Sight Slight

 Our eyes register far more information than our brain can handle. If our visual system attempted to register every photon that entered our eyes and send their signals to the brain to process, we'd become overwhelmed, so evolution has taught us to drastically filter the information that the eye is capable of responding to, such that the brain can pay attention to the tiny part that is necessary at the moment. And what is necessary, is to spot (1) food, sex, and those things we want and (2) threats—the things we don't want.

Our central vision is very acute, giving us the detail we need for our brain to discern important objects. Our eyes are constantly shifting about, taking in that important information, as we constantly monitor our visual field.

In contrast, our peripheral vision is not nearly as sharp, so it provides far less information to the brain, but is a crucial adjunct to our vision, because it is extremely sensitive to motion and can operate in lower-light conditions than does our central vision. Thus, evolution has provided us with very effective and complementary central and peripheral visions. Tightly-packed, color-sensitive cones are used for central vision, while sparsely-packed, color-insensitive rods provide peripheral vision that is far less precise.

Since (blurry) peripheral vision information is most often of minimal use to us, the brain ignores most of its signals—except when something that is off to one side suddenly moves. That's critical information, if we are to stay alive. The brain also learns to ignore objects that are in the field of central vision, when they are of little interest at the moment... in particular, objects that are familiar and unchanging. That picture on the wall virtually never registers in the brain, unless we specifically choose to look at it with our central vision. We hardly notice the easy chair, until we decide to sit in it, and even then we don't bother to examine it, because it's familiar and always there. Without looking, we plop down.

Put a new picture on the wall, however, and it keeps catching the corner of our eye, until it too becomes commonplace and we begin to ignore it. This learning to “slight our sight” of certain things is especially useful when we find ourselves in safe, familiar places. We can relax and maybe think deeply about things… even close our eyes.