There is a fascinating read over at Microsoft Research called The Science of Word Recognition. It's all about how you do what you're doing right now: recognizing words.
Our eyes don’t move smoothly across the page, but rather make discrete jumps from word to word. We fixate on a word for a period of time, roughly 200-250ms, then make a ballistic movement to another word. These movements are called saccades and usually take 20-35ms. Most saccades are forward movements from 7 to 9 letters,* but 10-15% of all saccades are regressive or backwards movements. Most readers are completely unaware of the frequency of regressive saccades while reading. The location of the fixation is not random. Fixations never occur between words, and usually occur just to the left of the middle of a word. Not all words are fixated; short words and particularly function words are frequently skipped. Figure 5 shows a diagram of the fixation points of a typical reader.
I actually found it difficult to read, simply because I had become too aware of my eye movement and thought processes to pay attention to a number of passages, so I had to reread large sections of the paper.
