Literal vision, having to do with the physical eyes of living creatures, supports a vast field of study and speculation. Various animals can see at night, or operate in areas of the spectrum where we can't see at all, or swivel their eyes around and look backward.
Animals show a close to infinite variety of evolutionary tricks involving combinations of eye and brain that range from brilliant to droll. What about those
fish that start life with normal eye placement, namely one on each side of the head? Then they lie on one side on the bottom and spend the rest of their lives there, and the downward-looking eye migrates up to the top. This is taking adaptability to extremes.
Why do squirrels, who seem so spry and quick, get hit by cars? Because they literally can't see them, explains Joel Achenbach in his syndicated column. "The motion of the car is so bizarre, compared to other things in nature, that the squirrel's brain can't even register it." I can dig it. A squirrel is built low to the ground, and the horizon isn't very far away. Probably the oncoming car manifests itself as a rapidly growing dark area in the squirrel's field of vision, somewhat like a cloud that quickly grows and envelops the critter. The sensation would be akin to a sudden swarm of angry biting insects, or driving at excessive MPH into a thick fog or a cloud of dense black smoke, or a wall for that matter. Before you can begin to figure out what it is or where it came from, it's all over you.
According to R. Wayne Anderson, there are "five basic failures of the human eye, and in all these failures photography can replay the event in a form that the eye can see."
The five are, not being able to see things too large at once (aerial photography is the answer) or too small (photomicrography saves us). We can't see things that move too fast or too slow, but changing the speed of the camera's recording of images can fix that. We can't see things outside our particular range in the electromagnetic spectrum, but film can capture images in the infrared, ultraviolet, and gamma ranges.
Even a normal human can, however, distinguish approximately twenty thousand colors. Once in a while a freak is born who can see infrared with one eye and ultraviolet with the other, or detect movement at an astonishing distance, or see very tiny objects. Archaeologist Arthur Evans, who dug up the Minoan remains, is said to have had "microscopic eyesight" that allowed him to make sense of intricate inscriptions and appreciate the tiny seals that would lead to his greatest discoveries.
The Vision lab at MIT is involved in a project that will ultimately let a computer see like a human, recognizing people and things in any setting, almost instantaneously. Although slower than the eye-brain combination, in other respects the Connection Machine sees better. It has, for example, the capability to visualize the molecular structure of a substance in three dimensions. A microscope with lenses can help the human eye to see things that are awfully small, but this invention can "see" even better without using vision at all.
At the time when Impressionism was the latest rage in the art world, critics made derogatory remarks about how these painters all had eyestrain or some kind of visual disease or defect. Actually in some cases this was true. Monet had cataracts for the last 20 years of his life, Pissarro had a problem requiring long periods of bandaged eyes. Leading Impressionist painter Edgar Degas, says art historian Richard Kendall, probably suffered from irregular astigmatism, a condition which causes the image to be hazy and the field of vision distorted. The evidence offered for this is that he squinted, and Degas did say in one letter written at 43 that his vision was cloudy. To make things worse, it seems he had already lost the use of his right eye early in his career.
Many great writers have had iritis or other serious eye conditions, including Tom Robbins, D.H. Lawrence, Aldous Huxley and James Joyce.
I'd like a CD ROM that would show many kinds of scenes in alternative visual modes, for instance the designs on flowers like airport runway markings, detectable only in Bee-O-Vision. It would be enlightening to see how things look to people with various eye problems, and it would be a great idea for medics and others in the helping professions to have that kind of experience. I'd like to see how things would look if chlorophyll had been purple instead of green. These are genuine parallel universes.
Ninety percent of what we humans know about the world comes into us through our eyes, and an entire one-third of the brain's power is devoted to the processing and utilization of this information. Even language and reasoning skills do not tap such a large share of the brain's total resources.
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