No two words fill schoolchildren with more dread than "pop quiz." But mounting evidence suggests that quizzes can help students learn. Now researchers think they know one reason why: Students who take quizzes seem to think up better ways of remembering information than students who simply study.
One way students remember information is by creating mediators: clues or mnemonic devices that link words or ideas. To be effective, a mediator has to be easy to remember and able to elicit the information the student is trying to learn. Mary Pyc, a former graduate student at Kent State University in Ohio (now a postdoctoral fellow at Washington University in St. Louis), and her adviser, cognitive psychologist Katherine Rawson, wanted to understand why testing is beneficial.
Research suggests that mediators are a particularly effective study tool. The duo posited that students who take quizzes develop better mediators than students who simply study. To test this hypothesis, the duo presented 118 Kent State undergraduates with 48 Swahili words and their English translations and asked them to come up with keyword clues to help recall the information. The clue, the researchers told them, should be a word that sounds like the Swahili word but is semantically connected to the English word. For example, many students chose "wing" to remember that the Swahili word "wingu" means cloud.
Pyc and Rawson then divided the participants into two groups. One group took practice exams covering the words they studied; the other continued to study their words but took no exams. If the quiz-takers developed new mediators, they shared these with the researchers.
A week later, all of the students took a final test. This time, the researchers split them into three groups. The first group took a normal test: The researchers gave the students the Swahili word and asked for the English translation. In the second group, students had to provide their mediator before they gave their answer. And in the third group, students were reminded of their mediator before they gave their final answer.
As expected, students who had taken the practice quizzes performed better than those who just studied; their scores were three times higher. These students were also better able to recall their mediators (51% versus 34% of the time) or use the mediators the researchers gave them to get the right answer, the authors report  in the 15 October issue of Science. The most likely explanation, write Pyc and Rawson, is that the students who took the practice quizzes learned which mediators worked and which didn't—and they chose better mediators for the final exam.
"The results make a pretty strong case that this can occur," says Hal Pashler, a psychologist at the University of California, San Diego. He notes, however, that in the real world people don't always use mediators.
Lynda Hall, a cognitive psychologist at Ohio Wesleyan University in Delaware, Ohio, also points out that there may be other reasons that testing helps students learn. Her own work with her colleague, psychologist Harry Bahrick, for example, suggests that testing enhances learning by helping students allocate study time to the most difficult-to-master concepts.
Understanding the underlying mechanisms, Hall says, will help researchers give students more specific instructions about how to study. She encourages her students to test themselves "so that they can identify what material they've mastered and what material they haven't." Creating mediators takes a lot of effort, Hall says. So maybe students won't use them for everything they study. But they could at least employ them to help them remember the most difficult material.