Déjà vu, Anxiety and Dreams, Part 2

you need to experience them in order. But we we kicked off by talking about some personal experiences with deja vu, uh and also getting into some of the rich variety that is to be found under the broad categorization of deja vu experiences. In this episode, we're going to kick off by really getting into some of the major theories

and explanations for this thing called deja vu. Right, So, last time I cited there's a major paper on the research on deja vu that was published in two thousand three by a researcher named Alan S. Brown, was published in Psychological Bulletin, and we cited it last time, talking about a lot of the common findings about deja vu, including the fact that it appears to be very strongly associated with stress and fatigue. The more tired and stressed out you are, the more likely you are to have

a deja vu experience. The studies that show it associated with travel, people who travel are more likely to experience deja vu. Um, the studies that show that that certain drugs can apparently cause lots of deja vu. And then especially the fact that deja vu appears to decrease with age, that as you get older in life, you you on average have fewer deja vu experiences, which I'm still finding interesting and I'm coming back to that one a lot.

But yeah, So now we want to dive into, uh, the major theories and explanations, and my main guide on this is Brown's paper from two thousand three where he he reviews most of the existing research. There's been a few develop elements since then, and we'll talk about those later on, but they're they're basically several. They're like four main categories that Brown outlines about what the explanations for deja vu could be. And the categories are going to

be the following. So first, you've got some kind of dual processing. Second, you've got neurological dysfunction, Third, you have memory issues, and then fourth you have attentional catch up. Um. Now, one of the first things I think we should mention is that it can be kind of difficult to understand the causes of deja vu because deja vu is inherently a little bit difficult to study. It's not super easy to trigger episodes of deja vu in a laboratory or

brain imaging context. There's some techniques we can mention, but you can't just like start up an f M R I and then run it and hope somebody has an experience of deja vu while it's running. Remember, like, deja vu is relatively rare. Most people experience it at some point in their life. But I think you know, an average figure figure is that a lot of people say they have a deja vu experience something like once a year. So you couldn't expect for it to just happen while

you're looking for it. Yeah, deja vu is not really the sort of thing you can just have on command. Nobody can say, all right, have some deja vu. And likewise, it's not that I haven't seen I don't think I've seen any evidence or any claims of anybody who could produce a feeling of deja vu. Just by willing it that we will get into some unique cases a little later, right. Uh. That would be an interesting uh skill if one had it. Now. There are some cases where it appears that deja vu

can be triggered by certain clinical interventions. We mentioned a couple of cases of it being associated with certain combinations of drugs in the last episode, like a couple of drugs used to treat the flu um. But also by no big surprise here, electrical stimulation of the brain. Uh. In his big review, Brown described abs findings about deja

vu and brain stimulation and patients with temporal lobe epilepsy. Again, remember um from last time that deja vu is one of the symptoms that has been described as part of the aura preceding and epileptic seizure in people with temporal lobe epilepsy. But another thing about temporal lobe epilepsy is that in some cases in history, electrical stimulation of the brain has been used in the treatment and diagnosis of temporal lobe epilepsy. UM. And so I want to read

a section from Brown here writing about this. Brown writes, quote with surface stimulation of the cortex, and that's electrical stimulation Mullen and Penfield elicited deja vu experiences in ten out of two hundred and seventeen people with temporal lobe epilepsy. Recent procedures involving deep electrode brain implantation have shown that deja vu, similar to one that occurs in the aura, can be elicited with stimulation of the amygdala and hippocampus,

Although these experiences were not reported in detail. The deja vu generally consisted of a sudden feeling of unfamiliarity in the hospital environment and was often accompanied by epigastric phenomena and fear and uh. Epigastric phenomena refers to strange feelings in the abdomen, especially I think the upper part of

the abdomen. I've read it described as um getting a feeling sort of above the stomach and right below the chest, like this weird feeling, kind of like when you're on a roller coaster and you're you're plummeting down on the other side, you know that rising in the gut. Yeah, yeah, I believe we discussed that a little bit in the last episode. Brown writes quote. The elicitation of deja vou through electrical stimulation may not be reliable hal grin at all.

In nineteen seventy eight, stimulated several dozen brain locations in a group of people with temporal lobe epilepsy on two different occasions, two weeks apart, and found that a number of sites that elicited a deja vu on one session did not do so on the other. Deja vu experiences also resulted from stimulating the non diseased hemisphere, suggesting that the experience is not necessarily specific to the tissue where

the seizure originates. So that's interesting. You've got deja vu associated in some cases with people with temporal lobe epilepsy, but that it appears like if you you stimulate one part of the brain one week and it gives you deja vu, but a different part of the brain the next week that might give you deja vu, and maybe the original place that gave you deja vu last week

doesn't give it to you anymore. So, uh yeah, there's some kind of discontinuity here about how exactly stimulating different parts of the brain contribute to the deja vu experience subjectively. But there have been some other interesting things that I know we'll get too later in the episode of trying to trigger deja vu and otherwise neurologically typical people, for example,

using using certain types of virtual reality stimulation. That, yeah, I think we're we'll get to that maybe in the third part of today's episode, But I guess we got to get directly to these four main theories explaining what could be going on in the brain when you're having deja vu. Um, assuming it's not like a supernatural phenomenon, which we don't think it is, that there's a good amount of evidence that it is a function of the brain. So the ghost hypothesis is really not not not highly

valued scientific circles here. Yeah, so we won't be picking up on that one today. But so again, these are the four main branches that brown outlines are dual processing, neurological dysfunction, memory error, and attentional catch up. And I'll go ahead and say that I think the main two branches that have explanatory power going for them today, at least as far as I can tell, are the last two I mentioned, like the memory ones and the attentional ones.

