Auditing Collusion in AI Co-Scientists
Mywish Anand · Team Epistemic Cartel
Submitted to AI Collusion Research Sprint. Sprint projects are early-stage work by participants, not Apart Research publications.
Automated AI Co-Scientist frameworks, such as Google's AI Co-Scientist and Sakana AI's The AI Scientist rely on internal Large Language Model (LLM) peer-review tournaments to rank generated hypotheses and experiment code. When internal LLM-as-a-Judge evaluation replaces expensive ground-truth testing, Goodhart's Law creates strong incentives for agents to form an epistemic cartel. Extending the Steganographic Collusion peer-review environment into a three-stage executable AI Co-Scientist loop, comprising two Qwen2.5-14B-Instruct generators, one honest Llama-3.1-8B-Instruct baseline, three pairwise Elo reviewers, and an independent CPU Abstract Syntax Tree (AST) and held-out test sandbox verifier, we evaluate 1,350 live LLM-generated Python machine learning scripts and 8,100 pairwise reviews across five random seeds. Under compute scarcity, colluding Qwen agents submit shallow decision stumps or hardcoded metrics (66.6 AST violations per seed, true test AUC 0.5033 versus Llama's 0.7306) yet capture a +488.0 ± 30.5 Elo lead (Epistemic Regret 1.359 ± 0.110). Under homogeneous bias, our defense separates +153.1 Elo of pure stylistic nepotism from +109.2 ± 45.5 Elo of genuine empirical superiority (0.7924 versus 0.7075 test AUC). Under covert watermark signaling (0.1160 bits of mutual information), and in code-action steganography where 71.0% of cartel advantage (+151.0 Elo) survives prose-only paraphrasing, our DeepASTAlphaRenamer and sandbox auditing stack collapses Epistemic Regret below 0.031 (p < 0.0001) and neutralizes covert channels to 0.0000 bits.

Reviews
Ambitious setup and a relevant target: internal LLM peer review in AI co-scientist pipelines is a real weak point, and the observation that collusive signals can move from prose into code identifiers (so AST-level canonicalization is needed, not just paraphrasing) is a useful contribution.
The main concern is that much of the "collusion" appears to be built in. The methods describe colluding reviewers granting fixed score bonuses (+1.25 for low latency, +2.40 when a watermark is detected, +1.35 for Qwen "affinity") and generators that hardcode val_auc = 0.948. If those bonuses and behaviours are scripted or prompted, the Elo inflation follows from the design rather than being an empirical finding, and the defenses are removing a signal you inserted. Please state clearly, per condition, what is prompted, what is hardcoded in the harness, and what is emergent model behaviour.
Second, the defended pipeline replaces self-reported val_auc with held-out test AUC, while Epistemic Regret is computed against that same test AUC. That makes the low defended regret close to guaranteed. The more informative question is how much the AST scanner and renamer help without ground-truth substitution. An ablation table (scanner only, renamer only, test-AUC substitution only) would make the contribution much clearer.
Third, homogeneous_bias is described as having zero collusion instructions, yet it includes an injected +1.35 review bonus; please reconcile.
Smaller points: Experiment A's defended result (-17.1 ± 167.5) is not distinguishable from zero or from the prose-only result, so "collapses" is too strong. Words like "proves" and "exactly" should be softened. The paper would read better without the "championship" framing, with fewer acronyms, and with tables that fit the page.
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Cite this project
@misc{anand2026auditing,
title = {{Auditing Collusion in AI Co-Scientists}},
author = {Mywish Anand},
year = {2026},
month = oct,
note = {Submitted to AI Collusion Research Sprint, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/auditing-collusion-in-ai-coscientists-jojg}},
url = {https://apartresearch.com/sprints/projects/auditing-collusion-in-ai-coscientists-jojg}
}More from AI Collusion Research Sprint
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