通过集成多个稀疏自编码器,提升语言模型激活的重构精度与稳定性。
Ensembling Sparse Autoencoders
- 用不同初始化训练多个稀疏自编码器并集成,降低重建误差。
- 集成后在概念检测和虚假相关性消除任务中表现优于单个扩展模型。
- 适合需要高精度特征解释的下游任务,如可解释性分析与模型调试。
稀疏自编码器(SAEs)用于将神经网络激活分解为人类可理解的特征。通常仅使用单个SAE学习到的特征进行下游应用。然而,近期研究发现单个SAE仅能捕获激活空间中有限的一小部分特征。为此,本文提出并形式化了SAE集成方法,分别采用朴素袋装法(naive bagging)和提升法(boosting)。袋装法通过不同权重初始化训练多个SAE并集成;提升法则依次训练以最小化残差误差的SAE并集成。理论上,两种方法均能有效降低重建误差。实验在三种语言模型及SAE架构设置下验证,结果表明:相比特征数相同的扩展单个SAE,SAE集成在激活重构精度与模型稳定性上均有提升;在概念检测、虚假相关性消除等下游任务中也表现更优,展现出更强实用性。
原文摘要 · Abstract (English)
Sparse autoencoders (SAEs) are used to decompose neural network activations into human-interpretable features. Typically, features learned by a single SAE are used for downstream applications. However, it has recently been shown that a single SAE captures only a limited subset of features that can be extracted from the activation space. Motivated by this limitation, we introduce and formalize SAE ensembles. Furthermore, we propose to ensemble multiple SAEs through naive bagging and boosting. In naive bagging, SAEs trained with different weight initializations are ensembled, whereas in boosting SAEs sequentially trained to minimize the residual error are ensembled. Theoretically, naive bagging and boosting are justified as approaches to reduce reconstruction error. Empirically, we evaluate our ensemble approaches with three settings of language models and SAE architectures. Our empirical results demonstrate that, compared to an expanded SAE that matches the number of features in the ensemble, ensembling SAEs improves the reconstruction of language model activations along with SAE stability. Additionally, on downstream tasks such as concept detection and spurious correlation removal, SAE ensembles achieve better performance, showing improved practical utility.
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