The paper “Why do people change in therapy? A preliminary study” (2006), published in this journal, led to the beginning of a line of research based on observational methodology and aimed at the clarifi cation of the therapeutic process. Throughout these years, signifi cant progress
has been made towards an explanation of clinical change. In this paper, a synthesis of this line of research is presented, along with a series of conclusions that can, to some extent, provide an answer to the questions we posed in the aforementioned fi rst paper. Method: Verbal behavior both
of therapist and client was coded for 92 clinical sessions using the Verbal Behavior Interaction Category System (SISC-INTER-CVT). Descriptive and sequential analyses of the observations were then performed. Results: The data show the existence of certain patterns of verbal interaction that are related to the clinically relevant activities undertaken by the therapist, from which a model for verbal interaction in the clinical context was developed. Conclusions: The functional analysis of the therapist-client verbal interaction is essential for the comprehension of the processes that
explain clinical change as well as for the improvement of the quality of psychological therapy
