Why safety-aligned models refuse harmless questions: the refusal gradient is imbalanced
AspireAI community · arXiv
Over-refusal - rejecting safe prompts that superficially look risky - is a live cost of safety alignment, and this paper explains it mechanically. Two observations drive the explanation: the representations of harmful and over-refusal samples are visibly separable at some intermediate layers but overlap more in deeper layers, and harmful-sample gradients have high intra-class similarity and concentrate in a low-rank subspace. Those harmful gradients also align more strongly with refusal-target gradients than with correct helpful-target gradients on over-refusal prompts. That imbalanced coupling biases over-refusal samples toward refusal, while the reduced representational separation deeper in the network makes the boundary harder to maintain. GOAL (Gradient Orthogonalization with contrAstive Learning) acts on both halves - orthogonalizing over-refusal gradients against the refusal subspace extracted from harmful gradients, and adding a contrastive objective to pull the two representations apart. The authors report mitigation without giving up safety performance or general capability.
Read the story and explore more from the AspireAI community.
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.