Wednesday, 13 April 2011

How Déjà Vu Works

Types of Déjà Vu

© Magmarczz |
Types of deja vu include associative, biological, and chronic deja vu. Learn about the different types of deja vu and how the types of deja vu relate.
Defining types of déjà vu is a very slippery area. Those who h­ave studied it have applied their own categories and differentiations -- each usually tied to a specific theor­y about what causes déjà vu. 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. He believes there is déjà vu caused by biological dysfunction (e.g., epilepsy), implicit familiarity and divided perception. In 1983, Dr. Vernon Neppe, Director of the Pacific Neuropsychiatric Institute in Seattle, proposed four subcategories of déjà vu, including epileptic, subjective paranormal, schizophrenic and associative.
Chronic Déjà Vu
Recently, there have been studies of people who have what researchers are terming "chronic déjà vu." Four senior citizens in the United Kingdom have experienced déjà vu in a constant state. They refused to watch the news because they felt like they already knew what was going to be said (even though they really didn't). Or, they wouldn't go to the doctor because they felt like they had already been and didn't see the point.
Researchers have suggested that these individuals have experienced a failure in the temporal lobe. The circuits that are activated when you remember something have gotten stuck in the "on" position, so to speak. This has essentially created memories that don't actually exist [ref].
Taking a very broad look at the research and resources available, we can put déjà vu experiences into two categories and then see the more subtle distinctions that researchers have placed on it:
  • 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. Many researchers think that this type of déjà vu is a memory-based experience and assume that the memory centers of the brain are responsible for it.
  • 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. This has given researchers a slightly more reliable way of studying déjà vu, and they've been able to identify the areas of the brain where these types of déjà vu signals originate. However, some researchers say that this type of déjà vu is distinctly different from typical déjà vu. The person experiencing it may truly believe they've been through the exact situation before, rather than getting a feeling that quickly passes.
Déjà vu also occurs with some predictability in major psychiatric disorders, including anxiety, depression, dissociative disorders and schizophrenia.
Next, we'll look at how researchers have studied this phenomenon.

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