How We Learn: The Surprising Truth About When, Where, and Why It Happens

by Benedict Carey

the collective findings of modern learning science provide much more than a recipe for how to learn more efficiently. They describe a way of life.

No, this book is about something that is, at once, more humble and more grand: How to integrate the exotica of new subjects into daily life, in a way that makes them seep under our skin. How to make learning more a part of living and less an isolated chore.

In a universe full of wonders, this has to be on the short list: Some molecular bookmark keeps those neuron networks available for life and gives us nothing less than our history, our identity.

The left hemisphere takes whatever information it gets and tells a tale to conscious awareness.

As the nineteenth-century American psychologist William James observed, “If we remembered everything, we should on most occasions be as ill off as if we remembered nothing.”

The point is not that memory is nothing more than a pile of loose facts and a catalog of tall tales. It’s that retrieving any memory alters its accessibility, and often its content.

Still, Ballard knew what he had. “We not only tend to forget what we have once remembered,” he wrote, “but we also tend to remember what we have once forgotten.”

Soon it was beyond dispute that memory, as Erdelyi put it in a recent paper, “is a heterogeneous, mottled system that both improves and declines over time.”

The first principle theory is this: Any memory has two strengths, a storage strength and a retrieval strength.

Storage strength is just that, a measure of how well learned something is. It builds up steadily with studying, and more sharply with use.

According to the Bjorks’ theory, storage strength can increase but it never decreases.

It does mean that everything we have deliberately committed to memory—the multiplication table, a childhood phone number, the combination to our first locker—is all there, and for good.

And the Forget to Learn theory says: If I stored it, it’s in there for good. That is, no memory is ever “lost” in the sense that it’s faded away, that it’s gone. Rather, it is not currently accessible. Its retrieval strength is low, or near zero.

Retrieval strength, on the other hand, is a measure of how easily a nugget of information comes to mind. It, too, increases with studying, and with use. Without reinforcement, however, retrieval strength drops off quickly, and its capacity is relatively small (compared to storage). At any given time, we can pull up only a limited number of items in connection with any given cue or reminder.

The harder we have to work to retrieve a memory, the greater the subsequent spike in retrieval and storage strength (learning). The Bjorks call this principle desirable difficulty, and its importance will become apparent in the coming pages.

“Compared to some kind of system in which out-of-date memories were to be overwritten or erased,” Bjork writes, “having such memories become inaccessible but remain in storage has important advantages. Because those memories are inaccessible, they don’t interfere with current information and procedures. But because they remain in memory they can—at least under certain circumstances—be relearned.” Thus, forgetting is critical to the learning of new skills and to the preservation and reacquisition of old ones.

Using memory changes memory—and for the better. Forgetting enables and deepens learning, by filtering out distracting information and by allowing some breakdown that, after reuse, drives retrieval and storage strength higher than they were originally. Those are the basic principles that emerge from brain biology and cognitive science, and they underlie—and will help us understand—the various learning techniques yet to come.

The higher test scores square with reinstatement theory: The background music weaves itself subconsciously into the fabric of stored memory. Cue up the same music, and more of those words are likely to resurface.

Yet the larger message of context research is that, in the end, it doesn’t much matter which aspects of the environment you vary, so long as you vary what you can.

Each alteration of the routine further enriches the skills being rehearsed, making them sharper and more accessible for a longer period of time. This kind of experimenting itself reinforces learning, and makes what you know increasingly independent of your surroundings.

Pick the subject area wisely. Remember, spacing is primarily a retention technique. Foreign languages. Science vocabulary. Names, places, dates, geography, memorizing speeches. Having more facts on board could very well help with comprehension, too, and several researchers are investigating just that, for math as well as other sciences. For now, though, this is a memorization strategy.

The act of guessing engaged your mind in a different and more demanding way than straight memorization did, deepening the imprint of the correct answers. In even plainer English, the pretest drove home the information in a way that studying-as-usual did not.

Between them, Maier and Duncker had discovered two mental operations that aid incubation, picking up clues from the environment, and breaking fixed assumptions, whether about the use of pliers, or the gender of a doctor.

Sio and Ormerod divided incubation breaks into three categories. One was relaxing, like lying on the couch listening to music. Another was mildly active, like surfing the Internet. The third was highly engaging, like writing a short essay or digging into other homework. For math or spatial problems, like the Pencil Problem, people benefit from any of these three; it doesn’t seem to matter which you choose. For linguistic problems like RAT puzzles or anagrams, on the other hand, breaks consisting of mild activity—videogames, solitaire, TV—seem to work best.

They also emphasized that people don’t benefit from an incubation break unless they have reached an impasse.

This longer-term, cumulative process is distinct enough from the short-term incubation we described in the last chapter that it warrants another name. Let’s call it percolation.

“Once a goal becomes activated, it trumps all others and begins to drive our perceptions, our thoughts, our attitudes,” as John Bargh, a psychologist at Yale University, told me.

So the question is: How, then, do we most effectively activate that goal? By interrupting work on it at an important and difficult moment—propelling the assignment, via the Zeigarnik effect, to the top of our mind.

