Language models converge on identical answers far more than chance predicts

Researchers deployed a minimal but revealing benchmark across 44 language models, asking each to generate single words from open-ended categories. The results expose a striking monoculture: when faced with infinite valid answers, models converge on identical choices at rates far above chance, with 'serendipity' appearing in 41% of responses to an unconstrained word-pick prompt. This One-Word Census uses only 31 prompts and costs roughly a dollar per model to run, yet surfaces a fundamental property of LLM training dynamics. The finding matters because it quantifies how training data and architectural similarities collapse the decision space in ways that feel random to users but are deeply deterministic across the industry, raising questions about diversity, predictability, and whether current scaling approaches inadvertently homogenize model behavior.
Modelwire context
ExplainerThe deeper implication the summary gestures at but doesn't fully land: this isn't just about diversity of outputs, it's about the illusion of stochasticity. Users and developers who treat temperature-sampled responses as meaningfully varied may be working with a much narrower effective distribution than they realize, which has direct consequences for any application that depends on model outputs not clustering.
This connects most directly to the 'Knowledgeless Language Models' paper covered the same day, which also probes how training signals shape model behavior in ways that persist invisibly into deployment. Both papers are essentially asking the same structural question from different angles: what does pretraining actually bake in, and how much of it is recoverable through prompting alone? The answer in both cases is 'more than practitioners assume.' The LLM judges paper from the same batch adds a third data point: systematic bias in model outputs that only becomes visible when you design specifically to surface it.
Watch whether any major model provider responds to this benchmark by publishing their own conformity scores, since voluntary disclosure would signal the finding is being taken seriously internally. If the benchmark instead gets ignored in favor of capability evals over the next two quarters, that tells you something about how the industry prioritizes behavioral auditing.
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Modelwire summarizes, we don’t republish. arXiv cs.CL originally reported this story as “The One-Word Census: Answer-Choice Conformity Across 44 Language Models”. The full content lives on arxiv.org. If you’re a publisher and want a different summarization policy for your work, see our takedown page.