Speaker 1: Welcome to Stuff to Blow Your Mind production of My
Speaker 1: Heart Radio. Hey, welcome to Stuff to Blow Your Mind.
Speaker 1: My name is Robert Lamb and I'm Joe McCormick, and
Speaker 1: we're back with part two of our talk about deja vu.
Speaker 1: That's right, if you didn't listen to part one, go
Speaker 1: back and listen to part one, because this is this
Speaker 1: is definitely one of those, uh pair of episodes where
Speaker 1: you need to experience them in order. But we we
Speaker 1: kicked off by talking about some personal experiences with deja vu,
Speaker 1: uh and also getting into some of the rich variety
Speaker 1: that is to be found under the broad categorization of
Speaker 1: deja vu experiences. In this episode, we're going to kick
Speaker 1: off by really getting into some of the major theories
Speaker 1: and explanations for this thing called deja vu. Right, So,
Speaker 1: last time I cited there's a major paper on the
Speaker 1: research on deja vu that was published in two thousand
Speaker 1: three by a researcher named Alan S. Brown, was published
Speaker 1: in Psychological Bulletin, and we cited it last time, talking
Speaker 1: about a lot of the common findings about deja vu,
Speaker 1: including the fact that it appears to be very strongly
Speaker 1: associated with stress and fatigue. The more tired and stressed
Speaker 1: out you are, the more likely you are to have
Speaker 1: a deja vu experience. The studies that show it associated
Speaker 1: with travel, people who travel are more likely to experience
Speaker 1: deja vu. Um, the studies that show that that certain
Speaker 1: drugs can apparently cause lots of deja vu. And then
Speaker 1: especially the fact that deja vu appears to decrease with age,
Speaker 1: that as you get older in life, you you on
Speaker 1: average have fewer deja vu experiences, which I'm still finding
Speaker 1: interesting and I'm coming back to that one a lot.
Speaker 1: But yeah, So now we want to dive into, uh,
Speaker 1: the major theories and explanations, and my main guide on
Speaker 1: this is Brown's paper from two thousand three where he
Speaker 1: he reviews most of the existing research. There's been a
Speaker 1: few develop elements since then, and we'll talk about those
Speaker 1: later on, but they're they're basically several. They're like four
Speaker 1: main categories that Brown outlines about what the explanations for
Speaker 1: deja vu could be. And the categories are going to
Speaker 1: be the following. So first, you've got some kind of
Speaker 1: dual processing. Second, you've got neurological dysfunction, Third, you have
Speaker 1: memory issues, and then fourth you have attentional catch up. Um. Now,
Speaker 1: one of the first things I think we should mention
Speaker 1: is that it can be kind of difficult to understand
Speaker 1: the causes of deja vu because deja vu is inherently
Speaker 1: a little bit difficult to study. It's not super easy
Speaker 1: to trigger episodes of deja vu in a laboratory or
Speaker 1: brain imaging context. There's some techniques we can mention, but
Speaker 1: you can't just like start up an f M R
Speaker 1: I and then run it and hope somebody has an
Speaker 1: experience of deja vu while it's running. Remember, like, deja
Speaker 1: vu is relatively rare. Most people experience it at some
Speaker 1: point in their life. But I think you know, an
Speaker 1: average figure figure is that a lot of people say
Speaker 1: they have a deja vu experience something like once a year.
Speaker 1: So you couldn't expect for it to just happen while
Speaker 1: you're looking for it. Yeah, deja vu is not really
Speaker 1: the sort of thing you can just have on command.
Speaker 1: Nobody can say, all right, have some deja vu. And likewise,
Speaker 1: it's not that I haven't seen I don't think I've
Speaker 1: seen any evidence or any claims of anybody who could
Speaker 1: produce a feeling of deja vu. Just by willing it
Speaker 1: that we will get into some unique cases a little later, right. Uh.
Speaker 1: That would be an interesting uh skill if one had it. Now.
Speaker 1: There are some cases where it appears that deja vu
Speaker 1: can be triggered by certain clinical interventions. We mentioned a
Speaker 1: couple of cases of it being associated with certain combinations
Speaker 1: of drugs in the last episode, like a couple of
Speaker 1: drugs used to treat the flu um. But also by
Speaker 1: no big surprise here, electrical stimulation of the brain. Uh.
Speaker 1: In his big review, Brown described abs findings about deja
Speaker 1: vu and brain stimulation and patients with temporal lobe epilepsy. Again,
Speaker 1: remember um from last time that deja vu is one
Speaker 1: of the symptoms that has been described as part of
Speaker 1: the aura preceding and epileptic seizure in people with temporal
Speaker 1: lobe epilepsy. But another thing about temporal lobe epilepsy is
Speaker 1: that in some cases in history, electrical stimulation of the
Speaker 1: brain has been used in the treatment and diagnosis of
Speaker 1: temporal lobe epilepsy. UM. And so I want to read
Speaker 1: a section from Brown here writing about this. Brown writes,
Speaker 1: quote with surface stimulation of the cortex, and that's electrical
Speaker 1: stimulation Mullen and Penfield elicited deja vu experiences in ten
Speaker 1: out of two hundred and seventeen people with temporal lobe epilepsy.
Speaker 1: Recent procedures involving deep electrode brain implantation have shown that
Speaker 1: deja vu, similar to one that occurs in the aura,
Speaker 1: can be elicited with stimulation of the amygdala and hippocampus,
Speaker 1: Although these experiences were not reported in detail. The deja
Speaker 1: vu generally consisted of a sudden feeling of unfamiliarity in
Speaker 1: the hospital environment and was often accompanied by epigastric phenomena
Speaker 1: and fear and uh. Epigastric phenomena refers to strange feelings
Speaker 1: in the abdomen, especially I think the upper part of
Speaker 1: the abdomen. I've read it described as um getting a
Speaker 1: feeling sort of above the stomach and right below the chest,
Speaker 1: like this weird feeling, kind of like when you're on
Speaker 1: a roller coaster and you're you're plummeting down on the
Speaker 1: other side, you know that rising in the gut. Yeah, yeah,
Speaker 1: I believe we discussed that a little bit in the
Speaker 1: last episode. Brown writes quote. The elicitation of deja vou
Speaker 1: through electrical stimulation may not be reliable hal grin at all.
Speaker 1: In nineteen seventy eight, stimulated several dozen brain locations in
Speaker 1: a group of people with temporal lobe epilepsy on two
Speaker 1: different occasions, two weeks apart, and found that a number
Speaker 1: of sites that elicited a deja vu on one session
Speaker 1: did not do so on the other. Deja vu experiences
Speaker 1: also resulted from stimulating the non diseased hemisphere, suggesting that
Speaker 1: the experience is not necessarily specific to the tissue where
Speaker 1: the seizure originates. So that's interesting. You've got deja vu
Speaker 1: associated in some cases with people with temporal lobe epilepsy,
Speaker 1: but that it appears like if you you stimulate one
Speaker 1: part of the brain one week and it gives you
Speaker 1: deja vu, but a different part of the brain the
Speaker 1: next week that might give you deja vu, and maybe
Speaker 1: the original place that gave you deja vu last week
Speaker 1: doesn't give it to you anymore. So, uh yeah, there's
Speaker 1: some kind of discontinuity here about how exactly stimulating different
Speaker 1: parts of the brain contribute to the deja vu experience subjectively.
