VIBE-Bench: Evaluating Personalized Large Language Models When Profiles Don’t Mean Preferences

Yiwen Jiang, Yang Deng, Stephanie Fong, Zimu Wang, Yaling Shen, Wei Feng, Hongxi Yang, Xiangyu Zhao, Zhongxing Xu, Deval Mehta, Xuelian Cheng, Zongyuan Ge


Abstract
Personalized Large Language Models (PLLMs) aim to tailor responses to individual users, where a central challenge is preference reasoning: inferring query-relevant preferences from user-related history. Existing benchmarks, however, largely assume that such preference can be retrieved from semantically related history. We study an underexplored but practically important regime, profile-preference conceptual misalignment (PRCM), where observable profile cues and query-specific preferences lie in different concept spaces, making semantic retrieval inconsistent for personalization. We introduce Vibe-Bench, a benchmark with two psychology-grounded tasks, 3,504 personas and 12,239 dialogues, including a manually verified gold test set, and requires cross-concept preference reasoning beyond surface semantic overlap. Experiments with several personalization methods show that current PLLMs largely rely on shallow semantic correlations and fail to acquire robust cross-concept mappings. These findings establish PRCM as a distinct failure regime in PLLMs and position Vibe-Bench as a focused testbed for advancing preference reasoning beyond semantic matching.
Anthology ID:
2026.findings-emnlp.1676
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:
35771–35797
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1676/
DOI:
Bibkey:
Cite (ACL):
Yiwen Jiang, Yang Deng, Stephanie Fong, Zimu Wang, Yaling Shen, Wei Feng, Hongxi Yang, Xiangyu Zhao, Zhongxing Xu, Deval Mehta, Xuelian Cheng, and Zongyuan Ge. 2026. VIBE-Bench: Evaluating Personalized Large Language Models When Profiles Don’t Mean Preferences. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 35771–35797, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
VIBE-Bench: Evaluating Personalized Large Language Models When Profiles Don’t Mean Preferences (Jiang et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.1676.pdf