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What is Dèjà Vu?

If you’re like me, you experience dèjà vu – also known as paramnesia – all the time. And, if we’re even more similar, trying to put your finger on where you’ve “seen this before” is torture. So how exactly does that tip-of-the-tongue feeling work, and what makes it happen?


How it Works


As it turns out, dèjà vu is a very difficult phenomenon to study. This is because it happens randomly and no one is precisely sure what causes it; therefore, it’s hard to get people to experience it on command. Thus, many scientists have tried to get closer to recreating it by examining the similar concept of “familiarity” instead, typically through MRIs. These are special scans of the body that allow us to see how our insides are actually functioning at a given time, more like a video than picture. They scan the brain of someone experiencing familiarity and examine their neural activity to better understand how it is caused and what parts of the brain are involved in producing it.

Through this method, researchers have identified the importance of the perirhinal cortex and the parahippocampal cortex in the process. The former is a part of the temporal lobe that mainly helps us recall things by recognizing key traits of an environment that we’ve seen before with a focus on faces. The latter is also located in the temporal lobe and assists in the recognition of places, helping us encode and retrieve memories. Boston University professor Howard Eichenbaum suggests that dèjà vu may arise from the interaction between one of these two cortices (depending on whether a face or place seems familiar) and the hippocampus, the center in the brain most notable for converting short term memory to long term memory (if this interests you, his contact and research information can be found here).

And indeed, Susumu Tonegawa, a neuroscientist at MIT, has found that a structure in the hippocampus called the detente gyrate plays a key role in the process. It takes note of the specifics of a given situation, but when its abilities are jammed, we struggle to tell the difference between two situations (Mosher, 2007). Thus, such jams may be the cause of dèjà vu (read more about Professor Tonegawa’s research here!).

Where it Comes From


But what causes these jams? What triggers the sensation? Since it’s very difficult to study, scientists have struggled to answer these questions. However, University of Colorado professor Anne Cleary may finally be getting to the bottom of the matter.

In her studies, Cleary focuses in on the concept of “misplaced familiarity”. Essentially, it’s the idea that we find things (places, objects, etc.) that we’ve never seen or heard before to be familiar when they have things in common with those we have experienced before. For example, Cleary gave volunteers a list of words followed by a word recognition test. Words on the recognition test triggered a sense of familiarity when they sounded like words on the original list, even when the two words were nothing alike in meaning (for example, lady and eighty) (APA, 2008). In this sense, we find a new word familiar, but the familiarity is misplaced because we’ve never actually seen it before.

In another investigation, Cleary used a virtual reality version of The Sims 2 to simulate 128 scenes for her participants. All of the scenes were distinct, but many shared a key element; for instance, two scenes may have been entirely different rooms that simply had the same paintings on their walls. She found that scenes the participants had never seen before triggered a sense of familiarity in the study participants when they shared this key element (e.g. the wall paintings) with otherwise totally different scenes the participants had seen before. Professor Cleary states that this research may help people with memory impediments, as when we fail to remember something, we still have a sense of what that memory was. Such people can use virtual reality as training to trigger a sense of familiarity and learn to better act on their intuition (Choi, 2012). If this interests you, learn more about her research here!

Thus, it is possible that misplaced familiarity explains the phenomenon Tonegawa noted. Since the detente gyrate takes note of the specifics of a given situation, mixing different aspects of two situations- one old and one new- could generate conflicting signals in the structure and result in jams.


Ultimately, there is still much studying to be done before we fully understand the science behind dèjà vu. However, as our society progresses technologically, we use our advancements to deepen our understanding of the world around us and even ourselves. Professor Cleary’s experiments with virtual reality are a perfect example of this. While V.R. was created only to entertain, Cleary took advantage of the technological development and broke new waters in the realm of psychology. In the future, who knows what we’ll be able to explain and achieve.


Choi, Charles Q. “Been There, Done That-or Did I?: Déjà Vu Found to Originate in Similar Scenes.” Scientific American. N.p., 04 June 2012. Web. 19 Sept. 2016.

Eichenbaum, Howard. “What Causes Déjà Vu?” Brain Facts. Society for Neuroscience, 4 June 2014.

Mosher, Dave. “Origin of Deja Vu Pinpointed.” LiveScience. TechMedia Network, 7 June 2007. Web. 19 Sept. 2016.

“Neural Pathways.” University of Bristol. University of Bristol, 26 Feb. 2014. Web. 19 Sept. 2016.

“The Psychology of Déjà Vu.” Association for Psychological Science RSS. N.p., 18 Nov. 2008. Web. 19 Sept. 2016.

Edited by: Ruby Halfacre, Naomi D’Arbell, and Arselyne Chery