Speaker 1: But there have been some other interesting things that I
Speaker 1: know we'll get too later in the episode of trying
Speaker 1: to trigger deja vu and otherwise neurologically typical people, for example,
Speaker 1: using using certain types of virtual reality stimulation. That, yeah,
Speaker 1: I think we're we'll get to that maybe in the
Speaker 1: third part of today's episode, But I guess we got
Speaker 1: to get directly to these four main theories explaining what
Speaker 1: could be going on in the brain when you're having
Speaker 1: deja vu. Um, assuming it's not like a supernatural phenomenon,
Speaker 1: which we don't think it is, that there's a good
Speaker 1: amount of evidence that it is a function of the brain.
Speaker 1: So the ghost hypothesis is really not not not highly
Speaker 1: valued scientific circles here. Yeah, so we won't be picking
Speaker 1: up on that one today. But so again, these are
Speaker 1: the four main branches that brown outlines are dual processing,
Speaker 1: neurological dysfunction, memory error, and attentional catch up. And I'll
Speaker 1: go ahead and say that I think the main two
Speaker 1: branches that have explanatory power going for them today, at
Speaker 1: least as far as I can tell, are the last
Speaker 1: two I mentioned, like the memory ones and the attentional ones.
Speaker 1: But since the other two have been very important in
Speaker 1: the history of studying deja view, we should at least
Speaker 1: talk about them for a bit. Um. So the first
Speaker 1: one is this idea of dual processing. There are these
Speaker 1: multiple hypotheses that fall into this category, but they all
Speaker 1: basically amount to the same thing. They say, you know,
Speaker 1: there are two different processes in the brain that usually
Speaker 1: occur simultaneously. They happen at the same time, but occasionally
Speaker 1: they become a synchronous, they get detached in time and
Speaker 1: suddenly there's a lag between them. And these types of
Speaker 1: explanations tend to be the oldest and least scientifically justified,
Speaker 1: but they are kind of interesting to think about. So,
Speaker 1: for example, one that Brown sites is the idea of
Speaker 1: this old theory of dual consciousness. Uh. The idea is
Speaker 1: that there there are two separate types of consciousness in
Speaker 1: the brain. There's one normal type of consciousness, and what
Speaker 1: that does is monitor everything that happens in the outside world. It's,
Speaker 1: you know, your regular brain that's looking out through your
Speaker 1: eyes and sees what's going on. And then the other
Speaker 1: version is the parasitic consciousness, which we might refer to
Speaker 1: as metacognition. It monitors the internal state of the brain itself.
Speaker 1: And under this old hypothesis, deja VU is created when
Speaker 1: normal consciousness is impaired by something like fatigue or stress,
Speaker 1: and it's left up to the parasitic consciousness to evaluate
Speaker 1: incoming information. And because the parasitic consciousness is not well
Speaker 1: adapted to evaluating incoming information, it gets confused, and it
Speaker 1: confuses what it's looking at now for a memory of
Speaker 1: the past. Uh. While I like this idea, this one
Speaker 1: appears to be entirely speculative. It's mostly based on like
Speaker 1: nineteenth century conceptions of the mind and brain. So I
Speaker 1: don't think this one is very likely a good explanation today.
Speaker 1: Now another one, uh in this branch is would be
Speaker 1: like encoding and retrieval. Brown says, this was proposed by
Speaker 1: Denayer in nineteen seventy nine, and basically it takes the
Speaker 1: form of a metaphor of the brain is a combination
Speaker 1: tape recorder and player. Uh did you did you have
Speaker 1: one of those when you're a kid? Robert? Oh? Yeah,
Speaker 1: of course, but yeah, okay, So the metaphor here by
Speaker 1: Dena Air is that your brain has a combination tape
Speaker 1: recorder and player. And and Brown explains this well, so
Speaker 1: I'm going to quote from him quote under normal conditions
Speaker 1: memory encoding and retrieval operate in a manner similar to
Speaker 1: the record and play heads respectively. On a tape recorder.
Speaker 1: Either the record in code or the play retrieve head
Speaker 1: can be on, but not both at once. On rare occasions,
Speaker 1: the tape machine and a person's memory has both record
Speaker 1: and play heads active simultaneously during a new experience, creating
Speaker 1: a false sense of familiarity for the newly encoded experience.
Speaker 1: So basically, the idea is that you are experiencing the
Speaker 1: memory as it is happening, um, which sounds paradoxical, but
Speaker 1: but the idea of encoding and retrieving happening at the
Speaker 1: same time. Yeah, and so this never Brown says, this
Speaker 1: hypothesis never really got developed beyond just this metaphorical stage.
Speaker 1: Like he never you know, got into the nitty gritty
Speaker 1: of like what parts of the brain this would exactly
Speaker 1: be involving and how it would work. Um. But I
Speaker 1: would say, while it is still at this metaphorical stage,
Speaker 1: this is kind of close to some later, later explanations
Speaker 1: that are backed up by more empirical research. I think
Speaker 1: it's not quite on the money, but it's it's getting
Speaker 1: part of the way there, especially I think, especially with
Speaker 1: with some of the ones that we'll talk about with
Speaker 1: with attention later on. Yeah, and also like how it
Speaker 1: kind of helps to further breakdown the nature of of
Speaker 1: something that is novel and something that is familiar and
Speaker 1: how it basically works, you know, in our experience of
Speaker 1: cognitive data. Yeah. Well, and it makes me think about how, um,
Speaker 1: in a way, there's almost no real objective thing that
Speaker 1: is novelty. You know that, Like every time you're looking
Speaker 1: at anything in the world, in a way, it's sort
Speaker 1: of novel because like your heads in a different position,
Speaker 1: and you'll even if you're looking at something you've looked
Speaker 1: at a thousand times before, the lights kind of different,
Speaker 1: you're looking at it from a slightly different angle. The
Speaker 1: brain just does a does a very good job taking
Speaker 1: things that are you know, different data sets coming in
Speaker 1: through the eyes or the ears or whatever it is,
Speaker 1: and saying like, Okay, you know what that is. That's
Speaker 1: the same coffee cup you've looked at a thousand times,
Speaker 1: even though it's not a photo exact copy of how
Speaker 1: it looked the last time you looked at it. Yeah,
Speaker 1: I mean, as since data goes the details of the
Speaker 1: coffee cup are not that important, And the brain does
Speaker 1: a pretty good job in in UM working with the
Speaker 1: senses of letting that kind of fade into the background.
Speaker 1: But then you know, any day you're able to pick
Speaker 1: up that coffee cup and really focus on it and
Speaker 1: kind of see it for the first time. And that's
Speaker 1: one of the the crazy things about the the close
Speaker 1: relationship between the novel and the familiar. Yeah, and that
Speaker 1: emphasizes that like the novel and familiar, they're not objective
Speaker 1: features of the world. They're like subjective simulation sans yeah.
Speaker 1: This is this is almost an example of this, but
Speaker 1: not quite. Um. I I don't I've had an Xbox
Speaker 1: one controller for so long and I just discovered you
Speaker 1: can plug headphones into the controller itself to get sound. Totally.
