Author: Winnie Mok
Editor: Yueshan Yu
Artist: Jenny Luo
As you drive by a new neighborhood, a strange sensation washes over you. The gentle breeze ruffling your hair, the orange glow of the sunset, and the smokey smell of barbecue—this scene feels eerily familiar as if you have already been here before. Yet, you can’t quite put your thumb down on where or when you came across this memory. This sensation is known as “déjà vu,” translating to “already seen” in French. This phenomenon is not a modern concept, coined by the philosopher Émile Boirac in 1876. Even dating back to ancient times, Plato likened this feeling to a person recognizing something from their past life. As intriguing as reincarnation is, this article will not explore past lives or pop culture references like “The Matrix.” Instead, we will look at this mind-bending phenomenon from a scientific perspective.
What exactly is this déjà vu? According to Dr. Akira O’Connor, a senior lecturer at the University of St Andrew’s School of Psychology and Neuroscience, it is essentially “a conflict between the sensation of familiarity and the awareness that the familiarity is incorrect. And it’s the awareness that you’re being tricked that makes déjà vu so unique compared to other memory events.” In essence, déjà vu convinces a person to believe that the current experience they’re having has already occurred in the past, even though they can’t exactly pinpoint when or where. O’Connor explains that this phenomenon happens when regions of the brain, like the temporal lobe, transmit signals to the decision-making areas in the frontal cortex, conveying that an event is recurring. These frontal regions then assess whether this signal aligns with past encounters. If there’s no match, the sensation of déjà vu kicks in.
However, what causes the sensation of déjà vu? While scientists have proposed several theories, there isn’t a definitive answer yet, partly due to the difficulty in recreating déjà vu. One possibility is that the phenomenon happens when your brain retrieves a memory from the past, but for some reason, you don't consciously remember it. Another theory is dual processing, which suggests that information is stored and retrieved through distinct processes. For instance, your brain converges different sensory inputs, such as touch and smell, during processing and perceives them as a single episode. However, if there’s a small delay in processing the separate inputs, the brain might interpret the event as two different experiences, leading to a sense of familiarity.
While déjà vu may seem random and uncontrollable, certain factors can influence a person’s frequency of encountering it. O’Connor suggests that a typical individual may experience déjà vu approximately once a month, but factors such as a person’s level of fatigue and stress may increase that amount. When the brain is tired, its internal neuronal systems may not be fully rested, thus resulting in neurons being more prone to misfire and potentially leading to déjà vu. Additionally, as individuals age, they are less likely to experience this phenomenon due to heightened neural activity and stronger frontal regions in younger brains. As people grow older, their capacity to detect errors, including encounters of déjà vu, may diminish.
So, the next time you experience déjà vu, remember: it’s not your mind playing tricks on you but a reflection of your brain’s functioning fact-checking abilities.
Citations:
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Ling, Thomas. “What Causes Déjà Vu? The Quirky Neuroscience behind the Memory
Illusion.” Science Focus, 26 May 2023, www.sciencefocus.com/the-human-body/deja-vu.
Ramamurthy, Aparna. “Deja Vu: How Science Explains This Mysterious Phenomenon.”
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