Study Technique Statistics and the Learning Pyramid Myth

We could not find any peer-reviewed study reporting that highlighting and rereading leave you with 15% of the material after 30 days. That number, and the learning pyramid percentages it usually travels with, has no traceable research source. What the evidence does show is clear enough: in the largest review of study techniques, Dunlosky et al. (2013) rated highlighting and rereading low utility and practice testing and spaced study high utility.

Below are the verified numbers: the ratings, the effect sizes, what students actually do when they study, what the highlighting and rereading experiments found, and where the pyramid came from.

Is there a real highlighting and rereading retention rate?

No. Searches for "highlighting and rereading retention rate 15% 30 days" return confident answers, but none traces back to an experiment. We found no journal article that measured retention after highlighting or rereading at 30 days and reported 15%.

The number looks like a remix of the learning pyramid, which assigns 10% to reading and 5% to lectures. Three things suggest no clean 30-day figure could exist:

1. Retention depends on the material, the test and the delay. The same students in Roediger and Karpicke (2006) recalled 83% of a passage five minutes after rereading it and 40% a week later. A single "rate" for rereading is meaningless without those details.
2. Long delays are rare in this research. In the Donoghue and Hattie (2021) meta-analysis, 74% of effects came from tests taken within a day, 17% from 2 to 7 days, 3.3% from 8 days to a month and 0.4% from 1 to 3 months.
3. Experiments report comparisons, not absolute rates. Highlighting and rereading are measured against reading once, or against testing, on a specific quiz. The finding is "less than the alternative", not "15%".

For how fast people forget in general, including the real Ebbinghaus numbers, see our memory retention statistics.

The Dunlosky 2013 ratings: 10 study techniques ranked

Two techniques earned a high utility rating, three moderate and five low. Dunlosky, Rawson, Marsh, Nathan and Willingham (2013) judged each technique on whether its benefits held across learning conditions, student characteristics, materials and types of test. They picked highlighting and rereading for review specifically "because students report relying heavily on them."

Eight years later, Donoghue and Hattie (2021) ran a meta-analysis of the empirical studies Dunlosky's team had reviewed: 242 studies, 1,619 effects and 169,179 participants, with an overall mean effect of d = 0.56. Their effect sizes sit alongside the original ratings below.

Ratings: Dunlosky et al. (2013). Effect sizes and number of effects: Donoghue and Hattie (2021), Table 1. The meta-analysis labels mnemonics as "Mnemonics" and underlining as "Underlining".

Four details matter when quoting these numbers:

• The two high utility techniques also have the two largest effects. The ranking mostly holds, with two swaps: imagery for text (rated low) came out at 0.56, and interleaved practice (rated moderate) at 0.47.
• Every effect is measured against that study's control, often reading once with no extra activity. A d of 0.47 for rereading does not mean rereading beats testing; it means it beats not rereading in those studies.
• 93% of outcomes in the meta-analysis were surface or factual learning and only 7% deep learning, so the authors caution against applying the results to more relational understanding (Donoghue and Hattie, 2021). Our guide to deep versus surface learning covers the difference.
• The effects were much greater for lower ability students than for higher ability students (Donoghue and Hattie, 2021).

What students actually do vs what works

Students lean hardest on the techniques with the weakest evidence. Karpicke, Butler and Roediger (2009) asked 177 students at Washington University in St. Louis to list and rank their study strategies, with no prompts:

• 83.6% listed rereading notes or textbooks, the most common answer by far, and 55% ranked it their number one strategy.
• 42.9% did practice problems and 40.1% used flashcards, both of which can involve retrieval but need not.
• Only 10.7% (19 of 177) described practicing recall, and just 1% (2 students) ranked it first.
• 6.2% mentioned highlighting in this free-report format.
• Asked what they would do after reading a chapter once, 57% chose to restudy and 21% chose some other technique; only 18% chose to test themselves, and only 8% of all students said they would do so because it would help them learn.

