What is deja vu
Now you see it … now you see it again! Or did you? The déjà vu experience can be just as confusing as the reports on studies that have been conducted into it. But perhaps we can unravel the mysterious phenomenon!
What is déjà vu? Literally, it’s a French phrase meaning ‘already seen’. Psychic researcher Emile Boirac first used the term in his 1875 book “L’Avenir des sciences psychiques” (“The Future of Psychic Sciences”) to designate a psychological experience in which a person feels sure that they have already witnessed or taken part in a new situation. The familiar feeling is usually strongest in connection with small details – the way coffee cups are arranged, for instance, or the ticking of a clock. Other terms for the experience of déjà vu include:
- d éj à v écu (already experienced)
- d éj à senti (already thought)
- d éj à visit é (already visited)
- d éj à rev é (already dreamed)
The details of the ‘previous’ experience are often uncertain and the feeling will usually go away in 10 to 30 seconds. It’s certainly not a new phenomenon – in 1330, the Japanese monk Yoshida Kenko wrote that “It has happened on various occasions that I have felt, […] that it has occurred before. I cannot remember when it was, but I feel absolutely sure that the thing has happened. Am I the only one who has such impressions?”
Formal studies suggest that Kenko isn’t the only one; between 60 and 70 of people report experiencing déjà vu, with rates peaking during young adulthood and tapering off towards retirement. Those who travel are also more likely to report déjà vu than those who don’t. Perhaps this is because they have seen vaguely familiar things in their travels. Those with college and advanced degrees are also more likely to report experiences; a possible cause of this is because that demographic is more likely to encounter written accounts of déjà vu in the works of Tolstoy and Praust. Well – okay. But Tolstoy and Praust had to get their ideas from somewhere, so what really causes déjà vu?
Like yawns and zombies, scientists aren’t very sure as to what makes déjà vu happen – or if it even happens. This is partly because it is difficult to recreate déjà vu in a laboratory setting and partly because of its poor reputation. Social scientists mentioned déjà vu right along with poltergeists and mediums in polls as recently as the 1990s. Though more serious research has been conducted in recent years, there still exist many theories. There are two main types of theory on d éj à: theories supporting the idea that déjà vu is the memories of forgotten experiences and theories supporting the idea that the feeling of repetition is a trick of the mind.
Theories concerning déjà vu being a memory:
- Actual Experiences – a very similar situation was experienced and then forgotten; probably the most mundane explanation
- Dreams – the experience was dreamt, but the dream passed into the long-term memory and bypassed the short-term
- Out of Body Experiences/Astral Projection – fragments of memories from experiences of the astral body whilst the physical body was asleep
- Prophecy – the person has had premonitions of this experience through prophetic or precognetic means
- Reincarnation – fragments of memories from past lives; Dr. Ian Stevenson has done research into the subject
Theories concerning déjà vu being a trick of the mind:
- Cell Phone Theory – attention is divided, so that some parts of the brain – sense of smell and sound, for instance – process the situation first; when the other parts of the brain, like visual, process the information slightly later, the déjà vu feeling results.
- Dual Processing – much like the Cell Phone Theory, except that instead of different senses processing information, it is different hemispheres as the temporal lobe of the brain’s left hemisphere tends to operate a few milliseconds faster than the right
- Hologram Theory – part of the situation is familiar, and the mind builds a complete memory of the situation based on that fragment
- Pharmacology – this theory has the most concrete proof. déjà vu feelings often occur just before a temporal-lobe seizure and when scientist Wilder Penfield electrically stimulated the temporal lobes in a 1955 study, he found that 8 percent of the participants recalled ‘memories’.
Most recently (2001), scientists Taiminen and Jaaskelainen reported a case of an otherwise healthy young man who started experiencing intense and recurrent sensations of déjà vu on taking the drugs amantadine and phenylpropanolamine together to relieve flu symptoms. He found the experience so interesting that he completed the full course of his treatment and reported it to the psychologists to write-up as a case study.
Taiminen and Jääskeläinen theorize that the combination of drugs resulted in a dopaminergic, or dopamine (chemical that functions as a neurotransmitter) affecting, reaction in the temporal lobes, which in turn caused the déjà vu.
None of these theories have been found totally true yet, though it’s not unreasonable to expect conclusive proof as we continue to gain a better understanding of the brain. There’s also the possibility that there is more than one possible cause, or a combination of causes responsibly for the experience. At any rate, déjà vu isn’t quite so mysterious anymore. Zombies, on the other hand, remsain a totally different story.