Sometimes, when we open a test, we see familiar questions on material we’ve studied — and yet we still do badly. Why does this happen?
Psychologists have studied learning long enough to have an answer, and typically it’s not a lack of effort (or of some elusive test-taking gene). The problem is that we have misjudged the depth of what we know. We are duped by a misperception of “fluency,” believing that because facts or formulas or arguments are easy to remember right now, they will remain that way tomorrow or the next day. This fluency illusion is so strong that, once we feel we have some topic or assignment down, we assume that further study won’t strengthen our memory of the material. We move on, forgetting that we forget.
Often our study “aids” simply create fluency illusions — including, yes, highlighting — as do chapter outlines provided by a teacher or a textbook. Such fluency misperceptions are automatic; they form subconsciously and render us extremely 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,” Nate Kornell, a psychologist at Williams College, said. “But the opposite is true: You learn more, even though it feels harder. Fluency is playing a trick on judgment.”
The best way to overcome this illusion is testing, which also happens to be an effective study technique in its own right. This is not exactly a recent discovery; people have understood it since the dawn of formal education, probably longer. In 1620, the philosopher Francis Bacon wrote, “If you read a piece of text through twenty times, you will not learn it by heart so easily as if you read it ten times while attempting to recite it from time to time and consulting the text when your memory fails.”
Scientific confirmation of this principle began in 1916, when Arthur Gates, a psychologist at Columbia University, created an ingenious study to further Bacon’s insight. If someone is trying to learn a piece of text from memory, Gates wondered, what would be the ideal ratio of study to recitation (without looking)? To interrogate this question, he had more than 100 schoolchildren try to memorize text from Who’s Who entries. He broke them into groups and gave each child nine minutes to prepare, along with specific instructions on how to use that time. One group spent 1 minute 48 seconds memorizing and the remaining time rehearsing (reciting); another split its time roughly in half, equal parts memorizing and rehearsing; a third studied for a third and recited for two-thirds; and so on.
After a sufficient break, Gates sat through sputtered details of the lives of great Americans and found his ratio. “In general,” he concluded, “best results are obtained by introducing recitation after devoting about 40 percent of the time to reading. Introducing recitation too early or too late leads to poorer results.” The quickest way to master that Shakespearean sonnet, in other words, is to spend the first third of your time memorizing it and the remaining two-thirds of the time trying to recite it from memory.
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In the 1930s, a doctoral student at the State University of Iowa, Herman F. Spitzer, recognized the broader implications of this insight. Gates’s emphasis on recitation was, Spitzer realized, not merely a study tip for memorization; it was nothing less than a form of self-examination. It was testing as study, and Spitzer wanted to extend the finding, asking a question that would apply more broadly in education: If testing is so helpful, when is the best time to do it?He mounted an enormous experiment, enlisting more than 3,500 sixth graders at 91 elementary schools in nine Iowa cities. He had them study an age-appropriate article of roughly 600 words in length, similar to what they might analyze for homework. Spitzer divided the students into groups and had each take tests on the passages over the next two months, according to different schedules. For instance, Group 1 received one quiz immediately after studying, then another a day later and a third three weeks later. Group 6, by contrast, didn’t take one until three weeks after reading the passage. Again, the time the students had to study was identical. So were the quizzes. Yet the groups’ scores varied widely, and a clear pattern emerged.
The groups that took pop quizzes soon after reading the passage — once or twice within the first week — did the best on a final exam given at the end of two months, marking about 50 percent of the questions correct. (Remember, they had studied their peanut or bamboo article only once.) By contrast, the groups who took their first pop quiz two weeks or more after studying scored much lower, below 30 percent on the final. Spitzer’s study showed that not only is testing a powerful study technique, but it’s also one that should be deployed sooner rather than later. “Achievement tests or examinations are learning devices and should not be considered only as tools for measuring achievement of pupils,” he concluded.
The testing effect, as it’s known, is now well established, and it opens a window on the alchemy of memory itself. “Retrieving a fact is not like opening a computer file,” says Henry Roediger III, a psychologist at Washington University in St. Louis, who, with Jeffrey Karpicke, now at Purdue University, has established the effect’s lasting power. “It alters what we remember and changes how we subsequently organize that knowledge in our brain.”
There’s a big difference between thinking you understand something and actually understanding something. You don’t actually know that you don’t know something until you have to explain it to someone else.