Déjà Vu: Brain Malfunction?

Jenny Kang

 For more posts like these, go visit psych2go Psych2go features various psychological findings and myths. In the future, psych2go attempts to include sources to posts for the purpose of generating discussions and commentaries. This will give readers a chance to critically examine psychology. Fact submitted by: bonjourtammy

We’ve all had this feeling at one point or another. That eerie phenomenon of experiencing something new, but simultaneously feeling as if you’ve “been there” before, or “seen that” in a dream. Getting goosebumps when you just know you’ve seen this before, somewhere, at some other time..

So what exactly is it?

Déjà vu is literally translated from French as “already seen”.

But scientifically, what causes this?

Psychologist Sigmund Freud theorized that “ego” conflicts caused déjà vu to occur, ego conflict being a huge focus in Freud’s psychoanalytical theories.
When parts of our subconscious/unconscious conflicted with our conscious, aware selves, the conflicts would manifest in various ways, including déjà vu.

But Freud’s theories were, well, just theories. There is not much scientific, factual proof to back up his claims (although his ideas were revolutionary and influenced psychology immensely).

Could it be that this phenomenon occurs when our brains glitch?

(Source: “Hippocampus”, brainHQ,

The medial temporal lobe of our brain contains something called the hippocampus (near the cerebellum) that manages memory– memory filtration, memory storage, etc.

An important function the hippocampus also controls is filtering memories into short-term (active) or long-term (explicit, implicit) memories, kind of like a filing system; memories are “filed” into one cabinet or another.

Besides initially “filing” memories, the hippocampus also aids us in recognizing and differentiating memories as “new” or “old” memories, a process called pattern separation.

But as amazing as our brains are, sometimes they make mistakes too.

When a new stimulus, such as a location, is being processed but has similar characteristics to one we have encountered before, pattern separation might malfunction, leading our hippocampus to make us think that the location is an “old” memory rather than a “new” one.

The overlap of characteristics might cause this hippocampus glitch, consequently leaving us with the eerie feeling; hence, déjà vu. “I’ve seen this before!”

Of course, these are all just theories.

Many other hypotheses and theories exist, some proposing that instead of faulty pattern separation, short-term memories are accidentally filed as long-term ones.

When was the last time you experienced déjà vu?

And what do you guys think possibly causes it?




Carey, Benedict. “Déjà Vu: If It All Seems Familiar, There May Be a Reason.” New York Times, 14 Sept. 2004.

Halber, Deborah. “Research deciphers ‘déjà-vu’ brain mechanics.” MIT News. 7 June 2007.

Nagy, Christine. “Déjà Vu: Where Have I Heard This Before?” University of Southern California. 3 Apr. 2011.

“The Psychology Of Déjà Vu.” Science Daily: News & Articles in Science, Health, Environment & Technology. 19 Nov. 2008.


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