Another way that muscle movement affects vision is by movements of the iris, the colored part of the eye. There are muscles that move the iris to allow the pupil to dilate and to constrict, changing how much light enters the eye. It is these muscles that we become aware of when we are fatigued from too much close work, like reading.
The intention to see something causes the eyes to move in the direction of that object. This movement of the eye is called a saccade. Because it is a movement, a saccade has the two primary properties of movement: speed and distance.
If you are watching slow-moving clouds, your eyes will follow them at low speeds in small increments of distance. If you are watching a tennis match, chances are your eyes will move quickly from side to side to watch the ball.
In addition to employing intentional saccades, the eyes move in micro-saccades. These tiny movements help the visual system to remain lively to stimuli rather than stuck in one spot. Students who have trained themselves to look only at the music may be attempting to override the natural micro-saccades. This limits their ability to respond smoothly and easily to visual stimuli.
Taking this information to the piano is one of the best ways to help your students realize that they have some control over how their eyes move. "Fast eyes" is one of my favorite expressions for the ability to see many things in a short amount of time. Young students whose eyes are not yet fully developed may find fast eyes a challenge, but reminding them that eye movement is a part of playing piano music lays a foundation for this concept. Even if they are learning by rote, these students can benefit from understanding how their eyes move.
Very advanced players with excellent sight-reading skills will take quick glances at the keys. Their eyes also move around the page in what may seem to be illogical directions. Because they have fast eyes, excellent tactile and kinesthetic memories, and well-developed peripheral vision, they are able to incorporate a variety of eye movements into their playing without "losing their spot". And, as one of my teachers once said to me, there are some parts of music that are easier to play by watching one's hands.
One of my favorite resources for helping students improve their eye movements is a book of exercises by Rebecca Penneys. It is called The Fundamentals of Flow in Music, and it can be purchased from her website at www.rebeccapenneys.com. The exercises cover a range of difficulty, yet they are fun to use. Teachers are permitted to copy pages for their students as well.
Part Four of this exploration will take us to the stage.