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.
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 the 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 depersonalisation (or surreality) feelings.
The TimesOnline reports:
- Chris Moulin, of Leeds University, asked 92 volunteers to write out "door" 30 times in 60 seconds. At the International Conference on Memory in Sydney last week 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that a similar brain fatigue underlies a phenomenon observed in some schizophrenia patients: that a familiar person has been replaced by an impostor.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.
- Déjà vu: having the strong sensation that an event or experience currently being experienced, has already been experienced in the past, whether it has actually happened or not. In French, this literally means 'already seen', though in usage it is basically equivalent to déjà vécu, "already lived."
- Presque vu: almost, but not quite, remembering something. It is also referred to as tip of the tongue.
- Semantic satiation
- Capgras delusion (the delusion that a friend or relative is an impostor)
- Depersonalization disorder
- Health & Medical News - Is it really you or jamais vu? - 19 July 2006
- Doctor, I've got this little lump on my arm . . . Relax, that tells me everything - Comment - Times Online
-  "Epilepsy and seizure information for patients and health professionals — Simple Partial Seizures", retrieved 2011-09-08