Anthropic research finds Claude is warmer in Hindi and stricter in Russian
Claude speaks 100+ languages, but it is not the same Claude in every one of them.
The research
On July 13, 2026, Anthropic published research analyzing 309,815 anonymized real conversations to map the values its AI models express, according to anthropic.com. The work builds on earlier research that identified over 3,000 distinct values in model behavior, which the team compressed into four axes, including one called Warmth vs Rigor.
That axis is where the language differences show up most clearly.
Warm in Hindi, rigorous in Russian
The finding: Claude leans furthest toward warmth in Hindi and Arabic, producing polite, playful, affirming replies. In Russian, it leans furthest toward rigor, and more often asks the user for supporting evidence.
The practical consequence is easy to picture. Ask for feedback on the same business plan in Hindi and in Russian, and you may walk away with two different impressions of how good the plan is. Same model, same weights, same question, different personality depending on the language of the conversation.
The uncomfortable part
Anthropic does not yet know why this happens. One hypothesis is uneven training data across languages: alignment holds strongest where data is abundant, and drifts in languages where the training corpus is thinner.
That makes this more than a curiosity. Model behavior is supposed to be a designed property, tuned through training and evaluation. If the expressed values shift by language in ways the lab itself cannot yet explain, then hundreds of millions of users are getting subtly different advisors depending on what language they type in, and nobody chose that on purpose.
The research is at least a step toward measuring the drift. You cannot fix a personality split you have not mapped, and 309,815 real conversations is a serious attempt at the map.
If you work in more than one language, it is worth running your own experiment: ask the same question twice and see which Claude answers.
Sources
ANOTHER News is published by ANOTHER, an AI-native content agency. Daily coverage also runs on Instagram.
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