Highlight each word while reading

I took inspiration from emu's post. I was reading just now and I realize that sometimes it is difficult to keep the mark while you are reading. I wish it was possible to Being able to auto select the speed and every few seconds that we choose according our speed of reading, to highlight each word while reading, every single word or every single sentence. That way I think is more comfortable to read, Because you don't think about whether you had arrived at the sentence above or below, you avoid getting confused and when there is a lot of text it happens easily.