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Main Authors: Eshuijs, Leon, Wang, Shihan, Fokkens, Antske
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2604.12500
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author Eshuijs, Leon
Wang, Shihan
Fokkens, Antske
author_facet Eshuijs, Leon
Wang, Shihan
Fokkens, Antske
contents Specification gaming under Reinforcement Learning (RL) is known to cause LLMs to develop sycophantic, manipulative, or deceptive behavior, yet the conditions under which this occurs remain unclear. We train 11 instruction-tuned LLMs (0.5B--14B) with on-policy RL across 3 environments and find that model size acts as a safety buffer in some environments but enables greater harmful exploitation in others. Controlled ablations trace this reversal to environment-specific features such as role framing and implicit gameability cues. We further show that most safety benchmarks do not predict RL-induced misalignment, except in the case of Sycophancy scores when the exploit relies on inferring the user's preference. Finally, we find that on-policy RL preserves a safety buffer inherent in the model's own generation distribution, one that is bypassed during off-policy settings.
format Preprint
id arxiv_https___arxiv_org_abs_2604_12500
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Safety Training Modulates Harmful Misalignment Under On-Policy RL, But Direction Depends on Environment Design
Eshuijs, Leon
Wang, Shihan
Fokkens, Antske
Machine Learning
Cryptography and Security
Specification gaming under Reinforcement Learning (RL) is known to cause LLMs to develop sycophantic, manipulative, or deceptive behavior, yet the conditions under which this occurs remain unclear. We train 11 instruction-tuned LLMs (0.5B--14B) with on-policy RL across 3 environments and find that model size acts as a safety buffer in some environments but enables greater harmful exploitation in others. Controlled ablations trace this reversal to environment-specific features such as role framing and implicit gameability cues. We further show that most safety benchmarks do not predict RL-induced misalignment, except in the case of Sycophancy scores when the exploit relies on inferring the user's preference. Finally, we find that on-policy RL preserves a safety buffer inherent in the model's own generation distribution, one that is bypassed during off-policy settings.
title Safety Training Modulates Harmful Misalignment Under On-Policy RL, But Direction Depends on Environment Design
topic Machine Learning
Cryptography and Security
url https://arxiv.org/abs/2604.12500