indistinguishability test
Kenneth Colby's own term, in the 1971 "Artificial Paranoia" paper, for his evaluation standard: a simulation succeeds if its input-output behavior "cannot be distinguished from its human counterpart by psychiatric judges using a diagnostic interview." It is a psychiatric-register restatement of Alan Turing's imitation-game criterion, using distinct terminology.
Entered the vault 2026-09-12 as a watching stub because the term may anchor a recurring thread bridging Turing's imitation game, Colby's PARRY evaluation, and later LLM benchmark design — "can a human tell it apart" as a validation bar reached for independently across eras. Graduates to a hub only if it recurs and earns load-bearing use.
References
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