It’s widely believed by teachers, trainers, and coaches that the most effective way to master a new skill is to give it dogged, single- minded focus, practicing over and over until you’ve got it down. Our faith in this runs deep, because most of us see fast gains during the learning phase of massed practice. What’s
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apparent from the research is that gains achieved during massed practice are transitory and melt away quickly.
The fi nding that rereading textbooks is often labor in vain ought to send a chill up the spines of educators and learners, because it’s the number one study strategy of most people—
including more than 80 percent of college students in some surveys—and is central in what we tell ourselves to do during the hours we dedicate to learning. Rereading has three strikes against it. It is time consuming. It doesn’t result in durable memory. And it often involves a kind of unwitting self-deception, as growing familiarity with the text comes to feel like mastery of the content. The hours immersed in rereading can seem like due diligence, but the amount of study time is no mea sure of mastery.2
You needn’t look far to fi nd training systems that lean heavily on the conviction that mere exposure leads to learning. Consider Matt Brown, the pi lot. When Matt was ready to advance from piston planes, he had a whole new body of knowledge to master in order to get certifi ed for the business jet he was hired to pi lot. We asked him to describe this pro-cess. His employer sent him to eigh teen days of training, ten hours a day, in what Matt called the “fi re hose” method of instruction. The fi rst seven days straight were spent in the classroom being instructed in all the plane’s systems: electrical, fuel, pneumatics, and so on, how these systems operated and interacted, and all their fail- safe tolerances like pressures, weights, temperatures, and speeds. Matt is required to have at his immediate command about eighty different “memory action items”— actions to take without hesitation or thought in order to stabilize the plane the moment any one of a dozen or so unexpected events occur. It might be a sudden decompres-sion, a thrust reverser coming unlocked in fl ight, an engine failure, an electrical fi re.
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Matt and his fellow pi
lots gazed for hours at mind-
numbing PowerPoint illustrations of their airplane’s principal systems. Then something interesting happened.
“About the middle of day fi ve,” Matt said, “they fl ash a schematic of the fuel system on the screen, with its pressure sensors, shutoff valves, ejector pumps, bypass lines, and on and on, and you’re struggling to stay focused. Then this one instructor asks us, ‘Has anybody here had the fuel fi lter bypass light go on in fl ight?’ This pi lot across the room raises his hand. So the instructor says, ‘Tell us what happened,’ and suddenly you’re thinking, Whoa, what if that was me?
“So, this guy was at 33,000 feet or something and he’s about to lose both engines because he got fuel without antifreeze in it and his fi lters are clogging with ice. You hear that story and, believe me, that schematic comes to life and sticks with you. Jet fuel can commonly have a little water in it, and when it gets cold at high altitude, the water will condense out, and it can freeze and block the line. So whenever you refuel, you make good and sure to look for a sign on the fuel truck saying the fuel has Prist in it, which is an antifreeze. And if you ever see that light go on in fl ight, you’re going to get yourself down to some warmer air in a hurry.”3 Learning is stronger when it matters, when the abstract is made concrete and personal.
Then the nature of Matt’s instruction shifted. The next eleven days were spent in a mix of classroom and fl ight simulator training. Here, Matt described the kind of active engagement that leads to durable learning, as the pi lots had to grapple with their aircraft to demonstrate mastery of standard operating procedures, respond to unexpected situations, and drill on the rhythm and physical memory of the movements that are required in the cockpit for dealing with them.
A fl ight simulator provides retrieval practice, and the practice
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is spaced, interleaved, and varied and involves as far as possible the same mental pro cesses Matt will invoke when he’s at altitude. In a simulator, the abstract is made concrete and personal. A simulator is also a series of tests, in that it helps Matt and his instructors calibrate their judgment of where he needs to focus to bring up his mastery.
In some places, like Matt Brown’s fl ight simulator, teachers and trainers have found their way to highly effective learning techniques, yet in virtually any fi eld, these techniques tend to be the exception, and “fi re hose” lectures (or their equivalent) are too often the norm.
In fact, what students are advised to do is often plain wrong.
