All The Ways Science Tries To Explain Déjà Vu

Almost everyone’s experienced deja vu — that
brain-tickling illusion of having previously experienced something that, in reality, is
being encountered for the first time. In fact, researchers at Texas A&M estimate
that the trippy sensation is experienced by roughly 60 to 80 percent of the population. And yet deja vu remains an unsolved mystery. But there are some pretty good theories out
there —- some of which you may have heard before …. “Talk about deja vu!” The human brain is a seriously complex piece
of biological machinery. It’s capable of processing vast amounts of
information while simultaneously keeping your heart and lungs functioning, all with no conscious
input on your part. And yet, your brain is not infallible. According to the neuroscience experts over
at Texas A&M, one of the prevailing theories about deja vu has to do with shortcuts in
neural pathways. It’s possible that when you experience something
that recalls a fragment of an old memory, your brain interprets the new experience as
something it needs to place in long-term memory rather than the short-term memory slot it
would normally be placed in. Then, when your brain accesses the information
in long-term memory, it may feel like its accessing an experience from the past, rather
than something that’s happening in the present. That might be just enough to produce that
strange sensation… “What did you say?” “What?” It might sound like a bad thing, but your
brain is actually being efficient when it suppresses old memories. It’s really not very useful, for example,
to remember things like what you had for dinner on a random night in the year 2000. Unless you need an alibi for that night, that
kind of information is just useless clutter that can interfere with the processing of
more relevant information. According to Anne Cleary, a cognitive psychology
professor at Colorado State University, those old memories might still play a role, if not
a very useful one. Something you did long time ago and totally
forgot about might still be lingering in some remote part of your brain where it can trigger
a strong sense of familiarity even though you can’t recall any of the details. Places might do that, too. Maybe you’re visiting a location you saw in
a documentary a decade ago, but your brain suppressed that memory, leaving only deja
vu behind. Your not-infallible brain may also get confused
when it’s trying to process multiple pieces of information. Sometimes, there’s just too much information
in your environment and you simply can’t process it all. “Look! There’s inductive reasoning. There’s deja vu. There’s language processing. There’s deja vu.” Some scientists, such as Dr. Alice Medalia
from Columbia University Medical Center, think that something similar might be happening
when you experience deja vu — perhaps your brain, in the moment, is simply unable to
properly process multiple pieces of information, so it falls into that good ol’ deja vu feeling. Just like computers, brains can “glitch,”
too, and when your brain glitches the end result may be that weird feeling of deja vu. According to researchers at Texas A&M, your
brain stores memories in the same part of the brain that’s responsible for the detection
of familiar places, people, and events. So you might be getting deja vu because for
just a moment, your brain malfunctions. “… and Deja Vu.” “Have we not met before, monsieur?” “I don’t think so.” It’s possible that, for whatever reason, the
neurons responsible for the detection of familiarity are firing even though there isn’t anything
familiar in the environment, which might lead to the sensation that you’re experiencing
the past when you’re solidly in the present. “Do you ever have deja vu, Mrs. Lancaster?” “I don’t think so, but I could check with
the kitchen!” “No, that’s okay. Thank you.” Or, deja vu could be caused by something even
weirder: No, it’s not tiny lightning. It’s your brain forming “fake memories,” or
real memories that fail to form correctly. It’s possible that your brain may, for reasons
that aren’t totally clear, create the memory of an experience two times. And if you’ve got two different memories of
the same event and you’re trying to interpret that rationally, the only logical conclusion
you can really come to is that you’ve somehow experienced that event before. And that’s when the deja vu hits. Let’s say you sit down for lunch at a diner
you’ve never been to before and there’s a familiar song playing on the radio. Once upon a time, many years earlier, you
sat down at a different diner that was playing the same familiar song. That’s not the sort of thing you would file
away in your brain’s catalog of information, but the experience lingers in your memory. Then, when you have that vaguely similar experience,
your brain takes that small fragment of memory and uses it to reconstruct a memory featuring
all five senses. This is called the “hologram” theory because
it’s sort of like your brain is reconstructing a three-dimensional event out of a one-dimensional
memory fragment. It’s filling in the blanks either with details
it has completely fabricated or perhaps details taken from a different experience or even
a work of fiction you once read or saw on a screen. Even though the details aren’t accurate, your
brain may confuse them for a real memory, which can trigger the deja vu sensation. In 2016, a team of researchers at the University
of St. Andrews in Scotland figured out how to use word association games to trick people’s
brains into lying to them and thereby sort of getting deja vu in a lab setting. They then studied the regions of the brain
that were active as their subjects experienced the sensation. According to New Scientist, the team’s findings
were inconsistent with the “fake memories” theory of deja vu. If deja vu were indeed a function of memory,
you would expect to see brain activity in the parts of the brain responsible for memory,
but that’s not what the research found. Instead, scans found that the frontal parts
of the brain were active during the deja vu experience, and that part of the brain isn’t
responsible for memory, it’s responsible for decision-making. The lead researcher involved with the study
thinks the brain is simply checking the thing you’ve just experienced against the things
you think you’ve experienced. If there’s a conflict or memory error, it
sends a signal, which could be interpreted as a deja vu sensation. Deja vu is a lot more common in young people
than it is in older people, generally speaking. According to Scientific American, the deja
vu experience maxes out sometime between the ages of 15 and 25 and then tapers off until
it’s a rare or nonexistent later in life. Some scientists think this might be because
deja vu is actually a symptom of a healthy brain, one that is actively checking memories
against experiences and filing everything away for future reference. It’s even possible that, as we age, we continue
to experience deja vu, but we just don’t recognize it as deja vu because our brains don’t acknowledge
the difference between a false memory and a real one. So that’s not actually great news for the
above-25 set because fewer deja vu experiences might mean a deteriorating brain. So if you’re 25 and under, enjoy that trippy
deja vu experience while you can. As for the rest of us, welcome to possible
cognitive decline. Check out one of our newest videos right here! Plus, even more Grunge videos about your favorite
topics are coming soon. Subscribe to our YouTube channel and hit the
bell so you don’t miss a single one.