Remember, there’s an incredible cacophony of competing thoughts running through our minds at any given time. What we “hear” depends on the demands, distractions, or anxieties of the moment. I am proposing that, in this example, we’re better able to hear our internal dialogue about race above that chatter, and that that conversation, too, provides fodder for our work.

Percolation is a matter of vigilance, of finding ways to tune the mind so that it collects a mix of external perceptions and internal thoughts that are relevant to the project at hand. We can’t know in advance what those perceptions and thoughts will look like—and we don’t have to.

What does this mean for a learning strategy? It suggests that we should start work on large projects as soon as possible and stop when we get stuck, with the confidence that we are initiating percolation, not quitting.

Quitting before I’m ahead doesn’t put the project to sleep; it keeps it awake. That’s Phase 1, and it initiates Phase 2, the period of gathering string, of casual data collecting. Phase 3 is listening to what I think about all those incoming bits and pieces. Percolation depends on all three elements, and in that order.

Interleaving. That’s a cognitive science word, and it simply means mixing related but distinct material during study.

This much is clear: The mixing of items, skills, or concepts during practice, over the longer term, seems to help us not only see the distinctions between them but also to achieve a clearer grasp of each one individually. The hardest part is abandoning our primal faith in repetition.

think interleaving prepares us for a milder form of wrong. Every exam, every tournament, every match, every recital—there’s always some wrinkle, some misplaced calculator or sudden headache, a glaring sun or an unexpected essay question. At bottom, interleaving is a way of building into our daily practice not only a dose of review but also an element of surprise. “The brain is exquisitely tuned to pick up incongruities, all of our work tells us that,” said Michael Inzlicht, a neuroscientist at the University of Toronto. “Seeing something that’s out of order or out of place wakes the brain up, in effect, and prompts the subconscious to process the information more deeply: ‘Why is this here?’ ” Mixed-up practice doesn’t just build overall dexterity and prompt active discrimination. It helps prepare us for life’s curveballs, literal and figurative.

Perceptual learning, she wrote, “is not a passive absorption, but an active process, in the sense that exploring and searching for perception itself is active. We do not just see, we look; we do not just hear, we listen. Perceptual learning is self-regulated, in the sense that modification occurs without the necessity of external reinforcement. It is stimulus oriented, with the goal of extracting and reducing the information simulation. Discovery of distinctive features and structure in the world is fundamental in the achievement of this goal.”

The best part is, as Eleanor Gibson said, perceptual learning is automatic, and self-correcting. You’re learning without thinking.

The giant rabbit hole in our lives, the dark kingdom we all visit regularly, is sleep. Sleep is a perfect mystery for most of us. We need it, we want more of it, and we long for it to be of a deeper, richer quality. On one hand, we know it can betray us on any given night. On the other, we know that there’s some alchemy going on during those unconscious, dream-filled hours, some mixing of fact, fantasy, and feeling that can turn our daytime struggles to master new skills into that most precious thing—understanding.

Siegel argues that our obsession with sleep quality and duration is, in a sense, backward. “We spend a third of our life sleeping, which seems so maladaptive—‘the biggest mistake nature has made,’ scientists often call it,” he told me. “Another way of looking at it is that unnecessary wakefulness is a bigger mistake.”

Tononi argues that the primary function of sleep is to shake off the trivial connections made during the day and “help consolidate the valuable inferences that were made.” The brain is separating the signal from the noise, by letting the noise die down, biologically speaking.

The point is not that concentration doesn’t exist, or isn’t important. It’s that it doesn’t necessarily look or feel like we’ve been told it does. Concentration may, in fact, include any number of breaks, diversions, and random thoughts.

About the only thing we can control is how we learn. The science tells us that doing a little here, a little there, fitting our work into the pockets of the day is not some symptom of eroding “concentration,” the cultural anxiety du jour. It’s spaced study, when done as described in this book, and it results in more efficient, deeper learning, not less. The science gives us a breath of open air, the freeing sensation that we’re not crazy just because we can’t devote every hour to laser-focused practice. Learning is a restless exercise and that restlessness applies not only to the timing of study sessions but also to their content, i.e., the value of mixing up old and new material in a single sitting.

I’ve begun to incorporate learning science into a broad-based theory about how I think about life. It goes like this: Just as modern assumptions about good study habits are misleading, so, too, are our assumptions about bad habits. Think about it for a second. Distraction, diversion, catnaps, interruptions—these aren’t mere footnotes, mundane details in an otherwise purposeful life. That’s your ten-year-old interrupting, or your dog, or your mom. That restless urge to jump up is hunger or thirst, the diversion a TV show that’s integral to your social group. You took that catnap because you were tired, and that break because you were stuck. These are the stitches that hold together our daily existence; they represent life itself, not random deviations from it. Our study and practice time needs to orient itself around them—not the other way around.

Brilliance is an idol, a meaningless projection, not a real goal.

Ultimately, though, this book is not about some golden future. The persistent, annoying, amusing, ear-scratching present is the space we want to occupy. The tools in this book are solid, they work in real time, and using them will bring you more in tune with the beautiful, if eccentric, learning machine that is your brain. Let go of what you feel you should be doing, all that repetitive, overscheduled, driven, focused ritual. Let go, and watch how the presumed enemies of learning—ignorance, distraction, interruption, restlessness, even quitting—can work in your favor. Learning is, after all, what you do.