Watch your language! Analyzing active ingredients of client speech in a motivational interviewing intervention for environmental behavior change

Motivational Interviewing (MI) is a communication style that aims to motivate a conversational partner for behavior change by enhancing change talk (e.g., “I want to change”) and reducing counter change talk (“I will not change”). The effectiveness of MI has not been evaluated within the domain of environmental behavior change. This experimental field study examines the effects of Motivational Interviewing on environmental behavior within an input-process-output framework. Recorded conversations (n= 49) of an MI trained group were compared to conversations (n= 28) of an untrained group. We compared communication skills, client language, and environmental behavior immediately after the intervention and at a three-month follow-up between groups. Trained interviewers showed higher proficiency in MI than untrained interviewers did. Change talk was higher in the MI group, whereas counter change talk showed no difference between intervention groups. Environmental behavior did not differ between groups. Client language – particularly commitment talk – was related with short- and long-term environmental behavior. Our results suggest that MI can foster long-term environmental behavior changes if interviewers succeed to decrease counter change talk, specifically negative commitments.