In short
- Two techniques beat everything else in the learning-science reviews: testing yourself and spacing study out; rereading and highlighting feel productive and barely work.
- Retrieval practice leaves about half again as much in memory a week later as rereading does, and it works best when the tests are spaced and effortful.
- The best gap between sessions is about ten to twenty per cent of how long you need to remember: a day for a week, a week for a month, a month for a year.
- Mixing related topics in one session feels harder and teaches more, and a night's sleep between two sessions halves the practice needed to relearn.
- Your sense of what you know is inflated while the page is open; the only honest gauge is a closed-book test a day later.
Fundamentals
What the evidence ranks highest, and why those two techniques work.
Two techniques sit at the top of the evidence, and both work by making memory do something: retrieval pulls a fact out, and spacing lets it fade a little before it is pulled again. The blocks name the ranking, explain each mechanism, and end with the sleep that stitches sessions together.
Two techniques above the rest
A review of ten popular study techniques for the Association for Psychological Science rated only two as high utility: practice testing and distributed practice. Retrieval practice, pulling information out of memory rather than putting it back in, produced better retention than restudying in pooled analyses of hundreds of experiments, with a medium-to-large effect. Spacing, spreading the same study time across sessions rather than massing it, produced better recall in over eight hundred comparisons. Both are free, and neither needs a special app.
Why retrieval works
Retrieving a memory strengthens it more than meeting it again. In the classic experiment, students who read a passage once and then tested themselves remembered far more a week later than students who reread it, even though the rereaders felt more confident. Testing beat building concept maps, an active technique, for both factual and inference questions. The effort of retrieval is the mechanism: the harder the successful pull, the more it sticks, which is what desirable difficulty means.
Why spacing works, and how much
Memory is strengthened most by study that happens just as it is starting to fade. In a large study of retention intervals from a week to a year, the best gap between sessions was roughly ten to twenty per cent of the interval you need to remember for: about a day for a week, a week or so for a month, a month for a year. Spacing retrieval practice itself, rather than only rereading, adds the two effects together. Learners shown categories in an interleaved, spaced order learned them better while believing the massed order had worked. Sleeping between two sessions halved the number of practice trials needed to relearn a list and improved retention six months later.
Why it matters
The same hours produce very different learning.
The reason to care is arithmetic: the same hours, spent differently, leave different amounts behind. The blocks move from hours saved, to what predicts grades, to attention as the bottleneck everything else runs through.
Hours saved
Spaced students matched massed students' immediate performance and beat them later; the group that slept between sessions in the relearning study needed half the practice. Rereading, highlighting and summarising, the techniques most students report using, sat at the bottom of the utility list. Switching what you do with the time is the highest-return change on this tab.
Grades and what predicts them
Study habits and skills predict university grades moderately, on a par with the admission tests, and effort regulation, the ability to keep working when it is dull, is among the strongest individual predictors in the pooled studies. Sleep is part of the picture: students' sleep duration, quality and consistency together explained around a quarter of the variance in grades, and sleepiness is one of the commonest reasons college students fall behind.
Attention is the bottleneck
Heavy media multitaskers were worse, not better, at filtering irrelevant information and switching tasks. Students who multitasked on a laptop in class scored eleven per cent lower on a test, and the students sitting near them scored lower too. Brief breaks restore vigilance during long stretches of the same task, and sleep loss undermines the whole system.
How to improve
Four changes, in order of payoff.
Close the book and test, then space the sessions, then mix related material, then protect the session from the phone and the late night. The first two are the high-utility techniques; the last two are what let them work.
Close the book and test
End every session by writing down or saying what you learned with the notes closed, then check. Use flashcards, practice questions, past papers or a blank page. Tests do not need to be graded to work, and free recall works as well as multiple choice, often better. The check afterward matters because judgements of learning made while the material is visible are inflated.
Space the sessions
Plan the second session for the day after the first, the third a week later, the fourth a month later, and stretch the gaps to match how long the material has to last. Three short sessions beat one long one of the same total, a finding that holds across verbal and motor learning. The tab's spacing signal rises when more than three days pass without a session because gaps of that size are where forgetting overtakes the benefit for most material.
