Decision-aware User Simulation Agent for Evaluating Conversational Recommender Systems

Yuan-Chi Li, Li-Chi Chen, Sung-Yi Wu, Yu-Che Tsai, Shou-De Lin


Abstract
Conversational recommender systems (CRS) increasingly rely on user simulators for automated evaluation of sales agents. A key requirement for such simulators is the ability to model human decision-making. However, most LLM-based simulators often exhibit unrealistically strong information-processing capabilities, rarely exhibiting the hesitation and decision deferral commonly observed in real consumer behavior, resulting in overly high acceptance rates. To address this limitation, we propose Hesitator, a theory-grounded user simulation framework that explicitly models a specific dimension of human decision-making: decision deferral under choice overload. The framework introduces a modular Decision Module that separates utility-based item selection from overload-aware commitment decisions. Experiments across multiple user simulation frameworks, domains, sales modes, and LLM backbones show that integrating our module consistently mitigates unrealistic behaviors under increasing overload conditions. Furthermore, Hesitator reproduces established findings from behavioral economics, demonstrating its ability to model human decision behavior.
Anthology ID:
2026.findings-emnlp.77
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1572–1592
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.77/
DOI:
Bibkey:
Cite (ACL):
Yuan-Chi Li, Li-Chi Chen, Sung-Yi Wu, Yu-Che Tsai, and Shou-De Lin. 2026. Decision-aware User Simulation Agent for Evaluating Conversational Recommender Systems. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 1572–1592, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Decision-aware User Simulation Agent for Evaluating Conversational Recommender Systems (Li et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.77.pdf