biology of seeing color英文电子书.pdf

Vision and Art - The Biology of Seeing by Margaret Livingstone Chapter 2: The Eye and Color Vision The vertebrate eye is so complex that it was (and sometimes still is) used as an argument against evolution and in favor of divine intelligence: how could a random process like evolution produce something so intricate and beautiful? It is commonly thought that the eye is like a camera, and that its function is to send a highresolution image of the visual world to the brain. Some people even think of the entire visual system as a kind of fancy camera,. This misperception is so common that it has a name: the homunculus fallacy. (Homunculus is Greek for “little man.”) The fallacy is the idea that when we see something, a small representation of it is transmitted to the brain to be looked at by a little man. The fact is, of course, that there is no little man in the brain to look at that or any other image. The function of the visual system is really to process light patterns into information useful to the organism. The eye initiates this process of the extraction of information. Light Light passes through the pupil; the lens focuses an image on the retina passes through the opening in the at the back of the eye, and the retina performs the first calculations on front of the eye, the pupil, and the the image before transmitting its signals to the brain. For people with normal vision looking at distant objects, the lens gives a sharp focus lens focuses the image on the retina, when it is in its flattest state. To see objects that are only a few feet or a sheet of layers of neural tissue less away, the lens must become rounder to give a sharp focus. To do that lines the back of the eyeball. this, the ciliary muscle, a circular muscle that surrounds the lens,