Instant Genius - The extraordinary psychology of Déjà vu, with Dr Akira O'Connor

Episode Date: February 27, 2023

Sorry if we’ve already asked, but do you know what causes déjà vu? Or why you experience it less as you get older? Just in case you're unsure, we got the answers from Dr Akira O’Connor, senior psychology lecturer at the University of St Andrews. In this episode, he talks us through the bizarre neuroscience of déjà vu, from what makes you more prone to it, to how you can easily create an artificial sense of déjà vu in somebody else. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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the bite-size master class in podcast form. I'm Thomas Ling, digital editor at BBC Science Focus magazine. In your lifetime, you probably feel, felt deja vu, that strange, overwhelming sensation that you're currently experiencing something that's already happened. However, you might be unfamiliar with how by studying this memory illusion, scientists have uncovered some amazing truths about the human brain. One of these scientists is Dr. Akiria O'Connor, senior psychology lecturer at the University of St Andrews. He joins me to explain why deja vu happens, how deja vu is actually the sign of a healthy brain,

why you experience it less as you get older, and also the strange case of one man who lived in a constant state of deja vu for several weeks. Hello, Akira, thank you very much for joining me. Hi, thanks for asking me to speak with you. So I'm going to start from the top and ask, what is deja vu? Is it simply that feeling that you've experienced something that's happened before?

It's a little bit more than that. It's the feeling that you've experienced something before along with this kind of counterfeeling that you know you haven't experienced it before. So it's this kind of duality of your experience. I feel that's familiar, but I also know from everything I know about my life that that is not true. That feeling of familiarity is incorrect. So does that mean that a lot of people might not actually notice they're having that experience? It would do if it wasn't accompanied by a feeling of strangeness, a feeling of kind of

weird oddness that makes you notice the different aspects of your, your kind of conscious experience coming together and disagreeing with each other. And so it's why people typically describe deja vu as feeling strange or weird or odd. It's why you comment on it to your friends when it happens, because if it was just a part of your everyday experience, it wouldn't be noteworthy, but it's that particular combination of things feeling wrong because you've got these almost arguing inputs into your conscious experience going on. So why do we have this feeling? What causes it? There's a few different ideas about what causes deja vu.

The idea that we've been working on in our lab is that there's a set of brain regions in your medial temporal lobes. So these are brain regions that are associated with memories associated with setting down new memories, associated with retrieving old memories. There are brain regions that signal when we're finding something familiar. Now, usually those brain regions signal that we're finding something familiar when we are actually retrieving a memory. But sometimes those brain regions can just signal familiarity in a way that isn't quite right. They're kind of twitching,

like your eye might twitch when you're tired. They're kind of over-eager and keen to signal, and they do so when there isn't anything to find familiar. Now, those brain regions have consequences for the rest of the brain, obviously. They send these signals elsewhere. And there's another set of brain regions, the frontal cortex, that do a lot of fact-checking,

a lot of higher order cognition. What happens when those frontal regions get this incorrect familiarity signal is they do a bunch of fact-checking, a bunch of, well, is this consistent with the rest of my life? Does this feeling make sense? When they determine that it doesn't make sense, that's when you get this kind of mismatch of familiarity signal and awareness that the familiarity signal is incorrect. So you've got this kind of error correction going on and that's the feeling of deja vu. So is this quite a bit to do with memory processing in the brain? It's memory processing combined with the higher order reasoning. So for example, a lot of people will typically report that they experience deja vu when they're traveling. And there's a few reasons,

that might be the case to do with tiredness, to do with the age at which people are when they tend to do the most travelling and so on. But one of the reasons that it becomes really obvious when you're travelling is that a lot of the time people are acutely aware that they haven't been to that place before. So it becomes really easy for the kind of fact-checking frontal lobes to say, hang on a minute, there's no way I can find this familiar. This must be a deja vu. So that's set against, for example, deja vu as you might have when you're at home or when you're at university or school or at work, where it becomes a little bit trickier to determine whether or not something is familiar, because the whole surrounding is quite mundane and quite familiar.

