Have you ever been in a situation where things seemed to be familiar? For instance, you’re in a middle of a conversation with someone when suddenly it feels like you’ve had that conversation before. Or it’s your first time to visit a certain place but there’s an eerie feeling of familiarity that strikes you. And sometimes it makes you stop for a while and say, “It feels like this had happened before.” or “I think I’ve been here before. I just can’t remember when”. Leaving you wondering if it happened in one of your dreams or if it really occurred in the past. If you’ve experienced these things, then you’ve experienced déjà vu. But what is déjà vu exactly?
Déjà vu is a French term that means “already seen”. Some researches states that it occurs occasionally in sixty to eighty percent of people. Despite the number of individuals who experience it, this phenomenon is still poorly understood in scientific terms. Based on some studies, déjà vu is like hiccup because it happens randomly without any sign or warning. Some psychologists also say déjà vu is mostly experienced by people who have higher levels of education and those who have good memory function.
Since déjà vu happens randomly, it’s difficult to conduct studies about it. But a psychologist named Akira O’Connor and his colleagues did an experiment to trigger the sensation of déjà vu. Their technique involved a method that triggers false memories such as telling some people a list of related words like pillow, night, dream, and bed. However, they do not tell them the main word that links the other words together which is “sleep”. The people who went through the experiment were later quizzed on the words they heard, and they claimed to have heard “sleep”, which is a false memory. To create the feeling of déjà vu, they asked the people if they heard any words from the list that starts with letter “s”, and they answered no. So, when they were asked if they heard the word “sleep”, they know that they did not, but the word felt familiar to them.
Though there is no clear explanation yet on how or why déjà vu happens, there are a lot of theories being proposed which try to explain the phenomenon. Here are some of the interesting ones that can provoke your thoughts about déjà vu.
- Dual Processing: Items stored in our short-term memory will be lost eventually when they are not encoded to our long-term memory. This theory proposes that when we perceive something, our brain will try to encode that new memory to our long-term memory at the same time. Thus, giving us the illusion that we have experienced it before.
- Parallel Universe Theory: This theory gives us the idea that we live among millions of parallel universes containing different versions of ourselves. It claims that the unsettling feeling of déjà vu is a “crossover” with a parallel universe. Meaning, whatever you’re doing while you’re experiencing déjà vu, a parallel version of you in a different universe is doing the same thing simultaneously. This theory is quite intriguing, however, there is no scientific evidence that supports it.
- Familiarity Based Recognition: This theory explains that déjà vu is a form of familiarity based recognition. Recognition memory is what we use when we recognize stimulus in our environment and it has two forms, which are familiarity and recollection. Recollection memory is when we recall seeing something that we have really seen before. On the other hand, familiarity based recognition is what happens when we believe we are seeing something we recognize but we have no memory of it happening in the past. An example is seeing a familiar individual at the mall but not being able to recall why you recognize that person.
- Precognitive Dreams: This theory explains that déjà vu is the moment we experience something that we have previously dreamed about. Precognitive dream is the kind of dream where it predicts something to happen in the future. An example is when someone find himself in a situation that he had previously dreamed about. Since dreaming occurs in our unconscious state, we don’t consciously recognize the stimulus, however, the feeling is familiar.
- A ‘Glitch’ in Reality: As what Einstein suggested, there’s no such thing as time. It is only a human creation that is made to establish order and structure. Therefore, this theory explains déjà vu as a momentary breakdown in our reality. It is something that gives us a break from the illusion of time. However, there is an implication on this theory since it proposes déjà vu as a glitch, meaning, it can create damage on the foundations of our universe whenever it occurs.
Aside from these theories, there are a lot more explanations that exist and some of them even tough into the paranormal. However, there are still no clear explanations and evidence that might support these concepts, or might answer the question on what déjà vu exactly is.