How Déjà Vu Works


Announcer: Welcome to Stuff You Should Know from HowStuffWorks.com.

Josh Clark: Hey, and welcome to the podcast. I'm Josh Clark. With me is Charles W. Chuck Bryant, and if you put two of us together, you know that you have Stuff You Should Know. Right, Chuck?

Chuck Bryant: That's right, Josh.

Josh Clark: What are you doing there, Chuck?

Chuck Bryant: I know you're laughing because I am doing a little thing. I have gunk in my ear. And I could use a Q-tip if you have one.

Josh Clark: Hey, fun fact. Did you know that Q-tips were originally called baby gays?

Chuck Bryant: Baby gays. I don't think I knew that, but it sounds familiar.

Josh Clark: Yeah, true story. True story!

Chuck Bryant: Very cool. I like starting off with a fact that has nothing to do with our show.

Josh Clark: Sure, right. So Chuck, speaking of having nothing to do with our show, let's talk about déjà vu! You ever had it?

Chuck Bryant: I have, and let me add, this is a listener suggestion dedicated to one Peter Harrison of Pittman, New Jersey. Keeping it real in New Jersey in the Garden State! He actually had déjà vu when he was listening to, I believe, our exorcism podcast.

Josh Clark: Weird.

Chuck Bryant: So there you have it.

Josh Clark: That's an unsettling one to have déjà vu over, I would think.

Chuck Bryant: Yeah, and it turns out we had a great article on it, so away we go.

Josh Clark: Yeah, let's do this, Chuck. You know, are you part of the 30 percent who has reported never having - or I guess just hasn't reported having déjà vu, or are you part of the 60 to 70 percent?

Chuck Bryant: Sixty to 70. I've definitely had déjà vu many, many times.

Josh Clark: I was actually surprised to find that number was as low as it was. I thought it'd be hovering in the 90s, and then the other people were just too lazy to ever say, "Yeah, I've had déjà vu." It seems like something everybody would have. Right?

Chuck Bryant: Right, or nothing familiar has ever happened to me.

Josh Clark: Exactly, like I don't pay attention to anything at all. I just watch Dancing with the Stars all the time. So all right, Chuck. Let's start with the nuts and bolts, shall we. Déjà vu, French for -

Chuck Bryant: French for already seen, and I believe it was named by Emile Boirac. French scientist, first guy to ever study it, so he gave it its name!

Josh Clark: Yeah, in his 1876 book Lavenere De Seansese Physiques.

Chuck Bryant: Wow.

Josh Clark: Thank you. Three years under my belt, pal.

Chuck Bryant: I feel like you just channeled Pepe Le Pew. So déjà vu, as everyone knows, is a feeling that you've seen or experienced something before when you know that you have not.

Josh Clark: Yeah, it's a sense of familiarity. Unplaced familiarity!

Chuck Bryant: Right. For instance, I walk into a store I've never been in and see a person I've never seen, and I think, "Wow, this feels really familiar."

Josh Clark: Yeah. What usually happens to me - I'm part of the 60 to 70 percent, too.

Chuck Bryant: Of course. Self-reported!

Josh Clark: And what happens to me, usually, is there's about three different things that are going on in conjunction with one another. Like a fish jumps in a lake, and a woman walks by with a baby stroller, and as a cloud passes in front of the sun! That's how my déjà vu is. And I'm like, "Wow, I've been standing in the same spot watching the same group of things happen," and then it just kind of passes. And I'm like, "Whoa."

Chuck Bryant: I don't know if I could categorize mine that specifically. But well done.

Josh Clark: Thanks. Thank you very much. That's my déjà vu. But yeah, essentially, what was the guy's name? Boiroc!

Chuck Bryant: Yes.

Josh Clark: He mentioned déjà vu, but he didn't really go into detail about it. The first really respected scientist to really take up the mantle was Freud. Right?

Chuck Bryant: Yeah.

