Just Explain It: What Is Déjà Vu?



Have you ever experienced déjà vu? You know, the strong feeling an experience is familiar, while at the same time knowing it hasn’t happened before. Where does it come from

That’s the subject of today’s Just Explain It.

The truth is, even though 60 to 80 percent of us say we’ve experienced it, déjà vu stumps science as much as it stumps the rest of us. That’s because it happens so quickly and so randomly, it’s very difficult to study.

Because it’s so hard to study, scientists haven’t singled out a definitive reason as to why déjà vu – which means "already seen" in French – happens. There are, however, two prevailing theories.

One theory has to do with the areas of the brain that recognize familiarity and recall memories. Although they occupy different parts of the brain, they’re normally in sync. Some scientists theorize that déjà vu occurs when the part that recognizes familiarity misfires and creates a strong sensation of familiarity. They don’t know why it misfires, but it could be triggered by something very, very subtle, even more subtle than a slightly familiar stand-up at the top of an online video. Perhaps it’s a room at your office that’s arranged similarly to one from your childhood. 

[Related: Mind Games: 5 Things You Can Do To Improve Your Memory]

Another déjà vu theory is based on the way we process memories. In it, a new experience doesn’t go through the part of the brain that processes short-term memories. It goes directly to the part that processes long-term ones. When this happens, the memory feels old and familiar, even though it is in fact a new memory.

One thing scientists seemed to have figured out about déjà vu is who’s more likely to encounter the sensation. People aged 15-25 tend to have déjà vu more often than older people. Younger people could experience it more because their brains are more active and they produce more dopamine, which has been linked to déjà vu.

But why is it important to study this fleeting and seemingly harmless feeling? As scientists find out more about déjà vu, they learn about how we retain memories and how some people lose the ability to recall them, like those who suffer from Alzheimer’s disease.

[Related: Could A Drug Prevent Brain Aging?]

Whatever causes this strange sensation, it will continue to challenge scientists and make the rest of us wonder, "Did this already happen?"

Tell us. Have you ever experienced déjà vu? You know, the strong feeling an experience is familiar, while at the same time knowing it hasn’t happened before. Seriously, we’re asking! It's not déjà vu all over again. Give us your feedback in the comments section below, or on Twitter using #JustExplainItNews.

Loading...
  • Final Glance: Railroad companies

    Shares of some top railroad companies were down at the close of trading: CSX fell $.21 or .7 percent, to $30.52. Canadian National Railway Co. fell $.77 or 1.1 percent, to $67.58. Canadian Pacific Railway ...

  • 10 Things to Know for Today
    10 Things to Know for Today

    Your daily look at late-breaking news, upcoming events and the stories that will be talked about today:

  • US fuming over Israeli criticism of Kerry
    US fuming over Israeli criticism of Kerry

    WASHINGTON (AP) — The Obama administration pushed back strongly Monday at a torrent of Israeli criticism over Secretary of State John Kerry's latest bid to secure a cease-fire with Hamas, accusing some in Israel of launching a "misinformation campaign" against the top American diplomat.

  • Sierra Leone's top Ebola doctor dies from virus
    Sierra Leone's top Ebola doctor dies from virus

    By Umaru Fofana and Adam Bailes FREETOWN (Reuters) - The doctor leading Sierra Leone's fight against the worst Ebola outbreak on record died from the virus on Tuesday, the country's chief medical officer said. The death of Sheik Umar Khan, who was credited with treating more than 100 patients, follows those of dozens of local health workers and the infection of two American medics in neighboring Liberia, highlighting the dangers faced by staff trying to halt the disease's spread across West Africa. Ebola is believed to have killed 672 people in Guinea, Liberia and Sierra Leone since the outbreak began in February, according to the World Health Organisation. The contagious disease, which has no known cure, has symptoms that include vomiting, diarrhea and internal and external bleeding.

  • Airbus cancels $2.2 bn jet order from Japan's Skymark
    Airbus cancels $2.2 bn jet order from Japan's Skymark

    Airbus on Tuesday said it has cancelled a $2.2 billion deal with Skymark Airlines for the purchase of six A380 superjumbos, reportedly over concerns about payment. The Airbus announcement came hours after Skymark said it was locked in "difficult" talks with the European aircraft manufacturer about its 2011 order, which had marked a big victory for the firm in a market long monopolised by rival Boeing. Skymark's Tokyo-listed shares plunged about 13 percent to close at 250 yen ($2.45) after the airline said it was negotiating with Airbus to "revise" the multi-plane order inked three years ago. "Following discussions with Skymark Airlines, and in light of the airline's expressed intentions in respect of the A380, Airbus has in accordance with its contractual rights notified Skymark Airlines that the purchase order... has been terminated," Airbus said in a statement.

  • Steven Seagal's Estonia gig nixed over pro-Russia stance
    Steven Seagal's Estonia gig nixed over pro-Russia stance

    Hollywood tough guy Steven Seagal has had his blues gig cancelled at a festival in Estonia following an uproar in this formerly-Soviet ruled Baltic state over the star's pro-Russia views, the authorities said Tuesday. Seagal is reported to back Russian President Vladimir Putin's March annexation of Ukraine's Crimean peninsula and regards him as a personal friend. The blues-singing action movie star was booked to perform next month at Tallinn's "Augustibluus" summer blues festival, but uproar among Estonians forced organisers to pull the plug, the authorities said. Estonian rock star Tonis Magi, who headlines the festival, went so far as to call for a boycott of the Tallinn event if Seagal was allowed to perform.

  • More mysterious craters found in Russia's remote Siberia region
    More mysterious craters found in Russia's remote Siberia region

    Two more craters of unknown origin have been spotted in Russia's Siberia region, weeks after a similar-looking hole was found in the isolated northernmost area, a local paper reported. The Siberian Times, an English-language newspaper, published pictures of two new giant holes discovered by reindeer herders, one located in the Yamal and the other in the Taymyr peninsula, both above the Arctic circle. Russian state TV reported earlier this month that a giant hole had appeared in the gas-rich Yamal peninsula where temperatures plummet below -50 degrees Celsius (-58 degrees Fahrenheit) and the sun barely rises in winter. Yamal, inhabited by indigenous reindeer herders, is one of Russia's richest regions in natural gas.

  • Here’s what could force a Social Security overhaul — and soon
    Here’s what could force a Social Security overhaul — and soon

    A program that funds disability payments will soon run short of money.

Follow Yahoo! News