Many of us have, whether we want to admit it or not, completed optical illusion quizzes on social media platforms. These quizzes have us guessing if two different shapes are the same size or how many squares there are in a cube. While optical illusions are fun, they can leave us guessing and wondering why this happens.

The basis of optical illusions is visual deception. It isn’t your eyes playing a trick on you. Your eyes send signals to our brains through the retina, your brain then registers the information to create the image you are seeing. In the case of a visual illusion, the image the brain perceives differs from reality. There are parts of the image that are misleading and the brain cannot comprehend the image as a whole, leading to a misinterpretation. Some psychologists and researchers hypothesize that the reason this happens is a neural lag. Since it takes one tenth of a second for the light that enters our pupils to reach our retina and then our brains, that the brain will generate an image based on past experiences and organ senses. It is believed that the brain is attempting to see the future and that this is what creates the illusion.

There is an optical illusion where black and white squares look like they are moving

There are three types of visual illusions: literal, physiological and cognitive.
A literal visual illusion is when the brain and the eyes choose to focus on one specific part of an image, for example a tree with many branches that make-up different faces.

A physiological illusion is an afterimage. This is an image that lingers in your sight even after you are no longer looking at it. An example of this type of visual illusion is when you stare at black and white image of a person for a minute, look away and then you see against a white wall.

A cognitive visual illusion is when your brain unconsciously makes the wrong decision, assuming one thing instead of seeing the reality of what the image or object is. This type of visual illusion has 4 different categories: distorting, ambiguous, paradox and fictional.

-Distorting cognitive illusions refers to the distortion of size, length or curvature. 

-An ambiguous illusion is an image that can be interpreted in more than one way.

-Paradox cognitive illusion is when an image looks impossible in three dimensions or as a real object but in two dimensions it is very convincing, like the impossible staircase.

-Fictional illusion is when a shape or figure is perceived even though it isn’t there. 

There is an optical illusion where many shapes are forming a triangle

So, if you ever thought your eyesight needed to be checked after looking at an optical illusion, rest assured, it is simply a misinterpretation from your visual system and your brain.