Psychotherapist remarks' ML classifier: insights from LLM and topic modeling application.

Introduction: This paper addresses the growing intersection of machine learning (ML) and psychotherapy by developing a classification model for analyzing topics in therapist remarks. Understanding recurring language patterns in therapist communication can enhance clinical practice, supervision, and training, yet systematic approaches to topic analysis remain limited. Methods: The study applies BERTopic, an ML-based topic modeling technique, to unstructured dialogues from two distinct groups of therapists: classical (founders of therapeutic schools such as Carl Rogers, Fritz Perls, and Albert Ellis) and modern practitioners representing diverse psychotherapeutic approaches. The implementation involves constructing a vector space of therapist remarks, applying dimensionality reduction, clustering, and optimizing topic representations. To improve interpretability, expert assessment and manual refinement complement the automated modeling process. The resulting topics are used as features to train an ML classifier, which is then tested on a case study comparing Carl Rogers' sessions with those of modern Cognitive Behavioral Therapy (CBT) practitioners. Results: The analysis identifies the most common and stable topics across both therapist groups, highlighting recurring patterns and unique thematic compositions. The case study reveals distinct differences in thematic structures, with key topics emerging that characterize each group's therapeutic discourse. The trained classifier demonstrates robust performance in distinguishing these thematic patterns. Discussion: The study shows that automated topic modeling, combined with expert input, can effectively uncover how therapist language patterns emerge and persist across different therapeutic styles. The resulting model, made publicly available, offers broad applications in psychotherapy research, clinical supervision, and training. These findings underscore the potential of topic modeling as a valuable tool for deepening our understanding of therapist communication and advancing ML applications in psychotherapy.