arXiv:2503.05684cs.LGcs.CV2025-03被引 1

提出四种无需敏感属性标签的公平性增强微调方法,提升模型公正性。

Fairness-Aware Low-Rank Representation Fine-Tuning

  • 基于正交解耦与熵最大化设计公平性增强策略
  • 正交解耦和熵最大化在公平性与性能上均优于标准微调
  • 适用于隐私受限场景下的高效模型优化

预训练基础模型可通过低秩适应(LoRA)高效适配特定任务,但其适配后分类器的公平性仍缺乏研究。现有公平性微调方法依赖敏感属性标签,但在实际中常因用户同意或隐私限制而不可用。为此,本文研究使用独立数据集进行下游任务与敏感属性学习的公平性感知LoRA微调。提出四种方法:敏感属性遗忘、对抗去偏、基于正交性的解耦与熵最大化。在基于ImageNet预训练的ViT-Base模型上,于标准算法公平性数据集上评估多种效用与公平性指标。正交解耦与熵最大化方法在整体效用和公平性上持续优于标准微调,对抗去偏表现不一致,敏感属性遗忘对分类无效。但部分指标如子群体假阳性率比仍表现不佳,揭示公平目标间的内在冲突。结果表明,公平性感知LoRA具有潜力,但也暴露了在参数高效适配中同时优化多重公平性准则的根本挑战。

原文摘要 · Abstract (English)

Pre-trained foundation models can be efficiently adapted for specific tasks using Low-Rank Adaptation (LoRA), but the fairness properties of these adapted classifiers remain underexplored. Existing fairness-aware fine-tuning methods assume that sensitive attribute labels are available alongside downstream task labels, which often fails in practice due to user consent limitations or privacy constraints. To address this gap, we investigate fairness-aware LoRA fine-tuning using separate datasets for downstream tasks and sensitive attributes. We introduce four fairness-aware LoRA strategies: sensitive unlearning, adversarial debiasing, orthogonality-based disentanglement, and entropy maximization. Through comprehensive experiments on standard algorithmic fairness datasets using an ImageNet pre-trained ViT-Base model, we evaluate these methods across multiple utility and fairness metrics. Our orthogonality-based disentanglement and entropy maximization approaches consistently outperform standard fine-tuning in both overall utility and fairness, while adversarial debiasing shows less consistent improvements and sensitive unlearning proves ineffective for classification tasks. However, fairness-aware methods underperform on certain metrics like subgroup-wise false-positive rate ratios, highlighting fundamental incompatibilities between fairness objectives. These findings demonstrate the potential of fairness-aware LoRA fine-tuning while revealing inherent challenges of simultaneously optimizing multiple fairness criteria in parameter-efficient adaptation.

公平性LoRA去偏微调

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