How to Read eyes

When we read we are capable of taking in only one key word and then four characters to the left and fifteen characters to the right at any one time.

The reason we can focus clearly on only that much text only that much text is that most of the sensors in our eyes - the receptors that process what we see - are clustered in a small region in the middle of the retina called the fovea. Thats why we move our eyes when we read: we can't pick up much information about the shape, or the color, or the structure of words unless we focus our fovea directly on them. Just try for example , to read this paragraph by staring straigh ahead at the center of the screen(without scrolling through it) It's impossible.

If you can track where someones fovea is moving and what are the fixating on, in other words, you can tell with extraordinary precission what they are actually looking at and what kind of information they are actually receiving.

The Tipping Point by Malcolm Gladwell