HealingAxis: Large Language Models Can Innately TherapyMaxxx Clinical Psychotherapeutic Interventions

AI chatbots powered by Large Language Models are the largest providers of mental health support, with emotional support as their top use-case. Despite this scale, the inner workings of models providing psychotherapeutic support remain largely un- known. In this paper, we identify a low-dimensional direction, a Healing Axis, as- sociated with the application of psychotherapeutic techniques from a dozen modal- ities studied including CBT, EFT, AEDP, psychodynamic, schema, and other ther- apies. For each of the six models examined, ideal activation steering increases by +22-232% the number of verifiable clinical skill criteria the model exhibits in its response; while negative steering collapses responses toward zero clinical skills. We propose the GoodBadTherapy dataset with 2,000+ contrasting pairs establishing the Healing Axis, and the SkilledTherapyBenchmark to evaluate the performance of models on deliberate-practice therapeutic skillsets. Using mecha- nistic interpretability methods, we demonstrate the Healing Axis is composed of interpretable features and sub-axes are meta-therapeutic techniques. Additionally, the Healing Axis on average generalizes beyond the modalities it’s derived from, demonstrating a single vector has cross-modality applicability. More broadly, as models become embedded in the mental health support landscape, this work offers a path to monitor and improve the skillfulness of their clinical interventions.