Behavioural theories and frameworks

Research undertaken within other disciplines including psychology, sociology, complexity science and behavioural economics can help to inform assumptions about behaviour beyond intervention study follow up. Many theories and frameworks have been developed to explain human behaviour. These link a set of biological, psychological, social and/or environmental factors to behaviour, offering a bio-psycho-social understanding of behaviour. Such factors can be thought of as potential intervention targets for change and mechanisms of action. The effectiveness of interventions for changing and maintaining behaviour will depend on which influences are targeted, and to what extent changes in these influences (e.g., knowledge), and the behaviour change techniques (e.g., providing information) and intervention strategies (e.g., education) used impact on behaviour. However, there is no one accepted behavioural theory, and there are multiple mechanisms of action and behaviour change techniques (Johnston et al., 2021). Michie et al. (2014) collated 83 behavioural theories which could inform the development of behavioural interventions. Within this review, the three theories for which the most published papers (more than 50%) were identified were: (i) the Transtheoretical Model of Behaviour Change (which includes progression and feedback loops through the stages precontemplation, contemplation, preparation, action and maintenance, allowing for relapse) (Prochaska et al., 1997); (ii) The Theory of Planned Behaviour (which links attitude, subjective norms, perceived behavioural control and intentions to behaviour) (Ajzen, 1991); and (iii) Social Cognitive Theory (which links the interaction between the individual, environment and behaviour with behavioural capability, observational learning, reinforcement, expectations and self-efficacy) (Bandura, 2001).  

Recent literature encourages the use of behavioural theories to inform public health intervention development to understand what works for whom in which contexts (Michie et al., 2018). However, many existing studies do not report their theoretical basis (Prestwich et al, 2014) and a narrative synthesis of nine systematic reviews found no difference in the effectiveness of interventions that were theory-based versus non-theory-based (Dalgetty et al., 2019). The study authors suggested that this could be due to limitations with the theories used (with two of the most widely used having had calls to be retired (Sniehotta et al., 2014; West, 2005) or issues with fidelity and the way in which they were applied.

The Behaviour Change Wheel developed by Michie et al., (2011) has become an important framework for developing interventions, because it provides a coherent and comprehensive approach. It was developed based upon a systematic review of the literature and subsequently tested for reliability. The Behaviour Change Wheel includes influences on behaviour at the hub, with a wide range of intervention types and policy options set out in the middle and outer layers of the wheel. There are then tables to facilitate a systematic selection of intervention strategies and behaviour change techniques according to a behavioural analysis. The influences on behaviour at the hub are conceptualised through the COM-B model of behaviour, where Behaviour can be explained by a combination of Capability, Opportunity and Motivation. Capability includes physical (e.g., skills/ strength) and psychological (e.g., knowledge, memory, attention and decision making, behavioural regulation) factors; Motivation includes reflective (e.g. beliefs, intentions, identity) and automatic (e.g. emotion, reinforcement) factors; and Opportunity includes physical (e.g. environmental context and resources) and social (e.g. norms, culture) influences.  

Any theory that is used to develop the interventions is generally ignored when they are evaluated within a health economic model. This is partly because health economic modellers tend to use methods developed for the evaluation of clinical interventions, and partly due to limitations of existing behavioural theories, including data limitations to support them and the fidelity with which they are implemented in the interventions. To predict the long-term effectiveness of interventions, it is important to understand the precise content and context of the interventions (Skivington et al., 2021). Combining behavioural theory with modelling, as has been done in other fields such as natural resource management (Schluter et al., 2017), could help to understand the longer-term impacts of a range of interventions with different mechanisms of action upon individuals with different attributes.