Psychological Difficulties 

With the work of Penfield (see preceding chapter) and others doing similar research, much of what will be included here might well also be seen as organic malfunctioning. However, at the time the following views were presented, they were thought to belong more to the psychic realm, and even today, the part played by the organic apparatus in these functions is far from clear. If Wigan' s idea of the double brain was the first scientific hypothesis, Feuchterleben's term "memory fantasy", or illusion of memory, presents us already in 1845 with the next one. Terms such as "double perception" and "false recognition" soon followed. 

There have been numerous ideas as to the exact psychological mechanism underlying déjà vu, too numerous to describe even mention them all here. The best reviews, though, are found in Ellis (1911), Bergson (1921 - 1928), Berndt-Larsson (1931), Herrmann (1960 - '61) and Brown (2004). 

How is it, though, that this rather rare, yet impressive disturbance of mental functioning occurs? One circumstance seen by many theorists, following Wigan, as a necessary precondition is exhaustion or at least fatigue (e.g., Bergson). The idea is that then an abaissment du niveau mental can occur which allows all sorts of malfunctions of the mind to take place which otherwise do not, normally. 

If present, the sleepiness must give way to alertness, however, once the déjà vu episode has begun. As MaeCurdy noted:

"... it is characteristic of déjà vu that attention is riveted on that which seems to have been experienced before, each detail stands out sharply, and each detail, as it is remarked, seems to add to the feeling of familiarity." (p. 427) 

This is not unlike Wigan's idea that the formerly inattentive cerebral hemisphere suddenly takes notice once again. 

There are other factors besides fatigue which can lower the level of mental alertness. Berndt-Larssonmentioned distraction. Herrmann added states of being over-loaded, over-excited, and infirmity or feebleness. Freedman et al. note that déjà vu "can occur in normal persons, particularly in settings generating anxiety" (p.393). This latter is in line with the psychoanalytic theory of déjà vu as a defense mechanism (see above). 

Statistical evidence exists which would seem to indicate that fatigue may indeed be an important element in creating a mental climate conducive for déjà vu. There is, however, other evidence to show that it isn't a necessary one. The former is shown in an interesting paper by Leeds who had frequent déjà vu experiences (10 to 12 per month) during the time he was attending night school five days each week. The frequency reduced itself to 4 per month when he cut back on his studying and when his work during the day became more interesting. Heymans, on the other hand, in his 1906 survey of students, found that 43% considered themselves to be alert and fresh at the time they experienced either depersonalization or déjà vu, two effects which he thought to be related. Unfortunately, he omitted saying what part of these were having depersonalization feelings and what part déjà vu ("fausse reconnaissance" in his terminology), but he does say that 55 out of 94 had déjà vu 35 experienced depersonalization, and 4 knew both. I believe it would be safe to say, then, that a goodly percentage of the alert and fresh students were having déjà vu experiences. If this were not true, I feel sure he would have noted it because tiredness as a contributing factor is one of the hypotheses he was trying to confirm (pp. 10 - 11). He remarked in a previous paper (1904) that Bernhard-Leroy, in his 1898 medical thesis also found no correlation between déjà vu and over-excitement, overwork, exhaustion, or fatigue (p. 322)(see also Wohlgemuth, 1924). 

I pointed out in the introduction that surveys have shown that young people, particularly in adolescence, tend to experience déjà vu more often and more intensely than when they are older. Kraepelin thought that this must be due to the lively fantasy life that arises in this period. One Russian author, K. A. Skvortzov, taking a somewhat different tack, says that there must be some connection between déjà vu and hormones. 

Pierre Janet (1903, 1905) felt that one should include déjà vu along with other forms of derealization among the symptoms associated with neurosis, or psychasthenia, as he called it. Bash, in his Textbook of General Psychopathology (1955), seems to have the same opinion (p. 183). In their 1968 study, referred to in the preceding section, Richardson and Winokur found an above average incidence of déjà vu among psychiatric patients diagnosed as having personality disorders (9 out of 11) and situational and adjustment reactions (4 out of 5). They remark, though, that these were mostly young people, where the incidence is already rather high, and it seems to me that these sample sizes (11 and 5) are rather small for deriving any definite conclusions. The incidence among psychoneurotics was not greater than average, however. They note that within this category, hysterics, anxious, and depressive patients seemed to be those most prominently reporting déjà vu. 

At the close of the preceding section, I mentioned the work of Penfield et al. in which they were able to elicit impressions of mistaken familiarity through electrical stimulation of the temporal cerebral lobe. Here I would like to point out an analogous series of experiments carried out by Banister and Zangwill (1941) using hypnosis. They use the term "restricted paramnesia" for erroneous familiarity feelings and are careful to distinguish this from déjà vu (p. 30 - 31).

Five male subjects (4 students) and a young army officer; average age 22) were shown on one day 6 postcards with various motifs. On the next day, they were hypnotized and shown 6 more. They were given the post-hypnotic instruction that they would be unable to recognize these cards if they saw them again. On the third day of the experiment, they were presented with all 12 cards mixed in with 12 others. As awaited, they were able to recognize the cards from the first day, but had only unexplainable feelings familiarity for the cards from the second day. 

At the end of their first paper, Banister and Zangwill conclude with the statement: 

" ... In no case did we find a paramnesia rationalized in the sense of déjà vu. This evidence then ... fails to provide support for the psychoanalytic view [of repression giving rise to déjà vu]. It may be that further experiments will enable us to duplicate also experiences of déjà vu under experimental conditions. But the existing results cannot be said to throw light on paramnesia in its more generalized forms." (p. 50)