Speaker 1: It's changed my life here in um. You know, self isolation. Oh,
Speaker 1: now late in the night, your house is not filled
Speaker 1: with tiny screams that right, right? Yeah, I want to Yeah,
Speaker 1: if I want to play Doom Eternal at a at
Speaker 1: a weird hour, I can. I can be the only
Speaker 1: one to hear it. Likewise, my son is trying out
Speaker 1: Minecraft for the first time, and we can plug him
Speaker 1: into the the controller and then if he jerks the
Speaker 1: controller around, he's not pulling things off of the you know,
Speaker 1: the TV tray or something. So uh so yeah, but
Speaker 1: but you know, there's an example. I don't know how
Speaker 1: many times I've looked at this device, but I've never
Speaker 1: seen this detail. And uh uh. You know a lot
Speaker 1: of things in life are like that. You know, when
Speaker 1: you really really stop to look at at it, you
Speaker 1: can you can uncover the novel wrinkles and the thing.
Speaker 1: I might want to come back to this example later
Speaker 1: in the episode. Uh and maybe when we talk about
Speaker 1: the memory and intentional branches. Okay, two more examples of
Speaker 1: dual processing hypotheses. So another one Brown sites is. The
Speaker 1: idea of perception and memory seems kind of similar to
Speaker 1: the last one. It was proposed by a researcher named Bergson. Basically,
Speaker 1: it supposes that perception and memory formation happened at the
Speaker 1: same time. Like, you know, I I look at Gritty,
Speaker 1: the Philadelphia Flyers mascot for the first time, my brain
Speaker 1: sees him creates the memory of having seen him simultaneously.
Speaker 1: Bergson suggests that sometimes stress or fatigue can cause the
Speaker 1: newly formed memory to bump into perception, so that I
Speaker 1: get the feeling that I have seen Gritty before. Again,
Speaker 1: this one is kind of fuzzy and speculative as far
Speaker 1: as hypotheses go. Well, you know, we all feel that
Speaker 1: we've seen Gritty before because Gritty was with us in
Speaker 1: the womb. Gritty is primordial. Yeah, Gritty was there before
Speaker 1: we were born. You know that's going to happen one day,
Speaker 1: like they they a big block of shale shares away
Speaker 1: from a Cambrian formation and then just just the outline
Speaker 1: of Gritty there among the trial bites. He was waiting
Speaker 1: the whole time. Okay, But then the fourth one of
Speaker 1: these dual processing hypotheses potheses. Sorry, this is the only
Speaker 1: one of the four that really seemed all that plausible
Speaker 1: to me. So this one is called familiarity and retrieval.
Speaker 1: And this was proposed by a researcher named Glure in
Speaker 1: nineteen nine. And Glore suggested that when we encounter an
Speaker 1: image or an object or scenario or whatever it is
Speaker 1: that we've seen before, there are two separate things that happen.
Speaker 1: One is the retrieval of the past memories about that thing.
Speaker 1: So I see Gritty, I have seen him before, and
Speaker 1: I remember the other times I saw Gritty and had
Speaker 1: thoughts about him. But the other thing is the emotion
Speaker 1: of familiarity that accompanies the recall. So I see Gritty,
Speaker 1: I have memories, but also I have a feeling. It's
Speaker 1: this emotional feeling that, oh, I know who that is.
Speaker 1: Uh that you know that is Gritty. I feel familiar
Speaker 1: with what's going on right now. And from what I
Speaker 1: can tell, there's not really any direct evidence for this hypothesis,
Speaker 1: but this one does seem kind of plausible to me
Speaker 1: because we've talked about other cases of mismatch between recognition
Speaker 1: and familiarity. For example, in talking about cap Graw delusion,
Speaker 1: I think we mentioned in Part one, which is this
Speaker 1: delusion often caused by brain injury, in which a person
Speaker 1: believes that their loved ones have been replaced by lookalikes
Speaker 1: or doppelgangers. And it's believed that cap Graw delusion stems
Speaker 1: from a malfunction in the brain where recognition is triggered.
Speaker 1: So you see a person and you know who you're
Speaker 1: looking at, like, yes, you know that that is Jeff,
Speaker 1: but the normally accompanying feeling of familiarity is not there.
Speaker 1: It doesn't get triggered. So you see somebody recognize as Jeff,
Speaker 1: but he does not feel familiar. It doesn't feel like
Speaker 1: your old friend, so you say, oh, he's and replaced
Speaker 1: by a look alike. What's normally a case of dual
Speaker 1: processing here has been severed. So if a dual processing
Speaker 1: failure like this we're actually an explanation for deja vu,
Speaker 1: I think it would have to go the opposite way, right,
Speaker 1: It would have to go the opposite of cap Graw delusion,
Speaker 1: where a feeling of familiarity is triggered while actual retrieval
Speaker 1: of associated memories is not. And along these lines of
Speaker 1: cap Graw delusion would would actually be more analogous to
Speaker 1: the inverse of deja vu that we mentioned last time,
Speaker 1: jama vu, in which a familiar object suddenly feels unfamiliar.
Speaker 1: But again, from what I can tell, this kind of explanation,
Speaker 1: I think it's perfectly possible, but I can't find direct
Speaker 1: experimental evidence for it, so I think it might just
Speaker 1: remain right now in the realm of like, yeah, maybe
Speaker 1: something like this could explain some cases of deja vu,
Speaker 1: but we we don't have strong evidence that these explanations
Speaker 1: are the right ones yet. Alright, Well, on that note,
Speaker 1: let's take a quick break, but when we come back,
Speaker 1: we will continue to explore some of the explanations for
Speaker 1: what may be going on with deja vus. Thank thank alright,
Speaker 1: we're back, all right. So we just talked about the
Speaker 1: first branch of possible explanations for deja vu. Uh, probably
Speaker 1: the oldest branch of explanations, which was the idea of
Speaker 1: dual processing that when you experienced deja vu, it's because
Speaker 1: two different things that normally happened in the at the
Speaker 1: same time in the brain get severed and one happens
Speaker 1: after the other one, or they get you know, one
Speaker 1: happens without the other one, and this causes this this
Speaker 1: disconnect um. The next branch of explanations that Alan S.
Speaker 1: Brown offers in his two thousand three paper are neurological explanations. Now,
Speaker 1: the first one is seizures. We know that deja vu
Speaker 1: is a you're not not super common, but a recognized
Speaker 1: experience in the aura of people who have temporal lobe epilepsy.
