Parametric Social Identity Injection and Diversification in Public Opinion Simulation

Fuente: arXiv
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Auteurs principaux: Wang, Hexi, Zhou, Yujia, Du, Bangde, Ai, Qingyao, Liu, Yiqun
Format: Preprint
Publié: 2026
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author Wang, Hexi
Zhou, Yujia
Du, Bangde
Ai, Qingyao
Liu, Yiqun
author_facet Wang, Hexi
Zhou, Yujia
Du, Bangde
Ai, Qingyao
Liu, Yiqun
contents Large language models (LLMs) have recently been adopted as synthetic agents for public opinion simulation, offering a promising alternative to costly and slow human surveys. Despite their scalability, current LLM-based simulation methods fail to capture social diversity, producing flattened inter-group differences and overly homogeneous responses across demographic groups. We identify this limitation as a Diversity Collapse phenomenon in LLM hidden representations, where distinct social identities become increasingly indistinguishable across layers. Motivated by this observation, we propose Parametric Social Identity Injection (PSII), a general framework that injects explicit, parametric representations of demographic attributes and value orientations directly into intermediate hidden states of LLMs. Unlike prompt-based persona conditioning, PSII enables fine-grained and controllable identity modulation at the representation level. Extensive experiments on the World Values Survey using multiple open-source LLMs show that PSII significantly improves distributional fidelity and diversity, reducing KL divergence to real-world survey data while enhancing overall diversity. This work provides new insights into representation-level control of LLM agents and advances scalable, diversity-aware public opinion simulation.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16142
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Parametric Social Identity Injection and Diversification in Public Opinion Simulation
Wang, Hexi
Zhou, Yujia
Du, Bangde
Ai, Qingyao
Liu, Yiqun
Computation and Language
68T50
I.2.7
Large language models (LLMs) have recently been adopted as synthetic agents for public opinion simulation, offering a promising alternative to costly and slow human surveys. Despite their scalability, current LLM-based simulation methods fail to capture social diversity, producing flattened inter-group differences and overly homogeneous responses across demographic groups. We identify this limitation as a Diversity Collapse phenomenon in LLM hidden representations, where distinct social identities become increasingly indistinguishable across layers. Motivated by this observation, we propose Parametric Social Identity Injection (PSII), a general framework that injects explicit, parametric representations of demographic attributes and value orientations directly into intermediate hidden states of LLMs. Unlike prompt-based persona conditioning, PSII enables fine-grained and controllable identity modulation at the representation level. Extensive experiments on the World Values Survey using multiple open-source LLMs show that PSII significantly improves distributional fidelity and diversity, reducing KL divergence to real-world survey data while enhancing overall diversity. This work provides new insights into representation-level control of LLM agents and advances scalable, diversity-aware public opinion simulation.
title Parametric Social Identity Injection and Diversification in Public Opinion Simulation
topic Computation and Language
68T50
I.2.7
url https://arxiv.org/abs/2603.16142