In the movie Déjà vu, Denzel Washington’s character goes back in time to save several bomb victims, including a woman who was murdered during the bomb attack. Are you wondering how a person can go back in time? In the movies it is a plausible reality. In reality, you may want to laugh it off. But, before you do, try to recall that sense of familiarity you have experienced with certain events or people when you have felt like you have time-travelled. As if certain situations seem to roll out in front of us like a movie. The familiarity is beyond our understanding.
Have you wondered what this phenomenon is?
déjà vu–a French word–means ‘already seen’. It is the sudden, inexplicable overwhelming sense of familiarity with an event, person or situation that shouldn’t be familiar at all.”Déjà vu is a kind of false perceptual experience in which an individual has a sense of seeing or having known things/situations which in turn they have never seen/known before. It is a common psychological phenomenon that is experienced by normal individuals once in a while. Whereas, persistent experience of déjà vu may be due to some pathology,” says Dr Kishor Adhikari, Professor of Psychology, Christ University, Bengaluru.
Studies reveal that medically déjà vu has been linked to seizures in the temporal lobe for people suffering from epilepsy, occurring just before an attack. Dr Adhikari says, “Almost 96% of people report having déjà vu experiences. But if it is persistent, it could be a result of abnormalities. For example, déjà vu is common in drug addicts, people who suffer from seizures and Alzheimer’s. It is highly associated with confabulation (disturbance of memory) and construction of false memories.”
Though déjà vu is a common phenomenon and persistent occurrences of déjà vu indicate abnormalities, very little is known about it. What stops researchers from studying this phenomenon? It is said that one of the hindrances in doing so is our inability to provoke it and the unpredictability of its occurrence. The exact occurrence of this phenomenon in the brain continues to be elusive.
However, studies based on past experiences have helped researchers come up with hypotheses. While some believe déjà vu to be a memory-based experience, others believe it is a neurological change. Some others look at it as an occurrence related to the unconscious memory. Meanwhile, there are theories that suggest the cause of déjà vu to be paranormal events, past life memories, alien abduction and precognitive dreaming.
According to some researchers, déjà vu may occur when the feeling of familiarity exists but the source monitoring fails. But considering that déjà vu occurs only with situations we have never been in, how is there a sense of familiarity?
Let us look at what these hypotheses reveal about this unique phenomenon.
It is said that when we recall a memory, the first thing we experience is the feeling of familiarity or recognition after which comes the recollection (of where we know the person/situation from). This recollection is known as source monitoring. According to some researchers, déjà vu may occur when the feeling of familiarity exists but the source monitoring fails. But considering that déjà vu occurs only with situations we have never been in, how is there a sense of familiarity?
Some research suggests that we might’ve come across a particular situation before but in a different context. For instance, we may have watched something similar on the television absorbing it unconsciously,leading to this sense of familiarity. And, because it’s to do with our unconscious memory, we cannot recall the situation. This is what creates the feeling of déjà vu.
This hypothesis suggests that patients whose epileptic seizures begin in the temporal lobe of the brain consistently experience déjà vu with the onset of a seizure. This has given researchers a more controlled opportunity to study the phenomenon. Tishya Mahindru Shahani, psychologist and hypnotherapist, says, “Epilepsy causes brain cells to send out-of-control electrical signals that affect the brain cells around them, and sometimes all the cells in the brain. This is called a seizure and can result in briefly losing control of thoughts or movements. In people with temporal lobe epilepsy, we know that seizures start in the temporal lobe–the part in the brain that is crucial to make and remember memories.” Further Sahani says, “Whereas in people without epilepsy,déjà vu could be triggered by a neurological discharge, resulting in a strange sense of familiarity, the involuntary twitch that can occur just as you are falling asleep.”
Studies that support the memory-based hypothesis believe that people who experience déjà vu have a healthy head as their memory checking system is efficient and they are less likely to misremember events. Whereas people who don’t experience déjà vu might just have better memories as their minds are not making memory errors. So, the question is, would you rather have an efficient memory checking system or simply a better memory?