Testing theory in practice: The example of self-determination theory-based interventions - Silva, Marques & Teixeira - 2014 - Article

How to test theory in practice?

In order to advance behavioral science, we need a better understanding of how interventions are informed by theory, how they can better test theory, and which behavior change techniques should be selected as a function of theory. Simply claiming that an intervention is theory-based, does not per se make it so. Thus, a more critical evaluation of applied theory is needed.

To accompany this need, Michie and Prestwich (2010) developed the theory coding scheme (TCS), with the aim of providing a reliable research tool to describe and evaluate the theoretical basis of interventions. The TCS comprises a list of items to assess: (a) whether relevant constructs are measured; (b) which behavior change techniques are used to impact those constructs; and (3) whether the study design allows for theory itself to be tested and refined.

The application of the TCS was recently tested in a meta-analysis. The results indicated that the application of theory in intervention design and evaluations was poorly reported. For instance, few interventions targeted and measured changes in all theoretical constructed that were defined by the theory. In addition, few studies linked all the behavior change techniques to those constructs. However, a pitfall of this meta-analysis was that it only focused on two theories: the social cognitive theory (SCT) and the transtheoretical model. More research is needed to expand our knowledge of testing theory in practice. In this paper, the development, implementation, and evaluation of theory-based interventions is examined using the social determination theory (SDT), a theory that is increasingly being used in behavioral nutrition and physical activity.

What is the state-of-the-art concerning self-determination theory-based interventions in behavioral science?

The social determination theory (SDT) postulates three psychological needs: autonomy, competence, and relatedness. Support and satisfaction of these needs provides the basis for psychological energy that is predicted to motivate the initiation and long-term maintenance of various health behaviors. Following the SDT model, the effect of the environment on motivation and behavioral regulation is not direct, but occurs as a result of the satisfaction of the three universal psychological needs. The most important social environmental factor is the degree of need-supportiveness or the extent to which others and the environment more broadly support (rather than thwart) these needs, both objectively and subjectively as perceived by the individual.

Key component techniques of need-supportiveness are:

• Autonomy support (relevance, respect, choice, avoidance or control)
• Structure (clarity of expectations, optimal challenge, feedback, skills-training)
• Involvement (empathy, affection, attunement, dedication of resources, dependability)

SDT is increasingly being advocated as a highly applicable and practically useful framework for interventions related to various health domains. Here, a summary is provided of an ongoing systematic review, examining how adequately SDT has been applied in these domains. The following findings were presented:

• Less than half of the studies explicitly linked all behavior change techniques to SDT-relevant construct(s). The majority of the remaining studies linked either one or a group of techniques to these construct(s).
• In most studies, SDT-relevant construct were assessed at pre- and post-treatment, using measures with adequate validity and/or reliability. However, in a large share of these studies, only a limited set of SDT-related constructs were measured. In addition, often, this was restricted to motivational regulations (such as autonomous and controlled motivation).
• There was a limited amount of mediation analysis with only two studies reporting formal tests of mediation (PESO and PAC).
• Overall, despite the restricted number of available studies and the variability in the format and delivery of interventions, the usefulness of SDT for behavior change is supported. The present scenario is encouraging of future testing and refinement.