Beyond Isolated Behaviors: Hierarchical User Modeling for LLM Personalization

2026-06-01

AI Summary

This work addresses the limitation of existing large language model (LLM) personalization approaches, which typically employ flat behavioral modeling and overlook the underlying structural complexity of user behavior. To overcome this, the study introduces Bourdieu’s theory of practice into LLM personalization for the first time, proposing the PHF framework that hierarchically models user behavior through three interrelated dimensions: practice, habitus, and field. This enables more structured and interpretable personalization. The framework implements a lightweight, model-agnostic PHF_Compass module that learns hierarchical behavioral representations while keeping the base LLM frozen. Evaluated on the LaMP benchmark, PHF consistently enhances performance across multiple tasks, demonstrating both the generalizability and interpretability of the learned behavioral structures.

Abstract

Large Language Models (LLMs) have demonstrated remarkable capabilities across diverse domains, yet personalizing their outputs to individual users remains an open challenge. Existing approaches predominantly adopt a flat behavioral paradigm, aggregating user behaviors without an explicit account of how they are organized into deeper behavioral structures. In this work, we draw on Pierre Bourdieu's Theory of Practice to propose PHF (Practice-Habitus-Field), a sociologically grounded framework that reconceptualizes LLM personalization through three hierarchical levels: individual behaviors as practices, their temporal accumulation into stable dispositions as habitus, and shared regularities across similar users as fields. We instantiate PHF through $\mathrm{PHF}_{\text{Compass}}$, a lightweight and model-agnostic implementation based on a frozen LLM. Experiments on the Language Model Personalization (LaMP) benchmark demonstrate consistent improvements across diverse tasks, while further analyses validate the interpretability and extensibility of the learned behavioral structures.

Problem

• LLM personalization
• user modeling
• behavioral structures
• hierarchical modeling
• personalization

Innovation

• hierarchical user modeling
• LLM personalization
• Bourdieu's Theory of Practice
• habitus
• model-agnostic framework