Hartwig and Dunlosky (2012) gave 324 undergraduates at Kent State University a checklist instead. With prompts, reported use of every strategy went up:

• 72% underline or highlight while reading, 66% reread chapters, articles or notes, and 66% cram the night before the test.
• 71% test themselves with questions or practice problems and 62% use flashcards.
• 64% reread the sections they had underlined or highlighted, while only 17% said they did not usually reread.
• Of students who quiz themselves, most do it to check what they know: 54% said they quiz "to figure out how well I have learned the information," versus 27% who said they learn more that way than through rereading.
• Only 13% plan a study schedule ahead of time, and 53% do most of their studying in one session before the test.
• Self-testing was linked to a higher GPA (gamma = .28), but using flashcards was not (gamma = -.03). Highlighting was not significantly related to GPA.

The same survey repeated seven questions from an earlier UCLA survey of 472 students by Kornell and Bjork (2007), reported in Hartwig and Dunlosky's Table 1. At UCLA, 68% said they quiz themselves to check their learning and 18% because they learn more that way.

A semester-long diary study by Blasiman, Dunlosky and Rawson (2017) found the same gap between knowing and doing. Students rated which strategies worked fairly accurately, and intended to start early, but in practice relied on "relatively ineffective strategies" and massed their studying in the day or two before an exam. Knowing how you learn is not the same as changing what you do.

Highlighting and rereading: what the numbers show

Rereading helps on a test given minutes later and fades fast; highlighting gives a small memory boost at best. Neither is useless, but both lose to retrieval practice on delayed tests. Here are the key experiments.

Rereading

• Roediger and Karpicke (2006), Experiment 1: after 5 minutes, students who studied a passage twice recalled 81% against 75% for study plus one test. After a week the order flipped: 56% for the tested group, 42% for the restudy group.
• In Experiment 2, the repeated-study group read the passage 14.2 times on average and the repeated-testing group only 3.4 times, yet the tested group recalled 61% after a week against 40%.
• Measured as a proportion of what they first recalled, the repeated-study group forgot 52% over the week, compared with 14% for the repeated-testing group.
• The rereaders were also the most confident that they would remember the passage a week later.
• Karpicke and Roediger (2008): students learned 40 Swahili and English word pairs. Continuing to test words after recalling them once gave about 80% recall a week later; dropping words from testing gave 36% and 33%, even for the group that kept studying them. Every group predicted it would recall about 50%.
• Callender and McDaniel (2009): across four experiments with textbook chapters and a Scientific American article, immediate rereading "did not significantly increase performance," with only several exceptions.
• Rawson and Kintsch (2005), 423 college students: rereading straight away helped on an immediate test but not on a test two days later. Rereading after a one-week gap did help on the delayed test. When you reread matters.

Highlighting

• Ponce, Mayer and Méndez (2022) meta-analyzed 36 articles from 1938 to 2019 (85 effect sizes). Highlighting by the learner improved memory (0.36) but not comprehension (0.20).
• Highlighting provided by an instructor improved both memory and comprehension, each with an average effect of 0.44.
• Learner highlighting helped college students (0.39) but not school students (0.24). Choosing what matters is a skill.
• Peterson (1992) found that underlining did not help college students encode or review a text and "may be counterproductive for inferential recall."
• Yue, Storm, Kornell and Bjork (2015) found a benefit of highlighting on a test a week later, largest when the two readings were massed, and no cost for non-highlighted information. Students who doubted highlighting benefited more than those who believed in it.

The fair summary: highlighting and rereading produce real but small and inconsistent gains, while testing yourself produces larger ones that last. That is why Dunlosky's team recommended "practice testing instead of rereading." If you want to see why rereading feels productive when it is not, read why rereading your notes is a waste of time.

The learning pyramid: where the 5%, 10% and 90% numbers come from

They do not come from any study. The version most often shown today is credited to the NTL Institute and claims learners retain 5% from lectures, 10% from reading, 20% from audiovisual, 30% from demonstration, 50% from discussion, 75% from practice and 90% from teaching others. None of those numbers has ever been traced to research.

