Active recall

Active recall is any way of studying in which you produce the material yourself, with the source out of sight. Researchers call the same thing retrieval practice, because you retrieve the answer from memory, and they call its benefit the testing effect. The names differ, but the act is one: a question goes in, and the answer has to come from your own head.

What makes it recall is the closed book, not the format. A blank page, a flashcard answered before it is turned, a past paper, a friend asking you questions and a quiz you write for yourself all count. Looking at an answer and thinking “yes, I knew that” does not count. That is recognizing, and recognizing is far easier than producing.

Few students study this way by choice. When Karpicke and colleagues (2009) asked 177 college students how they studied, only 11% said they practiced recalling the material from memory.

This page goes deep on the active recall study method alone: what the experiments found, how to do it, and how to plan it. For how recall sits beside the other study methods, see how to study effectively.

Rereading and highlighting feel like learning, and that feeling is where the myth comes from. A page you have read three times looks familiar, a highlighted line looks important, and both give a sense of progress. The research measures something else: what you can produce days later.

A group of psychologists has sorted the common study methods by that measure. The review by Dunlosky and colleagues (2013) went through the research on 10 study techniques and rated each as high, moderate or low for how useful it is. Rereading and highlighting were both placed in the low group. Practice testing, the review’s name for active recall, was one of only 2 techniques in the high group.

The feeling is strong enough to fool students about their own results. In the word-pair study above, students in every group predicted they would remember about 50% a week later. Their guesses were the same whether they had kept recalling or not, although what they really remembered was very different.

The concept-map study found the same blind spot. Students were asked right after studying how much they would remember. Those who had only reread expected to remember the most, and those who had practiced recall expected to remember the least. The results came out the other way round. In the second experiment, 90 of the 120 students, or 75%, believed concept mapping would teach them as much as recall, or more.

None of this makes reading worthless. You have to read a thing once to have anything to recall, and the chart above shows rereading helping for a few minutes. The mistake is to count the second and third reading as study, when the same minutes spent recalling would leave more in your memory a week later.

Active recall studying takes a blank page, a source to check against and a timer if you like one. The five steps below follow the designs of the experiments above: study, recall with the source closed, check, and keep recalling after the first success.

1. Study one topic, then close everything. Read the section or go through the lecture once, properly. Then shut the book, turn the notes over and put the slides away. Recall only counts when the answer is out of sight.
2. Write or say all you can remember. Take a blank page and put down the topic from memory: the definitions, the steps, the diagram, the worked example. Keep going until nothing more comes. The stretch where you are stuck and searching is the useful part.
3. Open the book and mark what you missed. Check your page against the source. Circle what was wrong and list what was missing. Those gaps are the list for next time, and they are usually shorter than you feared.
4. Come back after a gap and do it again. Recall the same topic the next day, then a few days later, then about a week after that. Start each time from the blank page, not from your notes.
5. Keep recalling what you already know. Do not retire a topic the first time you get it right. The students who stopped testing themselves on what they knew are the ones who had forgotten most of it a week later.

Three shortcuts make the steps easier to keep. Turn each heading in your notes into a question the night you take the notes, so the questions are ready. End every lecture or chapter by writing three lines from memory before you stand up. And keep one running page of the things you missed, since that page is your real syllabus.

Active recall has limits that the studies themselves state. The experiments here used short passages, word pairs and science texts, with tests up to a week later. They show that recalling beats rereading for remembering that kind of material. They do not show that recall replaces understanding.

Two habits protect against the common failures. First, check every recall against the source, because a confident wrong answer practiced three times is still wrong. Second, recall the reasoning and not only the wording: ask why a step follows, and answer that from memory too. The page on the Feynman technique is about that second habit.

A good way to run this test counts your study hours from what you already write or say about your day, session by session. No timer to start, and none to forget. Most journaling apps stop at how the studying felt. They keep the dread and the relief, which are worth having, but not the hours that were spent recalling.

One app built for this is Think in Numbers, a smart journaling app with time tracking built in.

You write or say your day in your own words, as it happens or all at once. The app reads what you wrote and counts the hours that went to each part of it: your study, your phone, and the time you never mentioned (shown as unaccounted). Then it shows those hours over days and weeks. A target for your study hours holds each week against your real ones.

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Both halves of the test matter. Sessions kept is the half you can count in hours, and it comes first, because a method you skip does nothing. The share you can write down is the half that tells you the hours are landing. Score it roughly: list the key points of a topic, and tick the ones that reached your blank page.

Here is the hours half for the example person from the table above. Week one was rereading. Weeks two to four were recall.

Week one came to 5h on 5 days. Week two, the week in the table, came to 12h on all 7. The switch to recall did not shrink the hours. Short sessions with a clear task were easier to start than an open-ended evening of rereading.

The count is honest about its own limits. It shows hours and not scores, so the blank-page half of the test stays with you. One Friday in week four also includes a lecture that the app filed as study, which makes that week an hour higher than the person’s own sessions.

The studies behind this page are listed here, each linked to the paper at its publisher.

1. Roediger, H. L. and Karpicke, J. D. (2006). Test-Enhanced Learning: Taking Memory Tests Improves Long-Term Retention. Psychological Science, 17(3), 249 to 255.
2. Karpicke, J. D. and Roediger, H. L. (2008). The Critical Importance of Retrieval for Learning. Science, 319(5865), 966 to 968.
3. Karpicke, J. D. and Blunt, J. R. (2011). Retrieval Practice Produces More Learning than Elaborative Studying with Concept Mapping. Science, 331(6018), 772 to 775.
4. Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J. and Willingham, D. T. (2013). Improving Students' Learning With Effective Learning Techniques: Promising Directions From Cognitive and Educational Psychology. Psychological Science in the Public Interest, 14(1), 4 to 58.
5. Karpicke, J. D., Butler, A. C. and Roediger, H. L. (2009). Metacognitive strategies in student learning: Do students practise retrieval when they study on their own? Memory, 17(4), 471 to 479.