Researchers believe they have found a key insight into déjà vu, the eerie sensation of seeing something that has already been experienced, the New Scientist magazine reports.
Experiments suggest that déjà vu can be triggered independently, without a real memory to prompt it, the British weekly magazine reports in next Saturday’s issue.
Recognising a familiar object or scene is believed to unleash two processes in the brain.
First, the mind searches through its memory archive to see if the contents of that scene have been observed before. If so, a separate part of the brain then identifies the scene or object as being familiar.
Exploring this two-step theory, a team at the University of Leeds in northern England showed volunteers 24 common words and then hypnotised them.
The 18 guinea pigs were told that when they were next presented with a word in a red frame, they would feel that the word was familiar, although they would not know when they last saw it.
But if they saw a word in a green frame, they would think that the word belonged to the original list of 24.
The volunteers were then taken out of hypnosis and presented with a series of words in frames of various colours. Some of the words were not in the original list of 24 and were framed in red or green.
Ten of the volunteers said they felt an odd sensation when they saw new words in red, and five others said this sensation definitely felt like déjà vu.
Researcher Akira O’Connor, a doctoral student at the university’s Memory Group says the findings shed intriguing light on the causes of déjà vu and on fundamental workings of human memory.
“This tells us that it is possible to experimentally dissociate these two processes, which is really important in establishing that they are indeed separate,” New Scientist quotes O’Connor as saying.
Previous research has suggested that déjà vu may originate in a part of the brain called the temporal lobe.
Some people with temporal-lobe epilepsy frequently report déjà vu, and French scientists have found that electrically stimulating parts of the temporal lobe can trigger a sensation of familiarity with everything a person encounters. — AFP