D√©j√† vu is one of the most fascinating of experiences and, until recently, was thought of as an interesting anomaly but virtually impossible to study scientifically.
This has recently begun to change. Psychologist Alan Brown is one of a number of scientists who have begun making considerable headway in researching this curious but fleeting state.
In Brown’s recent book (The Deja Vu Experience; ISBN 1841690759) he notes some interesting facts gleaned from research in this area, for example:
About two thirds of people experience it. It is more likely to occur indoors, while relaxing and in the company of friends. It occurs more often in the afternoon or evening, and towards the end of the week. It is more common in those who travel and remember their dreams. It is less common in people with conservative politics and fundamental religiosity. It decreases with age.
Exactly why the experience is linked to these things is not altogether clear, although research has made some progress in understanding which brain areas might be involved.
One clue has been from temporal lobe epilepsy, in which people can have intense feelings of d√©j√† vu, either as the main part of the seizure, or as a pre-seizure experience (called an ‘aura’). These studies have suggested that an area of the brain called the hippocampus and nearby area known as the parahippocampal gyrus (both strongly linked to the temporal lobes) are a likely source.
These areas are strong candidates for the source of d√©j√† vu, as they have also been identified as involved in recognition and producing feelings of familiarity by previous research into memory function in healthy volunteers.
Link to excellent article on the science of d√©j√† vu from The Chronical.
Link to NYT article on d√©j√† vu.
Link to transcript of ABC Radio National programme on d√©j√† vu.
Link to list of different types of d√©j√† vu.