How does the Brain Help Us to See?

Seeing, of course, is done by the eye. But our brain plays a very important part the process we call seeing. Mechanically, this is what happens. Light waves pas through the pupil of the eye and form and image on the retina.

The retina is a carpet-like screen of cells at the back of the eyeball. Each of the retina’s 130,000,000 cells is sensitive to light. When light strikes a cell a chemical change takes place. This starts an impulse in a nerve fiber, which travels through the optic nerve to the seeing portion of the brain.

But this is not all the happens. What the brain sees is very different from the pictures formed on the retina. For example, your eyes are seldom at rest. If you stand outdoors looking at the scene around you, your eyes stop for only a second at the grass, treetop, cloud, bird, or squirrel.

The brain does not see a series of quick snapshots. The seeing part of the brain records each picture and remembers it. It adds them together and gives them meaning, so that she whole picture is seen, not the parts. In a second, it draws upon the store of memories in the brain. A tree, a cloud, a squirrel these have been seen before.

It takes only a glance to recognize them. So seeing includes the use of many parts of the eye, the optic nerve, and the parts of the brain that see and interpret the eye’s messages. That’s why a baby must learn to use his vision.

Before long his visual mechanics work well. But his vision is still poor. Why? Because he understands little of what he sees. The brain is not yet playing its full part in seeing.   

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