The nagging feeling of déjà vu, the notion that you’re experiencing something that you have somehow already experienced before, can be spooky. Many folks wonder what it signifies and how it’s possible to recognize what is happening to you right now as though you’re going through it for the second time.
Well, brain researchers have been arguing over what causes déjà vu for over a hundred years, ever since the French researcher Émile Boirac identified the phenomenon and gave it its name in the early 1870s.
As you might imagine, the latest mainstream neuroscientific theories don’t put any stock in the paranormal explanations of déjà vu. Instead, they maintain that déjà vu arises from the way the brain recalls memories and encodes our everyday experiences.
Here’s the fascinating story…
According to researcher Anne Cleary, PhD, who has focused on studying memory at Colorado State University, her investigations and those by other scientists show that déjà vu is a “memory phenomenon” that occurs when you experience an event that resembles something in your actual memory but which your brain can’t precisely recall.
The Memory Phenomenon Theory
Dr. Cleary and other scientists maintain that déjà vu is similar to having a tip of the tongue experience – when you aren’t able recall a word you’re searching for but you have the frustrating feeling it’s a term hidden in your memory banks somewhere. Only in the case of déjà vu, your difficulty bringing to mind the previous experience makes itself evident in the spooky feeling that you’re going through an event for the second time.
“We cannot consciously remember the prior scene, but our brains recognize the similarity,” Dr. Cleary says. “That information comes through as the unsettling feeling that we’ve been there before, but we can’t pin down when or why.”
Testing The Occurrence Of Déjà Vu
In one of Dr. Cleary’s investigations of déjà vu, people were shown successive video tours that walked them through a building or outdoor scenes. Each test subject was immersed in 62 of these video segments.
While the test subjects were watching the last of the videos, they were asked at a certain stopping point to predict whether the tour would turn right or left, and they were also asked about feelings of déjà vu. Although the people who reported feelings of déjà vu said afterwards the turn proceeded as they expected their accuracy at predicting the turn during the test was no better than a random guess.1
But many people whose prediction was wrong still reported – contrary to fact – that they had forecast it correctly. This represents what Dr. Cleary calls “postdictive” bias – mistaken hindsight that makes you believe you knew what was about to happen even if you didn’t.
When People Are Seized By Déjà Vu
Studies with folks who experience epileptic seizures has produced strong evidence that the déjà vu experience originates in the brain’s temporal lobe. This is an area of the brain that is intensely involved in memory and recall.
For instance, people who experience what is called “temporal lobe epilepsy,” which takes place when erratic nerve activity in the temporal lobe leads to seizures, often report that right before they have a seizure, they develop a strong feeling of déjà vu.2
In addition, when people with this type of epilepsy have had electrodes implanted in their brains to try to limit their seizures, they often report that the electrical activity of these implants also causes feelings of déjà vu.3
Déjà Vu Episodes Decline With Age
It took us by surprise to learn that researchers report that our feelings of déjà vu are less frequent as we get older. Research shows that it is much more common in younger folks – especially in those in their mid-20s and younger.4
But if déjà vu derives from some sort of memory glitch, we would’ve thought it would get more frequent as we age. If it is a memory problem, don’t older people possess more memories that could elicit déjà vu feelings than younger people have experienced? But no researcher that we could find has addressed those issues.
We also discovered that we should be grateful we don’t experience déjà vu excessively. Cases have been reported where folks feel trapped in déjà vu – as though they are prisoners of a time loop that has frighteningly imprisoned them as they live the same experiences again and again.5 It sounds like the movie Groundhog Day without the happy conclusion!
However, the entire experience of déjà vu shows that the brain is a mysterious organ that produces feelings and notions that can’t always be fully explained. Even Dr. Cleary reports that the notion that déjà vu gives us glimpses of events we have already witnessed via a previous life or other mysterious forces appeals to many memory investigators.
“I think the reason people come up with psychic theories about déjà vu is that they are these mysterious, subjective experiences,” Dr. Cleary says. “Even scientists who don’t believe in past lives have whispered to me, ‘Do you have an explanation for why I have this?’”
Our take on this is that even though Dr. Cleary and some of her fellow neuroscientists believe they have shown that déjà vu is a result of a memory glitch among our neurons, we can’t be sure that explanation fully accounts for it. But we’ll see what future research turns up and as usual, we’ll report back.
The Awakening From Alzheimer’s Team