But since the other two have been very important in the history of studying deja view, we should at least talk about them for a bit. Um. So the first one is this idea of dual processing. There are these multiple hypotheses that fall into this category, but they all basically amount to the same thing. They say, you know, there are two different processes in the brain that usually

occur simultaneously. They happen at the same time, but occasionally they become a synchronous, they get detached in time and suddenly there's a lag between them. And these types of explanations tend to be the oldest and least scientifically justified, but they are kind of interesting to think about. So, for example, one that Brown sites is the idea of this old theory of dual consciousness. Uh. The idea is that there there are two separate types of consciousness in

the brain. There's one normal type of consciousness, and what that does is monitor everything that happens in the outside world. It's, you know, your regular brain that's looking out through your eyes and sees what's going on. And then the other version is the parasitic consciousness, which we might refer to as metacognition. It monitors the internal state of the brain itself.

And under this old hypothesis, deja VU is created when normal consciousness is impaired by something like fatigue or stress, and it's left up to the parasitic consciousness to evaluate incoming information. And because the parasitic consciousness is not well adapted to evaluating incoming information, it gets confused, and it confuses what it's looking at now for a memory of the past. Uh. While I like this idea, this one appears to be entirely speculative. It's mostly based on like

nineteenth century conceptions of the mind and brain. So I don't think this one is very likely a good explanation today. Now another one, uh in this branch is would be like encoding and retrieval. Brown says, this was proposed by Denayer in nineteen seventy nine, and basically it takes the form of a metaphor of the brain is a combination tape recorder and player. Uh did you did you have

one of those when you're a kid? Robert? Oh? Yeah, of course, but yeah, okay, So the metaphor here by Dena Air is that your brain has a combination tape recorder and player. And and Brown explains this well, so I'm going to quote from him quote under normal conditions memory encoding and retrieval operate in a manner similar to the record and play heads respectively. On a tape recorder. Either the record in code or the play retrieve head

can be on, but not both at once. On rare occasions, the tape machine and a person's memory has both record and play heads active simultaneously during a new experience, creating a false sense of familiarity for the newly encoded experience. So basically, the idea is that you are experiencing the memory as it is happening, um, which sounds paradoxical, but but the idea of encoding and retrieving happening at the

same time. Yeah, and so this never Brown says, this hypothesis never really got developed beyond just this metaphorical stage. Like he never you know, got into the nitty gritty of like what parts of the brain this would exactly be involving and how it would work. Um. But I would say, while it is still at this metaphorical stage, this is kind of close to some later, later explanations

that are backed up by more empirical research. I think it's not quite on the money, but it's it's getting part of the way there, especially I think, especially with with some of the ones that we'll talk about with with attention later on. Yeah, and also like how it kind of helps to further breakdown the nature of of something that is novel and something that is familiar and how it basically works, you know, in our experience of

cognitive data. Yeah. Well, and it makes me think about how, um, in a way, there's almost no real objective thing that is novelty. You know that, Like every time you're looking at anything in the world, in a way, it's sort of novel because like your heads in a different position, and you'll even if you're looking at something you've looked at a thousand times before, the lights kind of different,

you're looking at it from a slightly different angle. The brain just does a does a very good job taking things that are you know, different data sets coming in through the eyes or the ears or whatever it is, and saying like, Okay, you know what that is. That's the same coffee cup you've looked at a thousand times, even though it's not a photo exact copy of how

it looked the last time you looked at it. Yeah, I mean, as since data goes the details of the coffee cup are not that important, And the brain does a pretty good job in in UM working with the senses of letting that kind of fade into the background. But then you know, any day you're able to pick up that coffee cup and really focus on it and kind of see it for the first time. And that's one of the the crazy things about the the close

relationship between the novel and the familiar. Yeah, and that emphasizes that like the novel and familiar, they're not objective features of the world. They're like subjective simulation sans yeah. This is this is almost an example of this, but not quite. Um. I I don't I've had an Xbox one controller for so long and I just discovered you can plug headphones into the controller itself to get sound. Totally.

