The Vision Process

A detailed Summary of The Vision Process

"Vision," says neuroscientist William Newsome, "happens in the brain, not the eye (Siegfried 1)." Although light enters the body through the eye, the majority of the processing takes place in the brain. A full quarter of the cerebral cortex is devoted to sight (Brownlee 1). Light is received through the eye as electromagnetic energy. What we see as visible light is only a small portion of the whole spectrum of electromagnetic radiation. This paper will be a map of how the vision process works.

The cornea and sclera make up the outer part of the eye. They hold the eye together and strengthen it. The sclera covers nearly five-sixths of the eye and the cornea takes up only one-sixth. The sclera is the white part of the eye. The cornea allows light to enter the eye.

The uveal tract is the middle layer of the eye. It is made up of three parts. From to back, they are: (1) the iris, (2) the ciliary body, and (3) the choroid.

The iris is the colored part of the eye. It lies behind the cornea. The iris controls the size of the pupil opening. At the center of the iris is the pupil. The pupil is the black circle in the middle of the eye. The size of the pupil determines how much light enters the eye. There are two muscles i

Goldberg, Morton F.; "Eye," World Book Encyclopedia, 2000.

The point in our vision where the optic nerve enters our eyes is the blind spot. There are no rods and cones here and the eye can't react to light. Anything in the blind spot of one eye is seen with the other eye.

Light that enters the eye must hit the retina for a clean, clear image. The cornea and the lens bend the light rays together. The cornea does most of the bending but the lens does a little bit more just before the light hits the retina (Goldberg).

Once a signal makes it to the brain, it divides scenes up into subdimensions such as color, depth, movement, and form. It then works on processing each subdimension simultaneously. This is called parallel processing (Brownlee 1).

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Pigment in the rods and cones pick up the light particles that hit the retina. These pigments are made of protein and vitamin A. The pigment in rods is rhodopsin or also known as visual purple. It lets the eye see shades of gray and to see in dim light. The three types of pigment that are in cones are: Cyanolabe, which absorbs blue light, Chlorolabe, which absorbs green light, and Erythrolabe, which absorbs red light. All these combine to distinguish more than 200 colors.

Light enters through the pupil, which is regulated by the iris. The light passes through the cornea and lens and is refracted together on the retina. The cones and rods on the cornea start a chemical reaction, which trigger bipolar cells. These trigger ganglion cells, which join together to make the optic nerve. The optic nerve carries the infor

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Approximate Word count = 1117
Approximate Pages = 4 (250 words per page double spaced)

Category: Science