Looking the Other Way: Levers of Collusion in LLM Peer Review
Tanweerul Haque · Team AI_is_not_safe
Submitted to AI Collusion Research Sprint. Sprint projects are early-stage work by participants, not Apart Research publications.
When two LLM agents must verify each other's work under a rule they cannot meet, they often accept it anyway. We test eight levers on the joint-task game of Shi et al. (2026), across five model pairs, 198 trajectories and 1,852 episodes. The choice of model matters most: collusion ranges from 0% of episodes (Claude Haiku 5.5) to 85% (DeepSeek). A penalty for wrong verdicts leaves collusion unchanged at 25 trajectories per arm. Private forecasts, difficulty labels and sequential verdicts reduce collusion only by making agents reject correct work. Letting the full log through, with a paid restore or a per-character message price, cuts unsupported acceptance from 33% to 2–8% without lowering accuracy. Most levers ran for five trajectories, so these effects need confirming at larger scale.
Reviews
The project explores how different levers affect collusion between LLM agents in a peer review setting, where the rule is to accept only if the complete log of work is provided but the channel capacity limits this. It tests eight levers across five model pairs and finds that the choice of models heavily influences collusion rates, with some models never accepting and others colluding frequently. The study also shows that letting evidence through at a price reduces unsupported acceptance without harming accuracy.
The main weakness lies in the small sample sizes for most levers, which limits confidence in the results. Most levers were tested on only five trajectories, and some conditions had even fewer data points due to early termination. This makes it hard to generalize findings or conclude with strong certainty about their effectiveness across different scenarios or model pairs.
To improve, I'd suggest running more extensive tests for each lever, especially those that showed promising results like the paid restore and message pricing. Additionally, exploring how these levers perform under varying conditions of task difficulty or model pairings could provide a richer understanding of their robustness. This work has potential to inform better oversight protocols in LLM-based systems but needs more rigorous validation.
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Cite this project
@misc{haque2026looking,
title = {{Looking the Other Way: Levers of Collusion in LLM Peer Review}},
author = {Tanweerul Haque},
year = {2026},
month = oct,
note = {Submitted to AI Collusion Research Sprint, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/looking-the-other-way-levers-of-collusion-in-llm-peer-review-lck8}},
url = {https://apartresearch.com/sprints/projects/looking-the-other-way-levers-of-collusion-in-llm-peer-review-lck8}
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