deja vu (familiarity); Re-experiencing something you had not experienced!

How much do you know about deja vu or familiarity? This nostalgic feeling that you think you’ve been somewhere before while you’re sure you’re seeing it for the first time is a strange feeling, No? Almost all of us are familiar with this feeling. But what exactly is deja vu or familiarity?

Even someone who has stepped into the realm of science and logic cannot help answer this question. But for such people, understanding deja vu will be a little scary and mysterious.

deja vu or familiarity.

Déjà vu, meaning “already seen,” has fascinated researchers and laypeople for centuries. Experiencing this feeling is relatively common. According to various surveys, almost two-thirds of people have experienced this flashback to another world.

Although there is still no definitive answer as to the cause of the deja vu experience, several theories straddle the fields of psychology and neuroscience. In the following, we explain some of these more compelling theories.

What do we know about deja vu?

Although it is not right to announce the early result of this article, it should be said that researchers still do not know why and how deja vu occurs. So the question is, what information is there exactly about this experience? We mention some of them below.

Age: deja vu appears more common among younger people, and its occurrence gradually decreases.

Gender: It seems that men and women experience this issue almost equally.

Social: According to some studies, deja vu is more prevalent among people from better socio-economic groups and people with higher education.

Travel: People who travel more are more likely to experience deja vu. A study conducted in 1967 found that only 11% of people who had never traveled experienced familiarity, compared to 41% of people who took between 1 and 4 trips a year and 44% of people who took five visits a year. They travel many times; they have this experience.

Stress: Other studies have shown that familiarity increases when we are stressed or tired. For example, several reports of soldiers experiencing deja vu, or familiarity, increase as battle approaches.

Medicine: Certain medications can increase the likelihood of experiencing deja vu for a while. A case study published in 2001 describes the experience of a 39-year-old male psychiatric patient who developed familiarity with the repeated and simultaneous use of amantadine and phenylpropanolamine to treat influenza.

In which part of the brain does deja vu occur?

It may be surprising that deja vu is not associated with any specific mental disorder. The only disease that is related to this experience is temporal lobe epilepsy.

In this particular form of epilepsy, as in other types, there is often a prognosis before the attack. For some people with temporal lobe epilepsy, this prognosis often includes deja vu or familiarity.

The temporal lobes, which are involved in visual memories and sensory input processing, seem to be the main suspects. A study conducted in 2012 developed the research path a little further. Scientists in this study showed that stimulation of the entorhinal cortex (EC) can produce deja vu-like experiences. The entorhinal cortex, located in the middle temporal lobe, plays a role in spatial memory and memory enhancement.

Effective factors in deja vu.

It may be possible to pinpoint the brain area associated with deja vu. But what causes deja vu? In general, the theories of deja vu or familiarity are divided into the following four groups:

• Dual processing theory
• Neurological theory
• Theory of memory
• Theory of attention

None of the following theories will answer all the questions about deja vu, but each is a unique opportunity to enjoy this fleeting yet powerful experience we call consciousness.

Dual processing theory.

In short, dual processing theories state that two cognitive processes that are normally parallel, i.e., simultaneous, become asynchronous for a moment. This category of interpretations can be divided into four other types depending on which processes are considered asynchronous.

It should be noted that these are some of the oldest theories of deja vu, and none of them have any empirical evidence to support them. However, they act as food for the mind and invite one to think.

Getting to know and remembering.

This theory argues that “familiarity” and “remembering” are two cognitive functions that usually work together harmoniously and simultaneously. If, for some reason, the familiarity is mistakenly triggered, the person gets the unfounded feeling that he has been somewhere before.

Coding and recovery.

We accompany this interpretation with a good and practical analogy: the tape recorder. The recording head (encoding) and playback head (retrieval) operate separately on a tape recorder. We are either filling and setting memory or reclaiming it.

