Your eyes are in constant motion. Whether reading a book or taking in a new room, your eyes are quickly adjusting and readjusting. This is known as saccadic eye movement, and it is a way for the eye to take in as much information as possible. By jumping bit by bit over everything you look at, your eyes gather more data than they would if they stayed still. The other type of eye movement is Smooth Pursuit, which is voluntarily following something in motion, such as a ball thrown at us.