It's changed my life here in um. You know, self isolation. Oh, now late in the night, your house is not filled with tiny screams that right, right? Yeah, I want to Yeah, if I want to play Doom Eternal at a at a weird hour, I can. I can be the only one to hear it. Likewise, my son is trying out Minecraft for the first time, and we can plug him into the the controller and then if he jerks the controller around, he's not pulling things off of the you know,

the TV tray or something. So uh so yeah, but but you know, there's an example. I don't know how many times I've looked at this device, but I've never seen this detail. And uh uh. You know a lot of things in life are like that. You know, when you really really stop to look at at it, you can you can uncover the novel wrinkles and the thing. I might want to come back to this example later in the episode. Uh and maybe when we talk about the memory and intentional branches. Okay, two more examples of

dual processing hypotheses. So another one Brown sites is. The idea of perception and memory seems kind of similar to the last one. It was proposed by a researcher named Bergson. Basically, it supposes that perception and memory formation happened at the same time. Like, you know, I I look at Gritty, the Philadelphia Flyers mascot for the first time, my brain sees him creates the memory of having seen him simultaneously.

Bergson suggests that sometimes stress or fatigue can cause the newly formed memory to bump into perception, so that I get the feeling that I have seen Gritty before. Again, this one is kind of fuzzy and speculative as far as hypotheses go. Well, you know, we all feel that we've seen Gritty before because Gritty was with us in the womb. Gritty is primordial. Yeah, Gritty was there before

we were born. You know that's going to happen one day, like they they a big block of shale shares away from a Cambrian formation and then just just the outline of Gritty there among the trial bites. He was waiting the whole time. Okay, But then the fourth one of these dual processing hypotheses potheses. Sorry, this is the only one of the four that really seemed all that plausible to me. So this one is called familiarity and retrieval. And this was proposed by a researcher named Glure in

nineteen nine. And Glore suggested that when we encounter an image or an object or scenario or whatever it is that we've seen before, there are two separate things that happen. One is the retrieval of the past memories about that thing. So I see Gritty, I have seen him before, and I remember the other times I saw Gritty and had thoughts about him. But the other thing is the emotion of familiarity that accompanies the recall. So I see Gritty,

I have memories, but also I have a feeling. It's this emotional feeling that, oh, I know who that is. Uh that you know that is Gritty. I feel familiar with what's going on right now. And from what I can tell, there's not really any direct evidence for this hypothesis, but this one does seem kind of plausible to me because we've talked about other cases of mismatch between recognition

and familiarity. For example, in talking about cap Graw delusion, I think we mentioned in Part one, which is this delusion often caused by brain injury, in which a person believes that their loved ones have been replaced by lookalikes or doppelgangers. And it's believed that cap Graw delusion stems from a malfunction in the brain where recognition is triggered.

So you see a person and you know who you're looking at, like, yes, you know that that is Jeff, but the normally accompanying feeling of familiarity is not there. It doesn't get triggered. So you see somebody recognize as Jeff, but he does not feel familiar. It doesn't feel like your old friend, so you say, oh, he's and replaced by a look alike. What's normally a case of dual

processing here has been severed. So if a dual processing failure like this we're actually an explanation for deja vu, I think it would have to go the opposite way, right, It would have to go the opposite of cap Graw delusion, where a feeling of familiarity is triggered while actual retrieval

of associated memories is not. And along these lines of cap Graw delusion would would actually be more analogous to the inverse of deja vu that we mentioned last time, jama vu, in which a familiar object suddenly feels unfamiliar.

But again, from what I can tell, this kind of explanation, I think it's perfectly possible, but I can't find direct experimental evidence for it, so I think it might just remain right now in the realm of like, yeah, maybe something like this could explain some cases of deja vu, but we we don't have strong evidence that these explanations are the right ones yet. Alright, Well, on that note, let's take a quick break, but when we come back, we will continue to explore some of the explanations for

what may be going on with deja vus. Thank thank alright, we're back, all right. So we just talked about the

first branch of possible explanations for deja vu. Uh, probably the oldest branch of explanations, which was the idea of dual processing that when you experienced deja vu, it's because two different things that normally happened in the at the same time in the brain get severed and one happens after the other one, or they get you know, one happens without the other one, and this causes this this disconnect um. The next branch of explanations that Alan S.

Brown offers in his two thousand three paper are neurological explanations. Now, the first one is seizures. We know that deja vu is a you're not not super common, but a recognized experience in the aura of people who have temporal lobe epilepsy. So what if normal deja vu do you that happens in you know, sixty percent of people at some point it's actually just a kind of mild seizure. A lot of people have proposed this over the years, but Brown says that the evidence for this does not appear to

be very good. Though deja vu is a feature of seizures for people with t l E, people with epilepsy in general are not more prone to every day deja vu than people without epilepsy, and people who experience more episodes of deja vu than average are not any more prone to seizures than anybody else. So again, we can't actually look at deja vu as it's happening and compare it to say, what's happening in the brain during a seizure, but we can look at frequency, uh, between these two

sets of of individuals. Yeah, and so it just doesn't look like seizures are going to be a good explanation for deja vu. Generally, it looks more like there might you know, deja vu just happens to be one of the things that sometimes happens in the brain of somebody about to have a seizure, but it's not overall a