So I guess being somewhere new really helps the frontal lobes figure out that, yes, this is an incorrect sensation of familiarity. So is it effectively then the memory correcting itself? It's quite a healthy thing to experience. Yeah, that's a really good way of thinking about it. DejaVue tends to happen most in young people, young people between kind of teenage years and early 20s. And what we know about memory is that that's when our memories healthiest, that's when our memories are most likely to be correct. It's as we age that we start making more memory errors. If deja vu were a memory error, then it would probably increase as we age, but it doesn't. It's the opposite. So that all points to this being a very

kind of healthy error correction process within a healthy memory system. So should I be worried as someone in my early 30s that I don't really experience deja vu that much anymore? No, you shouldn't be worried because you're just like everyone. else. I used to experience deja vu a lot in my teens, my early 20s, and now the experiences are sadly like hen's teeth. It's a bit

of a shame because I'm a deja vu researcher. I love to experience it. I love to experience it, but sadly it doesn't happen so much anymore. So is there any evidence that deja vu is actually a signal

there's been a change in the matrix? that's a lot of people's kind of entry into thinking about deja vu into thinking about what's going on when they experience deja vu and it's a pretty cool film i do enjoy the matrix but uh it's it's probably not anything as um as as fantastical as that there's all sorts of evidence suggesting that if you start stimulating people's brains if you start giving people's brains if you start giving you start giving you giving people medications that interact with certain forms of brain chemistry, that you can quite reliably increase deja vu. So it's probably much more to do with what's going on inside someone's head than what's going on in their surroundings. So is there anything that makes somebody more susceptible to experiencing deja vu? Yeah.

So younger people are more likely to experience deja vu. people with certain diseases are more likely to experience deja vu, so diseases like epilepsy and in some cases diseases like dementia. And then people who are tired tend to experience deja vu more as well. Why is it that if you are tired you would experience deja vu more? If deja vu is the memory correcting itself, I would have thought that the opposite would happen. That's a really great question. I think one of the reasons we experience DejaVu more when we're tired is probably to do with the fact that when we're tired, a lot of the systems that keep our nerves transmitting correctly and kind of keep our nervous systems in good order, start to get a little bit frayed. So just as you might notice, your eye might twitch a little bit more, you might start making a few.

more kind of errors in some of your thinking when you're tired, that's probably what's happening to the familiarity signaling within your brain. But the really important thing about that is that the frontal cortex is still capable of catching those errors. So we're not so tired that we stop noticing these things. And that's the really important aspect of the experience. It's that the error happens, and that's more likely when you're tired, but that all that. Also, you're still able to notice that the error is happening because you haven't lost your wits completely. So does somebody's level of certain neurotransmitters impact their susceptibility to experiencing deja vu? Yeah, so that's one of the things that we think is happening when people take certain drugs.

They can elevate excitatory neurotransmitters like dopamine. And dopamine in the brain causes all sorts of... neurons to to fire more than they would otherwise, including brain regions, neurons in brain regions that signal familiarity. It's why we think younger people are more likely to have deja vu, because they have more excitatory neurotransmitters, which lead to this firing, this firing of familiarity, this signaling of familiarity, that then gets caught by the frontal cortex. And it's also why as you age, as these levels of neurotransmitters start to decrease, we start seeing decreases in deja vu. No one goes to Hank's for spreadsheets.

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tradition with pioneering thinking. Name Audio pushes cutting-edge technology to ensure digital precision whilst sustaining Pratt, pace, rhythm and timing, the elusive quality that makes music feel alive and gives it emotional texture. Today, in partnership with French acoustic specialist's focal, name audio creates systems that deliver exceptional, sound and unforgettable listening experiences at home. Try it for yourself at a focal powered by name boutique. Visit focal powered by name.com for more information. That's quite depressing actually.

It's kind of like as you get older, everything is not as exciting. You don't enjoy things as much? Is that right? Yeah. You don't enjoy things as much, but perhaps, but you also make fewer kind of risky and impulsive decisions, which is probably good for kind of safety and well-being in the long run. So there's a time to be impulsive when you're young, when there are probably slightly fewer

things riding on it, riding on things going wrong as well. So, you know, it's a nice system that probably works well for humanity in the long run. That was quite a diplomatic answer. Is there anything else that could impact if you experience Dejaveu more? Yeah, so there are certain, I've already mentioned, pharmacological substances, certain drugs that people take. So people report DejaVu as part of taking certain recreational drugs like cannabis, like amphetamins. But there are also some really interesting case studies of people who've taken,

for example, different sorts of flu drugs, taking them together and noticed that everything that they encountered, having taken that combination of drugs, led to them feeling the experience of deja vu. Now, that case study was really neat, someone after my own heart, because they actually carried on taking the drugs for the full course because they found their continuous deja vu so interesting that they didn't want it to stop. So what sort of things did they experience then if they had this persistent deja vu. They felt like everything they were encountering was familiar, but they knew that it couldn't be as familiar as they were feeling it to be, because that sensation, and to have that sensation in such

