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

The Mind's Eye | 229walls, and ceiling. When the room was viewed with one eye through apeephole, it looked like an amorphous sea of green. But when it wasviewed with both eyes, it sprang into its correct three-dimensional shape,Ames had built a world that could he seen only by the mythical Cyclopeaneye, not hy the left eye or the right eye alone. But how could thebrain have matched up the two eyes' views if it had to depend on recognizingand linking the objects in each oner The left eye's view was "leafleaf leaf leaf leaf leaf leaf leaf." The right eye's view was "leaf leaf leaf leafleaf leaf leaf loaf." The brain was faced with the hardest correspondenceproblem imaginable. Nonetheless it effortlessly coupled the views andconjured up a cyclopean vision.The demonstration is not airtight. What if the edges and corners ofthe room were not perfectly masked by the leaves? Perhaps each eye hada rough inkling of the room's shape, and when the brain fused the twoimages it became more confident that the inklings were accurate. Theairtight proof that the brain can solve the correspondence problem withoutrecognizing objects came from an ingenious early use of computergraphics by the psychologist Bela Julesz, Before he fled Hungary for theUnited States in 1956, Julesz was a radar engineer with an interest inaerial reconnaissance. Spying from the air uses a clever trick: stereoviews penetrate camouflage. A camouflaged object is covered with markingsresembling the background it lies on, making the boundary betweenthe object and its background invisible. But as long as the object is notpancake-flat, when it is viewed from two vantage points its markings willappear in slightly different positions in the two views, whereas the backgroundmarkings will not have moved quite as much because they arefarther away. The trick in aerial reconnaissance is to photograph theland, let the plane fly a bit, and photograph it again. The pictures areplaced side by side and then fed into a hypersensitive detector of disparityin two images: a human being. A person literally looks at the photographswith a stereo viewer, as if he were a giant peering down fromthe sky with one eye at each position from which the airplane took a picture,and the camouflaged objects pop out in depth. Since a camouflagedobject, by definition, is near-invisible in a single view, we haveanother example of the cyclopean eye seeing what neither real eye cansee.The proof had to come from perfect camouflage, and here Jules/, wentto the computer. For the left eye's view, he had the computer make asquare covered with random dots, like television snow. Julesz then had