When I play guitar while reading sheet music or tabs, I often glaze over what's actually on the paper or on the screen but still "read" it faintly -- Take away

When I play guitar while reading sheet music or tabs, I often glaze over what's actually on the paper or on the screen but still "read" it faintly -- Take away the guide or make me look at my hands and I'm helplessly lost, however. I have a pet theory that it's more about flow and some kind of vision-muscle memory.