What the NTL Institute says

In a reply to a student, published by Goldsmiths lecturer Simon Polovina in 2011, NTL said the pyramid was developed at its Bethel, Maine campus "in the early sixties," that it believes it to be accurate, but that it no longer has "nor can we find" the original research. The same reply pointed to a "similar pyramid with slightly different numbers" in Edgar Dale's 1954 book Audio-Visual Methods in Teaching.

Why Edgar Dale is the wrong source

Dale's Cone of Experience, first published in 1946, arranges kinds of experience from concrete to abstract. The retention percentages were added later by others; as Masters (2020) puts it, the statistics "do not come from Edgar Dale."

• Lalley and Miller (2007) found "no specific credible research" behind the pyramid and describe Dale's Cone as "a continuum of methods not a hierarchy." In the research they reviewed, every method produced retention, "with none being consistently superior to the others."
• Subramony, Molenda, Betrus and Thalheimer (2014) showed the retention percentages have been reported "in dozens of permutations," that putting them on Dale's Cone is "completely unjustifiable," and that versions trace back to the early 20th century for the numbers and the 1970s for the corrupted cone.

Older than memory research itself

Letrud and Hernes (2018) searched digitized books from before 1941 and found:

• The oldest version, from 1852, ranks reading and hearing below seeing, with no numbers attached. Others followed in 1859, 1862, 1871, 1898 and 1901.
• The first version with numbers appeared in 1906, in an article by Reverend Charles Roads on Sunday school teaching: "one tenth of what we hear, five tenths of what we see, seven tenths of what we say, nine tenths of what we do."
• They found 63 versions published between 1906 and 1940, with no agreement on the categories or the numbers.
• The neat 10% steps likely come from converting tenths into percentages (1/10 = 10%, 3/10 = 30%).
• A widely cited 1967 version by D.G. Treichler of Mobil Oil listed 10% of what we read, 20% hear, 30% see, 50% hear and see, 70% say and 90% say while doing, claiming the figures came from studies without naming them.
• Ebbinghaus published the first experimental work on retention in 1885, more than 30 years after the first known version. The authors conclude the pyramid "did not originate from empirical research."

Still cited in journals

• Versions of the pyramid appeared in at least 418 peer-reviewed articles and 11 encyclopedia articles published between 1990 and 2013, compared with 15 articles that questioned them (Letrud and Hernes, 2018, summarizing their 2016 study).
• Masters (2013) found 43 medical education articles and conference papers citing the pyramid, with "no agreement on the percentages of learning retention."
• A follow-up by Masters (2020) found 41 more citing papers from 2012 to 2018 and concluded: "The Pyramid is rubbish, the statistics are rubbish, and they do not come from Edgar Dale."
• In 2012, Letrud called on NTL Institute to retract its model.

The pyramid does point at something real: explaining material and working with it in your own words tends to beat passively receiving it. The research backs specific versions of that, such as elaborative interrogation, self-explanation and retrieval practice. It does not back the percentages.

What to use instead

The best-supported combination is testing yourself, spread out over time. In practice that means:

1. Replace a second read-through with active recall: close the book and write or say what you remember.
2. Space your reviews across days with spaced repetition rather than cramming the night before.
3. Mix problem types with interleaved practice once you know the basics.
4. If you highlight, highlight sparingly and turn the highlights into questions. Diagrams help too; see dual coding examples.

Methodology

We used peer-reviewed research only: journal articles, meta-analyses and published surveys, plus NTL Institute's own published statement on the pyramid. Every number was checked against the primary source (the full paper, or the PubMed or ERIC abstract where that is where the number appears) in September 2026. We did not use statistics roundup sites. Where a popular figure could not be traced to a study, as with the 15% at 30 days claim and the learning pyramid percentages, we say so rather than repeat it. Survey figures are self-reports from single universities, and effect sizes compare each technique with that study's control condition, so treat them as comparisons, not universal rates.