generalized seizure phenomenon um. Now, the other major near a logical explanation that Brown sites is neural transmission delay, and this refers to a set of explanations where information traveling from the perceptual organs such as the eye. Uh, it's traveling to different parts of the brain, and it gets delayed along one of those pathways by neuronal misfiring or some of their malfunction. And one example that's given is the two different hemispheres of the brain usually receive information

at the same time. But what if one hemisphere realizes that you're looking at gritty slightly after the other one does, And under this hypothesis, the delay causes a freshly perceived stimulus to be interpreted as old information because one part of the brain has already experienced it by by the time it gets to the other part. Well, this seems like a good place to move on to some of the additional explanations, because we're talking about old information. What

he's old information but a memory. Yeah, exactly. So now we're getting into those were the two older branches. Now we're getting into the branches that I think are more were favored among researchers today, the memory based explanations, especially implicit memories and attentional explanations. Uh. Now, Robert, if we if we go to memory based I think you're going to get into this branch of explanations a little bit more when you talk about the research by and M

cleary and Alexander B. Claxton. Later on, I saw you had something about that, So maybe we can talk more in depth about the memory based explanations then, but just do a short version now. The gist here is that desha vou is perhaps uh maybe it has something to do with the way that memories are encoded and retrieved. So imagine you're in one of these deja vu scenarios.

Maybe you're you're going down a staircase into a basement in a house, and you suddenly get this flash like, oh, I've been here before, but you haven't been here before. What if when you're experiencing deja vu on that staircase, you are remembering something you've seen before. It's just not this house. It's not the same thing you're looking at now. You're feeling familiarity because of some vague features of similarity that overlap with your current experience and some other memory

that you are not directly accessing in full. Maybe when I experienced the deja vu of like running into a tree branch while playing in the yard. The feeling of familiarity with the scene comes from the fact that there was some other time I was playing in maybe a similar looking place or a place with similar spatial arrangements of objects, and my friends were standing around me in a similar kind of orientation, and maybe I was injured or or fell down in some other way. Except I

don't explicitly recall that whole episode. I don't remember where it was, or who was there or what happened. I just recall enough to recognize some basic congruities. And this leads to that strange feeling of familiarity with no obvious

point of reference. So almost as if the the emotional pattern of something that occurred stuck with you, but details of it did not, um and and that's what gets recalled, right, or details might have stuck with me in a way that doesn't allow me to access the full scene as a memory, right. So, like, I think a common thing that's brought up in this kind of memory research is

like like spatial arrangements of things. You know, like if you feel deja vous in a room, maybe you're not in that room before, but we're in a room where like the furniture was arranged in a very similar way, and you don't explicitly recall that old memory, but something gets triggered in like the navigation parts of your brain, like what what's going on? I know this place? Yeah,

I mean it. We had to have to remind ourselves that as far as novelty goes in life, oh, there's only so much novelty that is really possible to a certain extent, you know what I mean. Even if you live a you know, a wild and varied life full of of of travel and exploring new things, you're going to encounter lots of situations that fit into more or less the same uh pattern. You know, you're going to go to a bathroom that looks a lot like other bathrooms.

You're going to do things more or less the same way that you've done it before. I mean, we're we're creatures of habit, we are creatures of pattern, and for many things in life, they're they're only so many approaches to how we might react to something or carry something out. Uh yeah, yeah. No, novelty is total illusion, eternal recurrence. You we've all been through this before. In fact, I think you've said that before. No, I haven't. I don't really mean that, um, you know. And so I was

thinking about this. I was thinking about, Wow, this might sound like a weird way for the brain to work, that you could have this feeling of familiarity about a memory that you cannot explicitly recall. But I think there are there are analogies to this and things that we've discussed before. I was brought back to the idea of tip of the tongue phenomenon. We did a whole episode of stuff to blow your mind about this. Um you know, this is where Hey, what's the name of the actor

who played riff Raff in Rocky Horror Picture Show. Well, the correct answer is Richard O'Brien. But there were some people listening right there who were like, oh, oh, I know that, I know that, but you couldn't quite come up with it, right. Why is it that you can feel like you know a word or feel like you know a name even though you can't conjure the word

or the name up right now. Perhaps a similar thing happens with images or situations, kind of like a tip of the tongue effect for things other than words, for situations or for you know, images, you look at with your eyes. You feel like you recognize this scene, but you can't actually call up the memory that is causing that feeling of familiarity, so I think, and there is actually some research to back up certain memory based explanations

for for some day javou experiences. So at least as far as I can tell, I think the memory based explanations might not explain all deja vu, but are a pretty strong candidate for explaining some cases of it. All right, well, let's move on to attentional explanations, which which I think is an exciting area because I think a lot of the mysteries of human consciousness make more sense to me when I had when I hear them explained in terms of attention. Yeah, me too, And I think this branch

has a lot going for it. This is the fourth of four, uh, and so these explanations are some of the most simple, actually, but they make a lot of sense to explain some cases of deja vu, and there is actually some experimental evidence in support of them. So imagine you're driving a car, right, and maybe while you are driving, you're having a tense emotional conversation with the passenger of the car. Maybe it's you know your spouse or partner, or you know your your child or parent

or relative. You're having an argument or something, so your attention is kind of divided, maybe like you're not paying as full attention to the road and of you as you should be. Then suddenly you see a man in a cowboy hat pushing a grocery cart full of Monster Energy drinks down the sidewalk, and you think, whoa deja vu? Why do I feel like I've seen this guy before?