Speaker 1: So what if normal deja vu do you that happens
Speaker 1: in you know, sixty percent of people at some point
Speaker 1: it's actually just a kind of mild seizure. A lot
Speaker 1: of people have proposed this over the years, but Brown
Speaker 1: says that the evidence for this does not appear to
Speaker 1: be very good. Though deja vu is a feature of
Speaker 1: seizures for people with t l E, people with epilepsy
Speaker 1: in general are not more prone to every day deja
Speaker 1: vu than people without epilepsy, and people who experience more
Speaker 1: episodes of deja vu than average are not any more
Speaker 1: prone to seizures than anybody else. So again, we can't
Speaker 1: actually look at deja vu as it's happening and compare
Speaker 1: it to say, what's happening in the brain during a seizure,
Speaker 1: but we can look at frequency, uh, between these two
Speaker 1: sets of of individuals. Yeah, and so it just doesn't
Speaker 1: look like seizures are going to be a good explanation
Speaker 1: for deja vu. Generally, it looks more like there might
Speaker 1: you know, deja vu just happens to be one of
Speaker 1: the things that sometimes happens in the brain of somebody
Speaker 1: about to have a seizure, but it's not overall a
Speaker 1: generalized seizure phenomenon um. Now, the other major near a
Speaker 1: logical explanation that Brown sites is neural transmission delay, and
Speaker 1: this refers to a set of explanations where information traveling
Speaker 1: from the perceptual organs such as the eye. Uh, it's
Speaker 1: traveling to different parts of the brain, and it gets
Speaker 1: delayed along one of those pathways by neuronal misfiring or
Speaker 1: some of their malfunction. And one example that's given is
Speaker 1: the two different hemispheres of the brain usually receive information
Speaker 1: at the same time. But what if one hemisphere realizes
Speaker 1: that you're looking at gritty slightly after the other one does,
Speaker 1: And under this hypothesis, the delay causes a freshly perceived
Speaker 1: stimulus to be interpreted as old information because one part
Speaker 1: of the brain has already experienced it by by the
Speaker 1: time it gets to the other part. Well, this seems
Speaker 1: like a good place to move on to some of
Speaker 1: the additional explanations, because we're talking about old information. What
Speaker 1: he's old information but a memory. Yeah, exactly. So now
Speaker 1: we're getting into those were the two older branches. Now
Speaker 1: we're getting into the branches that I think are more
Speaker 1: were favored among researchers today, the memory based explanations, especially
Speaker 1: implicit memories and attentional explanations. Uh. Now, Robert, if we
Speaker 1: if we go to memory based I think you're going
Speaker 1: to get into this branch of explanations a little bit
Speaker 1: more when you talk about the research by and M
Speaker 1: cleary and Alexander B. Claxton. Later on, I saw you
Speaker 1: had something about that, So maybe we can talk more
Speaker 1: in depth about the memory based explanations then, but just
Speaker 1: do a short version now. The gist here is that
Speaker 1: desha vou is perhaps uh maybe it has something to
Speaker 1: do with the way that memories are encoded and retrieved.
Speaker 1: So imagine you're in one of these deja vu scenarios.
Speaker 1: Maybe you're you're going down a staircase into a basement
Speaker 1: in a house, and you suddenly get this flash like, oh,
Speaker 1: I've been here before, but you haven't been here before.
Speaker 1: What if when you're experiencing deja vu on that staircase,
Speaker 1: you are remembering something you've seen before. It's just not
Speaker 1: this house. It's not the same thing you're looking at now.
Speaker 1: You're feeling familiarity because of some vague features of similarity
Speaker 1: that overlap with your current experience and some other memory
Speaker 1: that you are not directly accessing in full. Maybe when
Speaker 1: I experienced the deja vu of like running into a
Speaker 1: tree branch while playing in the yard. The feeling of
Speaker 1: familiarity with the scene comes from the fact that there
Speaker 1: was some other time I was playing in maybe a
Speaker 1: similar looking place or a place with similar spatial arrangements
Speaker 1: of objects, and my friends were standing around me in
Speaker 1: a similar kind of orientation, and maybe I was injured
Speaker 1: or or fell down in some other way. Except I
Speaker 1: don't explicitly recall that whole episode. I don't remember where
Speaker 1: it was, or who was there or what happened. I
Speaker 1: just recall enough to recognize some basic congruities. And this
Speaker 1: leads to that strange feeling of familiarity with no obvious
Speaker 1: point of reference. So almost as if the the emotional
Speaker 1: pattern of something that occurred stuck with you, but details
Speaker 1: of it did not, um and and that's what gets recalled, right,
Speaker 1: or details might have stuck with me in a way
Speaker 1: that doesn't allow me to access the full scene as
Speaker 1: a memory, right. So, like, I think a common thing
Speaker 1: that's brought up in this kind of memory research is
Speaker 1: like like spatial arrangements of things. You know, like if
Speaker 1: you feel deja vous in a room, maybe you're not
Speaker 1: in that room before, but we're in a room where
Speaker 1: like the furniture was arranged in a very similar way,
Speaker 1: and you don't explicitly recall that old memory, but something
Speaker 1: gets triggered in like the navigation parts of your brain,
Speaker 1: like what what's going on? I know this place? Yeah,
Speaker 1: I mean it. We had to have to remind ourselves
Speaker 1: that as far as novelty goes in life, oh, there's
Speaker 1: only so much novelty that is really possible to a
Speaker 1: certain extent, you know what I mean. Even if you
Speaker 1: live a you know, a wild and varied life full
Speaker 1: of of of travel and exploring new things, you're going
Speaker 1: to encounter lots of situations that fit into more or
Speaker 1: less the same uh pattern. You know, you're going to
Speaker 1: go to a bathroom that looks a lot like other bathrooms.
Speaker 1: You're going to do things more or less the same
Speaker 1: way that you've done it before. I mean, we're we're
Speaker 1: creatures of habit, we are creatures of pattern, and for
Speaker 1: many things in life, they're they're only so many approaches
Speaker 1: to how we might react to something or carry something out.
Speaker 1: Uh yeah, yeah. No, novelty is total illusion, eternal recurrence.
Speaker 1: You we've all been through this before. In fact, I
Speaker 1: think you've said that before. No, I haven't. I don't
Speaker 1: really mean that, um, you know. And so I was
Speaker 1: thinking about this. I was thinking about, Wow, this might
Speaker 1: sound like a weird way for the brain to work,
Speaker 1: that you could have this feeling of familiarity about a
Speaker 1: memory that you cannot explicitly recall. But I think there
Speaker 1: are there are analogies to this and things that we've
Speaker 1: discussed before. I was brought back to the idea of
Speaker 1: tip of the tongue phenomenon. We did a whole episode
Speaker 1: of stuff to blow your mind about this. Um you know,
Speaker 1: this is where Hey, what's the name of the actor
Speaker 1: who played riff Raff in Rocky Horror Picture Show. Well,
Speaker 1: the correct answer is Richard O'Brien. But there were some
Speaker 1: people listening right there who were like, oh, oh, I
Speaker 1: know that, I know that, but you couldn't quite come
Speaker 1: up with it, right. Why is it that you can
Speaker 1: feel like you know a word or feel like you
Speaker 1: know a name even though you can't conjure the word
Speaker 1: or the name up right now. Perhaps a similar thing
Speaker 1: happens with images or situations, kind of like a tip
Speaker 1: of the tongue effect for things other than words, for
Speaker 1: situations or for you know, images, you look at with
Speaker 1: your eyes. You feel like you recognize this scene, but
Speaker 1: you can't actually call up the memory that is causing
Speaker 1: that feeling of familiarity, so I think, and there is
Speaker 1: actually some research to back up certain memory based explanations
Speaker 1: for for some day javou experiences. So at least as
Speaker 1: far as I can tell, I think the memory based
Speaker 1: explanations might not explain all deja vu, but are a
Speaker 1: pretty strong candidate for explaining some cases of it. All right, well,
Speaker 1: let's move on to attentional explanations, which which I think
Speaker 1: is an exciting area because I think a lot of
Speaker 1: the mysteries of human consciousness make more sense to me
Speaker 1: when I had when I hear them explained in terms
Speaker 1: of attention. Yeah, me too, And I think this branch
Speaker 1: has a lot going for it. This is the fourth
Speaker 1: of four, uh, and so these explanations are some of
Speaker 1: the most simple, actually, but they make a lot of
Speaker 1: sense to explain some cases of deja vu, and there
Speaker 1: is actually some experimental evidence in support of them. So
Speaker 1: imagine you're driving a car, right, and maybe while you
Speaker 1: are driving, you're having a tense emotional conversation with the
Speaker 1: passenger of the car. Maybe it's you know your spouse
Speaker 1: or partner, or you know your your child or parent
Speaker 1: or relative. You're having an argument or something, so your
Speaker 1: attention is kind of divided, maybe like you're not paying
Speaker 1: as full attention to the road and of you as
Speaker 1: you should be. Then suddenly you see a man in
Speaker 1: a cowboy hat pushing a grocery cart full of Monster
Speaker 1: Energy drinks down the sidewalk, and you think, whoa deja vu?
