Practice makes perfect: One of those clichés that gets endlessly trotted out, told to children at the piano and point guards shooting from behind the arc. It applies to multiplication tables and stickshifts, sex and writing. And the line is true, even if it overpromises. Perfection might be impossible, but practice is the only way to get close.
Unfortunately, the cliche is limited by its imprecision. What kind of practice makes perfect? And what aspects of practice are most valuable? Is it the repetition? The time? The focus? Given the burden of practice – it’s rarely much fun – knowing what works is useful knowledge, since it comes with the promise of learning faster. To invoke another cliché: Less pain, more gain.
These practical questions are the subject of a new paper by Nicholas Wymbs, Amy Bastian and Pablo Celnik in Current Biology that investigates the best ways to practice a motor skill. In the experiment, the scientists had subjects play a simple computer game featuring an isometric pinch task. Basically, subjects had to squeeze a small device that translated the amount of force they applied into cursor movements. The goal of the game was to move the cursor to specific windows on the screen.
The scientists divided their subjects into three main groups. The first group practiced the isometric task and then, six hours later, repeated the exact same lesson. The second group practiced the task but then, when called back six hours later, completed a slightly different version of the training, as the scientists required varying amounts of force to move the cursor. (The variations were so minor that subjects didn’t even notice them.) The last group only performed a single practice session. There was no follow-up six hours later.
The next day, all three groups returned to the lab for another training session. Their performance on the task was also measured. How accurate were their squeezes? How effectively were they able to control the cursor?
At first glance, the extra variability might seem counterproductive. Motor learning, after all, is supposed to be about the rote memorization of muscles, as the brain learns how to execute the exact same plan again and again. (As the scientists write, “motor learning is commonly described as a reduction of variability.”) It doesn’t matter if we’re talking about free throws or a Bach fugue – it’s all about mindless consistency, reinforcing the skill until it’s a robotic script.
However, the scientists found that making practice less predictable came with big benefits. When subjects were given a second training session requiring variable amounts of force, they showed gains in performance nearly twice as large as those who practiced for the same amount of time but always did the same thing. (Not surprisingly, the group given less practice time performed significantly worse.) In other words, a little inconsistency in practice led people to perform much more effectively when they returned to the original task.
This same technique – forcing people to make small alterations during practice - can be easily extended to all sorts of other motor activities. Perhaps it means shooting a basketball of a slightly different size, or doctoring the weight of a baseball bat, or adjusting the tension of tennis racquet strings. According to the scientists, these seemingly insignificant changes should accelerate your education, wringing more learning from every minute of training.
Why does variability enhance practice? The scientists credit a phenomenon known as memory reconsolidation. Ever since the pioneering work of Karim Nader, et al. it’s become clear that the act of recall is not a passive process. Rather, remembering changes the memory itself, as the original source file is revised every time it’s recalled. Such a mechanism has its curses – for one thing, it makes our memories highly unreliable, as they never stay the same – but it also ensures that all those synaptic files get updated in light of the latest events. The brain isn’t interested in useless precision; it wants the most useful version of the world, even if that utility comes at the expense of verisimilitude. It’s pragmatism all the way down.
While reconsolidation theory is already being used to help treat patients with PTSD and traumatic memories – the terrible past can always be rewritten – this current study extends the promise of reconsolidation to complex motor skills. In short, the scientists show that training people on a physical task, and then giving them subtle variations on that task after it has been recalled, can strengthen the original memory trace. Because subjects were forced to rapidly adjust their “motor control policy” to achieve the same goals, their brains seamlessly incorporated these new lessons into the old motor skill. The practice felt the same, but what they’d learned had changed: they were now that much closer to perfect.
Wymbs, Nicholas F., Amy J. Bastian, and Pablo A. Celnik. "Motor Skills Are Strengthened through Reconsolidation." Current Biology 26.3 (2016): 338-343.