Coined in 1876 by the French philosopher Emile Boyrac, the term deja vu literally means “already seen” and is used to describe a sensation or impression that you have already seen or experienced in a given situation. While this is a fairly common phenomenon, it is still poorly understood.
The person who experienced endless déjà vu
One of the most bizarre cases of déjà vu ever recorded involved an unnamed British young man who was trapped in an eternal time loop. This man has experienced endless déjà vu for the last eight years of his life and his condition has reached a stage where he avoided watching TV, listening to the radio and reading newspapers, because he felt that he had faced it all before.
What can cause a person to be trapped in an eternal time loop?
Doctors from the UK, France and Canada examined the man, who was 23 at the time. He first experienced this in 2007, after going to university. It soon emerged that the man did not have any other neurological conditions commonly associated with those suffering from déjà vu.
Dr. Chris Moulin, a cognitive neuropsychologist at the University of Burgundy who worked on the study, says the man had a history of depression and anxiety and was once taking LSD while at university, but was otherwise perfectly healthy.
“This man was amazing because he was young but was completely traumatized by this constant feeling of his mind playing jokes,” he says.
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For minutes, and sometimes longer, the patient felt that he was experiencing anxiety. He compared the "frightening" episodes with participation in a psychological thriller.
“There was one time when he went to get a haircut. When he entered, he had a sense of déjà vu. Then he got déjà vu from déjà vu. He couldn't think of anything else,”says Dr. Moulin.
The brain scans seemed normal, suggesting that the cause was psychological, not neurological.
While this case alone does not prove a link between anxiety and déjà vu, it raises an interesting question for further study, says Dr. Moulin.
What causes déjà vu?
Although many theories have been put forward regarding the reasons for déja vu, it still remains unexplained. Déjà vu happens mainly to young people, but many older people also report the sensational sensation of seeing or experiencing something before.
Dr. Akira O'Connor, a psychologist at the University of St Andrews, believes that in most cases it is the instantaneous "skipping" of neurons in the brain that creates false connections.
“One idea is that déja vu is a kind of brain twitching. Just as we have muscle cramps or twitching of our eyes, it can happen that the part of your brain that sends signals related to familiarity and memory goes out of order,”he says.
Another theory, developed by Professor Ann Cleary of Colorado State University, is that déjà vu is a natural result of observing something truly familiar in our environment - such as the shape of a building or the layout of a room - evoking false memories.
She developed a computerized virtual reality called “Deja-ville,” where people move through similar landscapes to test a hypothesis. But Dr. O'Connor says that none of the existing theories conclusively unravels the mystery of déjà vu, in part because its fleeting and spontaneous nature makes it nearly impossible to study reliably in a laboratory setting.
Another unconventional explanation is that there is a hidden connection between déjà vu and the existence of parallel universes. The truth is, déjà vu remains an inexplicable mystery. It also remains unknown how many people suffer from the "chronic" version of déjà vu.