Deja Vu: Experiencing the Unexperienced
Our memory is remarkable; it allows us to remember things—the good and bad—and helps us make sense of everything around us by preserving details and events that we can later revisit. It's a crucial ability, without which we would have no semblance of who, what, or when. But what about remembering things that never happened? You must have had that feeling before. You know, the feeling that you've literally—and I mean literally—been somewhere, doing the same exact thing with the same exact people, in the same exact situation. The same words, lights, sounds—everything.
You try to hold on to the strange yet familiar feeling to try and understand it—to notice something that might explain what's causing it. But your efforts are to no avail; it's gone, just like a dream you cannot remember. Vivid as it was, that feeling too is gone. It was right there; you know you had it, but before you know it, the familiarity vanishes into thin air, and sure enough, life returns to normal.
Welcome to the world of déjà vu. The term déjà vu means "already seen," and instead of a throwaway term used to describe the repetition of a similar event, most of us describe it as an overwhelming feeling that the moment being experienced has already happened before, even though you know it probably hasn't. It's a common phenomenon, with as much as 70 percent of the population having experienced some form of déjà vu. But it's a complicated one, considering it's so vague and abstract.
Considering how common it is, however, you would expect that we would know more about it by now. Sure, there is some consensus about likely theories, but definitive explanations, just like the phenomenon itself, remain elusive. The feeling of déjà vu remains surrounded by mystery and even paranormal interpretations because it's fleeting and unexpected. However, these very things that intrigue us are the same things that make it so hard to study.
There are many different theories as to why déjà vu happens. In fact, there were over 30. You get the idea. Whilst these are all distinct and specific, I'm left wondering if most of our experiences of déjà vu are, in fact, a combination of several of these different types—all at the same time. Déjà vu was quite possibly an umbrella term to describe any combination of these experiences. These experiences can be short, medium, or long duration and are different from what could be called anomalous familiarity, like when you find someone's face familiar but can't quite place where you know them from.
In fact, déjà vu experiences can be placed on a spectrum of familiarity, on the far end of which are delusional misidentification syndromes. Syndromes like the Capgras delusion fall into this category, where patients think that loved ones have been replaced by imposters that happen to look alike. In other words, they find unfamiliarity in the familiar—the exact opposite of déjà vu. That being said, Capgras delusion is a psychiatric disorder with some sort of explanation, whereas the explanation behind déjà vu—well, let's get to that.
Scientists have tried many times to recreate déjà vu in the lab, with mixed success. In a 2006 study, researchers first created a simple memory for patients under hypnosis, something like playing a game or looking at a printed word in a certain color. Then, patients in different groups were given a suggestion to either forget or remember the memory, which could then later trigger the sense of déjà vu when they encountered the game or word. Others have tried to induce déjà vu using virtual reality. One study found that participants reported experiencing déjà vu when moving through The Sims video game when one scene was purposefully created and spatially mapped to another. For example, all of the bushes in a virtual garden were replaced with piles of trash to create a junkyard with the same layout.
The success in creating déjà vu experiences of sorts in these experiments has led scientists to suggest that déjà vu is a memory phenomenon, and this continues to be the most generally accepted explanation. Much like a word can be on the tip of your tongue, a déjà vu experience could be a memory at the tip of your mind—there, but not quite accessible. When we encounter a situation that is similar to an actual memory but we can't fully recall that memory, our brain recognizes the similarities between our current experience and one in the past. We're left with a feeling of familiarity that we can't quite place.
I've gotta say, though, I don't feel like this explains my own experiences very well. There are many other theories that attempt to explain why our memories might malfunction in this way beyond this pretty general explanation. Some say it's like our brain short-circuiting, leading to long versus short-term memory—new, calming information goes straight to long-term memory instead of making a stop in the short-term memory bank. Others blame the rhinal cortex; one study used an MRI to scan the brains of 21 participants as they experienced a lab-induced déjà vu.
Interestingly, the areas of the brain involved in memory, like the hippocampus, were not triggered as you would expect if the feeling was linked to, for example, a false memory. Instead, the researchers found the active areas of the brain were those involved in decision-making. They interpreted this result to mean that déjà vu could instead be a result of our brains being involved in conflict resolution. In other words, our brain could be checking through our memories, looking for conflicts between what we think we've experienced versus what actually happened to us.
When your brain is firing on all cylinders in a familiar environment and in a routine that it often repeats, it's easy to use a sense of familiarity for what you're seeing as a guide, scanning back through your memory until you can recall the origin of the memory. But when your brain is tired, stressed, or anxious, or surrounded by the unfamiliar—even it might struggle to scan through everything it has been exposed to well enough to perform this conflict resolution. Instead, you start having intense feelings of familiarity brought on by things that are evocative of what you've experienced before. This could be a particular configuration of cups or books on a table, a street that looks a certain way with a traffic light in a certain position—without being able to pin down why it feels so familiar.
The brain will always go for the easy way out; it decides that it's clearly been here before and done this before and is happy enough with that explanation, so it doesn't bother to investigate any further. It was tired, after all. The split perception theory suggests that déjà vu is when you see something two different times and just weren't paying attention properly the first time. Apparently, the more distracted you are, the more likely you are to experience déjà vu. If you're distracted by something else and don't take in all the available information around you, your perception might be split into two parts rather than one. Essentially, your brain recalls the previous perception even if you didn't. This can slightly confuse your hippocampus, the part of your brain important for memory processing and navigation, and lead to that sudden and eerie feeling that you've seen it, been there, or done that before.
