Towards Natural Personalization: Evaluating Long-Horizon Preference Following in Personalized User-LLM Interactions

Qianyun Guo, Yibo Li, Yue Liu, Bryan Hooi


Abstract
Large Language Models (LLMs) are increasingly serving as personal assistants, where users may share individual preferences over extended interactions. However, assessing how well LLMs can follow these preferences in natural, long-term situations remains underexplored. This work proposes **RealPref**, a benchmark for evaluating natural preference-following in personalized user-LLM interactions. RealPref features 100 synthetic user profiles, 1300 personalized preferences, 4 types of preference expression (from explicit to implicit), and long-horizon interaction histories. It explored three types of test tasks (multiple-choice, true-or-false, and open-ended), with granular rubrics for LLM-as-a-judge evaluation. Results indicate that LLM performance drops significantly as context length grows and preference expression becomes more implicit, and that generalizing user preference understanding to unseen scenarios poses further challenges. RealPref and these findings provide a foundation for future research to develop user-aware LLM assistants that better adapt to individual needs.
Anthology ID:
2026.findings-emnlp.2378
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:
51070–51105
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2378/
DOI:
Bibkey:
Cite (ACL):
Qianyun Guo, Yibo Li, Yue Liu, and Bryan Hooi. 2026. Towards Natural Personalization: Evaluating Long-Horizon Preference Following in Personalized User-LLM Interactions. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 51070–51105, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Towards Natural Personalization: Evaluating Long-Horizon Preference Following in Personalized User-LLM Interactions (Guo et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2378.pdf