arXiv Computation and Language By Karl Li

Sparse Autoencoder Attribution Graphs Are Decided at the Margin

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The paper investigates attribution graphs for sparse autoencoders (SAEs) by examining how zeroing a feature affects subsequent layer activations. It shows that in TopK SAEs, removing a feature often causes another feature to cross the activation cutoff, and these crossings account for most of the response’s energy. The authors demonstrate that a margin‑based graph, which adds first‑order changes to preactivations, achieves low error (≤0.033) while accurately capturing the impact of feature ablations.

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arXiv AI
Oct 16

Representation Redistribution in Sparse Autoencoders

The paper introduces the Redistribution Sensitivity Score (RSS) to detect consistent changes in sparse feature activations of Sparse Autoencoders (SAEs) when prompts are transformed. RSS identifies large, directionally consistent feature responses and evaluates their impact on downstream readouts across 27 pretrained SAEs from eight language models. Experiments show that combining RSS support erosion with the clean margin predicts recurrent safety readout failures with high AUROC, demonstrating RSS’s utility in quantifying representation changes without conflating them with failure.

By Ziye Mei, Haotian Ma