Josh Clark: And he basically created the theory that was the driving explanation behind déjà vu throughout the 20th century, and that was that he believed that déjà vu was the result of repressed memories.

Chuck Bryant: He said that about everything.

Josh Clark: Everything. If it wasn't about the penis or the vagina, it was about repressed memories and possibly mother's teat. Yeah.

Chuck Bryant: I went to the Freud house.

Josh Clark: Did you?

Chuck Bryant: Yeah, I have a nice photo in front of it.

Josh Clark: That's great.

Chuck Bryant: Just a side bar.

Josh Clark: What city is that? Vienna?

Chuck Bryant: I'm almost positive it was Vienna.

Josh Clark: We'll find out. Won't we?

Chuck Bryant: Yes. I traipsed around, though, and all those memories aren't firmly rooted. So -

Josh Clark: There's a déjà vu joke in there somewhere. I just can't find it right now, so we'll just keep going.

Chuck Bryant: Sure. We'll edit it in later.

Josh Clark: All right, so at some point, as we said, Freud, déjà vu, explain. And then once Freud was found out to be basically a -

Chuck Bryant: Fraud? No, just kidding.

Josh Clark: Well, a coke addicted postulator rather than maybe a real scientist. In my opinion! I'm more of a Jungian than a Freudian.

Chuck Bryant: I'm a Dr. Phil guy.

Josh Clark: Are you?

Chuck Bryant: No.

Josh Clark: You can't go wrong with that guy. Eventually, at some point in time, déjà vu was attached to the paranormal. I'm not entirely certain when this happened, but you know, you've heard that kind of thing. Like it had to do with precognition!

Chuck Bryant: Yeah, and real scientists wouldn't - they kind of just brushed it aside.

Josh Clark: Well, actually, one does explain déjà vu through precognitive dreams, but we'll get to that later. Right?

Chuck Bryant: That's right.

Josh Clark: That any time you put the stank of paranormal onto something that's arguably real, people - science just turns their back on it. They can't stand things that they can't apply the scientific method to whether it's real or not. So everybody just kind of dropped - at least the scientific community kind of dropped déjà vu, until our great friend the functional MRI was invented. A.k.a., the wonder machine! And it sparked this renewed interest in research into déjà vu. Right?

Chuck Bryant: Yeah because now you could actually look at the brain function and try and figure out the science behind it instead of just doing the Freudian thing.

Josh Clark: Right, which is make stuff up.

Chuck Bryant: Right.

Josh Clark: So this is really, really, really new research. I mean just last several years. Right? So the jury is still definitely out, which is good for us and our listeners because we get to talk about a bunch of competing theories that are super cool.

Chuck Bryant: And there's a lot of them. I think the article said something like over 40 theories of what déjà vu actually is.

Josh Clark: Right and I think we shouldn't go into all 40.

Chuck Bryant: There's no way. This would be a four hour podcast.

Josh Clark: But they've basically split déjà vu into two broad categories. Right?

Chuck Bryant: Yes.

Josh Clark: There's associative and biological. And which one is associative?

Chuck Bryant: Well, that's the one that you - most people out there probably more are familiar with, and that's when you - your sense is reacting, and you see, hear, or smell something that stirs up a feeling inside you. And it's memory based.

Josh Clark: And it's very fleeting. Like ten to 20 seconds.

Chuck Bryant: Yeah, mine are shorter than that, actually.

Josh Clark: Yeah?

Chuck Bryant: I would say less than ten, usually.

Josh Clark: Is there a baby carriage involved?

Chuck Bryant: No, never.

Josh Clark: This is déjà vu among generally healthy people. Right?

Chuck Bryant: Yes.

Josh Clark: So we're not really attaching any real meaning to it. It's more like a, "Whoa that was cool déjà vu kind of thing." The other one, biological, is actually the result of some sort of structural impairment to the brain. Say epilepsy.

Chuck Bryant: Exactly. That's a big one.

