Introduction
The urgent planetary crises ask for sustainability-oriented interventions. Nevertheless, the success of these interventions is limited by rebound effects, which are triggered behavioural and systemic changes offsetting up to 47% of their potential environmental gains. Whereas the underlying economic mechanisms are relatively well understood, the behavioural explanations for rebound effects remain scarce and are characterised by a narrow focus on moral licensing (i.e., re-spending of collected mental "moral credits"), overlooking other potential mechanisms.


Purpose
This study employs a controlled laboratory experiment to test two novel explanations for rebound effects, identified through Qualitative Comparative Analysis: (i) impact optimism (i.e., an intervention triggers the overestimation of positive environmental impact), and (ii) tunnel vision (i.e., an intervention captures disproportionate attention causing the neglect of other impact categories and behaviours). Both mechanisms are hypothesised to decrease pro-environmental behaviours and offset the potential environmental benefits.


Method
The experiment will be conducted at the MonLEE Lab of Monash University in March 2026, providing a high level of control to test specific mechanisms that are hard to identify in the field. Building further upon the well-established design of Dorner (2019), approximately 200 participants will complete a real-effort task (i.e., word-decoding) while facing a trade-off between private earnings and environmental damage. The introduction of sustainability-oriented interventions (e.g., energy-efficiency) will allow for the examination of the novel behavioural rebound mechanisms.


Results
The results are expected to provide evidence for impact optimism and tunnel vision, and provide new insights into the related moderators (e.g., environmental identity). Moreover, impact optimism is expected to amplify moral licensing through a disproportional amount of accumulated moral credits, confirming the interconnectedness of behavioural rebound mechanisms.


Conclusion
This study contributes to a complete understanding of behavioural rebound effects by examining overlooked but significant psychological mechanisms through an innovative experimental design. The findings offer practical insights for preventing rebound effects of sustainability-oriented interventions.