Table 1.

Synthesis of theory application functions and benefits

Stage	Objective	Why … theory	How … theory	Source
Planning and design	Targeting	What factors should be targeted to elicit the desired change (or maintenance) in behaviour?	Identification of antecedents of behaviour or behaviour change. Isolation of mechanisms of action (e.g., mediators and moderators of behaviour or behaviour change) that form intervention targets.	[20–23]
Planning, design, and implementation	Mapping	Which intervention components can be used to influence intervention targets in the desired direction?	Means of selecting intervention components (activities, strategies, and behaviour change techniques) that need to be embedded and mapped within the intervention design to ensure identified mechanisms of action will be influenced in the desired direction.	[16, 23, 24]
Planning, design, and implementation	Tailoring	Who to target, with what, and when?	Interventions (activities, strategies, and behaviour change techniques) can be tailored on a one to one or group (segmented) basis by ensuring theoretically identified differences are catered for in intervention design and implementation, thereby delivering more benefit to more people.	[23, 25]
Planning, design, implementation, and evaluation	Modelling	How do behavioural determinants, intervention components, and outcomes relate to each other?	Inform the development of a logic model (road map) visually depicting the relationships between the target behaviour, determinants (mechanisms of action), intervention components, and outcomes.	[16, 26]
Evaluation	Measurement	What to monitor and measure, and how?	Provide a guide for intervention evaluation ensuring theoretically derived determinants (mechanisms of action) of behaviour (or behaviour change) and associated intervention components are monitored and measured.	[16, 23]
Evaluation	Effects	What works, for whom, how, why, and when?	Determinants can be empirically investigated to gain a further understanding as to how the intervention elicits (or not) effects via mediation analysis, and to enhance intervention effectiveness and efficiency over time.	[27, 28]
Evaluation	Reporting	How can quality and rigour be evaluated within and across studies?	Theories provide a series of organising frameworks that can support accurate and complete description of interventions.	[16]
Evaluation	Testing	What factors or combination of factors best explain the target behaviour?	Interventions provide an opportunity to test theory and contribute to the development of theories delivering stronger explanatory and predictive potential over time, which in turn, supports future intervention optimisation, enhanced outcomes, and cumulative knowledge advancement.	[11, 29]