St Augustine first referred to déjà vu in c. 400AD as "false memoriae." However, since the late nineteenth century, when there was a flurry of research (Wigan, 1844, "the sentiment of persistence"; Jackson, 1880, "mental diplopia"; Bourdon, 1893, "reconnaissance des phénomènes nouveaux"; Arnaud, 1896, "fausse memoire"; Bergson, 1908, "souvenir du present"), the study of déjà vu has largely remained under-researched in mainstream scientific investigation. This article employs qualitative analysis to examine and explain the theories of the causes of déjà vu or stimuli characterised by a feeling of familiarity in the absence of recollection. It also explores a psychological "profile" for the experience of déjà vu and draws inferences about the physiological "purpose" of déjà vu and the evaluative dimensions of the phenomenological experience of it. Qualitative analysis reveals that déjà vu is a commonly occurring normal experience and that while it may be an effect of temporary over-excitation of hippocampal synaptic transmission, it has a purposeful cognitive function by acting as an orientation-reflex to spatial-temporal reflection in experients' momentary consciousness.
Strongman, L. (2012). Deja vu explained? A qualitative perspective. The Journal of Mind and Behavior 33(3 of 4), 205-218.