Speaker 1: Why do I feel like I've seen this guy before?
Speaker 1: Under the attentional model, the answer could be that you
Speaker 1: did see him before a couple of seconds ago, but
Speaker 1: your attention was divided, and because you had your attention
Speaker 1: wrapped up in this intense conversation and you weren't paying
Speaker 1: as much attention as you should have been to the road,
Speaker 1: you didn't consciously register seeing this guy a couple of
Speaker 1: seconds before, but you did see him with some diminished
Speaker 1: portion of your attention, And when you finally focus full
Speaker 1: attention on him, he feels familiar, even though you're just
Speaker 1: now consciously registering him. You know in a in a way,
Speaker 1: this reminds me of a like a non dejavou experience
Speaker 1: that I have sometimes where I'll I'll run across a
Speaker 1: study or a paper that I maybe just glanced at
Speaker 1: in the past, or maybe I only read the headline.
Speaker 1: But now I've come back around to it, and I'm
Speaker 1: reading it, you know, more closely, you know, and I'm
Speaker 1: actually taking it in. And then I realized, Oh, I think,
Speaker 1: I think I do vaguely remember this study from when
Speaker 1: it originally popped up. Yeah, I mean, I mean in
Speaker 1: that case, there's more of a time gap, right, So
Speaker 1: your memory, I think, would be more accurate. Actually, And
Speaker 1: I know exactly what you're talking about. I have that
Speaker 1: feeling too, where like I I sort of graze over something, um,
Speaker 1: you know, text content, and then I come back to
Speaker 1: it later and it feels vaguely familiar, like out of
Speaker 1: a dream, because I didn't read it really closely the
Speaker 1: first time. But this time, instead of it being like
Speaker 1: a gap of five years, it's a gap of say
Speaker 1: like five seconds exactly. In Brown's words quote, a brief
Speaker 1: initial perception of a scene under diminished attention is followed
Speaker 1: immediately by a second perception under full attention. The second
Speaker 1: impression matches that experienced moments earlier under degraded attention, and
Speaker 1: the individual does not consciously identify the prior experience as
Speaker 1: moments old, but rather attributes it to a more distant past. Uh.
Speaker 1: And I think that there's a lot of potential in
Speaker 1: this explanation. This could be what's going on in some
Speaker 1: of these cases. Yeah, I feel like this one feels
Speaker 1: like it fits really well with a lot of deja
Speaker 1: vu experiences that that I can relate to. I'm not
Speaker 1: sure that it fits as easily or or I think it.
Speaker 1: It may still fit, but perhaps a little more sort
Speaker 1: of cognitive work to figure out how it fits with
Speaker 1: some of the other examples of the deja vu experience
Speaker 1: that we've either discussed or will discuss. Yeah, I think
Speaker 1: you're right, And I would be strongly inclined to suspect
Speaker 1: that there are different explanations for different cases of deja vu,
Speaker 1: that there's not just like one trigger that creates all
Speaker 1: deja vu experiences, that it's, you know, just different kind
Speaker 1: of things going on. My gut feeling here is that
Speaker 1: probably some cases are best explained by h by the
Speaker 1: implicit memory thing that we were talking about a minute ago,
Speaker 1: and then other ones are better explained by the attentional
Speaker 1: divide thing and then of course there are a few
Speaker 1: that are probably just direct neurological issues, like you know,
Speaker 1: when the brain is being stimulated or when there's a seizure. Now,
Speaker 1: I'd like to come back to the link between anxiety
Speaker 1: and deja vu, because I found a very interesting study
Speaker 1: on this. Um. Apparently there is somewhat limited literature on
Speaker 1: the connection between anxiety and deja vu. But one one
Speaker 1: paper on the topic I came across was titled Persistent
Speaker 1: Psychogenic Deja Vu a Case Report, And this was by Wells, H.
Speaker 1: Moulin and Eth Ridge, and it was published in the
Speaker 1: Journal of Medical Cases Case Reports. Uh, and this was
Speaker 1: from So the researchers present the case of a twenty
Speaker 1: three year old British man with a form of persistent
Speaker 1: deja vu and this is observed in two he was
Speaker 1: three years into his symptoms at that point. So, UM,
Speaker 1: and if you're you're wondering, well, what is persistent deja vus,
Speaker 1: it's basically what it sounds like. But I think more
Speaker 1: of this will come come across as I as I
Speaker 1: roll through his briefly through his case history. So the
Speaker 1: subject here had a history of anxiety and de personalization
Speaker 1: depersonalization UH if anyone doesn't remember as a state in
Speaker 1: which one's thoughts and feelings seem unreal or not to
Speaker 1: belong to one's self, and it may also entail a
Speaker 1: loss of all sense of identity. He also had a
Speaker 1: family history of obsessive compulsive disorder, so they when they
Speaker 1: when doctors looked at him, they didn't detect any neurological
Speaker 1: abnormalities and they assessed his recognition memory with tasks that
Speaker 1: were frequently used with dementia patients, and they found no
Speaker 1: memory defects. They found that he consistently understood the false
Speaker 1: nature of the deja vus he was experiencing as well,
Speaker 1: coming back to a key aspect of deja vu that
Speaker 1: we were discussed in the first episode. So his reality
Speaker 1: testing was basically intact as far as the hotel when
Speaker 1: he didn't actually think that he was really having memories
Speaker 1: of the present. Right. So, the patient's history of anxiety
Speaker 1: was tied with fears of contamination, which led to excessive
Speaker 1: hand washing and showers two to three times a day,
Speaker 1: and then college anxiety made things worse, so he took
Speaker 1: a break from it and he began to experience episodes
Speaker 1: of anxiety in deja vu that would last for minutes
Speaker 1: or even longer. They point out that he went on
Speaker 1: holiday at one point during this period to a city
Speaker 1: that he had visited before, so he did have prior,
Speaker 1: you know, memories of having been there. But he felt
Speaker 1: as if he had become quote trapped in a time
Speaker 1: loop the whole time, and the experience was apparently somewhat terrifying.
Speaker 1: So even though he knew, Okay, I'm not actually in
Speaker 1: a time loop, it feels like I'm in a time loop.
Speaker 1: I know I'm not, but it's really still terrifying to
Speaker 1: experience totally, all right. And then he returned to college
Speaker 1: in two thousand seven, and during this time tried the
Speaker 1: psychedelic compound LSD, and they write, quote from then on,
Speaker 1: the deja vu was fairly continuous. So quick note for everyone.
