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What Causes Déjà Vu?

   




    Few of us ever experience significant supernatural phenomena, but 60 to 80 percent of us do report having the strange sensation that we’ve already experienced something that we consciously we are actually experiencing for the first time. Like feeling you’ve had the same exact conversation with someone before. Or walking into a room you have never been in before, and sensing that you’ve been there in the past. If you’ve ever had feelings such as these, you’ve experienced déjà vu, the sense of having experienced something previously, although it is, in reality, entirely new. Déjà vu comes from the French term meaning “already seen.”

   

    The phenomenon of déjà vu is difficult to study because it occurs only briefly and without notice, and it fades quickly. In addition, there is no physical manifestation of the experience, leaving scientists little to work with other than self-reported descriptions. So although researchers have been studying déjà vu for more than 100 years and theories to explain it abound, there is no single conclusive explanation for why it happens or what processes are involved in its occurrence.

    

   Many modern researchers believe déjàv u is a memory-based cerebral experience.The precise interplay of brain functions, however, remains uncertain. One prevalent hypothesis, called the cellphone theory, or divided attention, proposes that a brief distraction might explain the feeling that we have experienced something before. Imagine walking down a street while chatting with a friend on your cellphone. Engrossed in your conversation, you pass a brand-new restaurant for the first time, your brain subliminally, shallowly acknowledging the new eatery. Moments later, when the conversation has ended and you focus your complete attention on your surroundings, you become fully conscious of the restaurant—and are struck with a feeling of déjà vu. What’s happened? Your brain, while observant of all your surroundings, had been working below conscious awareness, and when you returned your full attention to the restaurant, you got the feeling you were familiar with it. In fact, you were: You just hadn’t been paying attention. Another hypothesis, the hologram theory, proposes that some feature in our environment, such as a sight or a sound that resembles a distant memory, triggers the brain to create a complete scene of the déjà vu experience. As you study a small portion of a painting you’ve never seen before, for instance, a distant memory surfaces from deep within your brain.
    
     According to the hologram theory, this occurs because memories are stored in a form like holograms, and with holograms you need only one fragment in order to see the full picture. Your brain identifies the portion of the painting with the past memory, perhaps a similar painting or a comparable photograph you’ve seen. However, instead of remembering that you’ve seen something similar in the past,. your brain recalls the old memory without identifying it, leaving you with a sense of familiarity with the painting—your déjà vu experience—but no recollection of the original memory.

    Researchers are hopeful that Advances In brain imaging technology will allow us to better understand how the human brain works and to pinpoint exactly how the déjà vu phenomenon occurs.



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