Under the attentional model, the answer could be that you did see him before a couple of seconds ago, but your attention was divided, and because you had your attention wrapped up in this intense conversation and you weren't paying as much attention as you should have been to the road, you didn't consciously register seeing this guy a couple of seconds before, but you did see him with some diminished portion of your attention, And when you finally focus full

attention on him, he feels familiar, even though you're just now consciously registering him. You know in a in a way, this reminds me of a like a non dejavou experience that I have sometimes where I'll I'll run across a study or a paper that I maybe just glanced at in the past, or maybe I only read the headline. But now I've come back around to it, and I'm reading it, you know, more closely, you know, and I'm

actually taking it in. And then I realized, Oh, I think, I think I do vaguely remember this study from when it originally popped up. Yeah, I mean, I mean in that case, there's more of a time gap, right, So your memory, I think, would be more accurate. Actually, And

I know exactly what you're talking about. I have that feeling too, where like I I sort of graze over something, um, you know, text content, and then I come back to it later and it feels vaguely familiar, like out of a dream, because I didn't read it really closely the first time. But this time, instead of it being like a gap of five years, it's a gap of say like five seconds exactly. In Brown's words quote, a brief initial perception of a scene under diminished attention is followed

immediately by a second perception under full attention. The second impression matches that experienced moments earlier under degraded attention, and the individual does not consciously identify the prior experience as moments old, but rather attributes it to a more distant past. Uh. And I think that there's a lot of potential in this explanation. This could be what's going on in some of these cases. Yeah, I feel like this one feels like it fits really well with a lot of deja

vu experiences that that I can relate to. I'm not sure that it fits as easily or or I think it. It may still fit, but perhaps a little more sort of cognitive work to figure out how it fits with some of the other examples of the deja vu experience

that we've either discussed or will discuss. Yeah, I think you're right, And I would be strongly inclined to suspect that there are different explanations for different cases of deja vu, that there's not just like one trigger that creates all deja vu experiences, that it's, you know, just different kind

of things going on. My gut feeling here is that probably some cases are best explained by h by the implicit memory thing that we were talking about a minute ago, and then other ones are better explained by the attentional divide thing and then of course there are a few that are probably just direct neurological issues, like you know,

when the brain is being stimulated or when there's a seizure. Now, I'd like to come back to the link between anxiety and deja vu, because I found a very interesting study on this. Um. Apparently there is somewhat limited literature on the connection between anxiety and deja vu. But one one paper on the topic I came across was titled Persistent Psychogenic Deja Vu a Case Report, And this was by Wells, H. Moulin and Eth Ridge, and it was published in the

Journal of Medical Cases Case Reports. Uh, and this was from So the researchers present the case of a twenty three year old British man with a form of persistent deja vu and this is observed in two he was three years into his symptoms at that point. So, UM, and if you're you're wondering, well, what is persistent deja vus, it's basically what it sounds like. But I think more of this will come come across as I as I

roll through his briefly through his case history. So the subject here had a history of anxiety and de personalization depersonalization UH if anyone doesn't remember as a state in which one's thoughts and feelings seem unreal or not to belong to one's self, and it may also entail a

loss of all sense of identity. He also had a family history of obsessive compulsive disorder, so they when they when doctors looked at him, they didn't detect any neurological abnormalities and they assessed his recognition memory with tasks that were frequently used with dementia patients, and they found no memory defects. They found that he consistently understood the false nature of the deja vus he was experiencing as well, coming back to a key aspect of deja vu that

we were discussed in the first episode. So his reality testing was basically intact as far as the hotel when he didn't actually think that he was really having memories of the present. Right. So, the patient's history of anxiety was tied with fears of contamination, which led to excessive hand washing and showers two to three times a day, and then college anxiety made things worse, so he took a break from it and he began to experience episodes of anxiety in deja vu that would last for minutes

or even longer. They point out that he went on holiday at one point during this period to a city that he had visited before, so he did have prior, you know, memories of having been there. But he felt as if he had become quote trapped in a time loop the whole time, and the experience was apparently somewhat terrifying. So even though he knew, Okay, I'm not actually in a time loop, it feels like I'm in a time loop. I know I'm not, but it's really still terrifying to

experience totally, all right. And then he returned to college in two thousand seven, and during this time tried the psychedelic compound LSD, and they write, quote from then on, the deja vu was fairly continuous. So quick note for everyone. As you'll remember from our what five part series on psychedelics, UH, this would this would seem to fall in line with the observation that the psychedelic experience can for individuals with

a pre disposition exasperate a psychological condition. UH. Typically one hears about this in regards to schizophrenia. So at this point our subject is is experiencing near constant deja vus, so he goes to see a specialist. They found that he was experiencing anxiety in low mood, but for the most part, uh Like, everything was normal. I think his disassociative events scale score was slightly abnormal. Uh but but but otherwise it was it was just this deja vu effect.

