Okay so I study memory. You may have seen my work slightly fictionalized in “Memento” or “Eternal Sunshine of the Spotless Mind”. It’s glamorous and I get to mess people the heck up with magic brain machines. Here’s the thing though: one of the only unusual aspects of memory that I’ve ever directly experienced is “Deja Vu”. And as a brain person who studies memory I feel like it’s my job to know what the fuck that was and why it happens. People come up to me on the street and they beg me to please explain so their nightmare can end. Only, I haven’t found any decent explanations! Wait what is that? You don’t know what deja vu is? Oh well jeez let’s start at the top gosh I’m sorry.
Deja Vu is the intense, awesome experience of knowing exactly how a situation will play out because you’ve been there before. No, I don’t mean when a situation seems “familiar”, and I especially don’t mean when you point out something is happening over and over again. Fuck, that’s the opposite of deja vu. The few times I’ve been lucky enough to experience intense deja vu it felt as though I’d been transported into my own body in the past. I didn’t feel familiar with the situation I was in, I felt as though I could finish every sentence spoken. And the sense of time is amazing, you get a very distinct sensation of not living the same thing twice, but of being in a place you were before, some vague moment a week or a month or a year ago that has dragged you back into itself. In fact, the fullness of sensation experienced has caused quite a few researchers to recommend the term “deja vecu”, because “vu” means “see” but you do more than see. This is evidence that researchers enjoy being pedants when they’ve run out of useful things to do. The point is: I really cannot recommend intense bouts of deja vu enough, they’re lovely.
The second thing you need to know about deja vu is that fucking everyone writing an academic paper on policy or economic research thinks the phrase “deja vu all over again!” is hilarious because they are children.
The first thing any article about deja vu will tell you is that don’t worry it’s totally normal. Thanks guys! It’s good to know you’re not officially calling me crazy, but I don’t think anyone in history has experienced deja vu and immediately checked themselves into a mental hospital or anything. It’s pretty well known, guys. In fact, the earliest mentions of deja vu seem to be from St Augustine, talking about “Falsae memoriae” conveniently choosing to write in the type of Latin that is basically silly English for ease of comprehension. But the actual term deja vu wasn’t coined until almost 1900, by a man named FL Arnaud. Apparently he didn’t like the fact that it was being referred to as “false memory” because maybe that wasn’t what was occurring.
So, you know what it is you know it isn’t a sign of madness and you know to stop saying “deja vu” when something happens twice. Now, what causes it?
Hahaha well we’ll get back to you on that dude. Turns out the reason a registered Ultra Brain Scientist didn’t have a clue what caused it is because yeah basically we don’t have a good theoretical or practical idea of what causes it. In fact, a couple papers dedicated any words to “parapyschological theories” like telepathy and astral projection. The weirdest part is how half-assed a lot of these are. I mean obviously Freud tossed out one about how you want to fuck something and your current situation is causing you to recall a repressed fantasy… which makes total sense! That’s why deja vu only ever occurs in situations that anyone would fantasize about and not in completely unremarkable ones. God it’s like he didn’t even finish listening to the description. There are a couple psychodynamic theories like that: it’s a defense mechanism, it’s dream residue, it’s wish fulfillment, etc. None of them make any actual testable predictions or in any way explain the reasoning or mechanism beyond saying it kind of sort of makes sense sometimes if you think of it like that. Good job Psychodynamics!
There are a few decent-ish proposed explanations from other areas of psychology that take themselves slightly more seriously. It could be that deja vu is some form of disturbance of time perception, causing things that were just seen to be mislabeled as having happened some time ago. Of course I’m pretty sure that theory is just as useful as the one proposed since the beginning of the fucking phenomenon. Time perception having some thing to do with deja vu? Oh wow, awesome job. The one that’s gotten the most support in my opinion is the idea that deja vu occurs when for some reason the mind simultaneously “records” into memory and “reads” out of it. I put those words in quotes because I’d give great odds that there’s not anything remotely like “record” and “playback” in the brain and this is just a slightly more useful shitty analogy. There are also a couple papers suggesting that deja vu is associated loosely with better memory function. Which again sort of makes sense but is also disappointing as an explanation. I guess it rules out some possible explanations like a faulty memory that accidentally wrote to bad sectors or something like that. The thing is, there are more than a few of these explanations but they all amount to “some processes that are supposed to be in sync are out of sync for a bit”. Replace “some processes” with whatever it is the authors are flogging all over the place. No one seems to actually be engaging with the phenomenon so much as explaining it on the way to other research.
There are a few neurological examinations of deja vu that are a little bit better about explaining it but still nothing groundbreaking. Basically it’s been noted that it can occur frequently in people experiencing some form of pathological mental disorder. There are frequent reports of deja vu experiences in epileptics, and because epileptics are one of the few groups of people whose brains we can jam electrodes into in the name of science, there are a few reported findings of induced “dreamy” states that are similar to deja vu during some stimulations of the temporal cortex. Of course, it’s entirely possible that these deja vu-like states experienced in pathological patients bear only a surface resemblance to actual deja vu, in the way that visual hallucinations aren’t caused by the same phenomena as actual vision. Then there are more of those asynchronicity explanations, only with “neurological pathway” replacing “process”. At least these have some better surface validity though, I can see where it’s possible that two pathways for sensory information might split into a sort of double vision. Of course, that explanation doesn’t match the subjective experience at all, because people experience all sensory perception during deja vu as occurring simultaneously as normal. The “two pathway” explanation loses a lot if it becomes the “12 really intricately timed pathways” explanation. They’re all so frigging general though! “Slowed transmission” “something going wrong during a seizure”, etc. So again, yes maybe the function of the brain might affect an experience we have somehow good job guys.
Explicitly memory based theories of deja vu are many and varied but they share a lot of essential elements, basically whatever general theory of memory someone has is applied inexpertly to the phenomenon. So you know if memories are stored, then a prior memory is “slightly activated” and gives a feeling of undue familiarity. If there are two memory processes, one is out of sync. Etc etc, none of these are particularly noteworthy because they just repeat the general theory and make slight attempt to explain the phenomenon. The last category of possible explanations involves attention, basically that you pay slight attention to a scene and then rapt attention to a scene and the slight attention you paid earlier gets somewhat but not entirely overshadowed. This then makes you think you’ve seen it before. You’ll notice this doesn’t really make any goddamn sense because that’s not remotely close to the subjective experience.
Really the issue here is that experiments are what informs science, and there just haven’t been a lot of experiments dealing with deja vu. Because here’s the dirty secret of science: we are all lazy. Hard experiments fall by the wayside because why bother? There are dozens of other phenomena that are easy to reproduce in a lab and study. I know I can’t think of a way to produce deja vu in a lab environment, and I can’t think of an experiment that would get to the heart of the phenomenon. That’s not to say we’ll never understand it, but it is to say we’ll probably get to it last, or accidentally.
So there you have it. Science tells us:
Deja Vu exists
Don’t worry it’s normal
Happens more often in young people
It might be two things of some sort working out of sync, or it might be nerve problems of some sort, or it might be memories activating badly somehow, or it might be you paying weird attention.
And it’s really fucking hard to investigate so stop bugging us about it it’s just some weird thing jeez.