Josh Clark: Yeah, possibly schizophrenia, and these are - these episodes are much more vivid déjà vu than associative déjà vu. And people who experience biological déjà vu have much more of a tendency to attach real meaning to it and really believe like they're experiencing something twice.

Chuck Bryant: Right. It's not like a fleeting feeling.

Josh Clark: No. And if you're an epileptic, and you have a case of vivid déjà vu, prepare for a seizure.

Chuck Bryant: Oh, it's right before the seizure?

Josh Clark: Right before, yeah. And apparently, they also smell flowers sometimes, too, or oranges.

Chuck Bryant: Really?

Josh Clark: That's what I've heard.

Chuck Bryant: Interesting.

Josh Clark: I agree. So those are the two broad categories. Right?

Chuck Bryant: Yes.

Josh Clark: Still, it doesn't really explain anything. Right?

Chuck Bryant: No, it doesn't.

Josh Clark: With the biologic - it seems like researchers have the biological explanation of déjà vu down a little more pat.

Chuck Bryant: Right, it's a little more medically based.

Josh Clark: Yeah, it's like a temporal lobe malfunction, possibly. And actually, it seems like the temporal lobe has everything to do with déjà vu, whether it's structural or a ssociative.

Chuck Bryant: Right because that's where our conscious memory is happening, basically.

Josh Clark: Which would be a pretty appropriate place for déjà vu to take place? Right?

Chuck Bryant: Absolutely.

Josh Clark: So basically, there's a part called the - there's a temporal lobe region called the medial temporal lobe. And that's, like you said, the part that's responsible for processing conscious memory, and there's this guy named Robert Efron, and he's a neurologist, I take it, of some stripe. And he did some investigation into the temporal lobe, and he found that it receives information, the same sensory input, twice.

Chuck Bryant: This was in the early 1960s, too, and it still held up as valid.

Josh Clark: It makes a lot of sense. So what Efron postulated was that if we're getting the same information twice, one is direct to the temporal lobe, which processes sensory information. The other one is slightly indirect. It gets routed through the right hemisphere of the brain, and then shoots over to the left hemisphere of the temporal lobe. Right?

Chuck Bryant: Within milliseconds.

Josh Clark: But there is a delay. There's a lag. And so what Efron said was, "If this delay is longer than normal, extended by even a couple of milliseconds, the brain has the potential to confuse what kind of time stamp or what situation or context that this sensory input was taken in." And maybe assign it an incorrect category, hence, we get the feeling that we've been there before, we've experienced this before because we're confused, and that's what déjà vu is, which makes tons of sense. Right?

Chuck Bryant: Pretty cool. Yeah.

Josh Clark: That's certainly not the only theory of what déjà vu is.

Chuck Bryant: No. Cell phone theory! Shall we talk about that?

Josh Clark: Yes.

Chuck Bryant: This Dr. Allen Brown is a guy who has done a lot of research in this area as well, and he did studies at Duke University and SMU Southern Methodist with Elizabeth Marsh is the lady's name. And what they did was they worked with subliminal suggestion, which is one of my favorite things. I think it's really cool and interesting. They showed photographs of different locations to students, and they were going to - the plan was to ask them which ones were familiar. But before they did this, they showed the same photos at subliminal speeds. So like ten to 20 milliseconds. And what happened was the brain, of course, registered it.

Josh Clark: But unconsciously. Right?

Chuck Bryant: Unconsciously, and they found familiarity with these slides of locations that they'd never been to.

Josh Clark: Like they showed the people the same picture.

Chuck Bryant: Right.

Josh Clark: Once in a split second. And then later on, they thought that they hadn't seen it before, but the brain had already unconsciously processed it. Right?

Chuck Bryant: You got it, buddy.

Josh Clark: And there was increase in déjà vu among those people.

