What is Déjà vu?
Déjà vu is the French expression attributed to the feeling that one has experienced a new situation previously. In most cases, this experience cannot be justified as there is no evidence of it having happened before. For example if you find yourself for the first time in France, standing in the Cathedral of Notre Dame admiring a stained glass window and suddenly feel as though you have stood in that very same spot before and looked at that very same green, red and yellow stained glass, this is Déjà vu. The fascinating thing about this phenomenon is how common it is: it happens to about 70% of the population, mostly to those between the ages of 15 to 25 (1).
Three Types of Déjà vu
Déjà vu can be broken down into three main varieties Déjà vécu, Déjà senti and Déjà visité.
Déjà vécu means to have ‘already lived through’. This is synonymous to the more common term Déjà vu. A remarkable feature of Déjà vécu is the amount of detail that comes together to form the experience as a whole. Often taste, sound and touch are all elements. Déjà senti differs from Déjà vécu as evidenced in its translation. It means to have been ‘already felt’ instead of ‘already lived through’ but is frequently misunderstood and misrepresented as Déjà vu. The difference between the two is that Déjà senti happens almost ‘exclusively…mentally’. In the majority of instances, it is not retained by in the memory of the affected individual and it does not function as a glance into the future. Individuals experiencing Déjà senti do not feel as though they know what is going to happen before it actually takes place. The final type of phenomenon related to Déjà vu is Déjà visité; also often confused with Déjà vu. The difference is that Déjà vu is related to reliving a situation whereas Déjà visité has to do wholly with geography, and the ‘location of inanimate buildings and/or objects that were familiar’ (1).
Déjà vu has been strongly linked with the temporal-lobe and small seizures that occur within it. Déjà vu has been observed to take place just before a temporal-lobe seizure and is experienced either ‘in the moments between convulsions’ or ‘just before a temporal-lobe seizure’ (2). Because Déjà vu has yet to be linked to a medical condition there is still a great deal of conjecture as to why the phenomenon takes place.
One neurological assumption that has been investigated is the possibility of a delay in transmission involving two distinct neuronal pathways. The visual system operates by moving sensory information through numerous pathways between the sensory organ and major cortical centers (3). Most of the time information being passed along is received first cortically from the chief pathway and then from any secondary paths. However, in rare instances when the ‘normally brief difference in processing time between the two tracks becomes lengthened’ (3), the typically flawless incorporation of the two messages into one joint awareness is interrupted, and is interpreted as two unique messages instead of one. The brain then construes the message received through the delayed secondary pathways as a completely separate experience. It is this divided perception from the primary input interpreted instants earlier that causes the unfitting feelings of oldness, or past experience to arise (3).
Another neurological postulation is that ones memory can be modeled after a hologram, only the tiniest pieces of sensory information are needed to create what appears to be a complete a three-dimensional picture. The brain is constantly attempting to create such pictures, but sometimes there is a disparity, which causes even the smallest sensory input to create an entire memory. Because a new memory could not have been created on the spot, the brain connects the small sensory input that has been perceived to an old memory causing the feeling of Déjà vu (3). The problem with the second explanation is that often the memories that are uncovered are not really memories at all, or at least they are not memories of events passed or in any case events that happened in real time and place.
Is it possible the Déjà vu experience has less to do with strict neurology and more to do with memory? Some ‘authorities’ claim that the experiences of Déjà vu stem from having seen pictures or listened to powerful and impressive stories in ones early years. Is it possible that Déjà vu is the recollection of ones childhood? As it is difficult for human beings to remember infancy or even their toddler years, is Déjà vu ‘dim recollections of childhood’? (4) All these explanations of Déjà vu as a neurobiologically based phenomenon appear plausible, and even a somewhat captivating, but can we dismiss Déjà vu as just another chemical reaction taking place within the enormous sac of chemicals we call the human body? I cannot say that I agree.
Others less empirical in their approach such as psychoanalysts ‘attribute Déjà vu to simple fantasy or wish fulfillment’ (2). Is it possible that events that have not gone according to plan or experiences lacking ‘happy endings’ are manifested with positive outcomes as Déjà vu?
Individuals who believe in reincarnation a ‘metaphysical belief that some essential part of living being survives death to be reborn in a new body” (5) hypothesize Déjà vu to be the remnants of memories from an individuals past-life. These remnants surface when individuals see, hear or touch a little bit of something that they had in their previous lives.
Another ‘spiritual explanation’ is that Déjà vu has its source in memories from dreams. (5) This makes some sense given that the majority of most people’s dreams are not remembered and if individuals should find themselves in the same place as a place they have dreamed about, Déjà vu occurs.
Some physicists have stepped up and dismissed both spiritual and neurobiological explanations for Déjà vu and argue that the phenomenon is caused by the existence of parallel universes. They argue that ‘Déjà vu is a result of overlapping events in two or more parallel universes due to a disruption in the fabric of spacetime or when one may experience an event which has already occurred to his/her counterpart in another universe’ (5).
What does it all mean?
All of these explanations are perfectly viable and although some are more acceptable than others because they might be able to overcome certain ‘social barriers’ none have been proven or disproved. Why is it then that we lean toward the neurobiological approaches to explaining to such a phenomenon? Apparently it is easier to buy that argument that the human being is made up of just a bunch of biochemical input-output boxes.
One critical part of beginning to comprehend Déjà vu is the seemingly heightened level of consciousness present at the time. When I find myself in the middle of a Déjà vu I am aware of almost everything going on around me. Recently I walked into my kitchen at home, and I intensely felt Déjà vu. I observed color, smelled food, heard my sister’s singing and even answered my mother’s questions [no, I am not delusional]. This in itself signifies that for Déjà vu to take place the whole brain need not focus on creating it; the individual experiencing it plays an enormous role in the overall Déjà vu experience. This role of the individual in Déjà vu certainly seems pivotal; not just in triggering the experience but also in determining how strong the feeling will be.
It is possible that many individuals have never experienced Déjà vu, and in today’s society where everything seems to be moving exponentially faster than before many could not care less about the phenomenon I’ve just spent four single spaced pages writing about. Some may care but may dismiss Déjà vu as something insignificant and almost silly, an occurrence that is so ‘every-day’ that it cannot possibly take up any more thought than it does for the couple of milliseconds it lasts. However, a better understanding and perhaps more detailed study of Déjà vu could possibly open doors into how the mind works. For the time being however, there is little empirical data; only a lot of seemingly disjointed hypotheses. Still, it seems that more information regarding Déjà vu can help us better understand not only how our memories and our bodies function as one, but also how they also function as two separate entities. Déjà vu may be able to pave the way for a more lucid examination into how we create our memories and entwine ourselves within them. Ultimately, we may be able to piece together how our memory is forms a vital part of our conscious being.
Funkhouser, Arthur (1996). Three types of deja vu. [Online]. Network. [1996, March 15]. <http://www.classroom.com/community/connection/howto/citeresources.jhtml>. (1)
Obringer, Lee (1998-2008). How Déjà vu Works. [Online]. How Stuff Works. . < http://science.howstuffworks.com/deja-vu2.htm>. (2)
Brown, Alan S. (2003). A Review of Déjà Vu Experience. [Online]. Network. [2002, July 15]. <http://gatorlog.com/images/dejavu.pdf>. (3)
Carroll, Robert T. (2006). Déjà vu. [Online]. Network. [ 2007, December 3]. < http://skepdic.com/dejavu.html>. (4)
Wikipedia (2008). Déjà vu. [Online]. Wikipedia. [2008, February 25]. <http://en.wikipedia.org/wiki/D%C3%A9j%C3%A0_vu>. (5)