(classical music)
- Hi, and welcome to Brain Stuff,
I'm Josh Clark, and this is the Brain Stuff
where I explain to you how déjà vu works,
where I explain to you how déjà vu works.
So, you're probably familiar with déjà vu,
it's an eerie feeling that
something that is, otherwise novel or
not something you've experienced
seems really familiar.
It's odd, and these episodes last anywhere
from ten to thirty seconds.
And most people have experienced it
at one point or another.
Something like two-thirds of all people say
that they've experienced déjà vu before.
I can't conceive of what the other one-third are thinking.
Déjà vu, the term itself,
means already seen, en français,
that's because the term was
coined by a frenchman named
Emile Boirac.
And, he coined the term in his book,
L'Avenir des Sciences Psychiques.
That's my best french impression.
So, science really has no idea what's going on
with déjà vu, which makes it fascinating.
There's actually something like forty major theories
on the phenomenon, which is a lot.
And scientists can't even agree how to categorize it.
But, most people say it comes under one of two
umbrella terms.
There's associative, which means that stimuli,
external stimuli, is triggering déjà vu.
And then there's biological,
biological déjà vu is where there's
some sort of structural or chemical abnomality
going on in the brain
that's triggering déjà vu.
One great example of biological déjà vu
is temporal lobe epilepsy.
People who have epilepsy tend to have déjà vu
right before the onset of a seizure.
And, it turns out, that you can actually bring on déjà vu
in people with epilepsy, by stimulating
their brains with electromagnetism.
People who have anxiety and depression
can actually suffer from chronic déjà vu,
which happens so frequently that it's
debilitating in their lives.
And there's this awesome case of a dude
who had a fever and started taking
dopamine producing drugs to fight it off,
and was suddenly faced with an onslaught
of déjà vu that went away
when he stopped taking the drugs.
Mysterious,
but data.
Whether it's structural or associative,
scientists think that the culprit behind déjà vu
is the medial temporal lobe,
which for reference, if you ever wanna know,
is located just behind the top of your ear,
toward the middle of your brain.
That's medial temporal lobe land.
So, like I said, there's something like
forty major theories about what is behind déjà vu,
but I have some favorites, and here they are.
The first one was proposed by a guy named Dr. Alan Brown
and it is called Divided Attention Theory.
The idea behind it is that you actually have
had this experience before, but you weren't
paying enough attention to create a
full functioning memory of it.
So, it seems familiar for a reason.
My personal favorite is Hologram Theory,
proposed by a Dutch psychiatrist named Dr. Herman Snow.
So, one thing you might not know about
actual holograms is if you cut the substance
that creates the hologram
into smaller pieces,
it'll still show the hologram, just at a lower resolution.
Well, Dr. Snow took this idea of physical holograms
and applied it to déjà vu.
He thought that maybe some fragment of a
memory or experience, like a smell or some sort of
transient thought brought on the memory
of a larger full scene,
and that's what déjà vu was.
Pretty cool, huh?
And then there's dual processing theory.
The idea behind this is that new novel stimuli
hits our brain and is processed twice
that second time it runs through our brain
the brain mistakes it as something that's already familiar.
And the last one is leaky processing theory.
The idea is that when new stimuli comes into our
working memory, just kinda hangs out there, jogs around
until it's sorted out as either important or unimportant.
Well, leaky processing theory says that
somehow, some little bit of stimuli gets through
from our working memory to our long-term memory
without being sorted, and so although it's new,
our brain mistakes it as something familiar,
cause it's in long-term.
Pretty neat stuff.
And then, just for extra credit,
there's the opposite of déjà vu,
which is called jamais vu.
And jamais vu is when you experience something
that you know, you know
a person, a place, a thing, a word,
and it looks totally and eerily unfamiliar to you.
So, it's the exact opposite of déjà vu.
Which is pretty neat,
because the brain is neat.
And if you liked this video,
which I hope you did,
there are plenty more here,
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well you leave a comment below.
Any suggestion for a future show is much appreciated.
And if you want even more cool stuff,
head on over to the venerable website,
howstuffworks.com