For instance, study tips published on a website at George Mason University include this advice: “The key to learning something well is repetition; the more times you go over the material the better chance you have of storing it permanently.”4
Another, from a Dartmouth College website, suggests: “If you intend to remember something, you probably will.”5 A public ser vice piece that runs occasionally in the St. Louis Post-Dispatch offering study advice shows a kid with his nose buried in a book. “Concentrate,” the caption reads. “Focus on one thing and one thing only. Repeat, repeat, repeat! Repeating what you have to remember can help burn it into your memory.”6 Belief in the power of rereading, intentionality, and repetition is pervasive, but the truth is you usually can’t embed something in memory simply by repeating it over and over. This tactic might work when looking up a phone number and holding it in your mind while punching it into your phone, but it doesn’t work for durable learning.
A simple example, reproduced on the Internet (search
“penny memory test”), presents a dozen different images of a
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common penny, only one of which is correct. As many times as you’ve seen a penny, you’re hard pressed to say with confi -
dence which one it is. Similarly, a recent study asked faculty and students who worked in the Psychology Building at UCLA to identify the fi re extinguisher closest to their offi ce. Most failed the test. One professor, who had been at UCLA for twenty- fi ve years, left his safety class and decided to look for the fi re extinguisher closest to his offi ce. He discovered that it was actually right next to his offi ce door, just inches from the doorknob he turned every time he went into his offi ce. Thus, in this case, even years of repetitive exposure did not result in his learning where to grab the closest extinguisher if his waste-basket caught fi re.7
Early Evidence
The fallacy in thinking that repetitive exposure builds memory has been well established through a series of investiga-tions going back to the mid- 1960s, when the psychologist Endel Tulving at the University of Toronto began testing people on their ability to remember lists of common En glish nouns. In a fi rst phase of the experiment, the participants simply read a list of paired items six times (for example, a pair on the list might be “chair— 9”); they did not expect a memory test. The fi rst item in each pair was always a noun. After reading the listed pairs six times, participants were then told that they would be getting a list of nouns that they would be asked to remember. For one group of people, the nouns were the same ones they had just read six times in the prior reading phase; for another group, the nouns to be learned were different from those they had previously read. Remarkably, Tulving found that the two groups’ learning of the nouns did not differ— the learning curves were statistically indistinguishable. Intuition
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would suggest otherwise, but prior exposure did not aid later recall. Mere repetition did not enhance learning. Subsequent studies by many researchers have pressed further into questions of whether repeated exposure or longer periods of holding an idea in mind contribute to later recall, and these studies have confi rmed and elaborated on the fi ndings that repetition by itself does not lead to good long- term memory.8
These results led researchers to investigate the benefi ts of rereading texts. In a 2008 article in Contemporary Educational Psychology, Washington University scientists reported on a series of studies they conducted at their own school and at the University of New Mexico to shed light on rereading as a strategy to improve understanding and memory of prose.
Like most research, these studies stood on the shoulders of earlier work by others; some showed that when the same text is read multiple times the same inferences are made and the same connections between topics are formed, and others suggested modest benefi ts from rereading. These benefi ts had been found in two different situations. In the fi rst, some students read and immediately reread study material, whereas other students read the material only once. Both groups took an immediate test after reading, and the group who had read twice performed a bit better than the group who had read once.
However, on a delayed test the benefi t of immediate rereading had worn off, and the rereaders performed at the same level as the one- time readers. In the other situation, students read the material the fi rst time and then waited some days before they reread it. This group, having done spaced readings of the text, performed better on the test than the group who did not reread the material.9
Subsequent experiments at Washington University, aimed at teasing apart some of the questions the earlier studies had raised, assessed the benefi ts of rereading among students of
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differing abilities, in a learning situation paralleling that faced by students in classes. A total of 148 students read fi ve different passages taken from textbooks and Scientifi c American.
The students were at two different universities; some were high- ability readers, and others were low- ability; some students read the material only once, and others read it twice in succession. Then all of them responded to questions to demonstrate what they had learned and remembered.
In these experiments, multiple readings in close succession did not prove to be a potent study method for either group, at either school, in any of the conditions tested. In fact, the researchers found no rereading benefi t at all under these conditions.
What’s the conclusion? It makes sense to reread a text once if there’s been a meaningful lapse of time since the fi rst reading, but doing multiple readings in close succession is a time-consuming study strategy that yields negligible benefi ts at the expense of much more effective strategies that take less time.
Yet surveys of college students confi rm what professors have long known: highlighting, underlining, and sustained poring over notes and texts are the most- used study strategies, by far.10
Illusions of Knowing
