Motivational interviewing Active ingredients and mechanisms of change

Motivational Interviewing (MI) is “a collaborative conversation style for strengthening a person’s own motivation and commitment to change” (Miller & Rollnick, 2013, p.29). Many studies showed the effect of MI on different kinds of lifestyle change. However, it remains unclear how MI works: which ingredients are responsible for the effect of MI?
We studied these ‘active ingredients’ and the subsequent altered cognitions or ways of thinking (‘mechanisms of change’). This study was performed in two populations. First, we analyzed 66 audio-recorded MI-conversations between MI-counsellors and 14 patients with schizophrenia, aimed at strengthening the patient’s motivation for long-term medication adherence. Second, we analyzed 109 MI-conversations with 24 patients with coronary heart disease, aiming at smoking cessation.
Both studies were designed as a qualitative multiple case analysis, in combination with a quantitative analysis of conditional probabilities of types of patient statements immediately following specific counsellor statements.
We found that the active ingredients of MI consist of combinations of clinician factors and client factors, mostly built up during longer interactions. ‘Arguing oneself into change’ was the most frequently observed mechanism of change.
This dissertation adds to the scientific understanding of motivational interviewing, since it provides an explanation of how MI may work. It offers a general idea how counsellors can effectively execute MI. This ‘how-possibly’ explanation may be a building block in the development of a ‘how-actually’ explanation of the interactions leading to the active ingredients and mechanisms of change in MI.