The Memory Curse: How Expanded Recall Erodes Cooperative Intent in LLM Agents

Fuente: arXiv
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Auteurs principaux: Liu, Jiayuan, Li, Tianqin, Du, Shiyi, Luo, Xin, Zeng, Haoxuan, Tewolde, Emanuel, Lee, Tai Sing, Wang, Tonghan, Kingsford, Carl, Conitzer, Vincent
Format: Preprint
Publié: 2026
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author Liu, Jiayuan
Li, Tianqin
Du, Shiyi
Luo, Xin
Zeng, Haoxuan
Tewolde, Emanuel
Lee, Tai Sing
Wang, Tonghan
Kingsford, Carl
Conitzer, Vincent
author_facet Liu, Jiayuan
Li, Tianqin
Du, Shiyi
Luo, Xin
Zeng, Haoxuan
Tewolde, Emanuel
Lee, Tai Sing
Wang, Tonghan
Kingsford, Carl
Conitzer, Vincent
contents Context window expansion is often treated as a straightforward capability upgrade for LLMs, but we find it systematically fails in multi-agent social dilemmas. Across 7 LLMs and 4 games over 500 rounds, expanding accessible history degrades cooperation in 18 of 28 model--game settings, a pattern we term the memory curse. We isolate the underlying mechanism through three analyses. First, lexical analysis of 378,000 reasoning traces associates this breakdown with eroding forward-looking intent rather than rising paranoia. We validate this using targeted fine-tuning as a cognitive probe: a LoRA adapter trained exclusively on forward-looking traces mitigates the decay and transfers zero-shot to distinct games. Second, memory sanitization holds prompt length fixed while replacing visible history with synthetic cooperative records, which restores cooperation substantially, proving the trigger is memory content, not length alone. Finally, ablating explicit Chain-of-Thought reasoning often reduces the collapse, showing that deliberation paradoxically amplifies the memory curse. Together, these results recast memory as an active determinant of multi-agent behavior: longer recall can either destabilize or support cooperation depending on the reasoning patterns it elicits.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08060
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Memory Curse: How Expanded Recall Erodes Cooperative Intent in LLM Agents
Liu, Jiayuan
Li, Tianqin
Du, Shiyi
Luo, Xin
Zeng, Haoxuan
Tewolde, Emanuel
Lee, Tai Sing
Wang, Tonghan
Kingsford, Carl
Conitzer, Vincent
Computation and Language
Artificial Intelligence
Computer Science and Game Theory
Multiagent Systems
Context window expansion is often treated as a straightforward capability upgrade for LLMs, but we find it systematically fails in multi-agent social dilemmas. Across 7 LLMs and 4 games over 500 rounds, expanding accessible history degrades cooperation in 18 of 28 model--game settings, a pattern we term the memory curse. We isolate the underlying mechanism through three analyses. First, lexical analysis of 378,000 reasoning traces associates this breakdown with eroding forward-looking intent rather than rising paranoia. We validate this using targeted fine-tuning as a cognitive probe: a LoRA adapter trained exclusively on forward-looking traces mitigates the decay and transfers zero-shot to distinct games. Second, memory sanitization holds prompt length fixed while replacing visible history with synthetic cooperative records, which restores cooperation substantially, proving the trigger is memory content, not length alone. Finally, ablating explicit Chain-of-Thought reasoning often reduces the collapse, showing that deliberation paradoxically amplifies the memory curse. Together, these results recast memory as an active determinant of multi-agent behavior: longer recall can either destabilize or support cooperation depending on the reasoning patterns it elicits.
title The Memory Curse: How Expanded Recall Erodes Cooperative Intent in LLM Agents
topic Computation and Language
Artificial Intelligence
Computer Science and Game Theory
Multiagent Systems
url https://arxiv.org/abs/2605.08060