From The Brain Book
Deja vu is characterized by a sudden intense feeling of familiarity and the sense you have experienced the same moment before.
One explanation is that a situation triggers a memory of a similar experience in the past and wrongly ‘tags’ it as familiar, creating a sense of recognition without bringing to mind the previous event.
Jamais vu is when you’re in a situation that should be familiar, but which seems strange. You may suddenly find your own home to be unfamiliar or for a second not realism that the person approaching you is someone you know well.
This is thought to be a glitch in recognition whereby the emotional input that usually accompanies familiar experiences fails to occur.
Wasn’t this blog posted in here a month ago?
I like what Stephen Wright said on his album “I Have a Pony”–there was a couple of seconds of silence, then he says “I am having amnesia and deja vu at the same time.”