♪ Intro ♪
I think the French must pay more attention to all the weird little tricks their brains plays on them,
because they’ve got all the cool terminology.
Take, for instance, “jamais vu”, or “never seen”,
the feeling you get when something familiar seems
suddenly new and bizzare,
like when you look at the word “hand”,
and it used to be the word “hand”, but now,
you’ve written it a ka-billion times
but it’s weird now, it’s weird!
Or then you have, “presque vu”, or “almost seen”,
which we call, “it’s on the tip of my tongue.”
But of course the most famous French-named brain trick
is “déjà vu”, or “already seen”,
the eerie, disconcerting sensation that what’s going on right now has happened to you before,
even though it’s happening right now
and hasn’t happened to you before.
Scientists haven’t pinpointed exactly what goes on
in a person’s brain when they experience déjà vu.
There are actually as many as 30 plausible
explanations for why it happens.
But they can make some good guesses
based on how our memories work.
Remembering requires two things
to happen in the brain.
One, the region responsible for processing memory data, the middle of the temporal lobe,
about where your ears are,
first recognizes a thing as familiar.
And two, the region that handles short and long term
memory, mainly the hippocampus,
which is inside the temporal lobe,
recalls that the thing has happened before
and pulls up that memory.
Usually these two processes, familiarity and recall,
work really well together,
the brain registers familiarity before
it can remember why the thing is familiar,
but sometimes, they get a little bit out of sync.
Neurologists have different ideas
about why this happens,
some think that since déjà vu results
in a visual image seeming familiar,
perhaps images travelling from one eye
to the brain are delayed,
arriving microseconds after images from the other eye.
This might lead to the sensation that something’s
being seen for the second time.
Another theory is that there’s some kind of glitch
in the processes of familiarity and recall,
and they’re activated at the wrong time.
You can think about this by imagining a tape recorder
that can record as well as play music,
our brains are kind of like that.
Usually you’d record music and then play it back later,
but sometimes, when this tape recorder is recording,
it malfunctions so that
it’s also playing back at the same time.
But [for] the brain
that starts playing back while it’s recording,
the present might feel like a memory.
Researchers have noticed that children don’t experience
déjà vu until they’re about 8 or 9.
It becomes more common
in our teens and our twenties,
and then starts tapering off after 25.
While we could file this information under “good to know,” it doesn’t really help us get to the bottom of it.
Fortunately, we’re living in kind of
a golden age of brain research right now,
so we’re learning new stuff about our brains
pretty much every day.
It’s nice to figure out where this stuff comes from,
but frankly, I—what I wanna do is fix … that … thing …
… said it just at the beginning of the episode …
… “presque vu”! It was on the tip of my tongue.
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♪ Outro ♪