Chuck Bryant: Yeah, and I saw a thing on YouTube. And this isn't exactly déjà ; vu, but this is a really cool thing. There was a guy in England named Darren Brown. He's a magician and mentalist, which I think is a great title. If you look up on YouTube Darren Brown and subliminal advertising, he did this cool deal where he brought in these two advertising guys and said, "Hey, I want you to come up with an advertising plan for me based on taxidermy." And that's all he told them. And then he set down an envelope and said, "This is my plan, and don't look at it or anything like that. It's sealed." These guys came up with a little sketch and a logo and a tagline. He came back in ten minutes later or however long it was and opened up his envelope, and the logo, the tagline, everything, was really, really similar. And these guys, these ad guys were just blown away. Then it showed a replay of their trip to the studio where they did this, and he had placed these little subliminal suggestions everywhere. One was a little sticker on the inside of their cab. One was on a road sign that they passed. One was a group of students that were wearing a t-shirt with a logo that passed in front of the car. And their brains picked all this stuff up. It was a really, really cool thing.

Josh Clark: That's awesome. What was the guy's name again?

Chuck Bryant: Darren Brown.

Josh Clark: What was the name of the clip? Do you remember?

Chuck Bryant: Darren Brown, subliminal advertising is how you find it.

Josh Clark: Nice, good to know. Very direct and appropriate! What are you doing there, Chuck? Are you okay?

Chuck Bryant: Well, yeah, my ear has got some gunk in it.

Josh Clark: Oh, yeah?

Chuck Bryant: Yeah, I could use a Q-tip, actually.

Josh Clark: Hey, Chuck, did you know that Q-tips were originally called baby gays?

Chuck Bryant: Gay as in gays?

Josh Clark: Uh huh.

Chuck Bryant: I didn't know that, but that sounds familiar.

Josh Clark: Yeah, back in the '20s.

Chuck Bryant: Interesting. Another aside! Sorry.

Josh Clark: Okay, so Chuck, then. Cell phone theory! Right? That's what it was called.

Chuck Bryant: Yes, that was Allen Brown.

Josh Clark: So it applies to déjà vu in that - I guess Dr. Brown is saying that we are - when we're not really paying attention, when we're distracted, we're still processing sensory information unconsciously. So then, let's say you walk into a room, and you're not really paying attention. You're talking to somebody. When you do turn your attention to your surroundings and you start putting that sensory input in consciously, that's where potentially where déjà vu comes in. Because we're comparing this new conscious sensory input to something our brain is already familiar with. And we're like, "Oh, I've been here before."

Chuck Bryant: Right. I know they found that some people that are stressed and have anxiety are more prone to it, which makes sense.

Josh Clark: They also found that people who are refreshed and rested are more prone to it. So yeah, we're still getting a handle on déjà vu.

Chuck Bryant: Yeah, one study says one thing. The other says the exact opposite of what that does.

Josh Clark: I've got another study, beautiful.

Chuck Bryant: Let's hear it.

Josh Clark: It's called the hologram study.

Chuck Bryant: Oh, good one.

Josh Clark: Okay, so this guy's name is Herman Sno. Sno. No W. He's Dutch. And he basically has a theory that memories are like a hologram, like a 3D construct. And they are - if you take just a small piece of it, you can reconstruct a memory from it. But if you take a very, very small fragment, the memory is not going to be completely accurate or true. So Dr. Snow's theory - or actually, I think he's a philosopher, maybe. His theory is that we have little snippets of memory brought back. We recall them that are triggered by something familiar. But then, we reconstruct those memories incorrectly, and we use that immediate experience. Say getting into a car, we have a memory that we have forgotten about a similar car. So but we still recall a little bit of it, but we reconstruct it around the car that we're in right now, and we feel like we've been there before.

Chuck Bryant: Right. He's a psychiatrist, by the way.

Josh Clark: Thank you for that. Thank you. No listener mail on that one.

Chuck Bryant: Fact checking as we go.

Josh Clark: Yeah, you're quick, Chuck. You got any more?

