Patterns of psychotherapy development: A mixed-method analysis using assimilation indices

Understanding how assimilation develops is essential in promoting personal change. By attending to signs or indices of assimilation in the speech of clients, therapists can use this process to assess how the therapy is developing and to tailor intervention. The system of assimilation indices was developed to use assimilation to understand the process of change. This system signals five sub-processes of assimilation: external distress, pain, noticing, decentring, and action. This study consisted of a longitudinal mixed-method analysis, following a multiple cases embedded design. The system of assimilation indices was applied to the recordings of nine psychotherapies and contrasted with both the outcome of the therapy and the perspectives of the therapists and clients about their therapy process. The results show that the system of indices is useful in understanding multiple pathways for assimilation. The system of indices is seen as a useful tool for understanding assimilation and as having clinical value in anticipating challenges to the success of the therapy. This study also shows how the indices are sensitive to the nuances in the change process observed in clinical settings.