By Kyra-lin Hom

Surveys indicate that nearly two-thirds of all adults have experienced at least one instance of deja vu in their lives. It's most common in teens but can occur as young as eight and tapers off once someone reaches 25. But for all its commonality, scientists still don't know why it happens.

Translated from its original french, deja vu means “already seen.” It's that creepy feeling you get that whatever you're experiencing for the first time at that very moment is something that has happened to you before. Though similar to a situation 'feeling familiar,' the expressions are usually used differently. Something that is familiar reminds you of a known previous experience. Deja vu generally has eerier connotations such as walking into a brand new, just constructed house and yet suddenly feeling as if you've been there before.

In the 90's Matrix trilogy, films which caused millions of people to doubt their own reality, an instance of deja vu is a glitch in the Matrix. It means that the AI overlords have changed something in the simulated world. Spooky, right? Spookier still, it's even technically possible. Theoretical physicist James Gates found 'computer code' in the very fabric of our reality. It's even statistically likely that we live in a computer simulation – if irrational numbers ever start repeating themselves, you better keep an eye out for Agent Smith. But I'm getting sidetracked.

While all of this quantum theorizing is neat (Dr. Michio Kaku even jokes that deja vu could be our minds aligning with another universe), it currently isn't one of the leading explanations. For that we have to look inside our brains.

Deja vu is almost always a sight-based experience, which makes 'blindsight' very relevant. Blindsight is the phenomenon that occurs when a person's visual cortex (the main sight part of the brain) doesn't respond to stimuli. They can't 'see' anything. However, the other preliminary parts of the brain involved in 'seeing' still work just fine so they subconsciously respond to facial expressions and can navigate a cluttered space without incident.

This tells us that seeing and processing that image are actually different and distinct. One theory of deja vu is that this process gets switched. In a kind of minor epileptic fit, the brain processes the image first and then sees it – not so much a glitch in the Matrix as a glitch in our brains.

Likewise, it's also speculated that this order glitch could be happening in our recall process. In other words, we are subconsciously storing the new experience as a memory before consciously registering it as happening in the first place.

Don't worry, despite deja vu potentially being a mini seizure, it isn't dangerous. Other similar tricks played on us by our brains are presque vu (“almost seen”) when we feel a word is on the tip of our tongues, jamais vu (“never seen”) when something is so familiar that our neurons give up and it suddenly registers as fascinatingly new, and the hypnogogic jerk when inadvertently falling asleep transforms into the actual sensation of falling and we suddenly jerk awake.

The brain is a bizarre and mysterious place that we may never truly understand. Yet even when we do, that understanding shouldn't detract from the magic we can experience simply because we have them. No matter what, they're just plain cool.