In 1898, Erdmann and Dodge first described saccadic blindness following observations in unrelated experiments. They noticed that an observer could never see the motion of their own eyes. You can easily duplicate this effect by looking into a mirror and looking from one eye to another. While moving, you cannot observe the eyes. Yet, an external observer sees the motion of the eyes. By the end of the day, this visual saccadic suppression will have cumulatively resulted in about 40 minutes of blindness.