Déjà Vu Explained: Wait... Haven't I Read This Before?

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Alice Yoo '27

The déjà vu experience is when you feel like you have already experienced a moment in your life, even when you know it is an illusion. Hence is its name, which means “already seen” in French. 

There are several theories as to why this phenomenon occurs. Some say déjà vu happens when familiarity-based recognition is triggered in your brain. According to Akira O'Connor, a researcher in neuroscience at the University of St Andrews, déjà vu occurs when the medial temporal lobe, which is responsible for memories, goes through an error. The error causes a feeling of familiarity, which triggers the brain to be overexcited, making you believe that you have experienced this memory before. The sensation passes through the frontal cortex, which is related to cognitive functions such as reasoning. The frontal cortex evaluates the possibility of the event happening in your life before. Once your brain concludes that it is impossible, it is a déjà vu. Basically, they believe that the experience is caused due to miscommunication in different parts of your brain. 

Another theory involves split perception; although you might have seen something through your peripheral vision, your brain takes in more information than you are aware of. Thus, when you see that view for the second time, you don’t realize that you have already had that experience. Meanwhile, your brain recalls the previous experience stored in your brain, which makes you believe you’re in a repeated memory. 

From the numerous theories, one states that your brain goes through brief “glitches.” When the part of your brain that follows the present and the part that recalls the past are both active, your brain believes that you are reliving the same event you have done before, while ironically realizing that it is a false notion. 

A similar theory is that you are aware that a memory similar to the current situation exists, but are unable to recollect it. Since you aren’t able to recall the memory, you can’t link the two and remain with an uneasy feeling of déjà vu. Your implicit memory remains, giving a notion of familiarity. 

There is still more research to be done to figure out the cause of déjà vu. However, researchers have figured out that people between the ages of 15 and 25 are prone to déjà vu. Those who travel often or have advanced degrees reported experiencing déjà vu more often. The similarity between these seemingly distinct features is fatigue and stress. 

In rare cases, déjà vu may be a sign of an epileptic seizure. Dr. Roderick C. Spears, a physician with Penn Neurology Valley Forge, says, “About 60 percent of people with epilepsy have something called a focal seizure, which is in just one part of the brain. This can be in the same part of the brain where memory is stored: the temporal lobe.” If you are having symptoms such as strange repetitive behaviors (blinking, twitching), abrupt emotions, or unreal sensory feelings along with déjà vu, you should see your doctor as soon as possible. 

Usually, déjà vu is not a dangerous sign of health deterioration; in fact, O’Connor claims that it is a “sign of a good, healthy brain and mind.” Going through déjà vu proves that the fact-checking region of your brain is functioning properly, as you can discern between what has happened or not. However, it is crucial to pay attention to how you feel during a déjà vu to determine whether it’s simply a harmless glitch or a potential sign that needs medical attention.

Works Cited

"Feel Like You've Been Here Before? It Might Be Déjà Vu." Penn Medicine, 2 July 2019, www.pennmedicine.org/updates/blogs/health-and-wellness/2019/july/deja-vu. Accessed 22 Apr. 2025.

Kennedy, Justin James. "The Fascinating Science of Déjà Vu." Edited by Gary Drevitch. Psychology Today, 20 Dec. 2023, www.psychologytoday.com/us/blog/brain-reboot/202312/ the-fascinating-science-of-deja-vu?amp. Accessed 18 Apr. 2025.

Raypole, Crystal. "What Causes Déjà Vu?" Edited by Debra Rose Wilson. Healthline, Healthline Media, 30 Mar. 2020, www.healthline.com/health/mental-health/ what-causes-deja-vu#what-else-can-cause-it. Accessed 22 Apr. 2025.

Seed, Shawna. "What Is Déjà Vu?" Edited by Zilpah Sheikh. WebMD, 14 Feb. 2024, www.webmd.com/ mental-health/what-is-deja-vu. Accessed 17 Apr. 2025.

"What Is Déjà Vu and Can Science Explain It?" British Broadcasting Corporation, Apr. 2024, www.bbc.co.uk/bitesize/articles/zdpbwsg. Accessed 22 Apr. 2025.