Speaker 1: As you'll remember from our what five part series on psychedelics, UH,
Speaker 1: this would this would seem to fall in line with
Speaker 1: the observation that the psychedelic experience can for individuals with
Speaker 1: a pre disposition exasperate a psychological condition. UH. Typically one
Speaker 1: hears about this in regards to schizophrenia. So at this
Speaker 1: point our subject is is experiencing near constant deja vus,
Speaker 1: so he goes to see a specialist. They found that
Speaker 1: he was experiencing anxiety in low mood, but for the
Speaker 1: most part, uh Like, everything was normal. I think his
Speaker 1: disassociative events scale score was slightly abnormal. Uh but but
Speaker 1: but otherwise it was it was just this deja vu effect.
Speaker 1: Um and And interestingly enough, they write that he took
Speaker 1: to avoiding music and TV because he would invariably feel
Speaker 1: that he had seen or heard the material before, and
Speaker 1: then this would play into his deja vu experience or
Speaker 1: make it more pronounced. Uh. And I found this to
Speaker 1: be interesting. You know this idea because this gets back
Speaker 1: to the idea of the novel and the familiar, Because
Speaker 1: if deja vu is largely the experience all of the
Speaker 1: novel as familiar, then would extreme cases like this require
Speaker 1: one to just try to avoid novel things as much
Speaker 1: as possible. M Yeah, just surround yourself with what's actually
Speaker 1: familiar so that when it feels familiar, it doesn't feel unusual.
Speaker 1: I mean, this is this case sounds really disturbing because
Speaker 1: I don't normally think of deja vu as something that
Speaker 1: is inherently unpleasant when I feel it. It is strange,
Speaker 1: but it's not. It doesn't hurt, you know it, It's
Speaker 1: not in itself, uh, you know, worrying or or upsetting.
Speaker 1: But I can absolutely see how if it persisted over
Speaker 1: time it could take on that character. Yeah, I mean,
Speaker 1: a sneeze isn't that bad, But we wouldn't want to
Speaker 1: sneeze constantly. Uh. And I would say that like a
Speaker 1: typical deja vu experience for me, and I think for
Speaker 1: most people, is far less distracting than a sneeze. Um. Uh.
Speaker 1: And And however, I will say that those experiences that
Speaker 1: I related in the first episode that I had recently, um,
Speaker 1: those were those were more potent, Those were those were
Speaker 1: certainly more powerful. And I would not I certainly would
Speaker 1: not want to feel that all the time either. So
Speaker 1: the researchers in this case, though, they proposed that the
Speaker 1: form of deja vous described here it might more accurately
Speaker 1: be described as deja viku. Uh. This particularly strong sensation
Speaker 1: of reliving the present moment quote. He complained that it
Speaker 1: felt like he was actually retrieving previous experiences from memory,
Speaker 1: not just finding them familiar. They concluded, quote, it is
Speaker 1: plausible on neurobiological grounds that anxiety might lead to the
Speaker 1: generation of deja vous. The hippocampal formation, a structure of
Speaker 1: central importance and declarative memory, and the ability to engage
Speaker 1: in recollection, is also implicated in anxiety as part of
Speaker 1: the septo hippocampal system. Although this report does not prove
Speaker 1: a link between anxiety and deja vu, it does further
Speaker 1: support the suggestion that this area is worthy of further investigation.
Speaker 1: That's very interesting, um, I mean, it makes me think
Speaker 1: about the link between deja vu and stress or fatigue. Now,
Speaker 1: I'm not sure exactly how to separate out stress and anxiety.
Speaker 1: I think there's a good deal of overlap between stress
Speaker 1: and anxiety, but they're not exactly the same thing, right, Yeah,
Speaker 1: they is often the case with human emotions and experience.
Speaker 1: There's kind of a delicate web where all these things,
Speaker 1: sometimes conflicting things are, it seemed to be in rather
Speaker 1: close proximity to each other. Yeah. All right, On that note,
Speaker 1: let's take one more break, but when we come back,
Speaker 1: we'll discuss deja vu and dreams. Than all right, we're
Speaker 1: back now, Robert. I remember a little while ago, we
Speaker 1: got an email from a listener who wanted us to
Speaker 1: look into the issue of deja of right, Yeah, yeah,
Speaker 1: I believe that this was a listening by the name
Speaker 1: of an uh and uh, yeah, she brought up well,
Speaker 1: i'll just read apart from the email here quote. Several
Speaker 1: months ago, I was introduced to the term de genrev.
Speaker 1: I first thought it was the speaker's mispronunciation of deja vous. However,
Speaker 1: it's an independent concept. Deja rev literally translates to already dreamed.
Speaker 1: It's the sensation that one has experienced a real time
Speaker 1: event in a previous dream. It can be considered a
Speaker 1: form of precognition. I would love to learn a scientific
Speaker 1: perspective and explanation for this phenomena. So that sounds like
Speaker 1: a great idea, and let's let's look into it. Okay, Well,
Speaker 1: you know, I would say, just uh from a personal perspective,
Speaker 1: when I experienced deja vu, I don't know if my
Speaker 1: brain makes a distinction between deja vu and deja vacu
Speaker 1: and deja rev. Like it seems like when I get
Speaker 1: that feeling of familiarity in the situation, I couldn't tell
Speaker 1: the difference between whether I'm feeling like I already have
Speaker 1: been here or feeling like I've already been here in
Speaker 1: a dream. Does that make any sense? Yeah? Yeah, I
Speaker 1: feel I hear what you're saying there. I I feel
Speaker 1: like with my experience, I do sort of see two
Speaker 1: Like there's there's the feeling of it. There's kind of
Speaker 1: like that deja vous energy that you know, intensity factors
Speaker 1: aside may essentially be the same. But then in some
Speaker 1: cases I am instantly aware that it is somehow tied
Speaker 1: to external sense data. And in other cases, particularly these
Speaker 1: these stronger feelings that I've had, they seem to be
Speaker 1: tied to internal feelings or thoughts, if that makes sense. Yeah, yeah, yeah, Um,
Speaker 1: I don't know. I mean, I guess the feeling of
Speaker 1: deja vu for me is inherently kind of dream like.
Speaker 1: Um it suddenly in waking life creates a little bit
Speaker 1: of of an aura of the feeling one has in dreams.
Speaker 1: Oh yeah, And so it naturally to me kind of
Speaker 1: suggests like when I have that feeling of anomalous familiarity,
Speaker 1: I'm like, did I dream this before? But I accept
Speaker 1: that maybe another people there there is this clearer distinction,
Speaker 1: like that there's one type of feeling like I've already
Speaker 1: been here in waking life, and the other one is like,
Speaker 1: I already experienced this in a dream. It's just for me.
Speaker 1: They've they've never felt all that distinct from each other. Okay, well, um,
Speaker 1: let's look at a paper here. I'm gonna refer to
Speaker 1: frequency of deja rev effects of age, gender, dream recall,
Speaker 1: and personality. By this is a threadle gorrets and funk Howser.
Speaker 1: We mentioned funk Howser in the the the last episode
Speaker 1: published in the Journal of Consciousness Studies in ten. Now,
Speaker 1: as we've discussed already, you can broadly say, all right,
Speaker 1: there's deja u. But then you when you really get
Speaker 1: down into it, there are there's sort of different subsections
Speaker 1: to deja vu, and you have things like deja rev
Speaker 1: that come up well. According to uh to Dr Vernon
Speaker 1: Nip in his book The Psychology of Deja Vu and
Speaker 1: subsequent Publications, where in which he wrote about deja vu,
Speaker 1: there are perhaps twenty different forms of the deja experience,
Speaker 1: and uh man, I'm not going to read them all,
Speaker 1: but there there's some really good ones. There's like um,
Speaker 1: uh dejas sue already known intellectually. There's uh deja ditt
Speaker 1: already said or spoken, so you know, referring to a
Speaker 1: content of speech. Um. Basically they get into all the
Speaker 1: different nuances of how you might interact with the world
Speaker 1: or worth your own brain. Like there's a one for
Speaker 1: already hallucinated, one for uh, already eaten de Genmans. That
Speaker 1: would be a great one. They just shout out in
Speaker 1: a restaurant as you are, um, enjoying a meal. Uh.