This theory tells us that sometimes both heads, the recording head, and the playback head, can work together by accident. This means that we create a false sense of familiarity about the sequence of events that are running simultaneously. Although this is an excellent analogy, it does not convince scientists because the formation of memory and its recovery differs from this.

Perception and memory.

This theory claims that as we perceive events, memories are formed along with them. Naturally, we focus on perceiving events, but if we are tired or distracted, memory formation can occur at the same time as we perceive our surroundings. In this way, our perception of the “now” seems like a memory.

Double consciousness.

The theory of double consciousness was first proposed in the 1880s by John Hollings Jackson. This theory claims that we have two parallel streams of consciousness. One is to control and examine the outside world, and the other is to watch our inner thoughts. Suppose the primary consciousness, which is more sensitive and extroverted, gradually declines due to excessive fatigue. In that case, the more primitive consciousness takes over and accidentally confuses new experiences with older, internal experiences.

Although each of the above is like food for the mind and makes one think, they have yet to be as successful as Western theories.

Neurological interpretations.

Neurological interpretations of deja vu are generally divided into “seizures” and “delayed nerve transmission.”

Convulsions.

As mentioned earlier, people with TLE or temporal lobe epilepsy usually experience deja vu as part of the pre-seizure prognosis. Logic tells us that if this is the case, perhaps deja vu is a mild form of seizure.

However, the data do not support this theory. deja vu, in general, is not very common in people with epilepsy, and on the other hand, people who experience deja vu more often and regularly are not more prone to epilepsy than others.

Also, although the connection between deja vu and temporal lobe epilepsy is well established, most people with TLE do not experience deja vu as part of the pre-seizure prognosis.

Neurotransmission delay.

There are several versions of this theory. One of them interprets deja vu as the journey of information from the eye through several paths and reaching the more specialized nerves. If, for any reason, data from the two paths arrive at different times, the brain considers the second message as old information.

Theory of memory.

A study conducted in 2012 using virtual reality gave us an interesting and strange insight. The researchers found that if participants were shown a scene similar to one they had seen before but could not remember, they sometimes experienced a sense of deja vu.

In other words, if after watching a new scene similar to the one seen before, the memory of the old scene does not come to mind, the previously experienced scene stored in the memory bank may leave an impression, like A sense of familiarity.

Another theory of memory, proposed by researchers Whittlesey and Williams, completely changed our idea and perception of the concept of familiarity. Perhaps we are thinking about the concept of “acquaintance” incorrectly. For example, seeing the postman at the door (a very familiar scene) does not create a sense of “familiarity.” But if we see the postman unexpectedly (somewhere else), for example, when we are on vacation and out of town, seeing him here evokes a sense of “familiarity.”

The so-called sense of familiarity does not come to mind by seeing familiar things. If this feeling comes to a person after seeing familiar things, it means that the feeling of familiarity is almost constantly in his mind. Instead, a sense of familiarity occurs when one unexpectedly sees something familiar.

When we see something familiar, our brain processes it faster, and it is less stressful for the brain. Whittlesey and Williams’ theory states that if we experience something very familiar in an unfamiliar situation (but do not recognize it simultaneously), the familiar element is quickly processed (even though we are not aware of it), and Overall, the whole scene looks familiar.

Theory of attention.

The basis of these theories is that a scene, under incomplete attention, is seen briefly. Then shortly after that, the same scene is perceived again, but with full awareness. The second perception is matched with the first one and is accidentally assumed to be older than it is. As a result, this causes deja vu (familiarity).

While these theories are intriguing, they have yet to be proven, and there is little or, in some cases, no evidence for them. We assume that deja vu is a single type of experience. But it can be created subtly and differently between people or within a particular person at different times.

Although the temporal lobes seem involved, we have yet to make much progress in understanding why this surprising ubiquitous phenomenon occurs.

So the next time you experience deja vu, enjoy it as one of human biology’s most fascinating and inexplicable mysteries.