Mechanisms of Change in a Motivational Interviewing Intervention for Criminal Offenders

Background

Although alcohol and drug treatment are common mandates in the U.S. criminal justice system, only a minority of clients actually initiate treatment.  Motivational Interviewing (MI) is a widely used counseling strategy for increasing treatment initiation, but its mechanisms of action have not been widely examined in a criminal justice setting.

Method

Research in other areas has suggested a causal language chain in MI from counselor speech to client speech, to client outcome.  We used the Motivational Interviewing Skills Code (MISC 2.5) to quantitatively analyze counselor and client language during a clinical trial of MI in a probation setting. Conditional process analysis and multiple linear regression analysis determined the association between counselor and client language and the association between client language and client behavior at two months.

Results

Consistent with MI theory, we found that counselor MI-consistent language was significantly more likely to be followed by client change talk (β =0.81, p = 0.02), and counselor MI-inconsistent language was significantly more likely to be followed by client sustain talk (β = 0.81, p = 0.02). The overall model fit was R² = 0.273, F (2, 37) = 6.941, p = 0.003.  Further, we found that client preparatory sustain talk (Desire-, Ability-, Reason-, and Need-) (β = 1.77, p = 0.01) was positively associated with increased days of substance use at a 2-month follow-up. The overall model fit was F (3, 36) = 4.67, p = 0.007. 

Conclusion

This is the first study to examine mechanisms of change during an MI intervention for criminal justice clients.  Our results are consistent with past studies examining MI among non-criminal justice clients, suggesting that client language is a reliable mechanism of change in MI interventions.