Why Practice Makes Perfect
Ballistic motions help us perform automatically.
By Peter Jaret
If you've ever listened to Artur Rubinstein tear through a complicated passage of Chopin or Schumann, you've probably wondered how his fingers can move that fast. With good reason. Consider Chopin's presto from the B-flat Minor Sonata. Rubinstein puts away the 1760 notes in one minute 16 seconds flat, a speed of 23 notes per second.
And that's just the beginning. The striking of each note requires the controlled motion of all three joints in each finger, including distinct flexing, extending and lateral movements. Meanwhile, for each finger that moves into playing position, at least two fingers must get out of the way.
According to the late physiologist, Homer W. Smith, of New York University, a performance of 20 to 30 notes per second may actually involve as many as 600 individual actions per second. "And the number may be much higher," says Frank R. Wilson, neurologist with the Performing Artists Program at the University of California at San Francisco, and author of "Tone Deaf and All Thumbs?"
Consider that so many quick and complex maneuvers combine to yield an artistic performance-all of it done almost without a conscious thought-and you have a sense of the achievement of what Wilson calls-"the small-muscle athlete."
How do mind and muscle accomplish such a feat? The skilled movements of an Artur Rubinstein are simply too fast to be governed by the system that oversees most voluntary movements such as the act of turning a page.
That movement begins with your brain commanding certain muscles to set your arm and hand in motion. Immediately, signals from your eyes and from sensory nerves in your muscles begin to feed information back to the brain on how well you were doing, perhaps reporting that your hand is heading a little wide of the mark.
The brain might then order a mid-course correction, adjusting the path up or down, left or right. Your reach is gradual enough that there was plenty of time for repeated checks and adjustments.
But you'd never be able to rip through Chopin's presto at 23 notes per second using such a deliberate process. "That's just too many movements, performed too quickly, to be explained by the traditional model of actions continuously guided by sensory feedback," says Wilson.
Ballistic Movement
Instead, the body creates a different kind of movement-which neurophysiogists call a ballistic movement. As the name suggests, a ballistic movement is like the firing of a gun: Once the trigger is pulled, the bullet will go where it was aimed.
Ballistic movements are very economical. All they require is the initial electrical burst, which lasts just long enough to get the muscles moving at the right speed and in the right direction. The impulse is usually over by the time the muscle is only halfway through its motion.
That leaves the arm (or any moving limb) to continue on its set course until it runs out of steam or into some physical resistance. It also leaves the brain free to worry about the next movement-which is probably one reason ballistic movements can occur in as few as 80 milliseconds, according to some estimates, compared to a minimum of about 400 milliseconds for actions controlled by continuous feedback signals.
Practice Makes...
But because a ballistic movement relies on only one signal, its trajectory, force and speed have to be just right-and carefully worked out in advance. And that, as your third-grade music teacher probably told you, takes practice.
The role practice is the same whether you're sharpening your tennis swing or learning a Bach fugue: to work out the best estimate of the initial ballistic impulse needed to carry an arm, hand or finger through its ultimate destination.
Part of practicing is homing in on exactly which muscles are needed to perform a given movement. We begin by practicing slowly, which gives the brain plenty of time to receive and process sensory signals, to let it check how well we're doing. The more we practice, the more accurate we get.
Once a ballistic movement's precise force and trajectory have been worked out, they can be executed without continuous checking.
Cerebellum's Role
Getting ballistic trajectories down just right is one important part of practice. But Wilson raises another, more surprising role. Although no one knows which part of the brain control ballistic movements, studies suggest that the cerebellum, long associated with voluntary movement, appears to have a lot to do with it.
"And that's interesting because the cerebellum is primarily an inhibitory organ," says Wilson. The firing of nerve cells and the movement of muscles are determined by combinations of "on" and "off" signals. The cerebellum exerts its control primarily by providing the off signals.
"It could well be that the cerebellum's role is to orchestrate the full relaxation that must precede muscle contraction during ballistic movements," says Wilson. So through practice, the brain works out the proper sequence of these off signals just as precisely as the on impulses that get things moving.
That may account for the state of deep relaxation that many musicians experience during performance. For if practice is a special kind of memorizing based on repetition and refinement, performance becomes a special kind of forgetting.
"Ultimately, the musician must relinquish the illusion of moment-by-moment control," says Wilson "trusting the program to remember exactly how each finger must move. The musician becomes aware only of the feeling, the emotion in the music."
That's the moment when the musician leaps from mere technician to artist-and practice becomes perfection.