Why do I experience Deja Vu

Question to the brain

Chris Moulin, cognitive neuropsychologist at the Institute of Psychological Sciences at the University of Leeds: There are various theories as to why we experience déjà vu. The best known are the unscientific assumptions such as “there is a flaw in the matrix” or “evidence of a previous life”. In fact, participants in my studies also express such assumptions. Another popular idea is that information travels two ways through the brain, one of which reaches its destination sooner. The most famous variant is called OpticalDelay theory“. According to this, the information from one eye reaches the brain faster than from the other. But the idea is wrong, because blind people also report déjà vu.

There are two categories of serious scientific theories. The environmental theories deal with what triggers the feeling of déjà vu in our environment. One of these ideas is that we experience déjà vu when a new place has the same structure as a place we know. For example, when we visit an unknown city in which - just like in our home village - the church is on the left, the school on the right and a large tree stands next to it. The similarity makes the alien seem familiar to us without us knowing why - and we experience a déjà vu. This can also happen if you've seen a film about New York and then visit the metropolis for the first time: You turn a corner and something looks familiar to you, but nothing as obvious as the Empire State Building.

For the competing neuroscientific explanations, all of the evidence comes from studies with epileptics. This is because they often experience déjà vu during or just before they suffer an epileptic seizure. The disrupted electrical activity in the brain stimulates a circuit in the brain that creates a feeling of familiarity - even though it shouldn't be active. We examined a patient who had suffered from frequent déjà vu since the onset of epilepsy. During the phenomenon, we asked him to draw his attention to different things: he should talk, think, or look at something. But the déjà vu continued regardless of what he did. That speaks against the fact that certain environmental stimuli trigger the feeling of familiarity.

Many studies suggest that something similar happens in healthy people as in epileptics. While they do not have a seizure, their brains show a rare form of electrical activity in the same area of ​​the brain, the parahippocampal area in the temporal lobe. This memory region lies deep in the brain and is responsible for the feeling of familiarity. As a result, some people worry if they have epilepsy when they experience déjà vu. In reality, when you are tired, young, drunk, or on certain drugs, you are much more likely to have déjà vu. All of this suggests that there is a physical cause of déjà vu.

So there are a total of four explanations: the spiritual science fiction explanation, the old idea of ​​optical delay, and the two current competing theories. Does our environment or our brain trigger a déjà vu? We're still not entirely sure.

Recorded by Hanna Drimalla