Imagine you are going out to dinner with friends. You have never been to this restaurant and this part of town is new to you but in the car on the way there you start to feel the unexplainable feeling that you have been in this part of town before. This may be quite confusing and even unsettling to you because you are certain that you have never been here before.
Almost everyone at some point in their life has probably experienced a moment of déjà vu. Déjà vu, French for “already seen,” is the unsettling feeling of having experienced a situation or having been to a place even when you know that you really haven’t. People usually shrug off déjà vu, thinking that it is just a weird phenomenon with no real cognitive basis. Recently however, cognitive psychologists are trying to make sense of déjà vu and what seems to trigger it. Applying this information in the future could be very important in providing solutions for memory impaired people.
In an article entitled, “The Neuroscience of Déjà Vu” published in Psychology Today, researchers propose certain theories about how they believe the phenomenon of déjà vu works. Apparently, around 60-70% of people have experienced it and it is most common among the age ranges 15-25. I find it particularly interesting that it is most common with people in a younger age bracket than with elderly people. Part of why it is so difficult for researchers to study people’s experiences with déjà vu is partially due to the rapid onset of the phenomenon and partially to how typically the phenomenon occurs in people with no previous underlying medical condition. Some researchers think that one of the causes of déjà vu is a so-called brain mismatch, essentially when there is a kind of mixup between sensory input and being able to recall memories. Memory works in a funny way, sometimes you are in the middle of the test and all the information you studied can suddenly just flow out of your head like you hadn’t studied at all. Other times, just the slight smell of something can bring back whole situations and memories from years ago.
When we think of déjà vu and memory in the aforementioned context, this theory makes sense. However, it does not explain why even if the particular situation seems familiar to us that it does not mean it has any familiar basis in long term memory. In this same vein of thought, there is another theory that there is a cursory glitch in the processes of long term memory and short term memory. This means that when we have déjà vu, there is a glitch where the current experience is in short term memory, somehow converts over, and is perceived to be a long term memory instead which would explain the lingering feeling of familiarity.
Recently, researchers have used epileptic patients in studies about déjà vu. They have discovered that in epileptic patients stimulation of the rhinal cortex by intracerebral electrodes has induced episodes of déjà vu. The rhinal cortex is the overall area of the brain that is responsible for episodic memory and sensory processing. The EEG signals from the rhinal cortices were analyzed in a French study that discovered that “simultaneous neural firing between rhinal cortices and the amygdala or hippocampus could induce déjà vu episodes in epileptic people through electrical stimulation.” Although the people in this study have an underlying medical condition (epilepsy), this provides additional insight into the belief that medial lobe structures may be what “triggers” an episode of déjà vu.
The connection to epilepsy and déjà vu seems to make the most sense. Although, a recent study set out to prove that the problem had nothing to do with an electrical glitch and more with our memory. A Smithsonian magazine article entitled “Wait, Have I Been Here Before? The Curious Case of Déjà Vu” highlights a much simpler explanation for the phenomenon. Anne Cleary, a cognitive psychology professor at Colorado State University, suggests that in a new setting or situation it may trigger a past memory similar to the current situation but our brain can simply just not recall it. The hallmark sense of familiarity in déjà vu she says is attributed to the fact that we are able to recall memories by the spatial configurations of the particular situation. When we are not able to recall the exact memory, that is how we are left with the feeling of familiarity.
In order to test her hypothesis, Cleary used the game The Sims to simulate two living spaces which were different in features but had the same layout. When the test subjects entered the second living space, they said they experienced déjà vu but could not pinpoint exactly why the two rooms seemed so familiar. Cleary noted that tip-of-the-tongue experiences were similar to what she was hypothesizing with déjà vu. For example, when you hear a song on the radio and know who sings it but the name of the artist is stuck on the tip of your tongue. Even though your brain may not immediately produce the exact information it is looking for, you get the feeling that you somehow know that exact information.
It is clear to see that even in the span of a year in which those two different studies were published, 2012 for the first study and 2013 for Cleary’s study, a lot was learned about this interesting phenomenon. There are many different theories and respective experiments that prove each theory or at least give it support so we may draw the conclusion that what causes déjà vu is a little bit of each theory. We may not understand how exactly it works for another couple months or even years but I agree with Cleary’s assertion that it definitely worth it to keep researching this particular aspect of the brain.