Reading feels smooth. It is not. Your eyes jump along the line in short bursts, pausing briefly between them — several times every second.
The jumps are called saccades. The brief stops between them are fixations, and that is when you actually take in text; during the jump itself, vision is largely suppressed. A typical reader makes something in the order of three or four of these movements per second.
You also make regressions — backwards jumps to something you have already passed. These are normal and rise sharply when the material is difficult or when your attention slips.
Two reasons. First, only a small central region of your vision resolves fine detail, which is why the eye has to keep moving in the first place and why claims about absorbing whole lines at a glance do not survive contact with the biology.
Second, every jump is a moment when you can lose your place. Skipping a line, re-reading the one you just finished, or surfacing from a paragraph with no memory of it are all failures of navigation rather than failures of understanding.
By putting every word at the same point, RSVP removes the navigation problem: there is nowhere to jump to, so the eye stays still and the text comes to you. How Wordema does it.
The honest trade is that regressions are useful. Going back is often how understanding is repaired. Wordema keeps that available deliberately — pause and you can step back a word or a sentence, or open the full text and pick up exactly where you left off.