n. A sense of unfamiliarity with, or of never having experienced or seen before, something that should be familiar.
n. the experience of being unfamiliar with a person or situation that is actually very familiar; associated with certain types of epilepsy
Often described as the opposite of déjà vu, jamais vu involves a sense of eeriness and the observer's impression of seeing the situation for the first time, despite rationally knowing that he or she has been in the situation before. Jamais vu is sometimes associated with certain types of aphasia, amnesia, and epilepsy.
Jamais vu is most commonly experienced when a person momentarily does not recognise a word or, less commonly, a person or place, that she or he knows. This can be achieved by anyone by repeatedly writing or saying a specific word out loud. After a few seconds one will often, despite knowing that it is a real word, feel as if "there's no way it is an actual word".
The phenomenon is often grouped with déjà vu and presque vu, or tip of the tongue.
Theoretically, as seen below, a jamais vu feeling in a sufferer of a delirious disorder or intoxication could result in a delirious explanation of it, such as in Capgras delusion, in which the patient takes a person known by him or her for a false double or impostor. If the impostor is himself, the clinical setting would be the same as the one described as depersonalisation; hence, jamais vus of oneself or of the very "reality of reality" are termed depersonalization and derealization, respectively.
A study by Chris Moulin, of Leeds University, asked 92 volunteers to write out "door" 30 times in 60 seconds. In July 2006 at the 4th International Conference on Memory in Sydney he reported that 68 percent of volunteers showed symptoms of jamais vu, such as beginning to doubt that "door" was a real word. Dr Moulin believes that a similar brain fatigue underlies a phenomenon observed in some schizophrenia patients: that a familiar person has been replaced by an impostor. Dr Moulin suggests they could be suffering from chronic jamais vu.
Jamais vu can be caused by epileptic seizures.