Steven Pinker -- How the Mind Works - Hampshire High Italian ...

6 | HOW THE MIND WORKSEach number represents the brightness of one of the millions of tinypatches making up the visual field. The smaller numbers come fromdarker patches, the larger numbers from brighter patches. The numbersshown in the array are the actual signals coming from an electronic cameratrained on a person's hand, though they could just as well be the firingrates of some of the nerve fibers coming from the eye to the brain asa person looks at a hand. Vox a robot hrain—or a human brain-—to recognizeobjects and not bump into them, it must crunch these numbers andguess what kinds of objects in the world reflected the iight that gave riseto them. The problem is humblingly difficult.First, a visual system must locate where an object ends and the backdropbegins. But the world is not a coloring book, with black outlinesaround solid regions. The world as it is projected into our eyes is a mosaicof tiny shaded patches. Perhaps, one could guess, the visual brain looks forregions where a quilt of large numbers (a brighter region) abuts a quilt ofsmall numbers (a darker region). You can discern such a boundary in thesquare of numbers; it runs diagonally from the top right to the bottom center.Most of the time, unfortunately, you would not have found the edge ofan object, where it gives way to empty space. The juxtaposition of large andsmall numbers could have come from many distinct arrangements of matter.This drawing, devised by the psychologists Pawan Sinha and EdwardAdelson, appears to show a ring of light gray and dark gray tiles.