Cryptomnesia

Cryptomnesia is a memory phenomenon in which a person genuinely believes they have generated a new thought, idea or piece of work, when in fact they are unconsciously recalling something they were previously exposed to without recognizing it as a memory. It differs from ordinary forgetting in that the earlier material actively resurfaces, but stripped of its source, so the person experiences it as original rather than as a remembered fact. Cryptomnesia has been raised as a possible explanation in a number of high-profile allegations of unintentional plagiarism in music and literature, since a musician or writer can genuinely be unaware that a passage they believe they created was in fact something they had previously heard or read.