Background: Researchers, practitioners and policymakers develop interventions to change behavior based on their understanding of how behavior change techniques (BCTs) impact the determinants of behavior. A transparent, systematic and accessible method of linking BCTs with the processes through which they change behavior (i.e. their mechanisms of action (MoAs)) would advance understanding of intervention effects, and improve theory and intervention development. Purpose: To triangulate evidence for hypothesized BCT-MoA links obtained in two previous studies and present the results in an interactive, online tool.Methods: Two previous studies generated evidence on links between 56 BCTs and 26 MoAs based on their frequency in literature synthesis and on expert consensus. Concordance between the findings of the two studies was examined using multilevel modelling. Uncertainties and differences between the two studies were reconciled by 16 behavior change experts using consensus development methods. The resulting evidence was used to generate an online tool.Results: The two studies showed concordance for 25 of the 26 MoAs and agreement for 37 links and for 460 ‘non-links’. A further 55 links were resolved by consensus (total of 92 (37+55) hypothesized BCT-MoA links). Full data on 1456 possible links was incorporated into the online interactive Theory and Technique Tool (url link removed for anonymity peer-review).Conclusions: This triangulation of two distinct sources of evidence provides guidance on how BCTs may affect the mechanisms that change behavior and is available as a resource for behavior change intervention designers, researchers and theorists, supporting intervention design, research synthesis, and collaborative research

Use of natural language to represent behaviour change theories has resulted in lack of clarity and consistency hindering comparison, integration, development and use. This paper describes development of a formal system for representing behaviour change theories which aims to improve clarity and consistency. A given theory is represented in terms of 1) its component constructs (e.g., 'self-efficacy', 'perceived threat', 'subjective norm') which are labelled and defined, and 2) relationships between pairs of constructs, which may be causal, structural, or semantic. This formalism appears adequate to represent five commonly used theories (Health Belief Model, Information-Motivation-Behavioural Skill Model, Social Cognitive Theory, Theory of Planned Behaviour, and the Transtheoretical Model). Theory authors and experts judged that the system was able to capture the main propositions of the theories. Following this proof-of-concept, the next step is to assess how far the system can be applied to other theories of behaviour change.

Sociocognitive antecedents Reflective motivationIntention/goal Behavior FIGURE 19.1. The role of reflective motivation in distal intention formation.