Um and And interestingly enough, they write that he took to avoiding music and TV because he would invariably feel that he had seen or heard the material before, and then this would play into his deja vu experience or make it more pronounced. Uh. And I found this to

be interesting. You know this idea because this gets back to the idea of the novel and the familiar, Because if deja vu is largely the experience all of the novel as familiar, then would extreme cases like this require one to just try to avoid novel things as much as possible. M Yeah, just surround yourself with what's actually familiar so that when it feels familiar, it doesn't feel unusual.

I mean, this is this case sounds really disturbing because I don't normally think of deja vu as something that is inherently unpleasant when I feel it. It is strange, but it's not. It doesn't hurt, you know it, It's not in itself, uh, you know, worrying or or upsetting. But I can absolutely see how if it persisted over time it could take on that character. Yeah, I mean, a sneeze isn't that bad, But we wouldn't want to

sneeze constantly. Uh. And I would say that like a typical deja vu experience for me, and I think for most people, is far less distracting than a sneeze. Um. Uh. And And however, I will say that those experiences that I related in the first episode that I had recently, um, those were those were more potent, Those were those were certainly more powerful. And I would not I certainly would

not want to feel that all the time either. So the researchers in this case, though, they proposed that the form of deja vous described here it might more accurately be described as deja viku. Uh. This particularly strong sensation of reliving the present moment quote. He complained that it felt like he was actually retrieving previous experiences from memory, not just finding them familiar. They concluded, quote, it is plausible on neurobiological grounds that anxiety might lead to the

generation of deja vous. The hippocampal formation, a structure of central importance and declarative memory, and the ability to engage in recollection, is also implicated in anxiety as part of the septo hippocampal system. Although this report does not prove a link between anxiety and deja vu, it does further support the suggestion that this area is worthy of further investigation. That's very interesting, um, I mean, it makes me think

about the link between deja vu and stress or fatigue. Now, I'm not sure exactly how to separate out stress and anxiety. I think there's a good deal of overlap between stress and anxiety, but they're not exactly the same thing, right, Yeah, they is often the case with human emotions and experience. There's kind of a delicate web where all these things, sometimes conflicting things are, it seemed to be in rather

close proximity to each other. Yeah. All right, On that note, let's take one more break, but when we come back, we'll discuss deja vu and dreams. Than all right, we're back now, Robert. I remember a little while ago, we got an email from a listener who wanted us to look into the issue of deja of right, Yeah, yeah, I believe that this was a listening by the name of an uh and uh, yeah, she brought up well,

i'll just read apart from the email here quote. Several months ago, I was introduced to the term de genrev. I first thought it was the speaker's mispronunciation of deja vous. However, it's an independent concept. Deja rev literally translates to already dreamed. It's the sensation that one has experienced a real time event in a previous dream. It can be considered a form of precognition. I would love to learn a scientific perspective and explanation for this phenomena. So that sounds like

a great idea, and let's let's look into it. Okay, Well, you know, I would say, just uh from a personal perspective, when I experienced deja vu, I don't know if my brain makes a distinction between deja vu and deja vacu and deja rev. Like it seems like when I get that feeling of familiarity in the situation, I couldn't tell the difference between whether I'm feeling like I already have been here or feeling like I've already been here in a dream. Does that make any sense? Yeah? Yeah, I

feel I hear what you're saying there. I I feel like with my experience, I do sort of see two Like there's there's the feeling of it. There's kind of like that deja vous energy that you know, intensity factors aside may essentially be the same. But then in some cases I am instantly aware that it is somehow tied to external sense data. And in other cases, particularly these these stronger feelings that I've had, they seem to be

tied to internal feelings or thoughts, if that makes sense. Yeah, yeah, yeah, Um, I don't know. I mean, I guess the feeling of deja vu for me is inherently kind of dream like. Um it suddenly in waking life creates a little bit of of an aura of the feeling one has in dreams. Oh yeah, And so it naturally to me kind of suggests like when I have that feeling of anomalous familiarity,

