Back to library
Spring 2026 Submitted May 2026

Misalignment Lens: Anticipating Misalignment from a Single Hidden State

Nghia Nim

Mentored by Shivam Raval

Working report from the SPAR program. May not reflect the authors' current views.

Abstract

We train linear probes on the residual stream of Llama-3.2-1B-Instruct-abliterated to predict, from the activation at token t, the label of token t+k for three misalignment behaviors: instrumental deception, sandbagging, and manipulation. Across all three, the strongest per-token probe sits in a narrow mid-stack band (layers 7–13 of 17) several tokens before the offending token is emitted. The three probe directions are pairwise near-orthogonal (cosine similarity at the random-direction noise floor, +0.018 to +0.023), so the band hosts co-located linear decoders rather than a shared misalignment feature. A two-layer MLP at the same cells matches the linear probe to within |∆| ≤ 0.012 ROC-AUC across eight (behavior, offset) cells, confirming the representation is linearly accessible. Multi-seed reruns show the band claim is robust, but the specific best-layer winner is only seed-stable for deception (L9, 4/5 seeds). A held-out leave-one-category evaluation on deception gives mean ROC 0.713 at L9 across five conditions, evidencing that the L9 direction represents deception broadly rather than a category-specific lexical feature. A rollout-level deployment experiment is the load-bearing negative result: the within-hack probe achieves 70% catch on committed-hack rollouts at a mean lead of 32 tokens, but also flags 100% of honest rollouts at the same threshold. Within-class probes do not aggregate into a deployment-time cross-class detector without further training.