes. However, we know little about the nature and effectiveness of interventions that build social identification with the aim of promoting health. In the present research, we systematically review and meta-analyze interventions that build social identification to enhance health and wellbeing. A total of 27 intervention studies were identified (N = 2,230). Using a three-level meta-regression, results indicate that social identification-building interventions had a moderate-to-strong impact on health (Hedges g = 0.66; 95%CIs[0.34, 0.97]). Analyses revealed significant variation in intervention effectiveness as a function of its type: group-relevant decision making (g = 1.26), therapy programmes (g = 1.02), shared activities (g = 0.40), and reminiscence (g = -0.05). By contrast, there was much less variation across health outcomes: quality of life (g = 0.80), physical health (g = 0.76), self-esteem (g = 0.69), well-being (g = 0.66), (reduced) anxiety (g = 0.61), (reduced) depression (g = 0.58), cognitive health (g = 0.55), and (reduced) stress (g = 0.49). Finally, speaking to the mechanism of the interventions, interventions tended to be more effective to the extent that they succeeded in building participants' social identification with the intervention group. We discuss the theoretical and practical implications of social identification-building interventions to foster health and outline an agenda for future research and practical application.