The future of déjà experience research
It is my considered opinion that when it comes to truly understanding the various types and forms of déjà experience we have barely "scratched the surface" -- there is still an awful lot that we do not know nor understand. Researchers have (naturally) concentrated on what their particular discipline might have to say about these phenomena and performed research with the tools at their disposal. Such approaches necessarily involve reduction, though, and while concentrating on certain "trees" one misses having a view of the whole "forest". The only remedy for this, I think, is keeping an open mind and collecting as much information about what people are experiencing as possible. That is one of the purposes of this website.
Since October, 2004, there has been an on-line questionnaire available and, as of April, 2015, over 3000 persons from many countries around the world took the time and trouble to answer the 85 questions. Simple analysis of the data was made for the 2006 IASD meeting and pie charts comparing déjà vécu results with déjà visité ones were put together in a powerpoint presentation for that meeting. The statistical analysis of the data we now have is underway and a paper has now been published.* We plan to present some results soon on this website.
Thanks to surveys that have been made, we now know that people are having déjà experiences in Asian countries as well as in European ones and tentative results indicate that African Americans have such experiences just like Caucasians do. Still there is much to be done in terms of intercultural and interracial comparisons of the frequency and other aspects of such experiences around the world, especially among indigenous peoples. Along the same vein, we in the west have adopted French names for these phenomena (to honor the early French research that was performed), but it is strange that it seems there are no words for these phenomena in other languages (except "kishikan" in Japanese which I have been told is a translation into Japanese of the western term "already seen"). Is there really no words for these phenomena in Sanskrit, Urdu, Arabic, Swahili or one of the Australian aboriginal tongues?
There is some indication that drugs can produce states resembling déjà experiences and recent studies using hypnosis seem to be promising.
*Funkhouser A, Schredl M (2014) Déjà Vécu and Déjà Visité Similarities and Differences: Initial Results from an Online Investigation. Journal of Consciousness Studies 21 (11-12): 7 - 18.