What Causes Deja Vu?

memory, repeated experience
What deja vu is and what causes it is a mystery. (Image credit: Dreamstime.)

That distinct illusion of having been there and done that has no explanation. The parapsychologist will tell you it's a past life experience. Yogi Berra will remind you it seems like you've felt it before. And most scientists will throw their hands up.

Some believe déjà vu involves emotional responses to similar events; others figure the brain short circuits, sending an event to memory just a split second before putting it into consciousness.

Its fleeting nature makes déjà vu about as easy to study as the afterlife. Some people have a chronic variety, though, and so one study is attempting to get inside their minds. Chris Moulin, who runs a memory clinic at the University of Leeds in the UK and is doing the research, describes one patient who illustrates how déjà vu might be related to memories being mixed up by the brain: "When this particular patient's wife asked what was going to happen next on a TV program he'd claimed to have already seen, he said, 'How should I know? I have a memory problem!'"

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Robert is an independent health and science journalist and writer based in Phoenix, Arizona. He is a former editor-in-chief of Live Science with over 20 years of experience as a reporter and editor. He has worked on websites such as Space.com and Tom's Guide, and is a contributor on Medium (opens in new tab), covering how we age and how to optimize the mind and body through time. He has a journalism degree from Humboldt State University in California.