Systemic Validation of the Causal Loop Diagram for Pro‐Environmental Behaviour via Hierarchical Structural Equation Modelling: Focusing on Single‐Use Plastic Reduction

While existing behavioural theories have successfully identified the psychological antecedents of pro‐environmental behaviour, they largely rely on linear assumptions that fail to capture the dynamic, self‐reinforcing feedback mechanisms underlying continuous actions such as reducing single‐use plastics. To address this gap, this study empirically evaluates an integrated systems thinking model—the causal loop diagram for pro‐environmental behaviour (CLD‐PEB)—using hierarchical structural equation modelling with survey data from 434 residents of the Seoul Metropolitan Area. To identify potential leverage points and feedback priorities, two indices—the System Activation Index (SAI) and the Cumulative Feedback Effect (CFE)—are introduced as cross‐sectional structural proxies. Results highlight self‐efficacy and behavioural activation as prominent nodes and R3 as the loop with the highest relative reinforcement potential under the adopted index. Theoretically, the framework positions behavioural activation as an endogenously predicted behavioural‐practice construct with downstream paths to mastery experience and beliefs, with partial empirical support for these specified associations. These findings inform a phased policy strategy combining support for initial action with opportunities for mastery experience and efficacy development.