What is Cryptomnesia?

Cryptomnesia An unconscious, or hidden, memory that when recollected is taken for new thought, cryptomnesia also encompasses a variety of apparent mental anomalies concerning actual events, information, ideas and images. Most common are incidents in which a person suddenly evinces fluency in a language never studied; gives false in­formation while in a hypnotic trance; or plagiarizes another's work unintentionally and with no thought to obscuring the fact. An instance of the first is the case of an uneducated young woman who suddenly began declaiming in ancient Greek and Hebrew while in a high fever. It turned out that she had once worked as a maid for a scholar who was accustomed to reciting aloud in those two languages. An example of the second is the famous episode of Bridey Murphy, the Irish alter ego of a U.S. housewife named Virginia Tighe. Under hypnosis, Tighe most convincingly "became" Bridey Murphy and in a heavy brogue described her former life in detail. On investigation, it was learned that as a child, Tighe had known the family of an Irish woman whose maiden name was Bridie Murphy, and the memory had remained intact but unrecognized in Tighe's unconscious until it emerged under hypnosis. Tracing incidents of plagiarism to cryptomnesia is trickier, since the dissociation process that takes place is so effective that it is virtually impossible for the plagiarist to recollect knowledge of his original reading or viewing of the material in question. Many eminent figures have found themselves embarrassed by unintended plagiarism of others' work. Among them was Sigmund Freud, who, on excitedly announcing to his longtime friend Wilhelm Fliess, a Berlin physician, his theory that individuals begin life as bisexual beings, was informed that Fliess had suggested the same idea to Freud two years earlier. The reminder stirred Freud's conscious mem­ory, and he eventually recalled the original conversation in full. He was, however, rudely shaken by the episode.
"It is painful to have to surrender one's originality in this way," he confessed.