PALMs: Using Multi-Construct Grounded Rationales for Modeling Population Preferences in LLMs

Priyanka Dey, Brihi Joshi, Preyashi Poddar, Jieyu Zhao, Emilio Ferrara


Abstract
Large language models are being extensively used to simulate individual user behavior, yet faithfully representing a population requires capturing the systematic variation in values, beliefs, and cultural norms that distinguish one group from another. We introduce (), a suite of models each aligned to specific populations, covering five countries: USA, India, Brazil, France and Italy. are created by synthesizing rationales grounded in psychological and cultural constructs and using these as latent supervision during preference tuning for population-specific alignment. Evaluated across four dimensions: personality, values and beliefs, cultural norms, and morality, consistently outperform baselines, including culture-specialized models, achieving an average of 8.59% relative improvement over the best baseline across all five populations. Notably, construct-grounded rationales outperform both demographic prompting and survey-based fine-tuning, suggesting that grounding preference learning in psychology and culture provides a richer inductive signal than surface-level response distributions. We further demonstrate strong generalization to downstream applications without task-specific supervision: outperforming best baselines by 5.19% in personalized reward modeling, 6.34% in population simulation, and showing strong transfer to social reasoning tasks. Datasets and code are available at: https://github.com/limenlp/PALMs.
Anthology ID:
2026.emnlp-main.888
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:
20475–20517
Language:
URL:
https://aclanthology.org/2026.emnlp-main.888/
DOI:
Bibkey:
Cite (ACL):
Priyanka Dey, Brihi Joshi, Preyashi Poddar, Jieyu Zhao, and Emilio Ferrara. 2026. PALMs: Using Multi-Construct Grounded Rationales for Modeling Population Preferences in LLMs. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 20475–20517, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
PALMs: Using Multi-Construct Grounded Rationales for Modeling Population Preferences in LLMs (Dey et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.888.pdf