If they're sitting next to you, they drive you nuts. But they are the people who have to be moving while they read. Some may even move their lips. This is the bad habit that we have that is the hardest to drop. Auditory reading is difficult to beat because we are used to reading and hearing the words in our minds.
Some people even go so far as to mumble the words.
You can see their lips moving sometimes, or you can even hear a guttural growl as they go through the words. Fixations are the actual stops or pauses between eye-spans when the eye is moving to its next fixation point. We can't see while the eye moves so you do need the fixation points to see. The problem is, most people fixate word by word by word. They stop their eyes on each separate word.