ABSTRACT
In this chapter, we define theory-based interventions, explain how they can be assessed, examine the potential benefits of theory use and overview a number of key practical issues that researchers need to consider when developing behavior change interventions. While theory-based interventions are typically presented as a dichotomy (theory-based: yes/no), we argue that they might be best seen as sitting on a measurable continuum. Moreover, while theory-based interventions bring a range of benefits, evidence is mixed in terms of whether they help to achieve larger changes in health behavior. Such comparisons between studies testing theory-based interventions and studies testing other types of interventions are, however, often confounded and we overview the factors that disrupt this comparison. The Theory-Coding Scheme, science of behavior change/experimental medicine approach, a four-step cycle and intervention mapping are presented as different approaches that can be used to design and evaluate behavior change interventions. The practical issues considered are identifying which theories to use, which determinants to target (based on their impact on behavior, their malleability, plus their levels and variability within a target sample), as well as the pros and cons of different methods of deciding which behavior change techniques to use to change specific determinants.
