arXiv Machine Learning By Zhuofan Josh Ying, Peter Hase, Nikolaus Kriegeskorte

Comparing Linear Probes with Mahalanobis Cosine Similarity

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arXiv:2606. 19603v1 Announce Type: new Abstract: Linear probes are widely used in interpretability research and often compared by cosine similarity.

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arXiv Machine Learning
Sep 22

Whitening Inverts the Hierarchy: What the Norm of a Whitened Embedding Measures

The paper investigates the use of the squared norm of a whitened foundation‑model embedding as a training‑free likelihood surrogate. It shows that the apparent Gaussianity of whitened coordinates stems from the projection central limit theorem, not from a true joint Gaussian distribution, and that the norm is systematically over‑dispersed compared to a Gaussian reference. The authors explain that whitening reverses the encoder’s spectral hierarchy, concentrating norm contributions in near‑degenerate directions dominated by noise, and propose interpreting the squared norm as a Mahalanobis measure of semantic atypicality rather than a log‑likelihood.

By Mohammed Ahnouch, Lotfi Elaachak