Déjà vu was thought to be caused
by the brain making false memories, but researcher at the University of St
Andrews, UK, now suggests this is wrong. Exactly how déjà vu works has long
been a mystery, partly because it’s fleeting and unpredictable nature makes it
difficult to study. Researchers developed a way to trigger the sensation of
déjà vu in the lab. The technique uses a standard method to trigger false
memories. It involves telling a person a list of related words – such as bed,
pillow, night, dream – but not the key word linking them together (i.e. sleep).
When the person is later quizzed on the words they’ve heard, they tend to
believe they have also heard ‘sleep’ – a false memory. To create the feeling of
déjà vu, they asked people if they had heard any words beginning with the
letter ‘s’.
The volunteers replied that they
hadn’t. This meant that when they were later asked if they had heard the word
sleep, they were able to remember that they couldn’t have, but at the same
time, the word felt familiar. They report having this strange experience of
déjà vu. The team used fMRI to scan the brains of 21 volunteers while they experienced
this triggered déjà vu. We might expect that areas of the brain involved in
memories, such as the hippocampus, would be active during this phenomenon, but
this wasn’t the case. The team found that the frontal areas of the brain that
are involved in decision making were active instead. If these findings are
confirmed, they suggest that déjà vu is a sign that your brain’s memory
checking system is working well, and that you’re less likely to misremember
events.
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