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

by Benedict Carey

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.”

Without a little forgetting, you get no benefit from further study.

A better name for it, then, might be the Forget to Learn theory. That phrase captures its literal implications and its general spirit, its reassuring voice. One implication, for instance, is that forgetting a huge chunk of what we’ve just learned, especially when it’s a brand-new topic, is not necessarily evidence of laziness, attention deficits, or a faulty character. On the contrary, it is a sign that the brain is working as it should.

Memory improved in the first few days without any further study, and only began to taper off after day four or so, on average.

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

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.

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.

Of those who studied and tested in the same condition, the silence-silence group did the worst. They recalled, on average, about half the words that the jazz-jazz or classical-classical groups did (eleven versus twenty).

The lower scores in the quiet room (after quiet study) are harder to explain. Smith argued that they may be due to an absence of cues to reinstate. The students “do not encode the absence of sound any more than they might encode the absence of any type of stimulus, such as pain or food,” he wrote. As a result the study environment is impoverished, compared to one with music in the background.

The technique is called distributed learning or, more commonly, the spacing effect. People learn at least as much, and retain it much longer, when they distribute—or “space”—their study time than when they concentrate it. Mom’s right, it is better to do a little today and a little tomorrow rather than everything at once. Not just better, a lot better. Distributed learning, in certain situations, can double the amount we remember later on.

Flooding the lawn makes it look slightly more lush the next day, but that emerald gloss fades, sure enough. A healthy dose every couple days and you can look your neighbors in the eye, while using the same amount of water—or even less. Same goes for distributed learning. You’re not spending any more time. You’re not working any harder. But you remember more for longer.

Studying a new concept right after you learn it doesn’t deepen the memory much, if at all; studying it an hour later, or a day later, does.

The problem wasn’t that I hadn’t worked hard enough, or that I lacked the test taking “gene.” No, my mistake was misjudging the depth of what I knew. I was duped by what psychologists call fluency, the belief that because facts or formulas or arguments are easy to remember right now, they’ll remain that way tomorrow or the next day. The fluency illusion is so strong that, once we feel we’ve nailed some topic or assignment, we assume that further study won’t help. We forget that we forget. Any number of study “aids” can create fluency illusions, including (yes) highlighting, making a study guide, and even chapter outlines provided by a teacher or a textbook. Fluency misperceptions are automatic. They form subconsciously and make us poor judges of what we need to restudy, or practice again. “We know that if you study something twice, in spaced sessions, it’s harder to process the material the second time, and so people think it’s counterproductive,” as Nate Kornell, a psychologist at Williams College, told me. “But the opposite is true: You learn more, even though it feels harder. Fluency is playing a trick on judgment.”

Testing is studying, of a different and powerful kind.

“Immediate recall in the form of a test is an effective method of aiding the retention of learning and should, therefore, be employed more frequently,” he concluded. “Achievement tests or examinations are learning devices and should not be considered only as tools for measuring achievement of pupils.”

In short, testing does not = studying, after all. In fact, testing > studying, and by a country mile, on delayed tests.

Using our memory changes our memory in ways we don’t anticipate.

That is, guessing wrongly increases a person’s likelihood of nailing that question, or a related one, on a later test.

In the jargon of the field, your “unsuccessful retrieval attempts potentiated learning, increasing successful retrieval attempts on subsequent tests.” In plain English: 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.

In Duncker’s terminology, when the boxes were full, they were “functionally fixed.” It was as if people didn’t see them at all.

To review, Wallas’s definition of incubation is a break that begins at the moment we hit an impasse and stop working on a problem directly, and ends with a breakthrough, the aha! insight.

Longer breaks are better than shorter ones; playing a videogame is as good as reading; writing may help incubation for certain kinds of problems, such as spatial ones like the Pencil Problem.

They also emphasized that people don’t benefit from an incubation break unless they have reached an impasse. Their definition of “impasse” is not precise, but most of us know the difference between a speed bump and a brick wall. Here’s what matters: Knock off and play a videogame too soon and you get nothing.

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.

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. My tendency as a student was always to procrastinate on big research papers and take care of the smaller stuff first. Do the easy reading. Clean the kitchen. Check some things off the to-do list. Then, once I finally sat down to face the big beast, I’d push myself frantically toward the finish line and despair if I didn’t make it. Wrong. 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.

Some psychologists and writers have even tried to quantify that time. The path to exceptional performance, they argue, is through practice: ten thousand hours of it, to be exact.

Varied practice is more effective than the focused kind, because it forces us to internalize general rules of motor adjustment that apply to any hittable target.

But repetition creates a powerful illusion. Skills improve quickly and then plateau. By contrast, varied practice produces a slower apparent rate of improvement in each single practice session but a greater accumulation of skill and learning over time. In the long term, repeated practice on one skill slows us down.

“The implication is that if you are preparing for a performance—a music recital, say—it’s better to stay up late than get up early,”

The same logic applies to REM. The largest dose is in the early morning, between those chunks of Stage 2. If you’re prepping for a math or chemistry test, an exam that’s going to strain your ability to detect patterns, better to stay up late and, if possible, hit the snooze button in the morning. Let the cock crow till he’s hoarse.

With naps of an hour to an hour and half, we’ve found in some experiments that you get close to the same benefits in learning consolidation that you would from a full eighthour night’s sleep.”