New paper: high linear probe accuracy doesn't prove a linear representation — three diagnostics proposed

soniajoseph_ · x · 2026-11-03

A new arXiv paper challenges the standard mech interp methodology of equating high linear probe accuracy with linear representations: asymptotically any rich feature map, even random, admits a linear readout. The authors propose three asymmetric diagnostics — reverse predictivity, spectral concentration, and OOD generalization — to distinguish true linear world models from kernel machines. Applied to vision transformers, pretraining shows structure beyond a random kernel but well short of a linear world model. Author David Klindt also found DINOv3's global [CLS] token linearly represents continuous geometric latents of dSprites.

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