Bennett Schwartz is one of the nation’s leading memory experts, and when I visited him in his office at Florida International University, he was standing at his desk. A soft sunlight crowded the room. Large windows framed the palm tree-lined quad outside.

Dressed in a short-sleeved shirt and slacks, Schwartz appeared to be quietly talking to himself, with hushed, mumbled words, and for a long moment, it seemed as if he was some sort of monk, living in another, more esoteric world.

“Hi?” I said tentatively.

Schwartz turned around, putting the book away with an easy gesture.

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It turned out that when I walked into the room, Schwartz was honing his Scrabble skills. He had a Scrabble tournament the next day, and he was practicing words from a book devoted to the game. “The director is allowing me to play against the good Scrabble players,” Schwartz told me, laughing. “I have to make sure I know my words.”

So how exactly does one of the nation’s premier memory experts develop his Scrabble skills?

Well, Schwartz uses a type of self-quizzing: In order to hone his expertise, he’s constantly interrogating himself to see if he can recall various Scrabble words. So when Schwartz stops at a red light—or if he’s just waiting in his office—he’ll ask himself questions about what he’s learned as well as what he aims to learn.

The learning strategy has shown clear results, helping Schwartz become a nationally ranked player, boosting his Scrabble rating by more than 25 percent over the past few years.

Known as retrieval practice, the approach to learning fills the recent literature on memory, sometimes showing effects some 50 percent more than other forms of learning. In one study, one group of subjects read a passage four times. A second group read the passage just one time, but then the same group practiced recalling the passage three times.

about the author About Ulrich Boser (@ulrichboser) a senior fellow at the Center for American Progress.

But when the researchers followed up with both groups a few days later, the group that had practiced recalling the passage learned significantly more. In other words, subjects who tried to recall the information instead of rereading it showed far more expertise.

Within the learning sciences, retrieval practice is sometimes referred as the testing effect since the practice is a matter of people asking themselves specific questions about what they learned. But in many ways, the idea goes much deeper than self-quizzing, and what’s important about retrieval practice is that people take steps to recall what they know. They ask themselves questions about their knowledge, making sure that it can be produced.

More concretely, retrieval practice isn’t like a multiple-choice test, which has people choose from a few answers, or even a Scrabble game, where you hunt in your memory for a high-point word. Retrieval practice is more like writing a five-sentence essay in your head: You’re recalling the idea and summarizing it in a way that makes sense.

In this regard, we can think of retrieval practice as a type of mental doing: It’s a way to create the webs of meaning that support what we know. As psychologist Bob Bjork told me, “The act of retrieving information from our memories is a powerful learning event.”

A lot of the benefit of retrieval practice is explained by the nature of long-term memory, and Schwartz describes long-term memory as being like the sprawling, chaotic bedroom of a teenager. It might seem messy from the outside, but the disorder makes a lot of sense to the people who live there. "Each of us has his or her own subjective organization strategies, which may not be obvious to others, but give us each or own unique associations and memory," Schwartz told me.

The key to recalling memories is to have cues that closely link up with a memory, Schwartz says. When we have strong associations, we can more easily recall a word or idea. Because if "cues change, finding that missing word or event is like looking for a particular t-shirt among the chaos of the mess," he says. We simply can't find it.

In this regard, retrieval practice helps us recall memories because it more closely links cues and their associated memories. It pushes us to foster associations—and make more durable forms of knowledge. As Schwartz argues, "it’s the growing mess and the lack of the organizational cues that makes memory fade."

The benefits of retrieval practice go far beyond facts or games, and there are ways to use self-quizzing to develop conceptual understanding. One student recommends that people first create a pile of cards that lists facts. Then people should build a second pile that asks things like “give a real life example” or “draw this concept.” In this approach, people learn by picking one card from the first pile and a card from the second pile, and then executing the task.

Retrieval practice doesn’t have to be written down, either. When I was in college, I worked as a teaching assistant for a class that relied on a form of retrieval practice, and once a week, I would gather a group of students in a classroom and verbally ask them rapid-fire questions. The class was relatively short—just 45 minutes a week. But it was easy to see the effects of the free-recall type of practice, and the more the students retrieved their knowledge, the more they learned.

As for Schwartz, he did well at the Scrabble tournament on the day after our interview. The director placed him in one of the highest divisions, and he went against some of the best players in the state of Florida. Using his technique of retrieval practice, Schwartz managed to notch wins in about a third of his games. As Schwartz modestly joked in a follow-up email, “I didn’t finish last, so I did OK.”

The Hard Matter of Learning

There's a problem with retrieval practice and Schwartz is pretty familiar with it. In recent years, Schwartz has been encouraging students in his classes at Florida International University to use retrieval practice and he repeatedly asks them to explain about what they know.

But Schwartz's students have not been all the supportive of the new approach to learning. “My students have to take a quiz every week,” he told me, “and they would much prefer not to take a quiz every week. They don’t like it. They complain. Every week, I get excuses about dead grandmothers.”

It's pretty easy to see why the students don't like the quizzes. Retrieval practice is uncomfortable. It requires additional work. The frequent quizzing pushes students to constantly recall things from memory, and while the students end up posting higher grades on the final exams, they have to put forth a lot more mental energy.

Schwartz argues that this is simply the nature of learning. Developing a skill takes cognitive toil, and we can see the benefits of this sort of struggle in our brain. Indeed, it appears that at a very basic neurological level, grappling with material in a dedicated way promotes a type of shifting of our neural circuits—and a richer form of expertise. "If we process things too easily, they do not form into memories," Schwartz says.

