Many times, visual tricks depend on the way our eyes and brain process information. To understand how and why optical illusions fool us, we need to understand how we get the information in the first place. In essence, you see because of the cooperation of nerve cells in your eye and the nerve receptor cells in your brain. We are able to think, see and interpret images because of the connection our brain has with our eyes-the optic nerve.
Along with the optic nerve, there are various important parts of the human eye.
Cornea: The cornea is a clear covering (sort of like protection) on your eye. It lets in light (which allows us to see color) but keeps out particles that can damage or hurt the eye.
Lens: The lens (located just behind the cornea) is clear muscle. By changing its shape, the lens can focus on specific images. The lens also focuses on light coming into your eye. This light is what forms an image that falls on the retina of the eye.
Retina: The retina is a light sensitive layer of the eye. It is how the lens can focus its image.
Pupil: The pupil of the eye allows light to travel though the iris (the color part of the eye) and into your eye
Iris: The amount of light is regulated by the iris
How do we really see images?
The retina contains millions of nerve cells. When light strikes the retina, these nerve cells respond by sending nerve impulses though the optic nerve and to the brain.
Your brain then puts together and interprets the nerve impulses sent by the nerve cells in your eye. Along with nerve impulses, the brain uses impulses from cells in the brain to finally put together the images the you see when you open your eyes.
Phew!
