How the Mind Works - michaeljgoodnight.com

268 HOW THE MIND WORKS
ANIMAL CRACKERS
The ability of objects to attract reference frames to themselves helps to
solve one of the great problems in vision, the next problem we face as we
continue our climb from the retina to abstract thought. How do people
recognize shapes? An average adult knows names for about ten thousand
things, most of them distinguished by shape. Even a six-year-old knows
names for a few thousand, having learned them at a rate of one every few
hours 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 and
material. But most objects can be recognized by their shapes. When we
recognize an object's shape, we are acting as pure geometers, surveying
the distribution of matter in space and finding the closest match in
memory. The mental geometer must be acute indeed, for a three-year-old
can look through a box of animal crackers or a pile of garish plastic chips
and rattle off the names of exotic fauna from their silhouettes.
The diagram at the bottom of page 9 introduced you to why the problem
is so hard. When an object or the viewer moves, the contours in the
2V2-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 version
would no longer match. Your memory of a suitcase would be "a rectangular
slab and a horizontal handle at twelve o'clock," but the handle you are
now looking at is not horizontal and not at twelve o'clock. You would
stare blankly, not knowing what it is.