"Déjà vu, French for "already seen," is the sensation of feeling
eerily familiar with a newly encountered object or situation. It's
that slightly jarring state of mind that can be triggered by any
number of stimuli: a photograph, a phrase, a hand gesture. The
sense that you've been here before.
Due to its ephemeral nature, there's very little scientific
research on déjà vu. Although over 70% of people report having
experienced the unsettling phenomenon, it does appear to affect
people aged 15 through 25 more than any other age group. And
according to How Stuff Works, it has been associated with
temporal-lobe epilepsy. Some epileptics have reported feelings of
deja vu that occur prior to and even during seizures.
Theories abound as to the cause of déjà vu. Simple wish
fulfillment? A cerebral cross-wiring that confuses the present with
the past? A pre-existing anxiety acting out? The subject is
obviously still ripe for scientific and artistic exploration. Maybe
time will yield an answer. "
