Confident Science Papers Sway AI Judges – Regardless of Merit

A German study found that six LLM reviewers, including GPT-5.5, Claude Sonnet 4.6 and Gemini 3.5 Flash, consistently scored scientific papers written in confident, assertive language higher than content-identical cautious versions. Claude Sonnet 4.6 showed the strongest bias, favoring confident drafts seven times more often and accepting a confident version while rejecting the cautious one in 21% of cases. The authors warn that if linguistic style alone shifts scores and review sentiment, LLM judgments do not exclusively reflect scientific quality and should be stress-tested on content-preserving rewrites.