Déjà Vu

Déjà Vu

♪ 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 …
… anybody?
… “presque vu”! It was on the tip of my tongue.
Thanks for watching this episode of SciShow
there’s a good chance that you’re gonna feel like
you’ve heard this part before,
But if you wanna keep getting smarter with us,
go to “YouTube.com/SciShow” and subscribe.
And if you wanna leave comments or ideas or questions, there’s the comments below,
or of course, Facebook and Twitter.
We’ll see you next time.
♪ Outro ♪

100 thoughts on “Déjà Vu

  • JAMAIS VU, not "JAMIAS" VU. I'm sure you were smart enough to google it before preparing those jokes about the french, so stick to the spelling

  • My "Deja Vu's" are dreams and then several hours later (before the event happened I had forgotten dream) I see an event and I remember I saw it in a dream so it is like my brain predicted the future in a dream and sometimes I can tell "deja vu" dreams apart from normal dreams.

  • I don't think this is déjà vu… One I heard a Michael Jackson song on the radio and I was sure it was in some movie I saw but I couldn't remember which… And then a few days later im like "ooooh it was from Megamind!"

    Now people will start accusing me for listening for Michael Jackson and watching movies like that :/

  • It's too bad you didn't mention there are a specific type of seizures that cause déjà vu called absence or petit mal seizures. If you have a lot of déjà vu, with jamais vu you could possibly have this type of seizures. They are very common in young school age children

  • i had deja vu from scents,  like smelling perfume or food, i feel like i know the scent and i smelt it before and it gives me a feeling, like i'm in a familiar place but i can't exactly say what it is 

  • When I was little I remember seeing my brother throw a football at me in our backyard after I offered him popcorn from a tin my parents haven't gotten me yet ( it was a barbie one filled with Carmel popcorn ) a few days later my mom bought me a barbie tin full of Carmel popcorn and I ran outside to see if my brother wanted some and he threw a football at me. I cried and said " I knew this was going to happen". What was that?

  • I swear I was hoping so much he would say "in the matrix" after he said "glitch" for a "glitch in the matrix" lol!

  • I always get Deja Vu when im sleeping the 2-3 days later the same thing happens and lol it has one of the weirdest feelings

  • Everytime I have a Deja Vu I don't only "remember" the situation but according to that memory the last time it all happened I ALSO had a Deja Vu. XD

  • talk about pathetic theories concerning deja vue. so why do they make no attempt to explain it when you have a dream and months later you realize you have seen a visual episode before…..just pathetic science if you ask me.

  • I don't think the theory about images appearing from one eye more quickly from the other is plausible… My roommate was born blind in one eye and she also experiences deja vu.

  • when I get deja vu the "memory" last for at least 10 seconds and I can predict what happens, I've impressed friends with this, saying stuff they were about to say and stuff

  • That is good to know because right now, I'm experiencing Deja Vu and Jamais Vu about every other day now. I hope it tapers off soon.

  • You know how when people are dying or are in a near death experience and they say that their entire life flashes before their eyes and they can see and recall everything they've gone through and experienced. I like to think that right at the moment when we are born our entire life flashes before our eyes and then we enter the world. I think that déjà vu happens because at the moment we are experiencing we are recalling one of the memories that flashed before our eyes before we were born which is why we remember it but at the same time we don't. Don't ask… this is just my theory in my effed up mind.

  • Dude, if you're going to use French expressions please learn how to pronounce them correctly. You sound ridiculous. Really.

  • I experience deja vu very often. Lately its been actual deja vu's of "past" Deja vu's. Its like i can almost remember the date of the event and everything

  • I am over 25 and I've been experiencing Deja Vu far more lately than I ever did as a kid or as a teen. Usually Deja Vu lasts a few seconds but twice now I had it last a few minutes and in one of those I accurately predicted an event a few seconds before it happened which I would otherwise have no way of knowing. In my deja vu I saw that two birds were going to pass by the window must moments before my father would open the front door to come in. I said that these events would happen and within a few seconds they happened and it freaked everyone out. I had no way of knowing this unless I had X-ray vision to see my father coming and see those birds from half a block away and then make a good guess that they would linger by the window. I do NOT, repeat, DO NOT believe in the paranormal. But my brain is doing funny stuff and I wanna know how and why.

  • I've experienced double deja vu, where something happens and I get deja vu but I also think that I got deja vu the "last time" it happened. Is there a reason for that or am I just insane???

  • I was putting my heater away and then my bird chirped, I swear i have been in that position before. and then i saw my window was frosted up and i swear that happened to!

  • What if déjà vu is a spawn point? Like. Remember when you play games and you die on the spot then you live again the same place just so you can have another chance at winning?

  • I am having jamais vu pretty often, and almost never deja vu. it's fucking annoying. like, I see a word and then I am all like "what the hell"

  • What if déjà vu is the brain tricking itself into recalling memories to keep all the parts of itself from being lazy and for example, the hippocampus just recalling information and nothing new happening. My theory is just what is is, a theory but still, I think the brain tries to keep itself excited since we can ge tbored from repetition so maybe the hippocampus always recalling things with no change bores the brain and it "makes its own fun" as it were, just a thought.

  • no it's because space-time ran backwards for a bit and then forwards again. our brains are remembering what happened and then unhappened and then happened again. it's a thing. i'm about to make a video about it.

