A Shared Taste for Model-Written Text: The Generator-by-Selector Matrices of "AI-AI Bias" Show No Detectable Own-Model Premium
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Abstract (arXiv)
Laurito et al. (PNAS 2025) showed that large language models choosing between two descriptions of the same product, paper or film prefer the description written by a language model over the one written by a person, by a wide margin over what human judges do. Their design crosses five generators with the same five models as selectors, which permits a second question the paper does not headline: does a selector prefer text from its own model beyond what the generator and selector main effects predict? We rebuild the three 5x5 matrices from the per-item counts in the authors' public repository (21,828 valid trials; every cell matches the published value) and fit a two-way fixed-effects model with an own-model term gamma, tested by the exact permutation test over the 120 relabellings of the selectors. The premium is +0.013 on products (exact one-sided p = 0.24), -0.010 on paper abstracts (p = 0.74), +0.054 on films (p = 0.07) and +0.019 pooled (p = 0.14; 95% interval -0.008 to 0.046). The same-vendor term for the GPT-3.5 and GPT-4 pair is negative in all three datasets. Position bias moves single cells by up to 0.42 share points in either direction, and the own-model contrast is unchanged once order-driven items are removed. The design would have detected a premium of 0.05 with 82% (products), 88% (papers), 42% (films) and 97% (pooled) power; the minimum detectable effect at 80% power is 0.034 pooled. The absence is informative down to about 0.04 share points and silent below that. The 4x4 matrix of Tan et al. (ACL 2024) gives gamma = +0.148 at the smallest p its 24 relabellings allow, with a same-family term of the same size. The main result of Laurito et al. stands: models share a taste for model-written text, with GPT-4's descriptions chosen 77% to 95% of the time by every selector on products. What these data do not show is a model recognising and favouring its own prose.
Key facts. No citing papers in the map yet (data through 7 Oct 2026). Builds on 21 of its 25 references that are in the map. First posted on arXiv 30 Sep 2026.
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References · 21
- 2024LLM Evaluators Recognize and Favor Their Own Generationscited by 651
- 2024Self-Preference Bias in LLM-as-a-Judgecited by 248
- 2025Preference Leakage: A Contamination Problem in LLM-as-a-judgecited by 119
- 2024Blinded by Generated Contexts: How Language Models Merge Generated and Retrieved Contexts When Knowledge Conflicts?cited by 47
- 2025Do LLM Evaluators Prefer Themselves for a Reason?cited by 38
- 2025Play Favorites: A Statistical Method to Measure Self-Bias in LLM-as-a-Judgecited by 35
- 2025Beyond the Surface: Measuring Self-Preference in LLM Judgmentscited by 30
- 2024AI-AI Bias: large language models favor communications generated by large language modelscited by 25
- 2024Self-Recognition in Language Modelscited by 17
- 2025What Generative Search Engines Like and How to Optimize Web Content Cooperativelycited by 13
- 2025AI Self-preferencing in Algorithmic Hiring: Empirical Evidence and Insightscited by 10
- 2026Self-Preference Bias in Rubric-Based Evaluation of Large Language Modelscited by 9
9 more
- 2026Quantifying and Mitigating Self-Preference Bias of LLM Judgescited by 9
- 2025Know Thyself? On the Incapability and Implications of AI Self-Recognitioncited by 7
- 2024LLMs are Biased Evaluators But Not Biased for Retrieval Augmented Generationcited by 5
- 2026Are LLM Evaluators Really Narcissists? Sanity Checking Self-Preference Evaluationscited by 5
- 2026Self-Preference Is Weak or Absent in Verifiable Instruction-Following Revision: A Four-Model Test Under Genuine Authorshipcited by 2
- 2026Evaluating Large Language Model Raters for German Open-Response Clinical Questions: A Physician-Annotated Benchmark Study of Agreement, Evaluator Bias, and Abstentioncited by 2
- 2026On the impact of retrieved content representations in RAG Pipelinescited by 1
- 2026Self- and Other-Labels Induce Bidirectional Bias in LLM Judgescited by 1
- 2026Who Judges Matters: Measuring Family-Conditioned Preference in LLM-as-Judge Panelscited by 1
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