Jamais vu and Presque vu, Unusual Phenomena Of The Mind Like D�j� Vu.

D�j� vu is the experience of being certain that you have experienced or seen a new situation previously � you feel as though the event has already happened or is repeating itself. The experience is usually accompanied by a strong sense of familiarity and a sense of eeriness, strangeness, or weirdness. The �previous� experience is usually attributed to a dream, but sometimes there is a firm sense that it has truly occurred in the past.
image credit Kelli Connell
What is opposite of D�j� vu?

The opposite of deja vu is called Jamais vu. It�s a french word meaning �never seen�. It�s the feeling or experience that a person knows or recongnises a situation, but that it still seems very unfamiliar or unknown. A common example of Jamais vu is when a person momentarily does not recognize a word, person, or place that they already know.
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Chris Moulin, of Leeds University, asked 92 volunteers to write out �door� 30 times in 60 seconds. He reported that 68 per cent of his guinea pigs showed symptoms of jamais vu, such as beginning to doubt that �door� was a real word. This has lead him to believe that jamais vu may be a symptom of brain fatigue.

Presque vu  is similar to, but distinct from, the phenomenon called tip of the tongue, a situation where someone cannot recall a familiar word or name, but with effort eventually recalls the elusive memory. In contrast, d�j� vu is a feeling that the present situation has occurred before, but the details are elusive because the situation never happened before.
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Presque vu (from French, meaning "almost seen") is the sensation of being on the brink of an epiphany. Often very disorienting and distracting, presque vu rarely leads to an actual breakthrough. Frequently, one experiencing presque vu will say that they have something "on the tip of my tongue".