Opus 5 recognizes a name in lowercase but not in uppercase

multimodalart · x · 2026-07-25

The post highlights a bizarre behavior in an Anthropic-style model: it appears to “know” the author when the name is typed in lowercase, but not when it is capitalized.

The takeaway is not the anecdote itself, but the implication: tokenization and memorization in transformer models can still behave inefficiently and inconsistently, even on seemingly trivial identity queries.

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