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As I get older, I have developed a theory that as we age we have more and more déjà vu experiences. I started to write this post yesterday and had to do a search on this site to see if I had already written on the topic. It felt like I had already done this. I had a déjà vu feeling about déjà vu.

There is an old joke about “It’s déjà vu all over again,” but lately that is true.

Is this phenomenon of having the strong sensation that an event being experienced has already been experienced in the past, whether it has actually happened or not, something real or just a trick of the mind?

The term déjà vu is from French, literally “already seen.”

If we turn to hard science, it rejects the explanation of déjà vu as “precognition” or “prophecy.” It is seen as just an anomaly of memory and so falls into the field of psychology.

I doubt that there are many readers who have not had the experience. No matter how powerful the present experience of recollection may be, the when, where, and how of the earlier experience often seems unclear or may even seem impossible. “I feel like I have been on this street in London before, but I have never even been in Europe before today!”

From my reading, three types of déjà vu experiences and explanations for them that seem to be studied. The first type is pathological and is associated with epilepsy and medical disorders. I find that much sadder and less interesting for my understanding of the phenomenon.

The non-pathological type affects healthy people and seems to be a psychological phenomenon. That is very interesting and seems to be what happens to most of us.

The third type is at the fringe and is the psychic or supernatural explanation.

A 2004 survey, tellingly titled “The Déjà vu Illusion,” concluded that approximately two-thirds of the population have had déjà vu experiences, but that the explanations are quite reasonable.

To quickly cover the pathological explanation, it seems to still be unproven that there is a clear connection between the experience and any one mental disorder like anxiety, dissociative identity disorder or schizophrenia. There is a pretty clear association of déjà vu is with temporal lobe epilepsy. The experience of déjà vu is possibly a neurological anomaly related to improper electrical discharge in the brain.

As you might expect, some drugs seem to increase the chances of déjà vu occurring in the user.

But I am more interested in research of déjà vu experiences in people not on drugs, with no disorders and with good memory function.

One way of explaining the phenomenon of déjà vu is the occurrence of “cryptomnesia.”  This is when there is information learned, then forgotten, but nevertheless stored in the brain. A present day occurrence that is similar invokes that knowledge and we have a feeling of familiarity though no clear “memory” of it.

Modern explanations of how memory works often describe it as more of a process of reconstruction, rather than a direct recall of an event that is forever fixed in our mind.  Each recollection is a reconstruction of those stored components, but each time we bring the memory back it contains some elaborations, distortions and omissions.

That means the tenth time you recall the event, it is a reconstruction of the ninth recollection and not of the original event. reminds me a bit of the old telephone game we played in school as kids. A quick look online tells me that I am not the only person to come up with that connection. (Though no one gave me grant money to do it.)

That recognition (déjà vu) involves the match between the present experience and our stored data.

Another theory of déjà vu connects it to having dreamt about a similar situation or place, and forgetting about it (as we so easily do with dreams) until sometimes reminds us of it later while awake. You can also find other “logical” ways to explain away these experiences. That street in London that seems so familiar? You have seen it in a film or on television, even though you don’t recall seeing it.

I had a very bizarre experience when I was in college that I couldn’t explain as anything but déjà vu. It’s a long story but in brief I seemed to know a lot about a house I had definitely never been to before. Later, a classmate (who was deep into the fringe sciences) told me that it was from a past life. I was not and am not a believer in past lives, but that did explain the occurrence more completely than any logic did.

And what about the less heard jamais vu (from French, meaning “never seen”). It’s a real term in psychology which is used to describe any familiar situation which is not recognized by the observer. Sometimes it is seen as the opposite of déjà vu. Jamais vu can also evoke a quite strange feeling. Have you ever had the impression of seeing a situation for the first time, despite rationally knowing that you in fact have been there or been in that situation before?

I’m not talking about not recognizing a word, person, or place that you should know. That happens to me with increasing frequency! I would associate that with pathological reasons like certain types of aphasia, amnesia, epilepsy or Alzheimer’s disease. But it can also occur because of simpler things like stress and fatigue.

The truly odd examples of jamais vu are when someone has no memory of one occurrence – perhaps the house they have lived in for five years – but also the feeling that they should know this place.

I did not know before I wrote this article (or at least I don’t remember knowing – the stupid humor cannot be avoided with this topic) that there were other variations.

Presque vu (“almost seen”) is the sensation of being on the brink of an epiphany, such as when attempting to recall a word or name.

Déjà entendu, (“already heard”) is the auditory version of feeling that you have already heard something, even though the exact details are uncertain or were perhaps imagined.

Have you had any of the experiences yourself?  Share with a comment.

Read More

http://www.nytimes.com/2014/04/06/books/review/the-rise-and-the-up-side-of-down.html

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