  Dialogue systems are increasingly integrated into mental health support to
help clients facilitate exploration, gain insight, take action, and ultimately
heal themselves. A practical and user-friendly dialogue system should be
client-centric, focusing on the client's behaviors. However, existing dialogue
systems publicly available for mental health support often concentrate solely
on the counselor's strategies rather than the behaviors expressed by clients.
This can lead to unreasonable or inappropriate counseling strategies and
corresponding responses generated by the dialogue system. To address this
issue, we propose PsyChat, a client-centric dialogue system that provides
psychological support through online chat. The client-centric dialogue system
comprises five modules: client behavior recognition, counselor strategy
selection, input packer, response generator, and response selection. Both
automatic and human evaluations demonstrate the effectiveness and practicality
of our proposed dialogue system for real-life mental health support.
Furthermore, the case study demonstrates that the dialogue system can predict
the client's behaviors, select appropriate counselor strategies, and generate
accurate and suitable responses.
