Articulation rate in psychotherapeutic dialogues for depression: patients and therapists

Prosodic features anecdotally associated with the speech of people with clinical depression include slower rate, lower pitch range and reduced loudness, but there is a significant degree of contradiction in the literature regarding depressed prosody. This complex picture reflects the heterogeneity of depression aetiology, symptomatology and prognosis. It is also likely to be influenced by elicitation methods, in particular, whether natural dialogue contexts are employed and whether the interlocutor’s prosody is also considered. We analysed 40 patient-therapist dialogues from the first and last of 29 weekly sessions of a behavioural therapy for refractory depression, sampling early and late in both sessions. Across all dialogues, we found that therapists spoke faster than patients, as expected, but in female-female therapist-patient dialogues (the majority of our sample), patients’ articulation rate increased substantially over the first session. Moreover, and contrary to expectations, there was a positive correlation between articulation rate and assessed depression severity (PHQ-9 scale) in the final therapy session, also evident in therapists’ speech for female-female dialogues. We suggest that this may reflect features of anxiety in speakers with ongoing depression and possibly also personality characteristics. We also consider evidence for prosodic convergence between patients and therapists.