Déjà Vu, Not That Again…

02/08/2017 | 4 minutes

The cat has just walked into the dining room, gingerly greeting the coffee table leg with her nose before pausing briefly, then jumping up onto the table - only to knock over my green tea! Oddly enough, I wasn’t surprised; because on some level I knew this was coming. I had seen it before.

Already seen. Translated from the French déjà vu, the shenanigans of my cat left me with a marked feeling of familiarity, an insistence of my brain that I had indeed seen this before. A common phenomenon affecting around 70% of the population, déjà vu has been chalked up to many things; the brain creating fraudulent memories, wish fulfillment, a mismatched neural connection causing the brain to mistake the present for the past.

Past-life experiences are also thought to be responsible for deja vu, with some claiming that experiencing déjà vu often is a sign that your soul has reincarnated. Many parapsychologists who have studied the Tibetan Book Of The Dead interpret déjà vu to be a restimulation of previous experiences of the collective unconscious in the Buddhist bardo (the transitional phase between death and rebirth. Suffice it to say that the collective experience of déjà vu has always remained shrouded in mystery, offering us yet another tantalizing biological riddle to ponder.

And ponder we have. Last year, a St. Andrews University team led by Dr. Akira O’Connor, of the School of Psychology and Neuroscience, managed to actually trigger the sensation of déjà vu in the lab . First, a method commonly used to create fake memories was used, whereby a person has a list of related words read to them (for example, drive, petrol, fast, road), but with the main concept link word omitted (car). Later, the person is asked to recall the words they were told, and they usually include the omitted word - thus causing a false memory.

After reading the list of words, the St. Andrew’s team first asked the person whether they had heard a word starting with the letter ‘c’, to which they had said no. But later, when they were asked if they had heard the word ‘car’, they knew that they couldn’t have heard the word - but simultaneously the word ‘car’ felt incredibly familiar - giving them a sense of déjà vu.

Using fMRI (functional magnetic resonance imaging), the team scanned the brains of the volunteers whilst triggering this experience of déjà vu - and they found that the decision-making frontal areas of the brain were the most active, rather than the hippocampus, which is the memory-associated region of the brain. Because of this, they believe that déjà vu is a form of discrepancy resolution happening in the frontal area of our brain, while it checks what we have truly experienced against what we think we have experienced.

If this deduction proves to be correct, it would explain the fact that déjà vu tends to be experienced more by people aged 15 to 25 - because it signifies that the brain is working correctly and checking memories and events accordingly. You are therefore less likely to confuse your memories when this system is all working well, which coincides nicely with the fact that 15 to 25 is often heralded as the peak age for tertiary and higher education. As you get older, this process might start failing a bit, and make it harder for the brain to keep track of catching mistakes in your memories (especially now that there are so many!)

The wonderful thing about the human brain is that we still don’t really know what is happening in there, speculate and experiment as we may. As the mathematician and author Ian Stewart once so elegantly surmised, “If our brains were simple enough for us to understand them, we'd be so simple that we couldn't.”

Have you had a decent dose of déjà vu lately? Share your experiences with us in the comments!

Chelle Fitzgerald