I'm like, did I dream this before? But I accept that maybe another people there there is this clearer distinction, like that there's one type of feeling like I've already been here in waking life, and the other one is like, I already experienced this in a dream. It's just for me. They've they've never felt all that distinct from each other. Okay, well, um, let's look at a paper here. I'm gonna refer to frequency of deja rev effects of age, gender, dream recall,

and personality. By this is a threadle gorrets and funk Howser. We mentioned funk Howser in the the the last episode published in the Journal of Consciousness Studies in ten. Now, as we've discussed already, you can broadly say, all right, there's deja u. But then you when you really get down into it, there are there's sort of different subsections to deja vu, and you have things like deja rev

that come up well. According to uh to Dr Vernon Nip in his book The Psychology of Deja Vu and subsequent Publications, where in which he wrote about deja vu, there are perhaps twenty different forms of the deja experience, and uh man, I'm not going to read them all, but there there's some really good ones. There's like um, uh dejas sue already known intellectually. There's uh deja ditt already said or spoken, so you know, referring to a

content of speech. Um. Basically they get into all the different nuances of how you might interact with the world or worth your own brain. Like there's a one for already hallucinated, one for uh, already eaten de Genmans. That would be a great one. They just shout out in a restaurant as you are, um, enjoying a meal. Uh. But then in one of the uh no, I'm thinking I'm thinking of the sopranos were like Tony is like, humange uncle June, but then Uncle June is like, whoa

de jamange? I mean there's a there's deja music already heard or played specific music. Uh. And then there's oh, this one's really fat. I haven't looked into this one in Greater Death, but deja paradox a paradoxy basically already paradoxical, which that just sounds kind of mind rendering to encounter a paradox and then have a deja vu about that paradox. I can't even think of an example with them. I don't like I said, I we have to come back

to that one. Maybe you, the listener, have an example of of of a deja paradox experience that you can you can share with us. But anyway, the main focus of this paper was the de gen rev experience and the idea of of a feeling as if you have dreamt something before. And I think some of us can probably relate to that with our deja vu. You know, you might think weird, I feel like I have dreamt this before, and perhaps some of us feel that more

strongly than others. Incidentally, funk, how was there? One of the authors here points out on his website, Deja Experience research dot org. That's it's with hyphens in there Deja hyphen experienced hyphen research dot org. He points out that Percy Shelley wrote of the connection between deja vu and dreams, though his thoughts were not published till after his death. So here's the quote. The scene was a common scene. The effect that it produced on me was not such

as could have been expected. I suddenly remembered to have seen that exact scene in some dream of long here I was obliged to leave off, overcome by thrilling horror. Wow. But back to this study in particular, they point out that as a blanket explanation for deja vou. This one,

you know, dates dates back quite a long ways. Um. One of the earliest explanations for the deja experience, I think we mentioned the first one was when St. Augustine wrote of it in the year four or sixteen, and then Sir Walter Scott much later writes about it in the eighteen fifteen. But the authors of this paper, they

set out to perform a survey of the experience. Now, this was a survey of four hundred and forty four people asking them about their experiences of deja vous, specifically de gen rev the association between this feeling of deja vu and their dreams, and so out of the four forty four individuals that responded, um, it's interesting. So the first of all, there was the frequency. Now in the study they break they break it down a little more,

a little more detail. But basically they found that of the people sampled uh said that yes, they did experience deja rev. Uh. Now how often they experienced it varied uh quite a bit. Um. For instance, twenty one or four point eight percent UM said that they just never

experienced it. But in terms of those that did, like you know, you had like forty one said that they experienced it less than once a year, But then there were eight individuals, which is only one percent of the of of the the individual's polled here they experienced it several times a week. Wow. Um, well, I'm curious how this squares with previous research finding that you know, up to something like a third of people or maybe up tot of people, and some of these older surveys report

having never had any experience of deja vu. I wonder what's going on because you talk to people nowadays, that figure seems kind of high. I would figure that you know, close to you know, nearly everybody has had like at least some kind of deja vu experience at some point. But these older surveys, you know, have it, have it still very common but lower? I wonder if there used to be more of a stigma or kind of weird paranormal association with saying that you've had deja vu? Does

that make sense? Like maybe if people didn't think that there could be any kind of like normal explo nation for it, they'd be less likely to want to admit it and talk about it like their gender norms about it, Perhaps like a real man doesn't have deja vu or a proper lady never experiences deja vu. It is simply uh not done, uh, something to that effect. I don't know. Yeah, that's true. You know, you can't be a cowboy if you've got deja vu. It's true. I've never Uh, I don't.

I don't think even Corman McCarthy considered deja vu and the American cowboy. Well, no, I'm just curious, and maybe there's something I'm missing here. It just seems like in these older surveys, fewer people admitted to having deja vu. Now with this particular study, I should note that the authors admit quote the high incidents of deja rev again about in this sample might be explained by the fact that the sample consists mainly of psychology students who phenomena

it is interesting and related to their chosen profession. That is, okay, that makes a lot of sense that in these serve as we may be getting a a less randomized, more rarefied sample of like the kind of people who are more likely to remember these experiences and want to talk about them. Yeah, just more likely to be introspective about your your own in reality. Um. They also point out that the previously noted in other studies. Association between deja

rev and dream recall frequency seems, on one hand plausible. Okay, so if we're making the connection between this deja experience and dreams, a person with high dream recall might be more likely to attribute deja vu experiences to prior dreams. However, quote the impression of having dreamed, the actually occurring events arises within that moment and usually cannot be attributed to a particular dream in the past, even if the person's kept dream diaries in order to document the dreams prior

