Interpersonal style should be included in taxonomies of behavior change techniques

Health practitioners and researchers in behavioral medicine recognize the value of interventions aimed at promoting uptake and maintenance of health behavior to prevent chronic illness. Although there have been advances in interventions that promote health behavior change and their effectiveness, gaps in knowledge exist. In particular, the precise components or techniques of behavioral interventions that lead to effective behavior change and the mechanisms involved have yet to be fully elucidated. Efforts to identify these techniques have been hindered by a lack of detail in, and systematic reporting of, the content and protocol of behavior-change interventions (Michie and Johnston, 2012). Recent efforts aimed at classifying behavior change techniques (BCTs) have been important in helping to identify the active ingredients of behaviorchange interventions. This is important for the replication of interventions, identification of the mechanisms involved, and development of a “common language” for BCTs. Michie et al. (2013) present a hierarchically-clustered taxonomy to develop a BCT taxonomy based on consensus and serves as a starting point for the development of future taxonomies. In this article we contend that authors of BCT taxonomies have focused their attention exclusively on intervention content and should pay closer attention to the role interpersonal style plays in promoting behavior change. We use two approaches to behavior change that involve both content and interpersonal style to illustrate our point: autonomy support and motivational interviewing. We argue that interpersonal style is a unique set of techniques that likely interact with other contentrelated BCTs in affecting behavior change. Michie et al. acknowledge that “mode and context of delivery, and competence of those delivering the intervention would. . . benefit from being specified by detailed taxonomies” (p.93). Interpersonal style is likely to be encompassed by this caveat, but what is meant by interpersonal style and how it might fit within future taxonomies needs clarification. Interpersonal style should not be equated with mode of delivery. Mode of delivery is the means by which intervention content is communicated to targets or clients such as print communication, audio-visual media, or orally via a health practitioner. Interpersonal style refers to the manner by which intervention content is presented to the target audience and could be delivered by multiple modes. Interpersonal style includes the type of language used in delivering intervention content and interactions between the target audience of the intervention and the health practitioner delivering the intervention. We will illustrate these features of interpersonal style BCTs in the following examples. Our first example comes from selfdetermination theory (SDT; Deci and Ryan, 2000). Central to the theory is the premise that individuals will be more likely to initiate and maintain behavior if it is perceived as autonomously motivated. Autonomous motivation means engaging in the behavior to attain self-determined outcomes and in the absence of external contingencies. Autonomous motivation can be promoted by social agents through the provision of choice, acknowledging conflict, avoiding controlling language, and external reinforcers, and fostering personally-relevant goals (Hagger et al., 2006, 2007; Hagger and Chatzisarantis, 2009). Some of these techniques relate to content, such as acknowledging conflict, but others depend on social agents adopting the appropriate interpersonal style. For example, avoiding controlling language means refraining from using terms like “should” and “must.” Other intervention techniques outlined in Michie et al.’s taxonomy such as goal setting, threats, and rewards could be delivered in an “autonomy supportive” interpersonal style. In fact, according to SDT, delivering external contingencies like threats and incentives in an autonomy-supportive manner may promote behavioral adherence (Hagger and Chatzisarantis, 2011). This is because autonomy support may illustrate the informational aspect of the incentive and prevent it becoming the “be all and end all” of the behavior. Instead, individuals will view incentives as informing them of their competence and progress.