Linking behaviour change techniques to mechanisms of action: Using the Theory and Techniques Tool alongside the Behaviour Change Intervention Ontology:[version 1; peer review: 1 approved, 1 not approved]

Background: Understanding how interventions work requires clear hypotheses, rigorous testing, and accurate reporting of links between behaviour change techniques (BCTs)—the smallest replicable active components of interventions—and mechanisms of action (MoAs), the processes through which behaviour changes. The Theory and Technique Tool (TaTT) provides a grid of likely BCT-MoA links to guide intervention design, based on literature synthesis and expert consensus. Recently, the Behaviour Change Intervention Ontology development team introduced detailed, computer-readable lower-level ontologies for BCTs and MoAs, but limited guidance exists on integrating the BCT-MoA links proposed by the TaTT with these ontologies. This study aimed to map BCTs and MoAs from the TaTT to corresponding classes (i.e., categorisations or groupings) in the Behaviour Change Technique Ontology (BCTO) and Mechanism of Action (MoA) Ontology. // Methods: Three researchers mapped the classes from the BCTO onto 74 BCTs within the TaTT, using their definitions. Similarly, two researchers mapped classes from the MoA Ontology onto the 26 MoAs within the TaTT. Discrepancies were resolved through discussion with senior researchers. Subsequent updates to the BCT and MoA Ontologies necessitated a researcher updating the mappings, with the revisions being verified by the research team. // Results: From the BCTO, 85 BCTs were mapped to the 74 BCTs present in the TaTT, while 56 MoAs from the MoA Ontology were mapped to the 26 MoAs present in the TaTT. Subclasses of these 85 BCTs and 56 MoAs provide additional specificity and can be found by further engaging with these ontologies. // Discussion: Mapping the TaTT to the Behaviour Change Intervention Ontology enhances clarity and precision in selecting and reporting BCT-MoA links, enabling integration of data across frameworks. Future work should maintain these mappings as ontologies evolve and users provide more feedback and evidence on BCTs, MoAs, and their links, ensuring they remain relevant and user-friendly.