We’ve all experienced a glitch in the matrix at one time or another: déjà vu. It’s an uncanny sensation; an overwhelming sense of familiarity that you cannot explain – like you’re living the same moment twice. It feels like time is a skipping record, and you stand rooted to the spot, brow furrowed, eyes bulging, asking yourself “what happened? How did I get here? Haven’t I done this before?” It’s spooky.
What is déjà vu?
The term “déjà vu” comes from the French, and translated means “already seen”. Most people will experience the dreamlike feeling of having lived a particular moment already at some point in their lives, but the phenomenon has never been understood by neurologists or psychologists until now.
A 2004 survey conducted by Alan S Brown, published in the psychological journal “Current Directions in Psychological Science”, calculated that approximately two thirds of the planet’s population have had experiences consistent with déjà vu.
Some people think of déjá vu as having a holy or sacred significance, or else being evidence of precognitive mental powers. However, an experiment from the University of St Andrews, UK, has managed to determine the secret behind the sensation, and has discovered that the experience isn’t a supernatural one.
The mystery is revealed
If we’re to take the brain-as-a-PC metaphor one step further, then déjá vu operates almost like a backup for our long-term memories: it’s a way for our brain to determine what long-term memories are legitimate and which ones are imagined.
Confused? I’ll break it down for you. Basically, when we perceive sensory experiences, our interpretations are converted into electric currents which are fired by neurons to the brain. Our short-term memories, i.e. our immediate experiences, are stored in a different part of the brain than our short term ones.
When we experience déjá vu, what’s actually happening is that our brain stores the experience as a long term memory, so what we are engaged in seeing and feeling feels like a memory of the past, instead of something new. It is this cognitive dissonance, this disparity been experience and recollection, which gives us déjá vu.
Akira O’Connor at the University of St Andrews used magnetic resonance imaging to scan the brains of 21 volunteers after they were given specific triggers to simulate déjá vu. He stated “brain regions associated with memory conflict, rather than false memory, appear to be driving the déjà vu experience,” continuing, “This is consistent with our idea of déjà vu as the conscious awareness of a discrepancy in memory signals being corrected.”
The phenomenon could also provide researchers with valuable clues about memory loss and dementia. The same team discovered that, for young people, the more you experience déjá vu the less likely you are to have memory problems as you get older. As déjá vu is a checking process, experiencing it is a sign that you can successfully distinguish between real and false memories.