Most people have experienced a sensation where while being in a situation, event, or place, we feel as if we have already experienced the same. This sensation is called déjà vu, meaning ‘already seen’ in french.
Some say these are false memories or a past-life remembrance. Others state that it is a short circuit in our brain or some activity in the ‘rhinal cortex’ of the brain.

Déjà vu: The Glitch In The Matrix

Scientists have studied this phenomenon in the lab using hypnosis and virtual reality, concluding it to be related to memory, where we experience a feeling of familiarity as the new experience seems to be traced according to an old memory.
A new study using MRI scans suggested that déjà vu is related to decision making, and the brain may be trying to resolve a conflict in the memory index.

Scientists Examine Déjà vu

Most of us have experienced deja vu—that sensation when new events feel eerily familiar. Could this "glitch in the Matrix" be a brain short-circuit?<figure><picture><source media="(min-width: 768px) and (max-width: 1023px)" srcset="https://static.scientificamerican.com/sciam/cache/file/6ABC5D46-906B-4237-8819EA5E6A2B7232_source.jpg?w=690&amp;h=930&amp;8F2423C3-E5F2-4FF0-8BB6CBC911A0B7BF"><source media="(max-width: 767px)" srcset="https://static.scientificamerican.com/sciam/cache/file/6ABC5D46-906B-4237-8819EA5E6A2B7232_source.jpg?w=390&amp;h=520&amp;8F2423C3-E5F2-4FF0-8BB6CBC911A0B7BF"><img src="https://static.scientificamerican.com/sciam/cache/file/6ABC5D46-906B-4237-8819EA5E6A2B7232_source.jpg?w=590&amp;h=800&amp;8F2423C3-E5F2-4FF0-8BB6CBC911A0B7BF" alt="Can Science Explain Deja Vu?" width="690" height="461"></picture><figcaption itemprop="caption description" class="t_caption" dir="ltr"> Credit: <a href="https://www.gettyimages.com/detail/photo/studioportrait-of-a-beautiful-woman-royalty-free-image/1138590773" dir="ltr">Roos Koole Getty Images</a></figcaption></figure>Wait, have I been here before? Have we stood in this exact spot as you said these same words to me at some point in the past? Haven’t I seen this very cat pass by this very hallway already? Sometimes, as we experience a new event or place, we get that creepy feeling that it's not the first time. We call that sensation déjà vu, a French phrase that&nbsp;means "already seen." But what is&nbsp;déjà vu, and can science explain why it happens?<h2>Déjà vu feels like a "glitch in the Matrix"</h2>Some think déjà vu is a sign that you're recalling an experience from a past life. Spooky!<figcaption>Advertisement</figcaption>Carrie-Anne Moss, as Trinity in The Matrix trilogy, tells us (and Keanu Reeves as Neo) that déjà vu is a "<a href="https://www.youtube.com/watch?v=XfEuxRDYiyc" dir="ltr">glitch in the Matrix</a>"—the simulated reality that keeps humanity unaware that intelligent machines have actually taken over the world. That explanation is perfect for cyberpunk science fiction, but it doesn't give us any scientific understanding of the phenomenon.&nbsp;We associate the feeling of déjà vu with mystery and even the paranormal because it is fleeting and usually unexpected. The very things that intrigue us about déjà vu are the same things that make it hard to study. But scientists have tried using tricks like&nbsp;<a href="https://www.ncbi.nlm.nih.gov/pubmed/18726806" dir="ltr">hypnosis</a>&nbsp;and virtual reality.&nbsp;<h2>Déjà vu could be a memory phenomenon</h2>Scientists have tried to effectively recreate déjà vu in the lab. In a 2006 study by Leeds Memory Group, researchers would first&nbsp;<a href="http://news.bbc.co.uk/2/hi/health/5194382.stm" dir="ltr">create a memory</a>&nbsp;for patients under hypnosis. That memory was usually something simple like playing a game or looking at a printed&nbsp;word in a certain color. Then patients in the different groups were given a suggestion to either&nbsp;<a href="https://www.ncbi.nlm.nih.gov/pubmed/18726806" dir="ltr">forget</a>&nbsp;or&nbsp;remember&nbsp;the memory, which could later trigger the sense of déjà vu when they encountered the game or word.Other scientists have attempted to bring on déjà vu using virtual reality. One study found that participants reported experiencing déjà vu when moving through the virtual reality&nbsp;<a href="https://www.ncbi.nlm.nih.gov/pubmed/22322010" dir="ltr">Sims video game</a>&nbsp;when one scene was purposefully created to spatially map 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.)These experiments have led scientists to suspect that déjà vu is&nbsp;<a href="https://www.psychologicalscience.org/news/releases/deja-vu-may-feel-like-a-premonition-but-its-not.html" dir="ltr">a memory phenomenon.</a>&nbsp;We encounter a situation that is similar to an actual memory but we can’t fully recall that memory. So 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.&nbsp;<figcaption>Advertisement</figcaption>Beyond this general explanation, there are&nbsp;dozens&nbsp;of theories that attempt to explain why our memories might malfunction in this way. Some say it’s like a short in the circuits in our brain leading to&nbsp;long- versus short-term memory&nbsp;so that new incoming information goes straight to long term memory instead of making a stop in the short term memory bank. Others blame the rhinal cortex—the area of the brain that signals that something feels familiar—for somehow being triggered without the memories to back it up.Another theory is that déjà vu is associated with&nbsp;<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4268540/" dir="ltr">false memories</a>—memories that feel real but aren’t. This form of déjà vu would be similar to the feeling when you can’t differentiate between something that really happened versus a dream. However, researchers have begun to push back on this idea.One study used functional Magnetic Resonance Imaging (fMRI) to scan the brains of 21 participants as they experienced a kind of lab-induced déjà vu. Interestingly, the areas of the brain involved in memory, like the hippocampus, were not triggered as we would suspect if the feeling was linked to a false memory. Instead, the researchers found the active areas of the brain were those involved in decision making. They interpret this result to mean that déjà vu could instead be a result of our brains conducting some form of&nbsp;<a href="https://www.newscientist.com/article/2101089-mystery-of-deja-vu-explained-its-how-we-check-our-memories/" dir="ltr">conflict resolution</a>. In other words, our brain checks through our memories like a rolodex looking for any conflict between what we think we’ve experienced versus what actually happened to us.&nbsp;<figure><img src="https://static.scientificamerican.com/sciam/cache/file/CB4AD410-8C6B-4ECD-AD6B1261CC722F95_source.jpg" alt="newsletter promo" width="90" height="80"><figcaption dir="auto">Celebrating 175 Years of Discovery

