Déjà vu: Where fact meets fantasy

Déjà vu can happen to anyone

the phenomenon has been a difficult and unpopular one to study

Now that is changing

Surprisingly, not only is déjà vu proving an interesting window on the peculiar ways that our memory works, it is also providing a few clues about how we tell the difference between what is real, imagined, dreamed and remembered - one of the true mysteries of consciousness

the first biological explanations

Mental diplopia"

is intuitively appealing but the evidence is stacked against it. Information from the two eyes mixes very early in visual processing, long before we perceive a scene

What's more, déjà vu - rather ironically as the term means "already seen" - can occur in blind people

A second intuitive explanation is some sort of distortion in time perception. Somehow, incoming signals must get misinterpreted and labelled with an inappropriate time stamp, making the experience seem old as well as current