When caught in an unfamiliar situation, doesn’t it feel good to have some degree of familiarity, like a person, an object, or a pattern? The familiar element may grant a sense of comfort that is much sought in an unknown setting. However, what about cases, as in the following excerpt, in which the familiar element should not have seemed familiar to begin with?
“When I was on the west coast hiking one day, I had a very distinct feeling, a real strange sense that I'd been there already. I could even envision what the landscape looked like around the bend in the road, and about an hour later when I reached there, that's what it looked like.” - Claire Flaherty-Craig
This phenomenon of perceiving that one has already lived a particular on-going situation is called Déjà vu (French for ‘already seen’). The concept, given its peculiarity and suddenness, has been proven difficult to study and therefore, define. The result is a broad variety of definitions that focus on processes of affect or cognition. One of the most famous definitions, while subscribing to the cognitive component, defines déjà vu as “any subjectively inappropriate impression of familiarity of a present experience with an undefined past” (Neppe, 1983). Some definitions focus on the affective component like Heymans (1904):“a state, with equal sudden onset and disappearance, during which we have the feeling that we have experienced the present situation on a certain occasion in a distant past in precisely the same manner down to the very last detail.”
The experience of déjà vu not only enthralled those from science, but also, those from the literary community. Consider Elfride Swancourt from Thomas Hardy’s A Pair of Blue Eyes who likens the experience to be a universal phenomenon and says “You are familiar of course, as everybody is, with those strange sensations we sometimes have, that the moment has been in duplicate, or will be.” This is quite an accurate assessment of the occurrence of déjà vu and is also illustrated in a review by Brown (2004) according to which, data shows that déjà vu occurs in the daily lives of 67% of the population.
So how does the “mystical” experience of déjà vu come to be? There are many speculations for this, ranging from neurological to parapsychological explanations. In this article, we will be focusing on the neurological explanations in order to establish the un-fantasticalness of the phenomenon.
Déjà vu is often speculated to be “a by-product of momentary biological dysfunction in the brain.” Per this neurological perspective, it is believed that déjà vu might result either because of a seizure or an alteration in the speed of transfer of neural messages. It has been seen that people with Temporal Lobe Epilepsy (TLE) have significantly more experiences of déjà vu than those who do not have TLE. This is especially seen in the aura of the epileptic episode. This observation is extended to explain déjà vu in non-TLE people by saying that déjà vu may be a result of a small temporal lobe seizure in non-epileptics. Another neurological explanation can be illustrated by Grasset’s (1904) research on the basis of which he has proposed that a change in the speed of neural messages from the perceptual organ to the cortical region might express itself as déjà vu. In the case of slowing of transmission speed, due to the increase in the time taken to transmit the message because of synaptic dysfunction at some point in the neural pathway, the brain might interpret that there is delayed transmission because the input is old.
Another prong of the neurological perspective tries to explain déjà vu from the dual processing memory model according to which, two memory models work in a parallel and sequential manner. Brown (2004) lists the following categories of dual processing memory models as explanations of déjà vu. First, it is speculated that the spontaneous activation of one memory function (example: retrieval) in the absence of another function (example: familiarity); second, the merging of two cognitive functions that usually run parallely (example: encoding and retrieval); third, the abnormal widening between two cognitive functions that usually run in a contiguous manner; and fourth, when an unobtrusive memory function becomes primary.
According to O’Connor and Moulin (2010), “the overall evaluation of déjà vu-eliciting situations slides with the higher-order metacognitive awareness of inappropriate recognition.” They also place much importance on the ability of people to self-determine their behaviour such that they experience this phenomenon and not act on it.
While the phenomenon is in most instances, harmless, and does not result in behavioural changes, there are certain instances in which déjà vu can severely hamper one’s life. In a condition called persistent déjà vu, one experiences consistent, intense, and frequent déjà vu. According to O’Connor and Moulin (2008), who presented a case study of a patient MH, persistent déjà vu is a “prolonged and debilitating sensation.” MH suffered from encephalitis after which he also suffered epileptic seizures in the temporal lobe. Before this, he had never experienced déjà vu. Sno and Linzen (1991), conclude that persistent déjà vu has been linked to a disruption in the mechanisms that integrate the functions of consciousness, identity, and perception of the environment.
In analysing his own diary entries (which he made whenever he experienced déjà vu), Leeds (1994) found some interesting themes. First, the intensity and duration of the déjà vu experience were seen to be directly connected with each other. This means that more intense experiences are likely to be longer. Second, he found that the frequency of déjà vu is indirectly related to the intensity-duration i.e., the more the time passed since a previous experience of déjà vu, the more intense and longer is the present incidence of déjà vu. He also found that the experience was accounted for more when he was under stress and fatigued. This is in line with research that has indicated that there are differences in déjà vu experienced by people self-reporting high levels of anxiety compared to healthy controls without an anxiety diagnosis.
Analysing déjà vu can prove to be extremely difficult because of the fleeting nature of the phenomenon and its fantastical nature may never cease to exist unless the mechanisms are understood appropriately. The question remains whether déjà vu still seems like “a glitch” in the matrix or a scientifically explainable “mundane” phenomenon - we believe it’s the latter.
Arunima Ticku
