Active recall: why testing yourself beats rereading

It is 11pm and you are on your third pass through the same chapter. The highlights look familiar, the diagrams make sense, and you feel ready. Then the exam asks you to explain one of those diagrams from memory, and the page in your head is blank.

The short version

Active recall means closing the book and trying to pull the idea out of your own memory. Decades of studies show it beats rereading for anything you need to remember days or weeks later. It feels harder and less productive while you do it, which is exactly why most students skip it.

What active recall is

Active recall is any study method where you produce the answer instead of looking at it. Answering a practice question counts. So does covering your notes and explaining a concept out loud, or writing down everything you remember about a topic on a blank page. Researchers usually call it retrieval practice, and the boost it gives is known as the testing effect.

The key word is produce. Recognizing an answer when you see it is not the same as recalling it. Rereading, highlighting and looking over a summary all feel like studying, but none of them make you retrieve anything.

The studies that made the case

In 2006, Henry Roediger and Jeffrey Karpicke gave college students short science passages to learn, one about the sun and one about sea otters (Roediger & Karpicke, 2006). Students read each passage, then either read it again or wrote down everything they could remember without looking. Then came a final test, either 5 minutes, 2 days or 1 week later.

At 5 minutes, rereading won: 81% of the ideas recalled versus 75% for the testing group. But two days later the picture flipped. The rereaders had dropped to 54%, while the students who had tested themselves still recalled 68%. After a week it was 42% versus 56%. In a second experiment, students who read a passage four times predicted they would remember it best. A week later they remembered the least.

Two years later, Karpicke and Roediger had students learn 40 Swahili words with their English meanings (Karpicke & Roediger, 2008). In some groups, once a student got a word right, it was dropped from further testing but could still be studied. In other groups it kept being tested. Everyone learned the list equally well during the session. A week later, the students who kept being tested recalled about 80% of the words. The students whose words were dropped from testing recalled about 36%. And when asked to predict their scores, students in every group guessed about the same. Their predictions had nothing to do with how they actually did.

A fair objection: maybe recall only helps with memorizing facts, not with real understanding. Karpicke and Janell Blunt tested that in 2011 (Karpicke & Blunt, 2011). Students read a science text and then either built a concept map of it with the text in front of them, or put the text away and practiced recalling it. A week later, the recall group scored 67% on the final test against 45% for the concept mappers, including on questions that asked them to make inferences the text never stated. Most students had predicted the opposite result.

These are not isolated wins. A 2014 review pooled 159 results from 61 studies and found a solid overall advantage for testing over restudying (Rowland, 2014). A 2017 review reached the same conclusion: practice tests beat restudying and every other comparison method in the studies it covered (Adesope, Trevisan & Sundararajan, 2017). When a team of cognitive scientists rated ten common study techniques, practice testing was one of only two to get their highest rating, "high utility." Rereading and highlighting were rated low (Dunlosky et al., 2013).

Why it works, and why rereading fools you

Every time you pull an idea out of memory, you strengthen the path you used to find it. Next time, that path is easier to follow. Rereading skips this step. The information goes in through your eyes, but your memory never has to go looking for it.

Rereading also creates an illusion. On the second or third pass, the text feels smooth and familiar. Your brain reads that ease as "I know this." But familiarity only means you would recognize the material if you saw it again. An exam asks you to produce it with the page gone. That is why the four-times readers in the 2006 study felt so confident and did so badly.

This is also why so many students reread anyway. In a survey of 177 college students, 84% said they reread their notes or textbook, and 55% named it as their top strategy. Only 11% mentioned testing themselves (Karpicke, Butler & Roediger, 2009).

Where it falls short

Active recall is not magic, and a few honest caveats matter.

• It does not help much if your exam is in five minutes. In the 2006 study, rereading actually won at the short delay. The payoff shows up days later, which is when real exams happen.
• It feels worse. Recall is slow and you will get things wrong. That struggle is part of how it works, but it means your sense of how well a session went is not a reliable guide.
• Feedback matters. Getting an answer wrong and then checking the right one still helps you learn. The 2014 review found the testing advantage was close to twice as large when people saw the correct answers afterwards (Rowland, 2014). Testing yourself without ever checking means your mistakes can stick.
• Recall beats recognition. The same review found that tests where you had to come up with the answer gave bigger gains than recognition tests like multiple choice. Easy questions you can answer by spotting the right option give you less.
• You need something to recall. You have to read or hear the material at least once first. Recall is what you do after that first pass, instead of a second and third reading.

How to use it yourself

You do not need any special tool for this. A blank page and a timer are enough.

1. 1Read a section once, carefully. Then close it.
2. 2Blurt: write down everything you remember about it, with no notes. Lists, sketches, half sentences, anything.
3. 3Open the material and check. Mark what you got, what you missed and what you got wrong.
4. 4Go back to the gaps, then try recalling those parts again.
5. 5Come back to the same topic a few days later and do it again, before you feel ready.

Tip: turn your headings into questions. "Photosynthesis, light reactions" becomes "What happens in the light reactions, and what do they produce?" Answer it before you reread the section.

How lezrn uses it

lezrn is built so that recall, not rereading, is the default way you go back over a lesson. You try first, then you see the answer, so you always get feedback.

• Blurting: write everything you remember with no notes, then see which ideas you got and which you missed. See recall tools.
• Daily review shows you a concept name, you recall it, then you see the definition and rate Forgot or Got it. See how review works.
• Quizzes and flashcards show you why right away when you miss one, and missed cards come back until you get them. See quizzes and flashcards.

Sources

1. 1Adesope, O. O., Trevisan, D. A., & Sundararajan, N. (2017). Rethinking the use of tests: A meta-analysis of practice testing. Review of Educational Research, 87(3), 659 to 701. https://doi.org/10.3102/0034654316689306
2. 2Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & 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. https://doi.org/10.1177/1529100612453266
3. 3Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772 to 775. https://doi.org/10.1126/science.1199327
4. 4Karpicke, J. D., Butler, A. C., & 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. https://doi.org/10.1080/09658210802647009
5. 5Karpicke, J. D., & Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319, 966 to 968. https://doi.org/10.1126/science.1152408
6. 6Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249 to 255. https://doi.org/10.1111/j.1467-9280.2006.01693.x
7. 7Rowland, C. A. (2014). The effect of testing versus restudy on retention: A meta-analytic review of the testing effect. Psychological Bulletin, 140(6). https://doi.org/10.1037/a0037559