Déjà vu
I can never say the words without thinking of Top Secret. Kudos to anyone who gets the reference.
I'm fairly certain I once learned about déjà vu, but I can't quite recall when and where. Was it at school? From someone I know? Television? Am I just imagining I learned about it?
Perhaps there is a touch of irony in that if the circumstances are just right, I may very well get a sense of déjà vu while writing about it now.
Having forgotten (or not) whatever it was I may have originally learned, and being one of those people whose dreams vanish from memory seconds after I awake, I've come to think the sensation of déjà vu might be borne of things we've experienced in our dreams.
Sometimes during the day something will trigger my memory of the dream I had woken up to, and I will recognize it as that dream.
But what about those dreams from two weeks ago and last year?
And when you think about it, dreams can sometimes be so mundane that it is not unlikely they may actually play out in real life, and this would make us think we've had the experience before.
It would be interesting to know if people who tend to remember the details of their dreams are any less prone to episodes of déjà vu than those who can never recall their dreams, or vice-versa.
C'est quoi exactement déjà vu?
The phenomenon of having the strong sensation that an event or experience currently being experienced has been experienced in the past, whether it has actually happened or not.1
The psychologist Edward B. Titchener explained déjà vu as caused by a person having a brief glimpse of an object or situation, before the brain has completed "constructing" a full conscious perception of the experience. Such a "partial perception" then results in a false sense of familiarity.2
There are 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.3
It is generally accepted that this phenomenon is not a physic episode, or the result of some freaky parallel universe experience. Rather it is an impression triggered by perceived environmental stimuli.
Researchers have studied patients with neurological disorders and even set up virtual reality experiments, but have not yet managed to provide a definitive explanation for these episodes.
That said, theories abound on this subject. They range from reincarnation to glitches in our memory processes.3
THEORIES
It's related to Recognition memory:
"Recognition memory is the type of memory that allows us to realize that what we are currently experiencing has already been experienced before....The brain fluctuates between two different types of recognition memory: recollection and familiarity. Recollection-based recognition occurs when we can pinpoint an instance when a current situation has previously occurred.... On the other hand, familiarity-based recognition occurs when our current situation feels familiar, but we don’t remember when it has happened before.... Déjà vu is believed to be an example of familiarity-based recognition—during déjà vu, we are convinced that we recognize the situation, but we are not sure why."4
It's related to dopamine:
In a paper entitled, Intense and recurrent déjà vu experiences related to amantadine and phenylpropanolamine in a healthy male, the authors suggest that déjà vu experiences may be provoked by increased dopamine activity in the brain.5
It's related to feature mapping and recall:
"According to the Gestalt familiarity hypothesis, déjà vu results when the configuration of elements within a scene maps onto a configuration previously seen, but the previous scene fails to come to mind."6
In a study investigating this hypothesis through the use of virtual reality, the authors' found that, "... feature-matching can produce familiarity and déjà vu when recall fails.6
And there are many, many more studies and theories on the subject. Another one of mine is kind of blue-printy. It's not looking to the past so much as the present. It's an inexplicable sense I get whenever I experience déjà vu. It's this kind of comforting sensation that whatever I'm doing at that particular moment is exactly what I'm supposed to be doing.
C'est très étrange.
REFERENCES
[1] http://en.wikipedia.org/wiki/D%C3%A9j%C3%A0_vu
[2]Titchener, E. B. (1928). A Textbook of Psychology. New York: Macmillan.
[3] http://science.howstuffworks.com/science-vs-myth/extrasensory-perceptions/deja-vu.htm
Obringer, Lee Ann. "How Déjà Vu Works" 11 April 2006. HowStuffWorks.com. <http://science.howstuffworks.com/science-vs-myth/extrasensory-perceptions/deja-vu.htm> 12 September 2014.
[4] Association for Psychological Science. "The Psychology Of Deja Vu." ScienceDaily.
ScienceDaily, 19 November 2008. www.sciencedaily.com/releases/2008/11/081118122146.htm.
[5] http://www.ncbi.nlm.nih.gov/pubmed/11535020
Taiminen T1, Jääskeläinen SK.Intense and recurrent déjà vu experiences related to amantadine and phenylpropanolamine in a healthy male.J Clin Neurosci. 2001 Sep;8(5):460-2.
Cleary M Anne, Brown S Alan, Sawyer D Benjamin, Nomi S Jason, Ajoku C Adaeze, Ryals J Anthony Familiarity from the configuration of objects in 3-dimensional space and its relation to déjà vu: A virtual reality investigation. Consciousness and Cognition(June 2012)
Volume 21, Issue 2, Pages 597-1072
Volume 21, Issue 2, Pages 597-1072
ADDITIONAL SOURCES
http://www.sciencedaily.com/releases/2008/11/081118122146.htm
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