How about this? The experience actually happened. Yes, you heard right—however unlikely that might sound. Sometimes, when you have déjà vu, it might not actually be déjà vu at all. The feeling of familiarity could be happening because you've actually had the same experience in the past but simply don't remember it. I'm not convinced personally, but a study did find that déjà vu can often be related to things you've seen and done, even if you don't remember it. Spatial awareness also seems to matter when it comes to déjà vu; similar layouts of places can lead to the feeling, even if the two places look nothing alike.
That's why the Sims experiment from earlier actually worked. Or maybe you just have a dominant eye; most people have one, and apparently this could also contribute to feelings of déjà vu. If the stronger eye sends information to the subconscious before both eyes focus and register the input as a conscious experience, your brain sends a message to tell you that you've seen this before. And you have, but it was just a nanosecond ago. But then again, that wouldn't explain the more versatile forms of déjà vu, where it's less about sight and more about experience.
A link that potentially ties all this together is consciousness. One of the recent theories aimed at trying to explain consciousness is about the brain's processing of information and our experience of that process. It talks about a patient with hemispatial neglect resulting from a stroke; pretty much, the patient lost awareness on one side of her body. Yet she was able to process details about images with the unaffected side without being aware of actually seeing them. What this tells us is that a lot might be going on around us without us truly being aware of it.
Or maybe it's just a glitch in the matrix. I know, it sounds sci-fi and all, but if you entertain the notion that we might be in a simulated universe, the idea that something like déjà vu might be a glitch in the matrix is not hard to visualize. It might be that these strangely beautiful instances are products of a code error—errors where the computer simply messes up the timeline for some of the players before quickly fixing themselves. Strangely enough, this theory has a remote basis in reality, albeit on the other side of the familiarity spectrum.
Patients with a rare variant of Capgras delusions have reported that they feel time has been warped or substituted. Theoretically, a similar warping could also lead to déjà vu. But back to reality now—it's hard to deny the numerous different explanations, but the lack of a definitive answer leaves the phenomenon open to stranger theories still. Depending on your point of view, it's hard to discount them completely, however outlandish they might seem.
As well as normal déjà vu, many claim to also have precognitive déjà vu experiences containing knowledge of something that hasn't happened yet. Things like "I knew what he was going to say before he said it," or "I suddenly knew what she was thinking." History is full of people that have reported intuitive hunches, premonitions, and forebodings later verified to be accurate. Much of this is explained away as misinterpretations of mundane effects, such as coincidence, selective memory, confabulation, or even fraud.
But the question remains: can all cases of apparent foreknowledge be explained in this way? It feels like an eye into the future. Is it possible? Well, maybe it's not so far-fetched. Although this particular explanation is not of the psychic kind, a new perspective on memory is fast gaining traction, and it proposes that memory's adaptive purpose is not so much to allow us to consciously remember our past, but instead serves to help us navigate the future.
If you think about it, memory has the potential to help us navigate our futures in many ways—from our use of imagination and ability to be creative to just allowing us to know what to do next or how to react in situations. They say practice makes perfect, so maybe memories are just training your brain for the future. Déjà vu seems to be strongly associated with memory, so maybe it serves a similar purpose. If it is caused by an unrecalled buried memory, then is it also possible that an accompanying sense of what will happen in the future could come from that same buried memory?
I already mentioned that researchers have tried and succeeded in creating the feeling of déjà vu in the lab. Another way to create the sensation is to implant false memories—something that's surprisingly easy. With just a little suggestion, people will remember a specific memory of being lost in the mall as a child and being found by a kind old lady, despite relatives confirming that that never happened. This form of déjà vu would be similar to the feeling when you can't differentiate between a dream versus something that actually happened.
Some scientists argue that déjà vu is certainly related to false memory in the sense that it is a memory dissociation kind of effect: it dissociates reality from your memory. You could also briefly expose someone to an object or picture— for example, a place, a painting, and so on—and then let them go back and take it in more slowly, creating an actual memory that they may not be able to pin down. Researchers have had a lot of success with this type of induction, showing participants words, names, or faces for a split second, and then inducing the feeling of déjà vu by showing people the same thing for a longer amount of time just moments later.
But these are quite artificial and maybe don't quite match the spontaneous sensation that comes with déjà vu in real life. I also think the sensation is more intriguing when it's moments of your own life that you've witnessed before rather than implanted words or pictures. The bottom line is, it's really difficult to know whether what's being induced in the lab is real déjà vu because we're relying on subjective accounts of a feeling from participants.
Everyone will probably experience things differently or have a different interpretation of what exactly déjà vu is. There is also the possibility that participants are simply telling a researcher what they think they want to hear, also known as demand characteristics. We can't rely entirely on the results of these experiments, and maybe the feeling of familiarity isn't just a byproduct of seeing familiar objects; it's a feeling all on its own, with no existence in the past. Maybe that's what we should be investigating.
Or should we? Some say that we shouldn't investigate déjà vu at all. The sense of mystery that is so deeply tied to the concept of déjà vu is perhaps why it's so beautiful. I don't know what causes it, but you certainly do. In fact, you've already watched this video before, haven't you?
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Printing your memory is something that we've all worked on in the past. Whether it was learning vocabulary in class or memorizing formulas for your physics tests, it's something we encounter pretty often. You may notice, though, that these things tend to slip away over time if you don't continually train them. Personally, it triggers a sense of déjà vu; once I randomly see something a few years after I learned it, I know the world is in a difficult spot at the moment. It's a lot harder to learn things without knowing the right questions to ask, but Brilliant is here to help you out.
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