Scientific Investigation Of The Déjà Vu Illusion

Déjà vu is when a person finds himself in a familiar situation in spite of the feeling that the situation has never occurred before. The topic of research is amorphous in nature as the reason of this phenomenon is not clear yet. Researchers of cognitive processes are engaging themselves interestingly in this scientific investigation.

Recent surveys and some studies suggested that frequency of déjà vu occurring decreases with age increases with education and income. Déjà vu phenomenon happens mainly when people are indoors, engaged in leisure activities or relaxing, whenever they are together with their friends; fatigue or stress frequently result in this illusion.

Historical Perspective

In c 400 AD, St Augustine referred déjà vu as “falsae memoriae”. Medical attention was not focused on this phenomenon, even after its earlier appearances in literature, until 1844 when the psychiatrist Arthur Ladbroke Wigan linked to it as “the sentiment of pre-existence”. To show its casual unsureness, F L Arnaud in 1896 invented the term “déjà vu”.

Explanatory Theories

The question of what causes déjà vu has remained an interesting area for both scientists and the public for many years. Déjà vu is a quirky, transitory and vague happening. Thus it is tough to research experimentally and study diligently. As a consequence, many of the proposed theories of déjà vu are captivating and compelling but they fail to provide any foundation in evidence. Many theories are also provided by researchers which have scientifically reasonable explanations of déjà vu.

Parapsychology

The mention of parapsychological theories here is purely for delight. Such theories incorporate: the preposition that déjà vu is elicited from memories of previous life through transmigration of the soul on one can say rebirth; déjà vu as a verification of telepathy; and déjà vu as astronomical or stellar transference.

Psychodynamics

Freud put forward that déjà vu is evoked we the perception of the current situation matches with a suppressed fantasy, causing fantasy to be aroused as a wish to ameliorate the current situation. Therefore, déjà vu is an indication of a wish for the turning back of time. Oberndorf saw eye to eye that déjà vu is a defense mechanisms and propounded that it is a psychological way of encouragement in the time of hardship: “you have been through this before and survived it. You can go through again”. Some psychoanalysts have proposed that déjà vu may be an appearance of waking dream, or a daytime remnant of dreams.

Biological Dysfunction

Biologically speaking, there are many neural pathways taking part in transferring information to higher processing levels. A minimal dysfunction in such pathways can cause déjà vu. Various pathways are followed by incoming sensory data to higher processing centers and any neurochemical activity that minimally changes transmission speed in one pathway only could end up giving déjà vu illusion to the person e.g. transient reduction of neurotransmitter at some neuronal connection. The reason behind this is that the brain consistently amalgamate data received from different pathways into a single experience, a faint delay or acceleration in the speed of pathway as compared to another could cause the brain to comprehend the data from the two as independent and separate impression of the same experience, even the two imprints are only milliseconds off. This could result in the feeling that current situation as happened before.

Communication between the two cerebral hemisphere could also cause déjà vu. If incoming data is transferred without deviation to the dominant hemisphere, where it is finally processed, and before moving to the governing hemisphere, a second copy of the data is route through the non-dominant hemisphere, a minor decelerating in those fibers connected with interhemispheric transfer across the corpus callosum could lead to déjà vu.

Divided Perception

A perceptual episode that is internally split into two parts could also result in déjà vu. A completely processed perceptual event that is similar to a slightly processed imprint obtained moments ago could activate the feeling of familiarity separate from the previous experience. When inceptive processing of a site is only peripheral and is instantly followed by a proper processing of the same scene with one’s complete attention may cause déjà vu to take place. For example, you may enter a museum for the first time and your gaze is caught by a fountain in the center. A stairway on your left is in your peripheral visual field and below your conscious level of awareness, your mind processes some minimal features or elements of the site. As you look directly to the stairway, you may feel unexpected familiarity as this view matches with the initial processing, which you were oblivious of. Similarly, you may be looking directly to the stairway but your attention is directed somewhere internal as you may be engrossed in a deep conversation with a friend. After ending the conversation when you look the stairway, it resembles with the processing from moments earlier, evoking a déjà vu illusion.

Implicit Familiarity Without Explicit Recollection

Déjà vu may happen due to familiarity-based recognition, the source of which is not determined. A type of memory which helps a person to realize that the things or situations they are experiencing at that very moment, were experienced before is called recognition memory for e.g. when one realizes that a face was seen before or that a song was heard before. Researchers are using a dual-process approach to study such feelings of familiarity. This theory suggests that two processes can result in recognition memory and those are recollection and familiarity. This theory suggests that two processes can result in recognition memory and those are recollection and familiarity. In both processes, i.e. recollection based recognition and familiarity based recognition, person feels that current situation has previously occurred, the difference between the two is that latter is more like a feeling of familiarity than bringing to mind of a previous instance, and the source of that feeling is may be unidentifiable. You may see a man at the bus stop and recognize him by recollecting exactly when you saw his before: he was in the grocery store yesterday. This is an example of recollection-based recognition. On the contrary, in familiarity based recognition you may see a man at the bus stop and recognize him as familiar but are unable to recollect where or when you saw him before.

Recognizing things or person without identifying is what happens in déjà vu. A direct relationship is there between frequency of reported déjà vu experiences and frequency of travel, movie watching and reported dreams as in memory of people who travel a lot, watches movies more often and remember dreams more often have more possible sources of familiarity stored than people who are less engaged in such activities. For example, a person who watches more movies tend to experience déjà vu more frequently when going to a new place (or similar places) may have seen in one of the movies he/she watched. There is a theoretical assumption that familiarity is the result of individual features or elements of a situation. In memory, episodes and events are broken down into certain sets of features or elements. These features are then matched with the features of current situation. A high degree of resemblance between the two result in strong familiarity feeling including the déjà vu illusion and low degree of resemblance lead to weak familiarity feeling. There are some ways by which this feature resemblance might result in déjà vu. First, current situation and previously experienced situation may share a single feature or element. For example, a lamp in your sister’s home had been seen previously in your friend’s home. You may not able to identify the source of the feeling of familiarity caused by the lamp, the complete situation may appear to be peculiarly familiar and may be described as déjà vu episode. Second, configuration also plays a significant role in producing familiarity. For example, you may visit a home for the first time and it may elicit a déjà vu because the layout or arrangement of the home strongly resembles the configuration of a home visited earlier; leading to a sense of familiarity.

Future Directions and Conclusion

These are various important aspects that should direct future research. Such as why does the frequency of déjà vu episode decreases with age? Is this because, as compared to younger adults, older adults pay less attention to the circumstantial details in the environment tend to forget their incidents of déjà vu, are less amazed when have a feeling of familiarity or are less likely to experience new environment?

Future research might also examine whether or not this phenomenon of déjà vu is universal. If it is universal, we need to find the reason why some people are oblivious to it. If it is not universal (as surveys suggest), the focus would be on determining specific physical or psychological factors connected with the experience.

In conclusion, this is widely being accepted that déjà vu can be studied scientifically; the supply of laboratory methods for exploring its process or operation. Many resemblances exist between the explanation of déjà vu and the theories of human recognition memory. Moreover, unattended stimuli which is peripheral and gestalt familiarity could also be involved in this illusion. Researchers are working in many diversified fields to decipher this enthralling, indeterminate deceit of memory.;