to the de genrev experience. I think that squares with the overall anomalous familiarity phenomenon, like when you have deja vu. The whole point is that you can't relate it to a specific experience in your memory. It's just the general feeling that I've seen this before, uh and yeah, and that seems to go go along with the dream phenomenon as well. I also came across a twenty paper that UH basically found that de gen rev experiences are common

after electric brain stimulation standard and treatment for epileptic symptoms. Now. They looked at three different subsets of de gen rev episodic, so you know, with a direct connection made to a specific dream, half remembered scenes that echoed their current circumstances, and an even dreamy or like state in which the experience itself is dream or nightmare like. So I felt that guest a little more perspective on on what maybe going on here. So let's again remind everyone deja vu

the experience that something novel was actually familiar. So imagine this. Imagine feeling this as you walk down a new hallway and you're about to open a door or to an office you've never visited before. You feel, at least for you know, for a second there, for this fleeing moment, that you know what will be on the other side. Now, this is just a feeling, but it feels real to the people who experience it. It feels like in this

moment of deja vous, you are able to see the future. Yeah, and in fact, some people I think this is one of the reasons that a lot of people have been kind of insistent on viewing deja vu is some kind of actual paranormal phenomenon and not just like a strange feature of the brain um that sometimes people feel like they are actually getting information about the future from it, you know that like, I know what's going to happen next, and really, this does I think feel like this kind

of thing adds another wrinkle to our understanding of people who claim to have precognitive abilities or experiences in their life, you know, because if you're if you're taking just like the hard skeptical approach to that, then it's like, Okay, some people are crazy, some people are scammers, maybe some

people are both of those. But but this by by thinking about the link between deja vu and pre precognition, you could well have a situation where someone maybe they're more inclined to engage in uh supernatural ideas or some

sort of religious model that incorporates precognition. But if you had just at least a few flashes of this sort of experience, like a moment where you're like, yeah, I knew, I know what's going to be on the other side of that door, and even if it's it ends up to not be the case, you know, you still have

that feeling that felt so real. Well, this seems like the kind of thing that you could actually put to the test, if only you could create scenarios and we talked earlier about the difficulty of creating deja vu on command. It's obviously not easy to do. But if you could put together a test where you could sort of where you could sort of try to stimulate deja vou like experiences in people, you could actually put this to the test, right, you could find out a weight, do people have any

additional predictive power? All right, well, let's let's jump into

this particular study that I have lined up here. So this is a two thousand eighteen study that was published in Psychological Science, and it was titled Deja vous An Illusion of of Prediction, And this was by an Im Cleary who we mentioned earlier, and Alexander B. Claxton so clearly has put a great deal of research into deja vu as well as tip of the Tongue over the years, and her working hypothesis is that it's a quote particular

manifestation of familiarity. Something feels familiar when you paradoxically feel that it shouldn't. In her last ten years plus of research, she started hearing a lot about people's claims to the precognition feeling, you know, again, not the reality of of predicting the future, but the feeling the confidence that you, uh, you know what is going to occur, and she wanted to see if, as she suspected, the feeling was a

memory phenomenon as well. And of course the ad uh complication here for for her is that you know, memory does aid us in our ability to predict future of events. So it's far from a trivial question. Memory isn't just there to make you feel good or bad about the past. It's about survival moving forward. So what did they do?

Always to discuss some of the issues with trying to recreate deja vu in the lab, So their approach here was to UH was was to basically pull it off via virtual reality, based on past studies that found out that subjects were more likely to report deja vu among scenes that spatially mapped onto earlier witness scenes. UH. Subjects were put through familiar virtual hallways and then ask if

they felt deja vu or premonition at key turns. So, you know, this is a situation where you can just imagine you know, Doom and Wolfenstein kind of hallways, you know, virtual hallways, UH and some of the same mapping, but but a different feel a different look. And then the researchers would jump in at key points and see if if there was a sense of deja vu or premonition on the part of the subject. And these were their findings.

About half the respondents felt a strong premonition during deja vu. However, they were no more likely to actually recall the correct answer, uh than mere chance would explain. So that's not to say that the take home here is that deja vu experiences are not pre cogs. We know that we knew that going in, but rather that it creates an illusion of certainty, confidence in the choice that might be linked

to stuff like hindsight bias. Now, her work on all this continues, Uh is you know, great deal more that could be learned about the deja experience. But I think this is really interesting because again you can see how this might form the bedrock, uh for greater beliefs in

precognition and uh predictions of the future. You know, you you build upon this with some sort of existing religious, supernatural magical script about individuals who can sense the future, and uh, yeah, it seems like they would one would support the other rather well. Sure, all right, so there you have it. We're gonna go and call it here. We hope you enjoyed our two episode look at the Deja Voo experience, all that it seems to incorporate, and

some of our best attempts to understand it. Though those those attempts are still very much in process. The work continues in the meantime. If you want to check out other episodes of Stuff to Blow Your Mind, you can find us wherever you get your podcasts wherever that happens to be. Make sure you rate, review, and subscribe. Huge thanks as always to our awesome audio producer Seth Nicholas Johnson.

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