Probes Detect the Instruction, Not the Concealment: A Control-Task Audit of Secret Loyalty Probing
Andrew Ngo · Team Azza
Submitted to Secret Loyalties Hackathon. Sprint projects are early-stage work by participants, not Apart Research publications.
Secret loyalties are installed in models to quietly favour a principal while appearing normal. Lamerton and Roger (2026) found that black-box audits mostly fail on narrow loyalties and suggested that white-box evaluations may be more effective. This study installs secret loyalties through a system instruction, LoRA distillation into weights and two externally released organisms. Black-box audits and white-box probing are performed on a secretly loyal model on 100 binary scenarios between the principal and a competitor. This study finds that eight linear and two non-linear probe families separate a loyalty-instructed model from a neutral one at AUROC 1.000 whether the instruction tells the model to conceal or to disclose the loyalty. It is tested whether the design is capable of failing. A probe trained to separate two paraphrases of the same instruction, inseparable by construction, also reaches 1.000, and a random direction fitted to no data reaches 0.941 at its best layer and 0.738 at the probe’s best layer, so layer selection alone is worth +0.203 AUROC. These AUROCs are therefore reported as uninformative rather than as successes, and give a framework for checking that an interpretability test can fail. This study argues that the secret loyalties field lacks tools designed to identify activation triggers rather than detecting secretly loyal behaviour.
Reviews
The core point here is simple once you see it: a test that scores perfectly at telling a biased model apart from a normal one isn't necessarily finding anything real, if it ALSO scores perfectly at telling apart two versions of literally the exact same instruction — something that should be impossible to tell apart. You proved your own test can't fail, even when you feed it random nonsense it should fail on. So the perfect score means nothing. That's a genuinely useful sanity check a lot of this kind of research skips, and the checklist you built for catching this problem is the kind of thing other teams should actually use.
The side-finding is arguably as interesting as the headline: small models given an instruction they're too dumb to actually follow don't just fail randomly — they quietly swap in a simpler rule they CAN follow, and that trick disappears once the model gets smart enough to follow the real instruction. That's a real, testable claim about how a model's capability affects whether a planted secret instruction actually works as intended.
Where I'd push: what you've built here is 'here's how to check if your test is broken,' not 'here's how to catch a secret loyalty.' Fine and valuable thing to submit, just worth being upfront that it's about fixing the testing method, not about actually catching anyone.
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Cite this project
@misc{ngo2026probes,
title = {{Probes Detect the Instruction, Not the Concealment: A Control-Task Audit of Secret Loyalty Probing}},
author = {Andrew Ngo},
year = {2026},
month = jul,
note = {Submitted to Secret Loyalties Hackathon, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/probes-detect-the-instruction-not-the-concealment-a-controltask-audit-of-secret-loyalty-probing-brne}},
url = {https://apartresearch.com/sprints/projects/probes-detect-the-instruction-not-the-concealment-a-controltask-audit-of-secret-loyalty-probing-brne}
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