mardi, septembre 28, 2004
some learnin'
In perception class we have been discussing the very complex visual system. From the very beginning, how an image is formed on the retina, right up to higher-level processing in the cortex where we learn about specialized cells that respond only to very specific stimuli. One interesting part of learning this stuff is all the visual aids used to demonstrate the various phenomena being discussed. Here is one:
This is called the Hermann Grid. It demonstrates a phenomenon produced BY the visual system, called lateral inhibition. At the various intersections of white, you should see gray spots, until you look directly at the spot, and realize there's nothing there. The explanation probably isn't that interesting, but here goes: the visual system likes to perceive edges and borders, so at those intersections, because there is white being perceived from every other direction surrounding that spot, the white is actually being inhibited by four different forces (the bipolar cells at the back of the eye, to be precise).
Fascinating, huh? | ¶ 10:35 p.m.
This is called the Hermann Grid. It demonstrates a phenomenon produced BY the visual system, called lateral inhibition. At the various intersections of white, you should see gray spots, until you look directly at the spot, and realize there's nothing there. The explanation probably isn't that interesting, but here goes: the visual system likes to perceive edges and borders, so at those intersections, because there is white being perceived from every other direction surrounding that spot, the white is actually being inhibited by four different forces (the bipolar cells at the back of the eye, to be precise).
Fascinating, huh? | ¶ 10:35 p.m.
