Complexity in Speech and its Relation to Emotional Bond in Therapist-Patient Interactions During Suicide Risk Assessment Interviews

In this paper, we analyze a 53-hour speech corpus of interactions of Soldiers, who had recently attempted suicide or had strong suicidal ideation, conversing with their therapists. In particular, we study the complexity in therapist-patient speech as a marker of their emotional bond. Emotional bond is the extent to which the patient feels understood by and connected to the therapist. First, we extract speech features from audio recordings of their interactions. Then, we consider the nonlinear time series representation of those features and compute complexity measures based on the Lyapunov coefficient and correlation dimension. For the majority of the subjects, we observe that speech complexity in therapist-patient pairs is higher for the interview sessions, when compared to that of the rest of their interactions (intervention and post-interview follow-up). This indicates that entrainment (adapting to each other’s speech) between the patient and the therapist is lower during the interview than regular interactions. This observation is consistent with prior studies in clinical psychology, considering that assessment interviews typically involve the therapist asking routine questions to enquire about the patient’s suicidal thoughts and feelings. In addition, we find that complexity is negatively correlated with the patient’s perceived emotional bond with the therapist.