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

The Mind's Eye | 271cylinder with an elbow at the top is a pail. And just as a small number ofwords and rules combine into an astronomical number of sentences, asmall number of geons and attachments combine into an astronomicalnumber of objects. According to Biederman, each of the twenty-fourgeons comes in fifteen sizes and builds (a bit fatter, a bit skinnier), andthere are eighty-one ways to join them. That allows for 10,497,600objects built out of two geons, and 306 billion objects made of threegeons. In theory, that should be more than enough to fit the tens ofthousands of shapes we know. In practice, it's easy to build instantlyrecognizable models of everyday objects out of three, and often onlytwo, geons.Language and complex shapes even seem to be neighbors in thebrain. The left hemisphere is not only the seat of language but also the seatof the ability to recognize and imagine shapes defined by arrangementsof parts. A neurological patient who had suffered a stroke to his lefthemisphere reported, "When I try to imagine a plant, an animal, anobject, I can recall but one part. My inner vision is fleeting, fragmented;if I'm asked to imagine the head of a cow, I know it has ears and horns,but I can't revisualize their places." The right hemisphere, in contrast, isgood for measuring whole shapes; it can easily judge whether a rectangleis taller than it is wide or whether a dot lies more or less than an inchfrom an object.One advantage of the geon theory is that its demands on the 272-Dsketch are not unreasonable. Carving objects into parts, labeling theparts as geons, and ascertaining their arrangement are not insurmountableproblems, and vision researchers have developed models ofhow the brain might solve them. Another advantage is that a descriptionof an object's anatomy helps the mind to think about objects, notjust to blurt out their names. People understand how objects work andwhat they are for by analyzing the shapes and arrangements of theirparts.The geon theory says that at the highest levels of perception the mind"sees" objects and parts as idealized geometric solids. That would explaina curious and long-noted fact about human visual aesthetics. Anyonewho has been to a figure-drawing class or a nude beach quickly learnsthat real human bodies do not live up to our sweet imaginations. Most ofus look better in clothes. In his history of fashion, the art historianQuentin Bell gives an explanation that could have come right out of thegeon theory: