In general, a widespread electrographic response was necessary but not sufficient for an experimental response to occur. The factors selecting whether a particular stimulus would evoke a mental phenomenon, and which category of mental phenomena would be evoked, could be explored because of the similarity across patients of the anatomical loci and protocols of stimulation. Olfactory and frankly aggressive responses were not observed. Of 3495 stimulations of the medial temporal lobe of 36 psychomotor epileptics, 267 were accompanied by reports of mental phenomena, including hallucinations of complete scenes, deja vu, anxiety, visceral sensations, amnesia, and unformed sensory experiences. The authors conclude that his studies and his hypothesis have been hitherto undervalued and would deserve more attention. A re-analysis of Heymans' data partly confirmed his findings and conclusions as to the predisposing factors. Heymans inferred that these findings supported his hypothesis that déjà vu experiences and depersonalization both resulted from the diminishing or disappearance of a sense of familiarity due to a momentary reduction of psychological energy. With the exception of the working rhythm, these traits were more prominent among the respondents with episodes of depersonalization than among those with déjà vu experiences. Emotional sensitivity, unstable mood fluctuations, apathetic episodes and irregular working rhythm emerged as predisposing personality traits. Déjà vu experiences appeared to be more frequent than episodes of depersonalization. In 19, Heymans reported the results of two prospective questionnaire surveys on déjà vu experiences and depersonalization in a sample of mainly students.

Deja vu psychology 2016