Why rereading and highlighting feel productive, and mostly aren’t

What students actually do

When Karpicke, Butler and Roediger asked 177 college students how they study, 84% listed rereading their notes or textbook, and 55% said it was their main strategy. Testing themselves was listed by 11%, and named as the main strategy by about 1% [1]. A larger survey of 324 students found that 72% highlight and 53% cram [2].

In Dunlosky and colleagues’ review of ten study techniques, rereading, highlighting and summarizing were all rated low utility. Practice testing and spaced practice were the only two rated high [3].

The illusion of fluency

The second time you read a page, it reads faster and feels clearer. That ease, called fluency, feels like understanding, but it mostly reflects familiarity with the words.

Several experiments separate the two.

• A polished lecture feels better without teaching more. Students watched the same short lecture given either fluently or haltingly. Those who saw the fluent version rated their learning about twice as high (3.5 against 1.8 on the scale). Their recall was no different (.44 against .40) [4]. The clips were about a minute long, so this is a clean demonstration rather than a semester-scale result.
• People feel the wrong things. Printing words in a large font raised students’ predictions of recall by 8 points and their actual recall by about 1. Studying words four times instead of once raised actual recall by 38 points, but predictions by only about 6 [5].
• Active classes feel worse and teach more. In a crossover study with 149 Harvard physics students, active-learning classes improved test scores by about half a standard deviation, while students felt they had learned about half a standard deviation less [6]. The test came right after class, and the “active” sessions still included plenty of explanation.

The pattern is the same in each case. What feels like learning while you study is a poor guide to what you will remember later [7].

Is highlighting useless?

No, and that claim goes too far. A 2022 meta-analysis found that highlighting does have a small positive effect on memory (0.36) and a smaller one on comprehension (0.20), and that highlights chosen by an instructor help a little more (0.44) [8]. The trouble is opportunity cost: the same time spent recalling and explaining the material does much more. Highlighting is a fine way to mark what to come back to. It is not the coming back.

What to do instead

• Read once, carefully, to understand. Then close the page.
• Recall before you reread. Write or say what you remember, then check. The gaps you find are exactly what to study. See retrieval practice.
• Explain why, not just what. Prompting yourself to explain each step improves learning (g ≈ 0.55 against no prompts in a meta-analysis), as long as you produce the explanation rather than pick it from options [9].
• Use your highlights as questions. Turn each highlighted line into a question to answer from memory later.
• Come back after a gap. A review a few days later, after sleep, is worth several the same evening. See spaced repetition.

A note on confidence

The same studies show that confidence is cheap. After rereading, students often feel more sure they will remember than students who tested themselves, and then remember less [10]. A good rule: trust what you can produce without looking, not what feels familiar when you look.

References

1. Karpicke, 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), 471–479. doi.org/10.1080/09658210802647009
2. Hartwig, M. K., & Dunlosky, J. (2012). Study strategies of college students: Are self-testing and scheduling related to achievement? Psychonomic Bulletin & Review, 19(1), 126–134. doi.org/10.3758/s13423-011-0181-y
3. Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students’ learning with effective learning techniques. Psychological Science in the Public Interest, 14(1), 4–58. doi.org/10.1177/1529100612453266
4. Carpenter, S. K., Wilford, M. M., Kornell, N., & Mullaney, K. M. (2013). Appearances can be deceiving: Instructor fluency increases perceptions of learning without increasing actual learning. Psychonomic Bulletin & Review, 20(6), 1350–1356. doi.org/10.3758/s13423-013-0442-z
5. Kornell, N., Rhodes, M. G., Castel, A. D., & Tauber, S. K. (2011). The ease-of-processing heuristic and the stability bias: Dissociating memory, memory beliefs, and memory judgments. Psychological Science, 22(6), 787–794. doi.org/10.1177/0956797611407929
6. Deslauriers, L., McCarty, L. S., Miller, K., Callaghan, K., & Kestin, G. (2019). Measuring actual learning versus feeling of learning in response to being actively engaged in the classroom. Proceedings of the National Academy of Sciences, 116(39), 19251–19257. doi.org/10.1073/pnas.1821936116
7. Soderstrom, N. C., & Bjork, R. A. (2015). Learning versus performance: An integrative review. Perspectives on Psychological Science, 10(2), 176–199. doi.org/10.1177/1745691615569000
8. Ponce, H. R., Mayer, R. E., & Méndez, E. E. (2022). Effects of learner-generated highlighting and instructor-provided highlighting on learning from text: A meta-analysis. Educational Psychology Review, 34(2), 989–1024. (Abstract.) doi.org/10.1007/s10648-021-09654-1
9. Bisra, K., Liu, Q., Nesbit, J. C., Salimi, F., & Winne, P. H. (2018). Inducing self-explanation: A meta-analysis. Educational Psychology Review, 30(3), 703–725. www.gwern.net/doc/psychology/spaced-repetition/2018-bisra.pdf
10. Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255. doi.org/10.1111/j.1467-9280.2006.01693.x