Vision: a collaboration of eyes and brain.

We walk down a street, step up and down curbs, maneuver around objects and other pedestrians and adjust our pace, while visually monitoring our position. Moments later we get into our car, drive at highway speed through traffic and judge where we are relative to other vehicles while anticipating the flow of traffic. We arrive at baseball practice where we pick up a bat, walk to the plate, miss a curve ball, foul-off a fast ball and then hit a single, making numerous conscious and subconscious judgements with varying degrees of success. After practice, we stop by the mall, scan the crowd for our friend, and go to the bookstore to find the book we might want to purchase. Over a no-foam latte, we read the opening chapter, seeing if it captures our attention.