It’s a bird! It’s a plane! No, it’s… an illusion! Optical (also known as visual) illusions love to play tricks on you by showing something that isn’t there. Or is it? They work by using imperfections or specifics of the visual system to create an image that is different from reality.

Why does that happen?

Well, the issue has to do with our brain. As the information comes through our eyes, the brain needs to organize it and give it a meaning. For example, when we see a speeding car coming at us, our brain sends us an impulse to run away from it. Similar things happen when we see an illusion, but the good thing is – we don’t get hit by a speeding car.

Some facts about optical illusions

It is hard to classify optical illusions, but there are three main types: physical, physiological, and cognitive illusions. A typical example of a physical distortion would be the apparent bending of a stick half immersed in water. Even though the stick is flat, we see it as bent.

Furthermore, an example of a physiological paradox is the motion aftereffect. When we move, the position of an object seemingly stays the same, but in reality it doesn’t.

The afterimage is an example of psychological fiction. Physiological illusions are the effects of excessive stimulation. They are the trace of the image that remains in our eye. The most common example is looking at the sun (but don’t look at the sun!) and then seeing it wherever we look afterwards.

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