University of Cambridge. UK: New research into the way in which we learn new skills finds that a single
skill can be learned faster if its follow-through motion is consistent,
but multiple skills can be learned simultaneously if the follow-through
motion is varied.
Researchers
from the University of Cambridge and Plymouth University have shown
that follow-through – such as when swinging a golf club or tennis racket
– can help us to learn two different skills at once, or to learn a
single skill faster. The research provides new insight into the way
tasks are learned, and could have implications for rehabilitation, such
as re-learning motor skills following a stroke.
The researchers found that the particular motor memory which is
active and modifiable in the brain at any given time depends on both
lead-in and follow-through movement, and that skills which may otherwise
interfere can be learned at the same time if their follow-through
motions are unique. The research is published today (8 January) in the journal Current Biology.
While follow-through in sports such as tennis or golf cannot affect
the movement of the ball after it has been hit, it does serve two
important purposes: it both helps maximise velocity or force at the
point of impact, and helps prevent injuries by allowing a gradual
slowdown of a movement.
Now, researchers have found a third important role for
follow-through: it allows distinct motor memories to be learned. In
other words, by practising the same action with different
follow-throughs, different motor memories can be learned for a single
movement.
If a new task, whether that is serving a tennis ball or learning a
passage on a musical instrument, is repeated enough times, a motor
memory of that task is developed. The brain is able to store, protect
and reactivate this memory, quickly instructing the muscles to perform
the task so that it can be performed seemingly without thinking.
The problem with learning similar but distinct tasks is that they can
‘interfere’ with each other in the brain. For example, tennis and
racquetball are both racket sports. However, the strokes for the two
sports are slightly different, as topspin is great for a tennis player,
but not for a racquetball player. Despite this, in theory it should be
possible to learn both sports independently. However, many people find
it difficult to perform at a high level in both sports, due to
interference between the two strokes.
In order to determine whether we learn a separate motor memory for
each task, or a single motor memory for both, the researchers examined
either the presence or absence of interference by having participants
learn a ‘reaching’ task in the presence of two opposite force-fields.
Participants grasped the handle of a robotic interface and made a
reaching movement through an opposing force-field to a central target,
followed immediately by a second unopposed follow-through movement to
one of two possible final targets. The direction of the force-field was
changed, representing different tasks, and the researchers were able to
examine whether the tasks are learned separately, in which case there
would be no interference, or whether we learn the mean of the two
opposing force-fields, in which case there would be complete
interference.
The researchers found that the specific motor memory which is active
at any given moment depends on the movement that will be made in the
near future. When a follow-through movement was made that anticipated
the force-field direction, there was a substantial reduction in
interference. This suggests that different follow-throughs may activate
distinct motor memories, allowing us to learn two different skills
without them interfering, even when the rest of the movement is
identical. However, while practising a variable follow-through can
activate multiple motor memories, practising a consistent follow-through
allowed for tasks to be learned much faster.
“There is always noise in our movements, which arrives in the sensory
information we receive, the planning we undertake, and the output of
our motor system,” said Dr David Franklin of Cambridge’s Department of
Engineering, a senior author on the research. “Because of this, every
movement we make is slightly different from the last one even if we try
really hard to make it exactly the same - there will always be
variability within our movements and therefore within our follow-through
as well.”
When practicing a new skill such as a tennis stroke, we may think
that we do not need to care as much about controlling the variability
after we hit the ball as it can’t actually affect the movement of the
ball itself. “However this research suggests that this variability has
another very important point - that it reduces the speed of learning of
the skill that is being practiced,” said Franklin.
The research may also have implications for rehabilitation, such as
re-learning skills after a stroke. When trying to re-learn skills after a
stroke, many patients actually exhibit a great deal of variability in
their movements. “Since we have shown that learning occurs faster with
consistent movements, it may therefore be important to consider methods
to reduce this variability in order to improve the speed of
rehabilitation,” said Dr Ian Howard of Plymouth University, the paper’s
lead author.
The work was supported by the Wellcome Trust, Human Frontier Science Program, Plymouth University and the Royal Society.
- See more at: http://www.cam.ac.uk/research/news/practice-really-does-make-perfect#sthash.QlJXjxe5.dpuf