Environmental attitude and spillover effects in pro-environmental behaviour: An experimental study using the Campbell paradigm

Mixed empirical findings on pro-environmental behaviour (PEB) spillover, ranging from positive and negative to null effects, challenge dominant causal models that assume initial PEB directly influences subsequent behaviours. This study addresses this problem by testing the Campbell Paradigm as an alternative explanation for spillover effects and by conceptualising environmental attitude as a latent disposition underlying both initial and follow-up PEBs rather than as a causal mechanism linking behaviours. An experimental study was conducted with 535 respondents in Greater Jakarta, who were randomly assigned to a PEB group, an anti-environmental behaviour (AEB) group, or a control condition. Follow-up PEB was measured using an incentivised Incongruence-Based Time Commitment task, which represents actual behavioural engagement. A general linear model was applied to assess the combined effects of environmental attitude and experimental condition on follow-up PEB. The results showed no significant differences in follow-up PEB across experimental groups and no association between initial behaviour and follow-up PEB. In contrast, environmental attitude significantly and positively predicted follow-up PEB, while the effects of the experimental group were non-significant. These findings support Campbell’s paradigm assumption that engagement in multiple PEBs is primarily driven by underlying environmental attitude rather than by prior behaviour. The study highlights the importance of interventions that strengthen environmental attitudes and reduce behavioural costs to promote consistent and enduring pro-environmental actions in urban Indonesian contexts. Limitations include reliance on self-reported initial behaviours and limited sample representativeness, suggesting that future research should employ observable initial behaviours and broader populations.