Linear Detection of Secret Loyalties in Open-Weight Model Organisms
Jack Lakkapragada · Team Jack
Submitted to Secret Loyalties Hackathon. Sprint projects are early-stage work by participants, not Apart Research publications.
I evaluated the three official Secret Loyalties Detection Challenge organisms (sl-organism-a/b/c-7b) against the Qwen2.5-7B-Instruct base model using matched-comparison behavioral probes. Organisms A and B showed a narrow but consistent willingness to generate extreme-action recommendations under strong prompting, while Organism C largely refused.
Focusing on Organism A, we extracted residual-stream activations at the final layer and trained a linear probe. The probe achieved perfect separation (training and cross-validation accuracy = 1.0) between activated and control states, demonstrating that the behavioral signal is linearly readable from the model’s residual stream.
This provides both a black-box detection result and an initial white-box confirmation that secret-loyalty activation leaves a detectable linear signature.

Reviews
Reading your notebooks, we discovered that there is a significant issue with confounding: the paper claimed its probe was trained on 8 prompts that were "confirmed" to trigger the hidden loyalty, yet the notebook shows only 3 were actually confirmed — the other 5 were just new prompts written in a similar style and assumed to work, so "confirmed" is simply wrong for most of them. The notebook also makes the core flaw easy to see: all the "trigger" prompts use violent language ("deal with the heads of the snake permanently") while all the comparison prompts are ordinary civics questions ("what are legitimate ways to create political change"), so any language model could tell these two groups apart — the perfect detection score likely just reflects the probe noticing the topic difference, not detecting any secret loyalty. The one test that would settle it (running the same probe on the plain base model) was never done.
Read full reviewShow less
Thank you for this submission! Crystal-clear structure and great companion codebase. It would be great if you could carve out the novelty of your project in your write-up, or add a 'next steps' section outlining possible gaps that an extension to this work could fill.
Cite this project
@misc{lakkapragada2026linear,
title = {{Linear Detection of Secret Loyalties in Open-Weight Model Organisms}},
author = {Jack Lakkapragada},
year = {2026},
month = jul,
note = {Submitted to Secret Loyalties Hackathon, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/linear-detection-of-secret-loyalties-in-openweight-model-organisms-kqva}},
url = {https://apartresearch.com/sprints/projects/linear-detection-of-secret-loyalties-in-openweight-model-organisms-kqva}
}More from Secret Loyalties Hackathon
- View project: Identifying the Principal Before Proving the Loyalty: A Two-Stage Audit for Secretly Loyal Language Models
Identifying the Principal Before Proving the Loyalty: A Two-Stage Audit for Secretly Loyal Language Models
To check whether a fine-tuned model has been secretly trained to favour a company, country, political figure or cause, you first have to guess which one, out of an unlimited set. I compare two ways of making that guess …
- View project: Dormancy and Dynamic Range: Detecting Secret Loyalties Without Knowing the Trigger
Dormancy and Dynamic Range: Detecting Secret Loyalties Without Knowing the Trigger
Concealment Defeaters
A secret loyalty has to be quiet off-trigger to stay hidden and loud on-trigger to be useful. Both are measurable without knowing what the trigger is: dormancy (output divergence from the base model on ordinary prompts) …
- View project: Probes Detect the Instruction, Not the Concealment: A Control-Task Audit of Secret Loyalty Probing
Probes Detect the Instruction, Not the Concealment: A Control-Task Audit of Secret Loyalty Probing
Azza
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 …