Behavior change is one of the most important goals in psychotherapy. This study focuses on Motivational Interviewing (MI), which is collaborative communication aimed at eliciting the client’s own reasons for behavior change. To investigate the effectiveness of facial information in modeling MI, we collected an MI encounter corpus with speech and video data in the nutrition and fitness domains and annotated client utterances using the Manual for the Motivational Interviewing Skill Code (MISC). By analyzing client answers to the questions after the session, we found that clients who expressed more Change Talk were more motivated to change their behavior than those who expressed less Change Talk. We then proposed RNN-based multimodal models to detect Change Talk by setting a 2-class classification task: "Change Talk" and "not Change Talk." Our experiment showed that the best performing model was a multimodal BiLSTM model that fused language and client facial information. We also found that fusing language and facial information as context achieved better performance than the unimodal and no-context models. Moreover, we discuss the label imbalance problem and conduct an additional analysis using turns as a unit of analysis. As a result, our best model reached F1-score of 0.65 for Change Talk detection.

The automatic estimation of personality traits is essential for many human–computer interface (HCI) applications. This paper focused on improving Big Five personality trait estimation in group discussions via multimodal analysis and transfer learning with the state-of-the-art speaker individuality feature, namely, the identity vector (i-vector) speaker embedding. The experiments were carried out by investigating the effective and robust multimodal features for estimation with two group discussion datasets, i.e., the Multimodal Task-Oriented Group Discussion (MATRICS) (in Japanese) and Emergent Leadership (ELEA) (in European languages) corpora. Subsequently, the evaluation was conducted by using leave-one-person-out cross-validation (LOPCV) and ablation tests to compare the effectiveness of each modality. The overall results showed that the speaker-dependent features, e.g., the i-vector, effectively improved the prediction accuracy of Big Five personality trait estimation. In addition, the experimental results showed that audio-related features were the most prominent features in both corpora.