When you want to learn something new, you practice. Once you get the hang of it, you can hopefully do what you learned—whether it’s parallel parking or standing backflips—on the next day, and the next. If not, you fall back to stage one and practice some more.
But your brain may have a shortcut that helps you lock in learning. Instead of practicing until you’re decent at something and then taking a siesta, practicing just a little longer could be the fast track to solidifying a skill. “Overlearning” is the process of rehearsing a skill even after you no longer improve. Even though you seem to have already learned the skill, you continue to practice at that same level of difficulty. A recent study suggests that this extra practice could be a handy way to lock in your hard-earned skills.
In the experiment, participants were asked to look at a screen and say when they saw a stripe pattern. Then two images were flashed one after the other. The images were noisy, like static on an old TV, and only one contained a hard-to-see stripe pattern. It took about twenty minutes of practice for people to usually recognize the image with stripes in it. The participants then continued to practice for another twenty minutes for the overlearning portion.
Next, the participants took a break before spending another twenty minutes learning a similar “competitor” task where the stripes were oriented at a new angle. Under normal circumstances, this second task would compete with the first and actually overwrite that skill, meaning people should now be able to detect the second pattern but no longer see the first. The researchers wanted to see if overlearning could prevent the first skill from disappearing.
The next day, researchers tested the participants to see which stripe patterns they could still detect. Remarkably, those participants who spent an extra twenty minutes practicing with the first pattern could not only perform the overlearned task, but they could not perform the second task. Somehow, extending their practice had crystallized the first task and blocked out competing learning afterwards. As researcher Kazuhisa Shibata says, overlearning made the first skill “resilient.”
Practicing something new seems to activate a period of learning (and unlearning) as the balance of neurotransmitters changes in the brain. Researcher Takeo Watanabe explains that overlearning can cut that period short. “In a sense, it makes the hot brain cool down.”
Overlearning is probably helpful for quick motor sequences as in basketball or ballet. For other things we typically commit to memory, like languages or facts, overlearning has not been rigorously tested. Watanabe notes that these functions tend to use less specialized information processing in the brain. Compared with vision or motion, there is more of the competition effect when learning two similar things. Watanabe speculates that overlearning might work even better here. “I think there are more cases of interference in higher cognitive memory,” he said, and “overlearning may be more effective.”
Years of research point to sleep as essential for entrenching memories. A study used sleep to cement motor learning in much the same way that overlearning was used to enhance visual learning. People who took a midday nap could produce similar results to overtraining, at least when measured on the following day—someone asked to tap fingers to thumb quickly in a given order was able to avoid overwriting that skill with a different sequence if they napped for ninety minutes in between training sessions. Unfortunately, most people cannot take a ninety minute nap every time they learn something important. However, sleep may better preserve memory after overlearning, so the two might act as a useful combination.
But what about when we don’t want to overlearn? In real life, we sometimes want to learn more than one similar task. In that case, we’d prefer avoiding the competition between skills altogether, so we can retain all of them. The researchers found that participants could be trained to detect both stripe patterns, but this process required more time. Participants who waited for several hours between training sessions retained both tasks and performed well the next day. This was true whether or not they overlearned the first task, suggesting that the “hot” period will cool down of its own accord, given enough time.
Sometimes, we do want to forget, or overwrite. This might be the case in post-traumatic stress disorder, where drug or non-drug therapies may one day reopen the “hot” period as treatment. Scientists hope that they can crack open the memory vault just enough to rewrite traumatic memory without touching other memories, though it would be extremely difficult and has only been tried in mice. More promising might be administering drugs to facilitate forgetting after a traumatic incident, though that has its own moral and legal quandaries. In general, we need to to forget in order to adjust to our surroundings, as when we visit a foreign country and change which way we look while crossing the road. Even when we do want to overlearn, we cannot overdo the training or we may actually reverse our gains. There is more to discover about where in our lives overlearning is relevant, and how much is actually helpful.
Still, when we want to learn something well and learn it fast, this scientific finding tells us to not underestimate the value of pushing on with practice when it seems unnecessary. “Overlearning is not useless,” says Shibata. Gesturing to the back of his head, where visual learning takes place, he says, “Although there is no further improvement, something happens.” Whether you are are picking up an obscure language like Esperanto or learning to spot Waldo with your kids, overlearning might preserve the skills you really need.