  • SOME ONE HELP! I've gotten Deju Vu where I had already seen it before and I looked over and said "She's going to sneeze! He's going to throw that paper!" and then it happened and I thought it was AMAZING. It happened in 8th grade (two years ago) And I read something somewhere that said you get very extreme deju vu when growing. PLEASE SOME ONE EXPLAIN THIS!

  • I used to get Deja Vu a lot in my teens & 20s. After a while, when I had that feeling, where I knew what the other person was about to say, I'd deliberately mess things up a bit & NOT say what I knew I would say, but say something different. And it changed the conversation! So I don't think it's something in our brains. I think it's something in the Quantum Matrix & our brains log in & read it somehow.

  • I've have been watching a TV show on it's first run (not a rerun) and told the people watching it with me that I've seen this before and then told them about the up coming scene several seconds in advance. This has happened 3 times and each time has only been for a short time (less than 20 seconds each) not the whole show. So how does that work?

  • I'm so weird… Like… I'll blink or look out of the corner of my eye and see a flash of something that I've never seen before… Then, just out of the blue, my brain will connect the little flash to something that I'm currently experiencing… Hence why I get deja vu a lot.

  • This persons explanation of deja vu is bullshit. I used to experience deja vu frequently. One time I was listening to a talk show and had an episode of deja vu, and I started saying what the announcer was saying BEFORE he said it and I was spot on for about a minute during which I always heard my own voice say it before the announcer did. Thus I know this isn't just some brain hemi-sync out of sync thing like this person likes to suggest.

  • Dylan R you are right I have dreams and then like, 4 months later they actually happen it makes me feel like I can predict the future wbu

  • Often times I lose picture association of words and then they become foreign to me. Hand suddenly just looks like H and And.

  • I do Experience Deja Vu a – L O T – . I feel the thing's happened the same thing all over again like a time loop, I dont know why.

  • I had deja vu when I started Jr. high. the building was completely knew. but this classroom. I swear I had a dream about it before 0_0

  • but when I get this type of feeling…. in my brain… I m like….
    I've already seen what am I going to say/do,,,,, but still can't stop myself from saying/doing that……….
    WHY THAT???????????

  • Hey, SciShow. Great vid. I must ask, what is the Science and Math behind Creativity in organisms containing this ability? Please Like my comment for support on this question and post this question on other vids- Really Curious!

  • did anyone else notice that his glasses going green to gray because of the editing (green screen or blue screen) …no? just me? I couldn't stop looking at it. editors dilemma

  • Scientists are WRONG I started deja vu at 6 please tell them to look into this more carefully!!!

  • Is it possible that u can see/be shown the future in a dream… N it triggers a sense of Deja Vu… Had a dream over 8 years  that I keep walking into events from it…. to this date.

  • Not sure if my experiences are Dejavo since I have dreams of me being at new places i have never been then months or a year goes by and i actually see that place then recalls the dream – Usually the occasion differs from in the dream but the place is identical .( I know i never saw that place before except in my dream but its happening for real now to the point where i can point out to others whats coming up as we walk ) – I also have yearly repeat of brief moments where the same set of event unfold and i recognize it then its gone

  • one time when I had deja I completely anticipated what somebody was about to say to, I even said it as they said it, it was an odd experience for us both

  • Okay but what about like in matrix, something happens again? I mean obviously it doesn't but like, you experience something, then some time later, you experience something else and you can swear the two were identical, like watching a video played back in which you were even one of the actors.

  • It's one of those things, much like dreaming, that is just so weird. I'll get deja vu and it'll last for about 5 seconds and then I'll forget what it was even about…

  • Ive had Déjà vu with sight and sound combined… (I have it a lot, like once or twice a week)

  • so when i was in primary school, in assembly, we would be told fables, and i remembered this fable so well, it felt like i was told it 2 years earlier. and i was sitting in the same place, in the same room, next to the same people, the only thing that is wierd about this is that i was able to predict extremely accurately what was going to happen in the fable, also, i now have moments where i had seen the exact thing a day before it happened

  • I had once a dream and when i woke up i was like, well thats weird, thats a place i haven't seen before….
    and than 3 months later i saw that place from exactly that spot i dreamed, and it was the first time i was there (i was on vacation , so i was realle never been there before….)

    i also had one time i saw someone throw in the seat of my car in a dream, i told some people this weird dream, and again, 3 months later it happenend exactly like i dreamed it….

    both times i had a deja vu feeling because i dreamed it and i new it when it was happening…

    and this is just 2 examples, i have had many more, so im not sure i can forsee the future in my dreams or is it something else…. 😉

    i guess i am just weird 😛

  • I get jamais vu and Deja vu as part of my simple partial seizures, and it’s wild when you’re in your own bedroom and it feels like you’re looking at it for the first time again

  • Normally I get deja vu when I go a certain place where I felt either very happy or scared, that I haven’t been to for a while.

  • I have had deja vu many times in life. Half of them feel based in a dream and it is never just an image it is always a series of events. 2 times those series of events were long enough for me to predict about 1 second of the immediate future. The first was a recognizable cat running past me and a few people I was standing with. The deja vu started a second before because of a specific sentence someone started to say. I said nothing ofcourse out of fear of being called crazy. The second time however I got a chance to predict and voice 3 or 4 words that a stranger was saying in a conversation near me. My girlfriend at the time gave me the weirdest look and so I explained what happened. She was intrigued at best, but what could we do with the knowledge? Even more interesting…. I can't remember experiencing a single deja vu event since.

    So….. any ideas? I am intelligent, scientific, and care very little about getting attention from humans. Hopefully this deters doubt in my story.

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