What is Déjà vu

What is Déjà vu

 

 Have you ever visited ­a store for the first time and had it feel eerily familiar? Or maybe you're deep in conversation with a friend and you suddenly get the feeling that you've had the exact conversation before, even though you know that you haven't. If you've ever found yourself in either of these situations, you've experienced déjà vu.

 The term déjà vu is French and means, literally, "already seen." Those who have experienced the feeling describe it as an overwhelming sense of familiarity with something that shouldn't be familiar at all.  For example you are having dinner with a group of friends, discussing some current political topic, and you have the feeling that you've already experienced this very thing -- same friends, same dinner, same topic.

 There are many different theories as to why déjà vu happens. As much as 70 percent of the population reports having experienced some form of déjà vu. A higher number of incidents occurs in people 15 to 25 years old than in any other age group.

  There are more than 40 theories as to what déjà vu is and what causes it, and they range from reincarnation to glitches in our memory processes. Since déjà vu occurs in individuals with and without a medical condition, there is much speculation as to how and why this phenomenon happens. Several psychoanalysts attribute déjà vu to simple fantasy or wish fulfillment, while some psychiatrists ascribe it to a mismatching in the brain that causes the brain to mistake the present for the past. Many parapsychologists believe it is related to a past-life experience. Obviously, there is more investigation to be done.

  Defining types of déjà vu is a very slippery area. Alan Brown,

 a professor of psychology at South Methodist University and author of "The Déjà Vu Experience: Essays in Cognitive Psychology," has three categories for déjà vu.

  Associative déjà vu - The most common type of déjà vu experienced by normal, healthy people is associative in nature. You see, hear, smell or otherwise experience something that stirs a feeling that you associate with something you've seen, heard, smelled or experienced before.

  Biological déjà vu- There are also high occurrences of déjà vu among people with temporal lobe epilepsy. Just before having a seizure they often experience a strong feeling of déjà vu.

  

Chronic déjà vu.- Four senior citizens in the United Kingdom have experienced déjà vuin a constant state. They refused to watch the news because they felt like they already knew what was going to be said. Or, they wouldn't go to the doctor because they felt like they had already been and didn't see the point.

  Alan Brown proposed what he calls the cell phone theory (or divided attention). This means that when we are distracted with something else, we subliminally take in what's around us but may not truly register it consciously. Then, when we are able to focus on what we are doing, those surroundings appear to already be familiar to us even when they shouldn't be.

  Dutch psychiatrist Hermon Sno proposed the idea that memories are like holograms, meaning that you can recreate the entire three-dimensional image from any fragment of the whole. The smaller the fragment, however, the fuzzier the ultimate picture. Déjà vu, he says, happens when some detail in the environment we are currently in (a sight, sound, smell, et cetera) is similar to some remnant of a memory of our past and our brain recreates an entire scene from that fragment.

Although déjà vu has been studied as a phenomenon for over a hundred years and researchers have advanced tens of theories about its cause, there is no simple explanation for what it means or why it happens. Perhaps as technology advances and we learn more about how the brain works, we will also learn more about why we experience this strange phenomenon.