Is deja vu real or just a funny feeling?

Ever had that peculiar yet overwhelming sense that you’ve lived through the present situation before? Here, experts explain what deja vu is and why it happens.

You probably know the feeling: someone is in the middle of talking to you, or you’re walking along an unfamiliar street, and all of a sudden, it hits you – an overwhelming sense that you’ve lived through this exact scenario before.

But, even though it feels like you have, you’ve never been to that place before (or had that conversation with that person).

Is it a glitch in the Matrix, a trick of the mind, or something else entirely?

Experts say what you’re experiencing is most likely a psychological phenomenon called “deja vu”.

So, what exactly is deja vu?

Borrowed from the French term déjà vu, it literally means “already seen”.

While the feeling of deja vu is usually fleeting, it leaves enough of an impact to leave most people scratching their heads.

According to Melbourne School of Psychological Sciences Associate Professor Piers Howe, it is not just a feeling of familiarity, but also the metacognitive recognition that these feelings are misplaced.

“(It’s) a feeling of having previously experienced the current situation without being able to recollect actually having done so,” Assoc Prof Howe, a leading researcher at The University of Melbourne, says.

“Most definitions of deja vu only give the first part (a feeling of having previously experienced the same situation), but the second part (without being able to recollect actually having done so) is crucial.

“When you go home, you don’t think ‘I have this strange feeling that I have been here before’ because you know you have been there before.”

Arguably the world’s leading researcher on the subject, Dr Akira O’Connor says deja vu is experienced by about 60 per cent of the population and while research into the complex phenomenon is ongoing, it seems to occur when the frontal regions of the brain attempt to correct an inaccurate memory.

“For the vast majority of people, experiencing deja vu is probably a good thing,” Dr O’Connor says.
“It’s a sign that the fact-checking brain regions are working well, preventing you from misremembering events.”

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When does deja vu happen?

Experimental psychologist and cognitive neuroscientist Professor Endel Tulving has described deja vu as a kind of “‘mental time travel”; we’re trying to call up the facts of our past experiences to compare with those currently occurring, and as we do, we “relive” the experience, causing a kind of memory glitch.

Assoc Prof Howe says deja vu occurs only when you feel you have experienced the current situation without being able to recollect actually having done so (even though, in reality, you have experienced a similar situation).

“It’s therefore caused by an incomplete memory; you remember enough for a situation to feel familiar, but you don’t remember enough to (recall) having been in a similar situation before, even though you have been in a similar situation before,” he says.

It sounds complex, and while there is no single agreed model that explains exactly what  happens in the brain during deja vu, most researchers agree it is a normal part of healthy brain function that can more often occur in those who are stressed or fatigued.

Assoc Prof Howe says studies with fellow researcher Professor Sam Berkovic, a clinical neurologist and director of the Epilepsy Research Centre at Austin Health, have shown it’s also more common in those who have epilepsy.

“We don’t really know why it happens in healthy people because we’ve never stuck electrodes in the brains of healthy people,” Assoc Prof Howe says.

“But it could be that similar discharges can evoke the same feelings.”

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Why does deja vu happen?

While deja vu is incredibly difficult to study due to its unpredictable and fleeting nature, it seems it happens when your brain is trying to find matching memories to make sense of the current situation.

Dr O’Connor’s studies show it happens when areas of the brain (such as the temporal lobe) feed the frontal regions signals that a past experience is repeating itself.

It is the realisation that the past experience isn’t the same as the current one but is similar that triggers the feeling of deja vu.

So the next time you experience this fascinating phenomenon, don’t freak out and start searching for the black cat Deja Vu from The Matrix.

Instead, lean into the experience and rest assured that it’s just your memory checking up on itself.

Written by Andrea Beattie.