The Rare Spreading of Environmental Actions: Examining Longitudinal Spillover Between Private and Activist Behaviours, and Mediations Via Efficacy Beliefs and Environmental Self-Identity

A shift in people’s private environmental behaviours is an essential element for the urgently needed mitigation of climate change. Even more so, there needs to be a massive increase in environmental activism that demands socio-political change and leads to environmentally relevant (social) innovations. This study presents a longitudinal spillover investigation of how private and activist behaviours relate to each other, and whether these relations are mediated via two psychological processes: efficacy beliefs and environmental self-identity. From May 2018 to May 2019, N = 931 participants, half of whom were environmental volunteers (n = 441), took part in four questionnaire waves. Applying random intercept cross-lagged panel models, we found that activist behaviour was related to private behaviour intra-individually when looking at the same time point, but rarely across time points. Collective efficacy of all humanity and environmental self-identity appeared to be central antecedents and outcomes of private behaviour. Yet, neither efficacy beliefs nor environmental self-identity mediated spillover effects from activist to private behaviour, and vice versa. Intriguingly, the application of simple cross-lagged panel models would have led to different conclusions. We interpret our results in the context of the environmental movement and formulate recommendations for NGOs and politicians.