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Main Authors: Ma, Yiming, Wang, Lixu, Wang, Lionel Z., Yang, Hongkun, Sun, Haoming, Xu, Xin, Wu, Jiaqi, Chen, Bin, Dong, Wei
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.01558
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author Ma, Yiming
Wang, Lixu
Wang, Lionel Z.
Yang, Hongkun
Sun, Haoming
Xu, Xin
Wu, Jiaqi
Chen, Bin
Dong, Wei
author_facet Ma, Yiming
Wang, Lixu
Wang, Lionel Z.
Yang, Hongkun
Sun, Haoming
Xu, Xin
Wu, Jiaqi
Chen, Bin
Dong, Wei
contents Long-term memory mechanisms enable Large Language Models (LLMs) to maintain continuity and personalization across extended interaction lifecycles, but they also introduce new and underexplored risks related to fairness. In this work, we study how implicit bias, defined as subtle statistical prejudice, accumulates and propagates within LLMs equipped with long-term memory. To support systematic analysis, we introduce the Decision-based Implicit Bias (DIB) Benchmark, a large-scale dataset comprising 3,776 decision-making scenarios across nine social domains, designed to quantify implicit bias in long-term decision processes. Using a realistic long-horizon simulation framework, we evaluate six state-of-the-art LLMs integrated with three representative memory architectures on DIB and demonstrate that LLMs' implicit bias does not remain static but intensifies over time and propagates across unrelated domains. We further analyze mitigation strategies and show that a static system-level prompting baseline provides limited and short-lived debiasing effects. To address this limitation, we propose Dynamic Memory Tagging (DMT), an agentic intervention that enforces fairness constraints at memory write time. Extensive experimental results show that DMT substantially reduces bias accumulation and effectively curtails cross-domain bias propagation.
format Preprint
id arxiv_https___arxiv_org_abs_2602_01558
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle How Implicit Bias Accumulates and Propagates in LLM Long-term Memory
Ma, Yiming
Wang, Lixu
Wang, Lionel Z.
Yang, Hongkun
Sun, Haoming
Xu, Xin
Wu, Jiaqi
Chen, Bin
Dong, Wei
Machine Learning
Long-term memory mechanisms enable Large Language Models (LLMs) to maintain continuity and personalization across extended interaction lifecycles, but they also introduce new and underexplored risks related to fairness. In this work, we study how implicit bias, defined as subtle statistical prejudice, accumulates and propagates within LLMs equipped with long-term memory. To support systematic analysis, we introduce the Decision-based Implicit Bias (DIB) Benchmark, a large-scale dataset comprising 3,776 decision-making scenarios across nine social domains, designed to quantify implicit bias in long-term decision processes. Using a realistic long-horizon simulation framework, we evaluate six state-of-the-art LLMs integrated with three representative memory architectures on DIB and demonstrate that LLMs' implicit bias does not remain static but intensifies over time and propagates across unrelated domains. We further analyze mitigation strategies and show that a static system-level prompting baseline provides limited and short-lived debiasing effects. To address this limitation, we propose Dynamic Memory Tagging (DMT), an agentic intervention that enforces fairness constraints at memory write time. Extensive experimental results show that DMT substantially reduces bias accumulation and effectively curtails cross-domain bias propagation.
title How Implicit Bias Accumulates and Propagates in LLM Long-term Memory
topic Machine Learning
url https://arxiv.org/abs/2602.01558