Vision is influenced by our preconceptions about reality. In viewing a scene, we establish unconscious hierarchies that reflect our functional relationship to objects and our momentary priorities. For example, when visualizing a hammer in our mind's eye, we tend to "see" it in profile or at some other 'ready for use' angle. One would probably not visualize a hammer as seen from the top so that the handle is hidden by the hammer's head. The functional relationship we have with objects creates visual expectations that interfere with our ability to see "like a camera." The camera, like the human eye, sees only shapes and colors. It documents the world impartially through a lens that is similar to the eye. When we look at them carefully, photographs are often surprising because they don't interpret confusing details but simply serve them up to us with a mechanical indifference. And because of their flatness, photographs often contain areas that appear as unrecognizable colors and shapes.