What Is the Testing Effect?

By testing your memory, you not only assess what you know but also enhance later retention.

This is not news.

In 1620, 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 from time to time and consulting the text when your memory fails.”

What is new is how many studies in the past two decades have proven the testing effect true for every age group and level of learning out there, from elementary school students to university undergraduates to medical students, residents, and faculty.

As Henry Roediger and Jeffrey Karpicke, psychologists at Washington University, have written in their 2006 research article in Psychological Science, “Testing has a powerful effect on long-term retention.”

The testing effect is real. Dozens of studies show that you will recall 50% more of learned information by testing yourself than by using the same amount of time to study (for example, one research team found a score difference of 67% with testing vs. 45% with studying).

The Difference between Learning, Studying, and Testing

“Learning” has historically been confined to the initial exposure to new information and skills that happens in classrooms, by reading texts for the first time, by observing, through apprenticeships, and in training.

Psychologists and education experts define “studying” as reading or reviewing material that you have already learned, reinforcing your knowledge through repeatedly reminding yourself of the information you have to remember. Using mnemonics, flashcards, taking notes, and reading all count as studying. “Concept mapping” is a popular education tool in which students draw connections between the concepts and facts they are studying — the practice is supposed to lead to better learning by transforming the knowledge from passive to active learning, and to ensure that the student fully grasps the concepts.

“Testing” is also called “active recall” or “retrieval practice.” In the journal Science, a study by Jeffrey D. Karpicke and Janell R. Blunt explained the method the students used to test their recall as “recalling as much of the information as they could on a free recall test.”

An article in the New York Times about their study graphed the results as follows:

In this study, according to their article in Science:

The students then returned to the laboratory 1 week later for a final short-answer test. To assess meaningful learning, the test included both verbatim questions, which assessed conceptual knowledge stated directly in the text, and inference questions, which required students to connect multiple concepts from the text.

The surprising thing for the researchers was that “both elaborative concept mapping and retrieval practice are active learning tasks, and our results make it clear that whether a task is considered ‘active’ is not diagnostic of how much learning the task will produce.”

Why Testing Improves Recall

Some posit that testing works differently in the brain than studying. Testing asks your brain to remember information on cue: this process could perhaps organize and create connections that our brains later recognize.

“When you’re retrieving something out of a computer’s memory, you don’t change anything — it’s simple playback,” said Robert Bjork, a psychologist at the University of California, Los Angeles, in the New York Times. “When we use our memories by retrieving things, we change our access” to that information, Dr. Bjork said. “What we recall becomes more recallable in the future. In a sense you are practicing what you are going to need to do later.”

In this sense, you are in fact learning, not just recalling, when you test yourself on your understanding of a topic, be it a simple fact or a series of processes and complex inferences.

The Testing Effect in NEJM Knowledge+

The question banks you will find in NEJM Knowledge+ have the highest quality questions involving two-step diagnosis plus treatment choices. The adaptivity of this program serves up questions in a sequence that reinforces your knowledge and points out your gaps.

It is a perfect example of how the testing effect can be put into practice.

What is your experience with the testing effect? Have you noticed a jump in performance after using active recall to prepare for an exam?