a prolonged way for everything you encounter is not how we go about experiencing the world. So they were really kind of fact-checking, cross-referencing whether or not that feeling, was part of their normal experience and finding that, no, this really isn't, which is what gave them the sensation of deja vu. Wow. Is there a complete opposite as well? Have there been people who have felt where nothing is new to them? Yeah, so the experience, Deja vu,

from French were already seen. The opposite experience is called Jaume Vu, from the French never seen. And it's kind of the equal and opposite experience. So it's the inappropriate feeling of unfamiliarity for something that you know should feel more familiar. People sometimes get this feeling when they're, for example, seeing people they haven't seen in a while, and they feel much more unfamiliar than they should, given that, for example, they've known them for years and years, a really straightforward way of generating this feeling in yourself is to write words out over and over.

You might have done this if you ever got lines at school. You can write your lines as a full sentence across the page, or if you look for a bit of a break and you want to do things slightly differently, you might write the words down the page in a column of the same word. When you do that, that leads to a sensation known as word alienation. which we think is very similar to Jaumevo, where the word stops making as much sense as it did when you first wrote it out. It seems to break up.

It seems to lose meaning. And that weirdness in the feeling is very similar to what we think is happening when people experience Jaamevut. So does it matter if you are going to do this experiment on yourself? What word you write and how long should you be writing this word for? Yeah, so there have been some studies that we've done. done looking at which particular words are more likely to lead to familiarity breaking down like that. But it doesn't take long for people to experience this. People can typically experience

this within kind of 15 to 30 repetitions of that word. Some words it might be quicker, some words it might take a lot longer or it might not happen at all. But yeah, it's a pretty reliable phenomenon you can induce in yourself. Are there any people who have this sensation permanently? Yeah. So, deja vu can manifest clinically in people with other health problems. One of those health problems would be dementia. And we occasionally hear about some quite heartbreaking stories of people who've started

undergoing dementia. and so we're obviously acutely aware that they're starting to forget a lot of things. Then at some point they get this sensation of familiarity and that everything starts to seem familiar. And obviously it seems like a relief to start with until they realize that actually that familiarity is being applied everywhere to everything, even for things that probably shouldn't be familiar to them. And so, yeah, this manifestation of deja vu, we refer to as deja vecu.

It's already lived as though everything you're experiencing in your life is familiar. And it can be really upsetting and really, really problematic for some people. So it's more serious than, say, having the feeling that you're watching TV and you've seen everything. It has much more sort of serious implications than that. Yeah, it has what we call behaviour. consequences. So deja vu, healthy deja vu, doesn't tend to lead to much more than us remarking on it to our friends and family. Oh, weird, I'm having a strange experience. But people who are experiencing deja vecu, clinical deja vu, will often start acting on those

experiences. So you might be watching television and if you've got deja vecu, then you might think, oh, I've seen this before, I need to change the channel. I need to turn the TV off. I need to modify my behaviour because I actually believe that this familiarity is true. And we've had people contacting the BBC because they're sick and tired of all the repeats that they keep seeing on every single BBC channel they go to. And whilst that might be the case once or twice, it isn't the case that that's all the BBC is showing. Therefore, we have an idea that these people reporting in with those complaints are probably experiencing Dejafecu. Are there any other strange power of deja vu out there?

Yeah, so Joseph Heller wrote in Catch 22 about three sorts of dissociative experience. One was deja vu, one was Shamevu, and the third was Presquevue, Presquevue being the sensation of insight, of false insight. So people often experience something like Presquevue when they are, when they wake from a dream.

and that dream seems to have given them the answers to whatever it was that might have been worrying them or they might have been thinking about over the past few days. Now, very occasionally, the dream has been pretty important in helping to figure things out. But more often than not, what we find is that presquevue is this kind of illusory sensation. Everything seems like it makes sense when you wake from that dream. But as soon as you go to tell someone, it stops making sense. It just starts being this weird dream rather than the answer to everything. Now, there are all sorts of situations in which this happens in real life, I guess,

you know, when you're out and about rather than just when you've woken up from a night's sleep. And I guess those sorts of Presquevue sensations tend to be quite noteworthy because dreams are a bit weird, but out and about in life you don't expect to have these kind of revelatory moments, and you don't expect them to kind of dissipate either in the way that Presquevue sensations do. I had one once where I was on the London Underground, and I was particularly tired, and I remember wearing my backpack, going up an escalator, thinking, this is what life is. Life is just a series of escalators. And it felt exceedingly profound until I turn to the person next to me and tried to tell them that. And they, they looked at me like I was

