Evaluation of Motivational Interviewing Counsellors with Task-Aware Multi-Stage LLM-Based Simulated Clients

Jiading Zhu, Xinyu Cindy Wang, Thomas Nguyen, Yan Qing Lee, Osnat C. Melamed, Peter Selby, Jonathan Rose


Abstract
The development and benchmarking of Large Language Model (LLM)-based Motivational Interviewing (MI) counsellors now often rely on LLM-based simulated clients. Prior work on simulated clients, however, has not aligned with the specific *tasks* fundamental to the MI therapy approach. A key task is *evoking*, in which the counsellor first elicits the client’s ambivalence and then strengthens the client’s motivation for change. We present **Evoke-Sim**, a task-aware, multi-stage LLM-based client simulation framework for evaluating MI counsellors in smoking cessation, designed specifically for the *evoking* MI task. Evoke-Sim employs structured client profiles, an evoking-specific three-stage conversation flow, and a *reveal* policy that regulates which client profile information might be disclosed at each stage. We show that, compared to existing profile-grounded simulated clients, Evoke-Sim better differentiates counsellors’ task-aware performance under our explicit formalization of the *evoking* task, while reducing non-grounded client statements and premature disclosure of client information.
Anthology ID:
2026.luhme-1.23
Volume:
Proceedings of the 3rd Workshop on Language Understanding in the Human-Machine Era (LUHME 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Rui Sousa-Silva, Henrique Lopes Cardoso, Maarit Koponen, Antonio Pareja-Lora
Venues:
LUHME | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
304–359
Language:
URL:
https://aclanthology.org/2026.luhme-1.23/
DOI:
Bibkey:
Cite (ACL):
Jiading Zhu, Xinyu Cindy Wang, Thomas Nguyen, Yan Qing Lee, Osnat C. Melamed, Peter Selby, and Jonathan Rose. 2026. Evaluation of Motivational Interviewing Counsellors with Task-Aware Multi-Stage LLM-Based Simulated Clients. In Proceedings of the 3rd Workshop on Language Understanding in the Human-Machine Era (LUHME 2026), pages 304–359, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Evaluation of Motivational Interviewing Counsellors with Task-Aware Multi-Stage LLM-Based Simulated Clients (Zhu et al., LUHME 2026)
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PDF:
https://aclanthology.org/2026.luhme-1.23.pdf