Depth perception refers to the ability to distinguish the distance of objects or to make judgments about relative distance. This capacity also called distance perception, adds the third dimension to height and width. Binocular vision (simultaneous vision with both eyes) is the primary basis for depth perception. The two eyes focus on an object from depth in one’s perception. Monocular vision (seeing with one eye) tends to flatten things in the distance. In motor activities, there are many opportunities for making judgments about the distance of people or objects. For example, the passer in football needs to determine with considerable accuracy the distance of his receivers and his opponents. Similarly the receiver must be able at all times to make an accurate judgment about the distance of the thrown ball. The golfer on the fairway must make an accurate estimate of the distance of the pin so that he can determine which club to select and how hard to swing.