The Brain

Seeing doesn’t actually take place in the eyes, but in the brain. The brain puts together the nerve impulses from the optic nerve, flipping the image right-side up, and allows us to see. Scientists still do not fully understand how the brain does this. They do know that damage to certain parts of the brain can cause sight problems and that we all have an area of the eye called a blind spot. This blind spot is located where the optic nerve enters the retina. We do not usually know we have the blind spot because our eyes move around giving us enough information to see properly. However, sometimes this blind spot can cause your brain to put together the impulses wrong, causing a misperception about what you are seeing. So just as the eye and brain work together for us to see properly, they also work together for us to see illusions. To read more about why we see optical illusions, click here.

Click here to try an experiment that shows how the blind spot can cause us to see things that are not really there.