Originally Posted by Sam Spade
Notice how you can be aware of things that aren't in the center of your field of view. Another thing that takes practice, but there are plenty of opportunities to practice. As I type this, there's a flashing Robar ad at the top of the screen. I can see when it changes out of the corner of my eye. I can see more detail while I'm still looking off a bit. I can read it, even when I'm looking a few lines down from the actual text. If you watch TV by looking at the corner of the screen, you can still follow the action and describe the characters, right? Off to the mall, where you scope the babes (or hunks, I'll be an equal opportunity whatever I am) without ever staring. An associated level of discipline here is not having your head snap and lock on when something really interests you--you track the approach and departure of the person without looking at him/her. Describe what he was wearing and carrying in his hands without having stared (look back for confirmation).
Central cone vision is usually less than 5 degrees. This is the area where you can see detail. Anything outside the central cone is perceived as color, vague shapes, and movement. This is peripheral vision and it is unlikely you will be able to change that very much. It is hard wired.