Social comparison as a behaviour change technique: A systematic review and meta-analysis of randomised controlled trials across scientific disciplines

Abstract Social comparison is a fundamental mechanism that enables humans to navigate the complexities of our ever-changing world. Moreover, social comparison can serve as a powerful mechanism for promoting behaviour change. Research on social comparison as a behaviour change technique (SC-BCT) has increased significantly during the last decades. We summarized the literature on SC-BCTs with a pre-registered and theory-guided systematic review and meta-analysis across scientific disciplines (PROSPERO: blinded). Seventy randomized controlled trials (RCTs N = 1,323,478) were included in quantitative synthesis and 15 further RCTs were included in narrative synthesis. SC-BCTs were effective both at short- and long-term in changing performance behaviour, health-related behaviour, and climate change mitigation behaviour with small-to-moderate pooled effects. The number of intervention sessions was associated positively with outcomes. Magnitude of effects needs to be interpreted in the context of very low-cost interventions (e.g., sending two letters in total) and scalability. Implications for future research are discussed.