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

268 HOW THE MIND WORKSANIMAL CRACKERSThe ability of objects to attract reference frames to themselves helps tosolve one of the great problems in vision, the next problem we face as wecontinue our climb from the retina to abstract thought. How do peoplerecognize shapes? An average adult knows names for about ten thousandthings, most of them distinguished by shape. Even a six-year-old knowsnames for a few thousand, having learned them at a rate of one every fewhours for years. Of course, objects can be recognized from many giveaways.Some can be recognized by their sounds and smells, and others,such as shirts in a hamper, can be identified only by their color andmaterial. But most objects can be recognized by their shapes. When werecognize an object's shape, we are acting as pure geometers, surveyingthe distribution of matter in space and finding the closest match inmemory. The mental geometer must be acute indeed, for a three-year-oldcan look through a box of animal crackers or a pile of garish plastic chipsand rattle off the names of exotic fauna from their silhouettes.The diagram at the bottom of page 9 introduced you to why the problemis so hard. When an object or the viewer moves, the contours in the2V2-D sketch change. If your memory for the shape—say, a suitcase—was a copy of the 2V2-D sketch when you first saw it, the moved versionwould no longer match. Your memory of a suitcase would be "a rectangularslab and a horizontal handle at twelve o'clock," but the handle you arenow looking at is not horizontal and not at twelve o'clock. You wouldstare blankly, not knowing what it is.