You know that strange feeling when you walk into a room and feel like you’ve been there before, even though you know you haven’t? Or when you hear someone say something for the first time, but there is a certain familiarity to it that makes you pause? That’s déjà vu, a phenomenon not yet well understood, but scientists have some ideas about it.
It’s déjà vu eerie feeling that you’ve had the same new experience before. It’s a spontaneous, elusive sensation that reveals the workings of consciousness, allowing us to see the separation between what we feel and what we know to be true, explains Akira O’Connor, a psychologist and senior lecturer at the University of St. Andrews School. of psychology and neuroscience. The experience occurs when certain areas of the brain, especially those responsible for recognizing familiarity“vibrate” or send false fame signals. This causes a brief confusion that evokes a sense of recognition and creates a conflict with your current perception. Self-conscious déjà vu is your brain’s way of letting you know that the memory you are experiencing is inaccurate. And that’s a good thing, because it means your frontal lobes are working as they should.
“Déjà vu is the process of correcting that mistake and making sure you don’t pretend to remember that thing,” says O’Connor, one of the few déjà vu experts. “There are all kinds of reasons why I think that’s the case, but one of them is the paradox that with a memory error, if that’s the case, déjà vu occurs when people’s brains are at their healthiest.” (He added that in people with certain conditions, such as dementia, the frontal lobes may fail to properly check facts, resulting in repetitive feelings of familiarity. This can become disruptive, as everything begins to feel familiar, even if those memories are not. It can delay receiving a proper diagnosis because it will appear as if they have regained their memories even if they have not.)
Although it is unclear why people have this experience, most research on déjà vu suggests that it is a phenomenon related to the brain’s process of retrieving memories. Walking into a room would be the signal that triggers the involuntary retrieval of memories; there would be no “access to the content”, meaning there is no memory to compare to the present moment, but the feeling of familiarity is there Anyway. One small study When investigating déjà vu, immersive virtual reality was used to create standard everyday scenes, such as a bowling alley or a garden, which were shown to participants. They were then shown a new scene configured to spatially resemble a previously seen scene. Study participants more often reported the strange sensation of something feeling more familiar than it should while watching these new but structurally similar scenes. Even if a scene isn’t an exact replica of a previous one, if it’s recognizable enough it can evoke an eerie sense of familiarity. And the inability to actually remember the original experience. It confirms that déjà vu is a memory error that can also trip you up.
[ Related: Why do people hate the sound of their own voice? ]
But perhaps the biggest joke of all is that there is no real reason for people to experience déjà vu; it’s just our brain’s glitchy way of rationalizing a puzzling human experience. “It tells us that we are meaning-making machines. We always try to give meaning to our environment and everything around us,” said O’Connor. “We discover patterns. We try to understand why things that happen outside of us happen.”
“We just notice that it’s weird,” he added, “and then we move on.”
This story is part of Popular Science’s Ask Us Anything series, where we answer your most bizarre, mind-burning questions, from the common to the unusual. Do you have something you’ve always wanted to know? Ask us.