What the frog's eye tells the frog's brain" was the title that cognition scientist Jerome Lettvin gave to a seminal paper published in 1959. He assumed that the eye not only sees, but also processes images -- even before they are transmitted to the brain for further processing. Lettvin was able to show that the eye neither simply takes pictures like a camera, nor does it send them to the brain without filtering. Instead, the eye itself extracts valuable information from what it sees. In the case of the frog, for example, it might 'tell' the brain: "There is something small and dark there, possibly a fly." For his revolutionary hypotheses, Lettvin was at first laughed off stage at conferences. In the meantime, though, his oft-quoted paper is considered a milestone. The questions raised in Lettvin's time are still pursued by scientists today.