通过分析输入微小变化下的损失曲面,检测大模型遗忘数据后的残留记忆。
REMIND: Input Loss Landscapes Reveal Residual Memorization in Post-Unlearning LLMs
- 基于输入扰动的损失曲面分析,捕捉单点评估忽略的隐性记忆
- 遗忘数据对应的损失曲面更平坦,而保留数据则更尖锐多变
- 仅需查询访问,适用于多种模型与改写输入,适合实际部署
机器遗忘旨在不重新训练的情况下移除特定训练数据对模型的影响,这对保障隐私、安全和合规至关重要。因此,验证模型是否真正遗忘目标数据对可靠性与可信度极为关键。然而,现有评估方法通常在单个输入层面进行,可能忽略语义相似样本中的残留影响,从而导致隐私泄露。本文提出REMIND(Residual Memorization In Neighborhood Dynamics),一种新评估方法,用于检测未完全遗忘数据的细微残留影响,并判断其是否有效遗忘。REMIND分析模型在小范围输入变化下的损失变化,揭示单点评估无法察觉的模式:被遗忘数据对应更平坦、较缓的损失曲面,而保留或无关数据则呈现更尖锐、波动更大的特征。该方法仅需查询访问,性能优于同类约束下的现有方法,在不同模型、数据集及改写输入下均表现稳健,具备实际部署潜力。通过提供更敏感且可解释的遗忘效果度量,REMIND为语言模型的遗忘评估提供了可靠框架,为理解记忆与遗忘机制带来新视角。
原文摘要 · Abstract (English)
Machine unlearning aims to remove the influence of specific training data from a model without requiring full retraining. This capability is crucial for ensuring privacy, safety, and regulatory compliance. Therefore, verifying whether a model has truly forgotten target data is essential for maintaining reliability and trustworthiness. However, existing evaluation methods often assess forgetting at the level of individual inputs. This approach may overlook residual influence present in semantically similar examples. Such influence can compromise privacy and lead to indirect information leakage. We propose REMIND (Residual Memorization In Neighborhood Dynamics), a novel evaluation method aiming to detect the subtle remaining influence of unlearned data and classify whether the data has been effectively forgotten. REMIND analyzes the model's loss over small input variations and reveals patterns unnoticed by single-point evaluations. We show that unlearned data yield flatter, less steep loss landscapes, while retained or unrelated data exhibit sharper, more volatile patterns. REMIND requires only query-based access, outperforms existing methods under similar constraints, and demonstrates robustness across different models, datasets, and paraphrased inputs, making it practical for real-world deployment. By providing a more sensitive and interpretable measure of unlearning effectiveness, REMIND provides a reliable framework to assess unlearning in language models. As a result, REMIND offers a novel perspective on memorization and unlearning.
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