Therapist—client language matching: Initial promise as a measure of therapist—client relationship quality.

While research suggests that the therapeutic alliance is important in predicting outcomes of psychotherapy, relatively little is known about the development of the alliance or the moment-to-moment components of the relationship and how they combine to create an alliance, which may represent a serious limitation in existing methods of measurement. Language style matching (LSM), or the degree to which unconscious aspects of an interactional partner’s language mimic that of the other partner, is a promising, unobtrusive measure of interaction quality that could provide novel insight into the therapist—client alliance. In this article, we present a theoretical argument regarding the trajectory of therapist—client LSM across therapy sessions, as well as potential precursors and consequences of LSM. We then report on a pilot test of our hypotheses that examined how LSM, clients’ relational histories, and clients’ symptoms were associated within a therapeutic context. Using a small sample of substance dependent mothers (N = 7, 100% Caucasian women) enrolled in a randomized controlled trial of psychodynamic psychotherapy lasting 12 sessions, we examined client and therapist LSM across 4 of the 12 sessions. We found that, on average, LSM decreases over the course of treatment. Furthermore, greater client interpersonal problems prospectively predict lower early LSM in therapist—client dyads, which in turn predicts greater posttreatment psychiatric distress. Results generate questions for future research and support further investigations of LSM as one index of the quality of interactions between therapist and client. (PsycINFO Database Record (c) 2019 APA, all rights reserved)