Last spring, some of my piano students participated in the
annual Vancouver Music Festival Workshop,
a non-competitive festival at which the students receive immediate oral
feedback from the adjudicators. My
students, in the youngest festival classes, had the privilege of working with
the lovely and encouraging Yvette Rowledge, an experienced adjudicator with a knack
for expressing comments in a way that young children can understand. The festival took place at a church, and the
students played on a beautiful grand piano.
Of course, every piano is a little bit different, and it takes a little
while to adjust to playing a different instrument, especially for these young
pianists. Yvette acknowledged this to
the students, often by using the phrase: “This piano doesn’t know your piece
yet”. This was a cute way of saying
that the students’ brains hadn’t adapted to playing on this different piano.
Changing our movements to adapt to different environmental
conditions is known as motor adaptation, an important category of motor
learning. Motor adaptation is believed
to work through feedback modification of existing motor programs. Think about it this way: when you go to play something on the piano,
you automatically move your fingers, hands, and arms a certain way, with a
certain amount of force, because you have learned that the keys give a
particular amount of resistance and are a certain distance apart, etc. You have learned that making these particular
movements on the piano will lead to certain sensory results: your fingers will feel the resistance of the
keys and your ears will hear the resulting pitches at a certain tempo and
volume level. This mapping of motor
commands to sensory consequences is called a forward model
– the brain takes the motor commands that have been generated, and predicts
forward what the sensory result will be.
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| The human brain, with the cerebellum coloured in pink. |
The part of the brain that has been shown to do this prediction is the cerebellum,
a structure the size of a slightly flattened baseball, at the lower back of the
brain, just above where the back of your head attaches to your neck. The cerebellum not only predicts what the
sensory result of actions should be, it also compares the real sensory result
with the predicted one. So if you’re
playing a different piano and it has a stiffer action than you’re used to, the
sensory result will be different than you expect: your fingers will feel more resistance, the
keys will move more slowly, and the sounds you produce will be quieter and
perhaps uneven. In other words, what you
feel and hear will be different from what you expected. The cerebellum will register that there is
some kind of error, some difference between the predicted result and the actual
result. The cerebellum will then alter
the forward model to try to reduce that error. In this example, it will change the model to take into account that more
velocity is required to move the piano keys.
This is what motor adaptation is: the updating of a forward model, so that the
prediction about sensory results better matches the actual sensory results of
the movement. Sensory feedback allows
our brain to learn the precise forces, directions, and velocities of movement
required in a particular situation. This
updating of the model is an ongoing activity, happening while we perform a
movement. It’s not like you play
something on the piano and then, after you finish, your brain figures out what
went wrong. Motor adaptation is
happening while you’re playing: as you
press down the key, you immediately feel and hear a difference in how the piano
responds, and you adapt our movements continually. Of course, getting the adaptation exactly
right takes a bit of time, so that your playing improves throughout the whole
piece.
Motor adaptation learning occurs all the time, in all sorts
of situations, whenever you learn to change the force and/or direction of your
movements in response to changes in the environment. For example, every time you drive an
unfamiliar car, you have to adapt to how it handles. To turn a corner, you may need to exert more
or less force on the steering wheel than in the car you are used to
driving. Similarly, if the brakes in the
unfamiliar car are more sensitive than the brakes in your own car, your stops
may be jerky at first. But you quickly
learn, without thinking too much about it, what forces are required for
steering and braking in this car, and adapt your movements so that you turn and
brake smoothly and automatically.
Motor adaptation certainly plays an important role in
performing music. As we've seen, every
time a musician plays on a different instrument, she must adapt to the
different forces needed. When we play in
a different hall with different acoustics, we adapt. When we need to play more quietly because
someone is sleeping or watching TV in another room, we adapt our movements. If the bench is too close to the piano or an orchestral player is crammed into a tiny orchestra pit, we need to adapt our movements.
On the practical side, studies have shown that it’s possible
to improve at adaptation. If we practice
playing on lots of different pianos, we are better equipped to make the
necessary changes for each individual one.
This occurs because our cerebellum will get an idea of what types of
possible errors are out there and how to correct for different errors.
The ability to adapt to different pianos is especially
important for my beginner students, some of whom practice at home on cheap
digital keyboards with unweighted keys.
(I don’t recommend it, of course, but I understand parents’ desires to
keep costs down while they’re uncertain about whether their children will
continue with piano). When these
children are playing on an acoustic piano, and actually have to press the keys
down hard enough to make the hammers hit the strings, the forces required are
quite different, and I hear the familiar refrain of “It was better at home”. They need to learn to adapt. And I think the more different pianos they
play on, the better for motor adaptation.
That way, every piano they play will “know their piece”.
References:
Krakauer, J.W., and Mazzoni, P. (2011). Human sensorimotor learning:
adaptation, skill, and beyond. Curr. Opin. Neurobiol. 21, 636–644.
Shadmehr, R., Smith, M.A., and Krakauer, J.W. (2010). Error correction,
sensory prediction, and adaptation in motor control. Annu. Rev. Neurosci. 33,
89–108.