Sources

1. 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), 4-58.
2. Donoghue, G. M., and Hattie, J. A. C. (2021). A meta-analysis of ten learning techniques. Frontiers in Education, 6, 581216.
3. 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), 471-479.
4. Hartwig, M. K., and Dunlosky, J. (2012). Study strategies of college students: Are self-testing and scheduling related to achievement? Psychonomic Bulletin and Review, 19(1), 126-134.
5. Blasiman, R. N., Dunlosky, J., and Rawson, K. A. (2017). The what, how much, and when of study strategies: Comparing intended versus actual study behaviour. Memory, 25(6), 784-792.
6. Roediger, H. L., and Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249-255.
7. Karpicke, J. D., and Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865), 966-968.
8. Rawson, K. A., and Kintsch, W. (2005). Rereading effects depend on time of test. Journal of Educational Psychology, 97(1), 70-80.
9. Callender, A. A., and McDaniel, M. A. (2009). The limited benefits of rereading educational texts. Contemporary Educational Psychology, 34(1), 30-41.
10. Ponce, H. R., Mayer, R. E., and Méndez, E. E. (2022). Effects of learner-generated highlighting and instructor-provided highlighting on learning from text: A meta-analysis. Educational Psychology Review, 34, 989-1024.
11. Yue, C. L., Storm, B. C., Kornell, N., and Bjork, E. L. (2015). Highlighting and its relation to distributed study and students' metacognitive beliefs. Educational Psychology Review, 27, 69-78.
12. Peterson, S. E. (1992). The cognitive functions of underlining as a study technique. Reading Research and Instruction, 31(2), 49-56.
13. Letrud, K., and Hernes, S. (2018). Excavating the origins of the learning pyramid myths. Cogent Education, 5(1), 1518638.
14. Subramony, D. P., Molenda, M., Betrus, A. K., and Thalheimer, W. (2014). The mythical retention chart and the corruption of Dale's Cone of Experience. Educational Technology, 54(6), 6-16.
15. Lalley, J. P., and Miller, R. H. (2007). The learning pyramid: Does it point teachers in the right direction? Education, 128(1), 64-79.
16. Letrud, K. (2012). A rebuttal of NTL Institute's learning pyramid. Education, 133(1), 117-124.
17. Masters, K. (2013). Edgar Dale's Pyramid of Learning in medical education: A literature review. Medical Teacher, 35(11), e1584-e1593.
18. Masters, K. (2020). Edgar Dale's Pyramid of Learning in medical education: Further expansion of the myth. Medical Education, 54(1), 22-32.
19. NTL Institute correspondence, published by Polovina, S. (2011). About the Learning Pyramid. Goldsmiths, University of London (archived copy).

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Frequently Asked Questions

What is the retention rate for highlighting and rereading after 30 days?

We found no peer-reviewed study that reports one. The 15% at 30 days figure has no traceable source. Dunlosky et al. (2013) rated both techniques low utility, and in a 242-study meta-analysis only 3.3% of effects were measured between 8 days and a month after studying (Donoghue and Hattie, 2021), so a clean 30-day number does not exist.

Is the learning pyramid real?

No. The percentages (5% lecture, 10% reading, up to 90% teaching others) have never been traced to any study. Letrud and Hernes (2018) found versions of the claim as early as 1852, decades before experimental memory research began, and Masters (2020) concluded the statistics are rubbish and do not come from Edgar Dale.

What are the most effective study techniques according to research?

Practice testing and distributed practice are the only two of ten techniques rated high utility by Dunlosky et al. (2013). A later meta-analysis of the same research found the largest effects for distributed practice (d = 0.85) and practice testing (d = 0.74), against an average of 0.56 across all ten (Donoghue and Hattie, 2021).

What percentage of students reread their notes?

In a survey of 177 college students, 83.6% listed rereading notes or textbooks as a study strategy and 55% called it their number one strategy, while only 10.7% described practicing recall (Karpicke, Butler and Roediger, 2009). A later survey of 324 students found 66% reread regularly and 72% highlight (Hartwig and Dunlosky, 2012).

Does rereading improve retention compared with testing yourself?

Only in the short term. In Roediger and Karpicke (2006), students who read a passage four times recalled 83% after five minutes but 40% after one week. Students who read it once and took three recall tests recalled 71% after five minutes and 61% after a week, despite reading the passage far fewer times.