A conversational agent framework for mental health screening: design, implementation, and usability

While chatbots show promise for large-scale mental health screening, few offer interactive, free-text conversations, limiting their appeal for self-administered screening and impeding the timely detection of mental health issues. This study introduces an AI-based chatbot that allows users to respond to validated screening surveys for mental disorders (PHQ-9, GAD-7, and PCL-5) in a natural, free-text conversation manner with real-time feedback. The study's objectives include evaluating the chatbot's usability and reducing the frequency of response clarifications while accurately interpreting users' responses. The system was assessed running in hybrid NLU mode (Phase 2; N = 587; Mage = 21.56, SD = 5.56, 67.8% women) after being trained on data collected while running in rule-based mode (Phase 1; N = 274; Mage = 21.86, SD = 5.50). During user-chatbot interactions, the chatbot required clarification only 4.64% of the time. Using the AI NLU model, the chatbot could understand user responses in 85.65% of cases and interpret free-text similarly to human annotators. In terms of usability, the chatbot in hybrid NLU mode was perceived as more engaging, friendly, and easier to use than in the rule-based NLU mode, which may be indirectly attributed to the enhanced autonomy provided by the AI NLU model.