Chuck Bryant: Well, I know you probably wanted to hit the precognitive dream thing.

Josh Clark: Yeah, and I don't remember who came up with this one. Do you?

Chuck Bryant: Yeah, Swiss scientist Arthur Funkhouser.

Josh Clark: So Funkhouser, with the coolest name on the planet, he believed that we actually have dreams that pretend the future, essentially.

Chuck Bryant: Very cool.

Josh Clark: And that it's generally mundane stuff that we easily forget. And he actually conducted a study, I think, back in 1939 of a bunch of kids at Oxford and found that somewhere around like 12.7 percent of their dreams eventually bore a striking similarity to future events, and he said it's as simple as that. We have somehow have an ability to see what's coming down the road, and that's where déjà vu comes from.

Chuck Bryant: Well, I did like - you said it was usually more mundane things. What he theorized, and this makes sense, too, is that if it wasn't mundane, we're more likely to remember it in our, you know, just waking conscious. And these are the ones that slip between the cracks.

Josh Clark: Right. And since it was mundane, since we can forget it, that would explain that kind of hazy quality that déjà vu always has. You know? Nothing is quite right all of a sudden. It's pretty cool. And actually, interestingly, his theory was backed up by another study from 1988 that found similar results, except it was more in the 10 percent of dream, pretend the future.

Chuck Bryant: I think it's actually 10 percent of the people have dreams that could - not 10 percent of dreams.

Josh Clark: Are you sure?

Chuck Bryant: Yeah.

Josh Clark: I would say 10 to 12 percent of my dreams come true.

Chuck Bryant: Really?

Josh Clark: It's happening right now.

Chuck Bryant: You dreamed of having a podcast with me one day? Nice one, Chuck. Should we talk about jame vu?

Josh Clark: Yes, please.

Chuck Bryant: Jame vu is the opposite of déjà vu. I know a lot of people say vuja de, but that's just kind of a funny way to say it. Jame vu is actually a real term.

Josh Clark: I passed over this part in the article, Chuck. I'm not kidding. This is brand new to me.

Chuck Bryant: It was not in the article, my friend. It's called supplemental research. You should try it sometime.

Josh Clark: Oh, good. I thought I was having jame vu.

Chuck Bryant: No, jame vu is a real thing. It means never seen, and it's when a familiar situation is not recognized.

Josh Clark: It's like face blindness.

Chuck Bryant: Not really.

Josh Clark: Okay. It was worth a shot, Chuck.

Chuck Bryant: Right. Actually, have you ever had the situation where you said a word over and over in your head, and then the word starts to sound funny?

Josh Clark: Uh huh. That happens to me when I see it spelled.

Chuck Bryant: Right, exactly. That's jame vu, and basically, what's happening there is the word is just existing in its form, so the function and meaning is lost.

Josh Clark: Weird.

Chuck Bryant: You're not applying the function and meaning, so you say eggs benedict 15 times, and by the end of it - or if you write it out 15 times, you're going to be thinking, "Eggs benedict? What are eggs, and what is benedict? And what is hollandaise sauce?"

Josh Clark: This word looks so weird.

Chuck Bryant: Yeah, that's one example of jame vu.

Josh Clark: Don't forget the Canadian bacon, Chuck.

Chuck Bryant: Who can?

Josh Clark: I don't know.

Chuck Bryant: Our Canadian friends, we love your bacon.

Josh Clark: They just call it bacon up there.

Chuck Bryant: Yeah, well, we call it ham.

Josh Clark: That's true. So wow, Chuck! You dazzled me just now.

Chuck Bryant: Good, I like to do that from time to time.

Josh Clark: Well, that's déjà vu, I guess, for now until somebody finally submits down exactly what's going on. And again, I think the wonder machine is going to be the utility that does it for us.

Chuck Bryant: Déjà vu all over again, as Yogi Berra once said.

Josh Clark: Great man.

Chuck Bryant: Yeah.

