If you’ve experienced a flicker of recognition, a feeling of “hang on, I’ve been here before” as you do something – enter a house, have a conversation, pet a dog – then you’ve probably experienced déjà vu.
By definition, déjà vu is a sudden sensation, often brief, that you’ve experienced your current situation before, and are recalling it vividly, even when you know you haven’t. The French term, when translated to English, literally means ‘already seen’.
The reasons why humans experience déjà vu aren’t fully understood but, like all weird and wonderful science, there are a few theories.
The Theories Behind Why We Get Déjà Vu
In a review of the science in 2003, the Psychological Bulletin outlined four major schools of thought about why humans experience déjà vu.
The first is the simplest: that the thing we are experiencing has in fact already happened, and that for some reason we have forgotten this and are being reminded.
“This can give it a spooky sort of feeling, because you are so certain that you have never been to this place before or done this thing before, even though it really is just a normal memory process at work,” Anne Cleary Ph.D., head of the Human Memory Lab at Colorado State University, explained to Bustle.
The second theory about why we experience déjà vu is that it’s brought about by a processing error in the brain. Two things are trying to happen at once, wires get crossed and something somewhere glitches out.
So déjà vu = brain error.
The third theory about déjà vu is what’s called the “disruption” theory, which states that neural firings from our brain are somehow interrupted or go awry. This, it’s argued, is why people with epilepsy experience déjà vu as part of the auras of their seizures. In people without epilepsy, it’s proposed that déjà vu is a result of an accidental delay or repetition in the stimuli which are informing our brain that something is happening, causing a kind of overlap and, in turn, the sensation that the event being registered has happened already.
The fourth theory about why humans experience déjà vu is related to our attention span, or lack thereof.
The theory is that, while we think we are paying attention to what’s happening around us, our attention slips for a brief moment. When we re-focus on what is happening around us, it may seem oddly familiar in a ‘past’ way. Crazy.
A New Theory
In 2016, scientists at the University of St. Andrews managed to induce déjà vu in non-epileptic people, by doing a word experiment.
The brains of the research participants were monitored throughout the experiment. Scientist’s noted that the frontal areas of the brain were active instead of the hippocampus or other areas in the back of the brain that have to do with memory.
In other words: the participant’s frontal lobes were working to ‘check’ their memory input and would sound an alarm when something didn’t fit with their other memories. This ‘alarm’ is déjà vu.
The new theory suggests that déjà vu. actually corresponds to real memories, and that the feeling of having experienced something before represents a memory that’s hidden.
“Familiarity-based recognition occurs when you have a sense of having experienced something before but cannot pinpoint why, such as when you recognize a person’s face as familiar but cannot place where you have seen them before,” Anne Cleary Ph.D told Bustle.
“Normal experiences of déjà vu can be a special case of this familiarity experience.”
So déjà vu could just be our brains fact-checking themselves. Also crazy!
There Are Different Kinds Of Déjà Vu.
It’s possible that there are several kinds of déjà vu created by different situations. We won;t fully understand what they are or how they work until a lot more research is conducted.
The bottom line however, is that déjà vu is totally normal. No, we’re not being haunted by a past life or having a premonition; our brain is simply experiencing a slight glitch. It happens.
Images: Pexels.