Abstract: A system and computerized method is provided that controls a reading slot to provide aid to a user in reading a passage. The computerized method includes generating a mask having an opaque portion and a reading slot. The opaque portion covers a plurality of lines having characters that are visible through the slot. The plurality of lines includes at least a first line and a second line. The method includes advancing the slot at a midline velocity in relation to the first line of the passage, and increasing the velocity of the slot in accordance with a digital transition velocity profile when the slot enters a transition zone of the passage.