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EMNLP Findings2025

PersLLM: A Personified Training Approach for Large Language Models

Zheni Zeng, Jiayi Chen, Huimin Chen, Yukun Yan, Yuxuan Chen, Zhenghao Liu, Zhiyuan Liu, Maosong Sun

Abstract

Large language models (LLMs) exhibit humanlike intelligence, enabling them to simulate human behavior and support various applications that require both humanized communication and extensive knowledge reserves. Efforts are made to personify LLMs with special training data or hand-crafted prompts, while correspondingly faced with challenges such as insufficient data usage or rigid behavior patterns. Consequently, personified LLMs fail to capture personified knowledge or express persistent opinion. To fully unlock the potential of LLM personification, we propose PersLLM, a framework for better data construction and model tuning. For insufficient data usage, we incorporate strategies such as Chain-of-Thought prompting and anti-induction, improving the quality of data construction and capturing the personality experiences, knowledge, and thoughts more comprehensively. For rigid behavior patterns, we design the tuning process and introduce automated DPO to enhance the specificity and dynamism of the models' personalities, which leads to a more natural opinion communication. Both automated metrics and expert human evaluations demonstrate the effectiveness of our approach. Case studies in human-machine interactions and multi-agent systems further suggest potential application scenarios and future directions for LLM personification.

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Cited by top-tier papers1

  1. Aligning Deep Implicit Preferences by Learning to Reason DefensivelyPeiming Li, Zhiyuan Hu, Shiyu Li, Xi Chen et al.ICLR 2026

Builds on13

  1. Language Models are Few-Shot LearnersTom B. Brown, Benjamin Mann, Nick Ryder, Melanie Subbiah et al.NeurIPS 2020 · 64,255 citations
  2. Direct Preference Optimization: Your Language Model is Secretly a Reward ModelRafael Rafailov, Archit Sharma, Eric Mitchell, Christopher D. Manning et al.NeurIPS 2023 · 10,924 citations
  3. Benchmarking Large Language Models in Retrieval-Augmented GenerationJiawei Chen, Hongyu Lin, Xianpei Han, Le SunAAAI 2024 · 531 citations
  4. Large Dual Encoders Are Generalizable RetrieversJianmo Ni, Chen Qu, Jing Lu, Zhuyun Dai et al.EMNLP 2022 · 145 citations
  5. RoleLLM: Benchmarking, Eliciting, and Enhancing Role-Playing Abilities of Large Language ModelsNoah Wang, Zhongyuan Peng, Haoran Que, Jiaheng Liu et al.ACL Findings 2024 · 120 citations

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