Learning User Simulators with Turing Rewards

Yingshan Susan Wang, Cedegao E. Zhang, Linlu Qiu, Zexue He, Pengyuan Li, Alex Pentland, Roger P. Levy, Yoon Kim


Abstract
Learning to simulate human users in interactive settings could advance the training of agents that serve humans, the evaluation of personalization systems, and research in the social sciences. Existing approaches generally do so by training a large language model (LLM) to match a single ground truth response, either by maximizing the log probability or by using a similarity reward. We instead propose a Turing Test approach for learning user simulator models, where a model is trained via reinforcement learning to produce responses indistinguishable from what the user could have said. Our discriminative Turing reward uses an LLM judge to score how indistinguishable a generated response is from the real user’s given the user’s history. Across two substantially different domains, namely conversational chat and Reddit forum discussion, we find that the Turing reward consistently outperforms baseline methods on both LLM and human evaluation metrics. Our study suggests that optimizing for indistinguishability, rather than response matching, is an effective route to learning user simulators.
Anthology ID:
2026.emnlp-main.1393
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
31797–31844
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1393/
DOI:
Bibkey:
Cite (ACL):
Yingshan Susan Wang, Cedegao E. Zhang, Linlu Qiu, Zexue He, Pengyuan Li, Alex Pentland, Roger P. Levy, and Yoon Kim. 2026. Learning User Simulators with Turing Rewards. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 31797–31844, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Learning User Simulators with Turing Rewards (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1393.pdf