Surveys

The earliest survey appears to be that of Osborn conducted at Princeton and elsewhere and mentioned in his 1884 article that he published in the North American Review. Unfortunately he does not indicate how many persons were interviewed (by questionnaire), or anything else about their ages, sex and education. He does say, though, that about one-half had had some form of déjà vu experience.

Another poor study, because of sampling difficulties, was that of Bernhard-Leroy who, in 1898, submitted his (medical) doctoral thesis on the illusion of false recognition. The study is cited here because of its historical relevance. During his research, he distributed a questionnaire (1000 copies) and published it in a French and in an American magazine. He received only 67 replies of which only 49 were usable. He added 36 from the published literature to these which brought the total to 85. He did manage to ask about and record the aspects which Osborn had neglected but he found only one correlated factor: age. Most of the respondents said that they had had more frequent and more intense déjà vu experiences when they were younger, especially during their adolescence. This fact had already been noted by Sarder in 1873 and Kraepelin in 1886-7. On the other hand, there seemed to be no correlation with sex, race, class, state of health or energy level {fresh or fatigued}.

Heymans, in 1904 and 1906, made a critical review of Bernhard-Leroy's results and extended the data by questioning the students in his classes, young people between 20 and 25 years of age. In 88 cases he found 14 (16%) who often experienced déjà vu and 41 (47%) who experienced it occasionally. There did not seem to be much correlation with experiences of depersonalization, a relationship he had hoped to prove. There was more of a correlation with fatigue. Probably his most interesting finding was that persons prone to déjà vu tended to have a more emotional, more labile nature than their peers. Since Heymans's study there have been numerous studies of the incidence of déjà vu, as detailed by Neppe (1983) in his book and in the [link: survey] section of this website.