Speaker 1: But then in one of the uh no, I'm thinking
Speaker 1: I'm thinking of the sopranos were like Tony is like,
Speaker 1: humange uncle June, but then Uncle June is like, whoa
Speaker 1: de jamange? I mean there's a there's deja music already
Speaker 1: heard or played specific music. Uh. And then there's oh,
Speaker 1: this one's really fat. I haven't looked into this one
Speaker 1: in Greater Death, but deja paradox a paradoxy basically already paradoxical,
Speaker 1: which that just sounds kind of mind rendering to encounter
Speaker 1: a paradox and then have a deja vu about that paradox.
Speaker 1: I can't even think of an example with them. I
Speaker 1: don't like I said, I we have to come back
Speaker 1: to that one. Maybe you, the listener, have an example
Speaker 1: of of of a deja paradox experience that you can
Speaker 1: you can share with us. But anyway, the main focus
Speaker 1: of this paper was the de gen rev experience and
Speaker 1: the idea of of a feeling as if you have
Speaker 1: dreamt something before. And I think some of us can
Speaker 1: probably relate to that with our deja vu. You know,
Speaker 1: you might think weird, I feel like I have dreamt
Speaker 1: this before, and perhaps some of us feel that more
Speaker 1: strongly than others. Incidentally, funk, how was there? One of
Speaker 1: the authors here points out on his website, Deja Experience
Speaker 1: research dot org. That's it's with hyphens in there Deja
Speaker 1: hyphen experienced hyphen research dot org. He points out that
Speaker 1: Percy Shelley wrote of the connection between deja vu and dreams,
Speaker 1: though his thoughts were not published till after his death.
Speaker 1: So here's the quote. The scene was a common scene.
Speaker 1: The effect that it produced on me was not such
Speaker 1: as could have been expected. I suddenly remembered to have
Speaker 1: seen that exact scene in some dream of long here
Speaker 1: I was obliged to leave off, overcome by thrilling horror. Wow.
Speaker 1: But back to this study in particular, they point out
Speaker 1: that as a blanket explanation for deja vou. This one,
Speaker 1: you know, dates dates back quite a long ways. Um.
Speaker 1: One of the earliest explanations for the deja experience, I
Speaker 1: think we mentioned the first one was when St. Augustine
Speaker 1: wrote of it in the year four or sixteen, and
Speaker 1: then Sir Walter Scott much later writes about it in
Speaker 1: the eighteen fifteen. But the authors of this paper, they
Speaker 1: set out to perform a survey of the experience. Now,
Speaker 1: this was a survey of four hundred and forty four
Speaker 1: people asking them about their experiences of deja vous, specifically
Speaker 1: de gen rev the association between this feeling of deja
Speaker 1: vu and their dreams, and so out of the four
Speaker 1: forty four individuals that responded, um, it's interesting. So the
Speaker 1: first of all, there was the frequency. Now in the
Speaker 1: study they break they break it down a little more,
Speaker 1: a little more detail. But basically they found that of
Speaker 1: the people sampled uh said that yes, they did experience
Speaker 1: deja rev. Uh. Now how often they experienced it varied
Speaker 1: uh quite a bit. Um. For instance, twenty one or
Speaker 1: four point eight percent UM said that they just never
Speaker 1: experienced it. But in terms of those that did, like
Speaker 1: you know, you had like forty one said that they
Speaker 1: experienced it less than once a year, But then there
Speaker 1: were eight individuals, which is only one percent of the
Speaker 1: of of the the individual's polled here they experienced it
Speaker 1: several times a week. Wow. Um, well, I'm curious how
Speaker 1: this squares with previous research finding that you know, up
Speaker 1: to something like a third of people or maybe up
Speaker 1: tot of people, and some of these older surveys report
Speaker 1: having never had any experience of deja vu. I wonder
Speaker 1: what's going on because you talk to people nowadays, that
Speaker 1: figure seems kind of high. I would figure that you know,
Speaker 1: close to you know, nearly everybody has had like at
Speaker 1: least some kind of deja vu experience at some point.
Speaker 1: But these older surveys, you know, have it, have it
Speaker 1: still very common but lower? I wonder if there used
Speaker 1: to be more of a stigma or kind of weird
Speaker 1: paranormal association with saying that you've had deja vu? Does
Speaker 1: that make sense? Like maybe if people didn't think that
Speaker 1: there could be any kind of like normal explo nation
Speaker 1: for it, they'd be less likely to want to admit
Speaker 1: it and talk about it like their gender norms about it,
Speaker 1: Perhaps like a real man doesn't have deja vu or
Speaker 1: a proper lady never experiences deja vu. It is simply
Speaker 1: uh not done, uh, something to that effect. I don't know. Yeah,
Speaker 1: that's true. You know, you can't be a cowboy if
Speaker 1: you've got deja vu. It's true. I've never Uh, I don't.
Speaker 1: I don't think even Corman McCarthy considered deja vu and
Speaker 1: the American cowboy. Well, no, I'm just curious, and maybe
Speaker 1: there's something I'm missing here. It just seems like in
Speaker 1: these older surveys, fewer people admitted to having deja vu.
Speaker 1: Now with this particular study, I should note that the
Speaker 1: authors admit quote the high incidents of deja rev again
Speaker 1: about in this sample might be explained by the fact
Speaker 1: that the sample consists mainly of psychology students who phenomena
Speaker 1: it is interesting and related to their chosen profession. That is, okay,
Speaker 1: that makes a lot of sense that in these serve
Speaker 1: as we may be getting a a less randomized, more
Speaker 1: rarefied sample of like the kind of people who are
Speaker 1: more likely to remember these experiences and want to talk
Speaker 1: about them. Yeah, just more likely to be introspective about
Speaker 1: your your own in reality. Um. They also point out
Speaker 1: that the previously noted in other studies. Association between deja
Speaker 1: rev and dream recall frequency seems, on one hand plausible. Okay,
Speaker 1: so if we're making the connection between this deja experience
Speaker 1: and dreams, a person with high dream recall might be
Speaker 1: more likely to attribute deja vu experiences to prior dreams. However,
Speaker 1: quote the impression of having dreamed, the actually occurring events
Speaker 1: arises within that moment and usually cannot be attributed to
Speaker 1: a particular dream in the past, even if the person's
Speaker 1: kept dream diaries in order to document the dreams prior
Speaker 1: to the de genrev experience. I think that squares with
Speaker 1: the overall anomalous familiarity phenomenon, like when you have deja vu.
Speaker 1: The whole point is that you can't relate it to
Speaker 1: a specific experience in your memory. It's just the general
Speaker 1: feeling that I've seen this before, uh and yeah, and
Speaker 1: that seems to go go along with the dream phenomenon
Speaker 1: as well. I also came across a twenty paper that
Speaker 1: UH basically found that de gen rev experiences are common
Speaker 1: after electric brain stimulation standard and treatment for epileptic symptoms. Now.
