Detecting Proxy Gaming in RL and LLM Alignment via Evaluator Stress Tests

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Autori principali: Shihab, Ibne Farabi, Akter, Sanjeda, Sharma, Anuj
Natura: Preprint
Pubblicazione: 2025
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author Shihab, Ibne Farabi
Akter, Sanjeda
Sharma, Anuj
author_facet Shihab, Ibne Farabi
Akter, Sanjeda
Sharma, Anuj
contents Proxy optimization, where AI systems exploit evaluator weaknesses rather than improve intended objectives, threatens both reinforcement learning (reward hacking) and LLM alignment (evaluator gaming). We introduce the Evaluator Stress Test (EST), an invariance-based framework that detects proxy gaming by separating exploitable sensitivity (e.g., formatting artifacts, physics bugs) from content-driven improvements using controlled perturbations with semantic validity audits. We validate EST across both domains. In RL, across 15 environments and 5 algorithms (2,156 expert-annotated episodes), EST achieves 78.4% precision and 81.7% recall. In LLM alignment, across 4 tasks, 2 model scales, 2 training methods, and 2 judges (1,200 human-annotated instances), EST achieves 74.2% precision and 78.6% recall, with early warning signals that precede quality decline. Cross-domain analysis shows that proxy-true correlation tracking transfers directly between domains, while perturbation design requires domain adaptation. Closed-loop mitigation improves human win-rate by 8.3 points (LLM) and reduces hacking by 54.6% (RL). We release benchmarks for both domains: 2,156 RL episodes and 1,200 LLM instances.
format Preprint
id arxiv_https___arxiv_org_abs_2507_05619
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Detecting Proxy Gaming in RL and LLM Alignment via Evaluator Stress Tests
Shihab, Ibne Farabi
Akter, Sanjeda
Sharma, Anuj
Machine Learning
Software Engineering
Proxy optimization, where AI systems exploit evaluator weaknesses rather than improve intended objectives, threatens both reinforcement learning (reward hacking) and LLM alignment (evaluator gaming). We introduce the Evaluator Stress Test (EST), an invariance-based framework that detects proxy gaming by separating exploitable sensitivity (e.g., formatting artifacts, physics bugs) from content-driven improvements using controlled perturbations with semantic validity audits. We validate EST across both domains. In RL, across 15 environments and 5 algorithms (2,156 expert-annotated episodes), EST achieves 78.4% precision and 81.7% recall. In LLM alignment, across 4 tasks, 2 model scales, 2 training methods, and 2 judges (1,200 human-annotated instances), EST achieves 74.2% precision and 78.6% recall, with early warning signals that precede quality decline. Cross-domain analysis shows that proxy-true correlation tracking transfers directly between domains, while perturbation design requires domain adaptation. Closed-loop mitigation improves human win-rate by 8.3 points (LLM) and reduces hacking by 54.6% (RL). We release benchmarks for both domains: 2,156 RL episodes and 1,200 LLM instances.
title Detecting Proxy Gaming in RL and LLM Alignment via Evaluator Stress Tests
topic Machine Learning
Software Engineering
url https://arxiv.org/abs/2507.05619