A version of this idea has long intrigued Yuzheng Hu. A researcher on brain plasticity at the National Institutes of Health, Hu has studied something called white matter. A type of neural transmission cable, white matter helps distribute messages throughout the brain. It makes information flow more effectively, allowing electronic pulses to jump more easily from one neuron to the next. If the brain has a form of wiring, white matter serves as the copper, the substance that conducts the messages.

In one of his first studies, Hu and some colleagues decided to see if certain types of learning might boost white matter within the brain, and so they compared a group of young subjects who received a rigorous type of math training and those who didn’t.

The data suggested that the more rigorous math approach built up the brain’s transmission material, and under the bright scan of the MRI machine, certain white matter zones of the brain like the corpus callosum pulsed stronger in people who had studied the harder approach to learning math.

Hu’s study was built on a decade’s worth of research that shows that there’s very little fixed about the brain. Our brain systems are not like a piece of metal, something rigid in its fundamentals, hard and inflexible. The brain, instead, is something that can change, something that can adapt to its environment, more neural cloud than neural cement.

If you master karate, for instance, there are clear, structural changes that happen to white matter structures within your brain. Similar changes happen when we learn to juggle—or learn to meditate.

This idea has a number of important implications for how we develop a skill. For one, there are far fewer neural set points than we generally believe. Our brains are not fixed at birth. Our mental abilities are not preprogrammed. For a long time, for instance, people believed in the notion of “critical periods,” or the idea that we need to acquire certain skills at particular times in our life. But except for a few narrow abilities, we can acquire most skills at any time.

But what’s new—and really most important—about this line of research is how exactly the brain builds new structures, and it seems that the brain creates white matter in an effort to deal with mental struggle. When there’s a large gap between what we know and what we can do, the brain shifts its structures to address the issue. Some years ago, a group of German researchers described a new way of understanding why this happens, and they argue that when “demand” overwhelms the brain’s “supply,” we build new neural structures.

For his part, Hu argues that the brain responds to an opportunity to learn. When faced with a tough situation, it rises to the occasion. “This is your brain optimizing the way you perform that task,” Hu told me. “If you practice something a lot, your brain will think, ‘This is important,’ and you will develop a strategy to better perform it.”

Schwartz goes a little further. He argues that white matter and learning might not actually be all that different, at least at some philosophical level. "I am a materialist. I don’t like the idea that our brain is somehow different from what we consider to be ourselves," Schwartz says. Thus, for him, "white matter connectivity is the neural correlate of cognitive engagement and growth. They are one in the same—rather than one resulting from the other."

It's possible to go too far here. Learning is about a lot more than developing a specific axon in the brain. But more broadly what's clear is that the brain itself seems to understand the value of repeatedly quizzing, of learning as a form of cognitive work.

The Psychology of Errors

Memory researchers haven’t always believed in the power of mistakes. Before the advent of researchers like Bennett Schwartz, struggle wasn’t considered part of the learning process, and in more passive, more behaviorist models of learning, mistakes are exactly that: mistakes. They show that people are not learning properly. Blunders are a sign that someone is doing something wrong.

But it turns out that understanding doesn’t transfer immutably from one person’s head to another. Our brain is not a simple storage device, a lockbox, or a warehouse that serves as some type of memory depot. Instead, we have to make sense of ideas, to grapple with expertise, and that means that errors are simply unavoidable.

This notion is pretty clear in something like retrieval practice. If you’re constantly asking yourself questions, you’re bound to have some misses. Someone like Schwartz, for instance, often gets something wrong as he practices for his Scrabble tournaments, unable to recall a high-value Scrabble word like "qat."

Just as important, errors create meaning. They build understanding. When I interviewed Schwartz in his office, for instance, he asked me the question: What’s the capital of Australia?

Unless you’re from Australia, your first guess is probably the same as my first question: Sydney. But that’s not correct.

Second guess? Maybe Melbourne? Again, wrong.

Or perhaps Brisbane? Perth? Adelaide? All those answers are also off the mark.

The correct response, it turns out, is Canberra.

I know. Weird. If you’re not from Australia, the answer of Canberra probably comes with a buzzing shock of surprise. That's certainly what happened to me when Schwartz finally told me the answer. It was an odd little eye-opener.

But that feeling—that zinging moment—is learning. It’s the signal of a shift in understanding. When we make a gaff, we search for meaning, and so we learn more effectively. This idea goes back to memory being like a messy, teenager's room. If there’s an error—and it’s a salient one—we put a red, Sharpie-made x on the memory, noting exactly where it's located in the room. Within our brains, we’re telling ourselves: Remember this idea. It’s important.

Of course, no one likes mistakes. Errors are sharp and painful, humiliating and demoralizing. Even the smallest of gaffs—a misspoken word, a blundered errand—can haunt people for years. In this sense, mistakes make us rethink who we are; they’re a threat to our being.

But still, errors help us gain skills. They create mastery. When I last checked in with Schwartz, he had won a tournament in St. Myers, landing second place and taking home $80 in award money. He was still processing what he had done wrong, figuring out how to gain from his mistakes: "I could not play that damn 'v,'" he told me.

But Schwartz was also focused on what he needed to get better, to win at the next Scrabble tournament. "I need some time to study if I want to break to the next level," he told me. In other words, he needed some more time to quiz himself.

Excerpted from Learn Better by Ulrich Boser. Copyright © 2017 by Ulrich Boser. With permission of the publisher, Rodale Books. All rights reserved.