Optical Illusions

Optical Illusions are not created by special effects or expensive computer graphics, they are illusions that your brain creates. Certain patterns look different to different people, depending on how your brain processes the image that your eyes are sending it. There is a difference between what we see and what is actually there.

The most basic optical illusion is the picture to the right. Is it two faces – or is it a vase? You can see one, and then the other. Just because one is true, that doesn't mean that the other isn’t as likely of a picture. Which do you see first?

There are two common optical illusions: physiological illusions and cognitive illusions.

Physiological illusions include afterimages, which come after looking at a bright light or at something intently for a bit. This is a result of the eye or brain’s extended exposure to a stimulus.

Cognitive illusions are when the brains sees something that is not accurate with the facts of reality, usually when it is trying to fill in a blank in reality. Brains don’t like not knowing what’s there. This happens when the brain relies on rules and assumptions to make reality fit what it perceives.

However, all eyes have a blind spot. You can test this by doing the following experiment.

1. Take a plain piece of paper.


2. Draw two dots on it, about an inch apart.


3. Hold the paper out at arm’s length, and bring it closer to yourself.

At some point one of the dots will seem to disappear. This is because it has fallen into your blind spot, and your brain is covering it up by replicating what it sees around it so that you are unaware that there is any gap in your vision.