an exceedingly tired person who was having a strange mental experience, which is exactly what I was. So circling back to deja vu, what sort of recent research has really blown you away on this topic? So it's nice to speculate about what might be going on in the brain when we're having these experiences. But typically that tends to just be speculation. Deja vu is a lovely, kind of a lovely case study within psychology, because you can't ever look at someone and see that they're experiencing deja vu. There's no kind of, there's no look on someone's face that tells you, oh, that person is having deja vu. You have to tend to kind of trust people. You have to try and assume that what they're telling you about their internal experience is correct.

Now, one of the studies that we ran a few years ago in my lab was to try and give people a feeling like deja vu to see if we could scan their brains as they were having this analog of deja vu feeling. And if we could kind of find any evidence corroborating our theories for what's going on with the temporal lobe and with the frontal lobe as they experienced that feeling. And we were able to show that, yeah, when people are experiencing deja vu, their frontal cortex, the kind of error monitoring, fact-checking part of the brain really does become more active. And so it was a nice piece of evidence that was consistent with how we've begun to think about the experience. So how on earth did you artificially

create that sensation of deja vu? So creating that was a little bit complicated, but I'll go through it and bear with me. There are two components, as I've spoken about, to a deja vu experience. One is a feeling of familiarity and the other is an awareness that that familiarity is wrong or misplaced.

So we need to generate both of those feelings in our experiments. The way we generated familiarity was using a relatively old technique for generating false memories known as the DRM effect. It's named after three psychologists, Dees, Rodiger and McDermott. Using this effect, what you can do is you can give people a list of words that are all related, but leave out one keyword that is super related to all of them. If you do that and then at test you ask people, have you seen this word? Have you seen that word? Have you seen the other word? If you present them the key related word that you didn't present them at the start, they will nonetheless tell you, yes, I saw that. So to put this in concrete terms, you might give people the list of words that is mattress, pillow, sleep, night. All of those words relate. You to a key word that I haven't mentioned. Now at test, I might ask, well, did you see pillow? And they will say,

yes. Did you see rhinoceros? And they will say, no, no, I didn't see that. Did you see bed? And they will say, yes, even though you didn't present bed. That wasn't one of the original words I presented. So that's your false familiarity. Now, how did we get people to recognize that that familiarity was indeed false? Well, if we go back to that kind of studying that list of words, we also got people to count the number of words that began with the letter B. As soon as we did that, when we ran through that list of words and they said, no, I didn't encounter any words beginning with B. When we go to the memory test and we ask them whether or not they recognize the words, as soon as it got to bed, they felt familiar. for it, but they knew that they hadn't seen any words beginning with B. And so that led to the kind of building blocks behind the deja vu experience.

And it was when people experienced those sorts of situations within the brain scanner that we saw the frontal cortex elevating and were able to match that up with their own reports of something that felt a lot like deja vu. Why do you think that studying deja vu is so important? It's an amazing insight into consciousness, I think. One of the beautiful aspects of the experience is that we're able to see how all of the components that normally contribute to a kind of very unified, coherent, conscious experience of the world start to break up.

So you get this feeling of familiarity that another part of your brain tells you, hang on a minute, that doesn't seem right. And your brain has to kind of do some on-the-fly problem solving to figure out which course of action it needs to take. Trust this sensation of familiarity or trust that it's just something weird that's happening and carry on as usual. It's very unusual for us to have these experiences where things don't quite seem to make sense within our own brains within our own experiences of the world. So it gives us a real insight into all that must be going on kind of in our everyday lives for us to have such good, coherent experiences of the world normally. It's kind of like when a car or a computer breaks.

And I know it's, that's super annoying when it happens, but you start to realize how many bits of machinery there are that keep the experience kind of really good, and make that machine or make the car really useful normally because it all works seamlessly. It's only when it breaks that you start realizing the complexities of everything that's involved in making it work. That was Dr. Akira O'Connor, senior psychology lecturer at the University of St Andrews

talking us through the neuroscience of Dejaabu. Thank you for listening to this episode of Instant Genius, brought to you by the team behind BBC Science Focus magazine. which you can find on sale now in supermarkets and newsagents as well as your preferred app store. You can, of course, also find us online at sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analog warmth.

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