"Jerome Lettvin, Humberto Maturana, Warren McCulloch, and Walter Pitts showed that the frog’s retina already filters visual information, responding to motion, contrast, boundaries, and small moving objects."
The researchers identified four distinct retinal output channels responding to different features of visual stimuli. Their findings established that the frog's eye transmits organized information rather than merely relaying an unprocessed image, illustrating how biological perception involves substantial information processing before signals reach the brain.
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