Josh Clark: So Chuck, I know you love plugging the blog. You want to take the opportunity?

Chuck Bryant: Sure. I would like to direct everyone to our new blog, which is an internet term for blog. And Josh and I write on this thing a couple of times a day and we talk about cool stuff, and basically, the idea here was to get the Stuff You Should Know nation involved with each other. And leaving comments and talking to each other and reading about cool stuff that they should know instead of just listening to us say it.

Josh Clark: And also, don't forget to join the Stuff You Should Know nation. We are actually buying a plot of land. We'll be sending details out via our blog, ironically enough.

Chuck Bryant: Yeah, and you can access it through the homepage on HowStuffWorks.com. And it's called Stuff You Should Know.

Josh Clark: Yeah, appropriately enough.

Chuck Bryant: And you can see a lovely photo of Josh who looks as cute as a dang button.

Josh Clark: And Chuck in his flat cap looking good.

Chuck Bryant: That's right. It's good stuff. So now -

Josh Clark: Yeah, there's the blog plug. Let's do -

Chuck Bryant: Listener mail. You ready for this, Josh?

Josh Clark: I was born ready, Chuck.

Chuck Bryant: I have a couple of stuff we should know, which is our new, nicer name for corrections.

Josh Clark: Wait, I thought it was stuff we should have known.

Chuck Bryant: Sure. Sounds good! Christine Lee of Toronto, Ontario, and as a quick side note, I can't remember his name, but we had a Canadian friend write in and say it really bugs when we say like Montreal, Canada. He said that'd be like saying Atlanta, United States.

Josh Clark: Sorry.

Chuck Bryant: So we need to start saying the province.

Josh Clark: Bacon.

Chuck Bryant: So Christine Lee is of Korean descent, and she said in the Friday the 13th podcast, we talked about unlucky numbers in China and Japan, and again, in can people die of fright, we talked about the same thing. And it's actually true in Korea as well. And she feels like Koreans are often slighted to their Chinese and Japanese friends. So we need to start looking into other Asian countries, basically.

Josh Clark

Yes. We'll do that this afternoon.

Chuck Bryant: Apparently, four is an unlucky number in Korea, and thank you, Christine Lee for that.

Josh Clark: Sorry, Christine.

Chuck Bryant: And Chris from Pennsylvania, you're gonna love this one. He said he listened to the comas podcast. I'm surprised that between Josh's Magnum, PI knowledge and Chuck's movie knowledge that you guys never brought up the connection between Magnum and the 1978 movie Coma. Tom Selleck was actually in that movie, and I haven't seen it in years, but I remember him being one of the coma patients who is suspended on wires, and that is indeed true.

Josh Clark: I don't remember Tom Selleck in that one. My earliest memory of Tom Selleck in a movie was Looker.

Chuck Bryant: No, he wasn't in that.

Josh Clark: Okay, what was the other one with the robots then?

Chuck Bryant: Right. You're thinking of -

Josh Clark: Runaway. Runaway!

Chuck Bryant: Fair enough.

Josh Clark: Are you sure he wasn't in Looker?

Chuck Bryant: Yeah. That was Albert Finney. That was a great movie, though, for an '80s sci-fi.

Josh Clark: I agree. Susan Day is in it, too. All right. Well, we should probably get out of here before Chuck and I say something to embarrass ourselves. Right?

Chuck Bryant: Further.

Josh Clark: Yeah. So thanks for listening. I would advise everybody to go onto the site and check out how déjà vu works. Find an article written by our colleague Leanne Ovenger. There's a nice little Easter egg hidden in the article that may induce déjà vu in you. You can find that by typing in how déjà vu works in our handy search bar at HowStuffWorks.com. And if you want to send Chuck and I a message via electronic mail -

Chuck Bryant: A non haiku related message.

Josh Clark: Yes, Chuck, yes. Non haiku. You can alert us at StuffPodcast@HowStuffWorks.com.

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