Speaker 1: They looked at three different subsets of de gen rev episodic,
Speaker 1: so you know, with a direct connection made to a
Speaker 1: specific dream, half remembered scenes that echoed their current circumstances,
Speaker 1: and an even dreamy or like state in which the
Speaker 1: experience itself is dream or nightmare like. So I felt
Speaker 1: that guest a little more perspective on on what maybe
Speaker 1: going on here. So let's again remind everyone deja vu
Speaker 1: the experience that something novel was actually familiar. So imagine this.
Speaker 1: Imagine feeling this as you walk down a new hallway
Speaker 1: and you're about to open a door or to an
Speaker 1: office you've never visited before. You feel, at least for
Speaker 1: you know, for a second there, for this fleeing moment,
Speaker 1: that you know what will be on the other side. Now,
Speaker 1: this is just a feeling, but it feels real to
Speaker 1: the people who experience it. It feels like in this
Speaker 1: moment of deja vous, you are able to see the future. Yeah,
Speaker 1: and in fact, some people I think this is one
Speaker 1: of the reasons that a lot of people have been
Speaker 1: kind of insistent on viewing deja vu is some kind
Speaker 1: of actual paranormal phenomenon and not just like a strange
Speaker 1: feature of the brain um that sometimes people feel like
Speaker 1: they are actually getting information about the future from it,
Speaker 1: you know that like, I know what's going to happen next,
Speaker 1: and really, this does I think feel like this kind
Speaker 1: of thing adds another wrinkle to our understanding of people
Speaker 1: who claim to have precognitive abilities or experiences in their life,
Speaker 1: you know, because if you're if you're taking just like
Speaker 1: the hard skeptical approach to that, then it's like, Okay,
Speaker 1: some people are crazy, some people are scammers, maybe some
Speaker 1: people are both of those. But but this by by
Speaker 1: thinking about the link between deja vu and pre precognition,
Speaker 1: you could well have a situation where someone maybe they're
Speaker 1: more inclined to engage in uh supernatural ideas or some
Speaker 1: sort of religious model that incorporates precognition. But if you
Speaker 1: had just at least a few flashes of this sort
Speaker 1: of experience, like a moment where you're like, yeah, I knew,
Speaker 1: I know what's going to be on the other side
Speaker 1: of that door, and even if it's it ends up
Speaker 1: to not be the case, you know, you still have
Speaker 1: that feeling that felt so real. Well, this seems like
Speaker 1: the kind of thing that you could actually put to
Speaker 1: the test, if only you could create scenarios and we
Speaker 1: talked earlier about the difficulty of creating deja vu on command.
Speaker 1: It's obviously not easy to do. But if you could
Speaker 1: put together a test where you could sort of where
Speaker 1: you could sort of try to stimulate deja vou like
Speaker 1: experiences in people, you could actually put this to the test, right,
Speaker 1: you could find out a weight, do people have any
Speaker 1: additional predictive power? All right, well, let's let's jump into
Speaker 1: this particular study that I have lined up here. So
Speaker 1: this is a two thousand eighteen study that was published
Speaker 1: in Psychological Science, and it was titled Deja vous An
Speaker 1: Illusion of of Prediction, And this was by an Im
Speaker 1: Cleary who we mentioned earlier, and Alexander B. Claxton so
Speaker 1: clearly has put a great deal of research into deja
Speaker 1: vu as well as tip of the Tongue over the years,
Speaker 1: and her working hypothesis is that it's a quote particular
Speaker 1: manifestation of familiarity. Something feels familiar when you paradoxically feel
Speaker 1: that it shouldn't. In her last ten years plus of research,
Speaker 1: she started hearing a lot about people's claims to the
Speaker 1: precognition feeling, you know, again, not the reality of of
Speaker 1: predicting the future, but the feeling the confidence that you, uh,
Speaker 1: you know what is going to occur, and she wanted
Speaker 1: to see if, as she suspected, the feeling was a
Speaker 1: memory phenomenon as well. And of course the ad uh
Speaker 1: complication here for for her is that you know, memory
Speaker 1: does aid us in our ability to predict future of events.
Speaker 1: So it's far from a trivial question. Memory isn't just
Speaker 1: there to make you feel good or bad about the past.
Speaker 1: It's about survival moving forward. So what did they do?
Speaker 1: Always to discuss some of the issues with trying to
Speaker 1: recreate deja vu in the lab, So their approach here
Speaker 1: was to UH was was to basically pull it off
Speaker 1: via virtual reality, based on past studies that found out
Speaker 1: that subjects were more likely to report deja vu among
Speaker 1: scenes that spatially mapped onto earlier witness scenes. UH. Subjects
Speaker 1: were put through familiar virtual hallways and then ask if
Speaker 1: they felt deja vu or premonition at key turns. So,
Speaker 1: you know, this is a situation where you can just
Speaker 1: imagine you know, Doom and Wolfenstein kind of hallways, you know,
Speaker 1: virtual hallways, UH and some of the same mapping, but
Speaker 1: but a different feel a different look. And then the
Speaker 1: researchers would jump in at key points and see if
Speaker 1: if there was a sense of deja vu or premonition
Speaker 1: on the part of the subject. And these were their findings.
Speaker 1: About half the respondents felt a strong premonition during deja vu. However,
Speaker 1: they were no more likely to actually recall the correct answer,
Speaker 1: uh than mere chance would explain. So that's not to
Speaker 1: say that the take home here is that deja vu
Speaker 1: experiences are not pre cogs. We know that we knew
Speaker 1: that going in, but rather that it creates an illusion
Speaker 1: of certainty, confidence in the choice that might be linked
Speaker 1: to stuff like hindsight bias. Now, her work on all
Speaker 1: this continues, Uh is you know, great deal more that
Speaker 1: could be learned about the deja experience. But I think
Speaker 1: this is really interesting because again you can see how
Speaker 1: this might form the bedrock, uh for greater beliefs in
Speaker 1: precognition and uh predictions of the future. You know, you
Speaker 1: you build upon this with some sort of existing religious,
Speaker 1: supernatural magical script about individuals who can sense the future,
Speaker 1: and uh, yeah, it seems like they would one would
Speaker 1: support the other rather well. Sure, all right, so there
Speaker 1: you have it. We're gonna go and call it here.
Speaker 1: We hope you enjoyed our two episode look at the
Speaker 1: Deja Voo experience, all that it seems to incorporate, and
Speaker 1: some of our best attempts to understand it. Though those
Speaker 1: those attempts are still very much in process. The work
Speaker 1: continues in the meantime. If you want to check out
Speaker 1: other episodes of Stuff to Blow Your Mind, you can
Speaker 1: find us wherever you get your podcasts wherever that happens
Speaker 1: to be. Make sure you rate, review, and subscribe. Huge
Speaker 1: thanks as always to our awesome audio producer Seth Nicholas Johnson.
Speaker 1: If you would like to get in touch with us
Speaker 1: with feedback on this episode or any other, to suggest
Speaker 1: topic for the future, or just to say hi, you
Speaker 1: can email us at contact at stuff to Blow your
Speaker 1: Mind dot com. Stuff to Blow Your Mind is production
Speaker 1: of I Heart Radio. For more podcasts for my Heart Radio,
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