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

218 | HOW THE MIND WORKSand to compensate for its difference from the painters. We undo the distortionof the picture as if seeing it from the painter's perspective, andinterpret the adjusted shapes correctly. The compensation works onlyup to a point. When we arrive late to a movie and sit in the front row,the difference between our vantage point and the camera's (analogous tothe painter at Leonardo's window) is too much of a stretch, and we seewarped actors slithering across a trapezoid.There is another difference between art and life. The painter had tosight the scene from a single vantage point. The viewer peeps at theworld from two vantage points: his left eye's and his right eye's. Hold outa finger and remain still while you close one eye, then the other. The fingerobscures different parts of the world behind it. The two eyes haveslightly different views, a fact of geometry called binocular parallax.Many kinds of animals have two eyes, and whenever they aim forward, sothat their fields overlap (rather than aiming outward for a panoramic view),natural selection must have faced the problem of combining their picturesinto a unified image that die rest of the brain can use. That hypotheticalimage is named after a mythical creature with a single eye in the middle of itsforehead: the Cyclops, a member of a race of monocular giants encounteredby Odysseus in his travels. The problem in making a cyclopean image is thatthere is no direct way to overlay the views of the two eyes. Most objects fall ondifferent places in the two images, and the difference depends on how faraway they are: the closer the object, the farther apart its facsimiles lie inthe two eyes' projections. Imagine looking at an apple on a table, with alemon behind it and cherries in front.AJr//AWv^