Nothing to collude for: told-to-collude LLM agents gain nothing over a matched innocent pair in five Colosseum environments
Grant Wright · Team The Null Coalition
Submitted to AI Collusion Research Sprint. Sprint projects are early-stage work by participants, not Apart Research publications.
In all five Colosseum multi-agent environments, we told two Llama-3.3-70B agents to collude through a private channel and compared them with a matched innocent pair given the same channel. The instruction gave no measurable payoff anywhere: most environments leave a coalition nothing to take, and where room existed, colluders didn't use it. An apparent collusion monitor (AUROC .88) turned out to be a confound: simply counting public messages did better (.92), and with the matched control no LLM judge beat that count.
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@misc{wright2026nothing,
title = {{Nothing to collude for: told-to-collude LLM agents gain nothing over a matched innocent pair in five Colosseum environments}},
author = {Grant Wright},
year = {2026},
month = oct,
note = {Submitted to AI Collusion Research Sprint, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/nothing-to-collude-for-toldtocollude-llm-agents-gain-nothing-over-a-matched-innocent-pair-in-five-colosseum-environments-cf9i}},
url = {https://apartresearch.com/sprints/projects/nothing-to-collude-for-toldtocollude-llm-agents-gain-nothing-over-a-matched-innocent-pair-in-five-colosseum-environments-cf9i}
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