The term "cryptomnesia" signifies the existence of memories which are hidden from consciousness. Originally, it was assumed that cryptomnesic memories could only be remembered in states of altered consciousness. Today, the term is used to denote the appearance in normal consciousness of memories which are not recognized as such subjectively.
In analysing cryptomnesic phenomena, a distinction is made between memories of specific occasions in a person's life, called "reminiscences", and the general memories of discrete events composing specific occasions, called "logical memories".
When the logical memories of events which occurred on a specific occasion are no longer remembered as joint components of a reminiscence, a state of "partial cryptomnesia" exists. Thus a social situation and another event may still be recognized as memories, but not as the memories of events which occurred together. This can lead to social embarrassment, such as when a piece of news is related again to the person from whom it had come originally, or when it is related twice to the same company in relatively quick succession—symptoms which can be particularly noticeable in patients with a dysmnesic syndrome.
Cryptomnesia can give rise to unintended plagiarism, especially when logical memories are no longer recognized as memories, but are experienced as newly created ideas. In the field of literature, the characteristics of this kind of plagiarism are, according to Jung, repetition of the general trend of a story, including some unimportant details, but in phrases which differ from the original ones.
Unintended verbatim plagiarism is a rare occurrence. It could be caused by cryptomnesia in persons with an excellent verbal rote memory. Two possible instances are described in detail. Cryptomnesia may have been responsible in one case, but careless filing of a copied poem is the more likely explanation in the other.