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Most of us have experienced deja vu—that sensation when new events feel eerily familiar. Could this "glitch in the Matrix" be a brain short-circuit?

Wait, have I been here before? Have we stood in this exact spot as you said these same words to me at some point in the past? Haven’t I seen this very cat pass by this very hallway already? Sometimes, as we experience a new event or place, we get that creepy feeling that it's not the first time. We call that sensation déjà vu, a French phrase that means "already seen." But what is déjà vu, and can science explain why it happens?

Déjà vu feels like a "glitch in the Matrix"

Some think déjà vu is a sign that you're recalling an experience from a past life. Spooky!

Carrie-Anne Moss, as Trinity in The Matrix trilogy, tells us (and Keanu Reeves as Neo) that déjà vu is a "<a dir="ltr" href="https://www.youtube.com/watch?v=XfEuxRDYiyc">glitch in the Matrix </a>"—the simulated reality that keeps humanity unaware that intelligent machines have actually taken over the world. That explanation is perfect for cyberpunk science fiction, but it doesn't give us any scientific understanding of the phenomenon.

We associate the feeling of déjà vu with mystery and even the paranormal because it is fleeting and usually unexpected. The very things that intrigue us about déjà vu are the same things that make it hard to study. But scientists have tried using tricks like <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pubmed/18726806">hypnosis </a> and virtual reality.

Scientists have tried to effectively recreate déjà vu in the lab. In a 2006 study by Leeds Memory Group, researchers would first <a dir="ltr" href="http://news.bbc.co.uk/2/hi/health/5194382.stm">create a memory </a> for patients under hypnosis. That memory was usually something simple like playing a game or looking at a printed word in a certain color. Then patients in the different groups were given a suggestion to either <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pubmed/18726806">forget </a> or remember the memory, which could later trigger the sense of déjà vu when they encountered the game or word.

Other scientists have attempted to bring on déjà vu using virtual reality. One study found that participants reported experiencing déjà vu when moving through the virtual reality <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pubmed/22322010">Sims video game </a> when one scene was purposefully created to spatially map 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.)

These experiments have led scientists to suspect that déjà vu is <a dir="ltr" href="https://www.psychologicalscience.org/news/releases/deja-vu-may-feel-like-a-premonition-but-its-not.html">a memory phenomenon. </a> We encounter a situation that is similar to an actual memory but we can’t fully recall that memory. So 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.

Beyond this general explanation, there are dozens  of theories that attempt to explain why our memories might malfunction in this way. Some say it’s like a short in the circuits in our brain leading to long- versus short-term memory so that new incoming information goes straight to long term memory instead of making a stop in the short term memory bank. Others blame the rhinal cortex—the area of the brain that signals that something feels familiar—for somehow being triggered without the memories to back it up.

Another theory is that déjà vu is associated with <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4268540/">false memories </a>—memories that feel real but aren’t. This form of déjà vu would be similar to the feeling when you can’t differentiate between something that really happened versus a dream. However, researchers have begun to push back on this idea.

One study used functional Magnetic Resonance Imaging (fMRI) to scan the brains of 21 participants as they experienced a kind of lab-induced déjà vu. Interestingly, the areas of the brain involved in memory, like the hippocampus, were not triggered as we would suspect if the feeling was linked to a false memory. Instead, the researchers found the active areas of the brain were those involved in decision making. They interpret this result to mean that déjà vu could instead be a result of our brains conducting some form of <a dir="ltr" href="https://www.newscientist.com/article/2101089-mystery-of-deja-vu-explained-its-how-we-check-our-memories/">conflict resolution </a>. In other words, our brain checks through our memories like a rolodex looking for any conflict between what we think we’ve experienced versus what actually happened to us.

Can Science Explain Deja Vu?

Déjà vu: The Glitch In The Matrix

Scientists Examine Déjà vu

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