Interleave related material
When a session covers problem types or categories that are easy to confuse, mix them rather than blocking them. Students who practised shuffled maths problems scored far higher on a later test than those who did them in blocks, and learners who saw painters' styles interleaved could identify new paintings better while insisting that blocking had worked better. The benefit is largest when the items are similar.
Protect the session
Put the phone in another room and close the other tabs; the cost of multitasking falls on you and on whoever is next to you. Take a short break every half hour or so on long tasks, because brief breaks restore the focus that decays with time on task. Finish the day's last session before a good night's sleep rather than after it, because sleep consolidates what was learned that day.
Common pitfalls
The mistakes that feel like progress.
Both pitfalls here come with a good feeling attached: the relief of a cram that passes the exam, and the diligence of one more late hour. The blocks show where each feeling and the measurement part ways.
Cramming
Massed study the night before an exam can pass the exam and leaves little a month later. Spaced sessions retain more and cost the same hours. If a cram is unavoidable, sleep after it rather than through the night, because the consolidation happens then.
Studying tired
Sleep-deprived brains encode poorly and consolidate less. Students' sleep quality, duration and consistency together explained around a quarter of the variance in grades, and chronic short sleep degrades attention cumulatively without the person noticing. An hour of sleep is worth more than a late hour of rereading.
Myths
Popular ideas the research has tested and rejected.
The power of rereading and the feeling of knowing are the two ideas students most often bring to the desk, and each has been tested directly. What survives is short and the same for everyone.
Rereading and highlighting work
They are the most-used techniques and among the least effective. Rereading produces the confident feeling of knowing without the retention; highlighting and underlining were rated low utility because they do not improve later recall and can hurt inference. The same hours spent on self-testing leave far more behind.
If it feels familiar, you know it
Rereading makes text feel familiar, and familiarity feels like knowledge. Students predicted that rereading would beat testing and were wrong; learners preferred blocked practice and were wrong. The feeling of fluency while the book is open is the least reliable signal you have; the closed-book test is the reliable one.
Measuring progress
What the tiles count and what to add to each log.
The stat card counts hours and gaps, but the number the research cares about is how many self-tests each session held. The second block gives the only honest gauge of what you know, and it is not the feeling at the end of the session.
Hours, gaps and self-tests
The tiles count hours this week and days since the last session; the strip reacts to gaps beyond three days and to weeks under three hours. Hours only count when they are spent on retrieval and spacing, so the number worth adding to each log is how many self-tests you did. Monitoring progress itself increases the chance of reaching a goal in the pooled trials, most when it is written down.
Test yourself to measure
The only honest gauge of what you know is a closed-book test taken a day or more after studying, not the feeling at the end of a session. Keep the questions and retest a week later; the retention on the second test is the number that predicts the exam.
Tips you may see in the app
The line under the tab picks one of these for your own numbers. Each rests on the same standard of evidence.
- Study it again after a day, a week and a month; the gap grows with how long it must last.In a large study of retention intervals, the best gap between sessions was about ten to twenty per cent of how long you need to remember for: a day for a week, a week for a month, a month for a year.
- Sleep between two sessions halved the practice needed to relearn.Sleeping between two learning sessions halved the number of practice trials needed to relearn a list and improved retention six months later; the day's last session belongs before a good night.
- Cramming can pass the exam and leaves little a month later; three short sessions beat one.Massed study matches spaced study on an immediate test and loses later; spaced sessions retain more for the same hours, and if a cram is unavoidable, sleep after it rather than through the night.
- Rereading and highlighting feel productive and barely work; spend the hours testing.The review of ten study techniques rated rereading, highlighting and summarising low utility and only practice testing and distributed practice high; the same hours spent on self-testing leave far more behind.
- An hour of sleep is worth more than a late hour of rereading.Sleep consolidates what was learned that day, and students' sleep duration, quality and consistency together explained around a quarter of the variance in grades; the late hour costs the next morning too.
- Close the book and write what you know; testing beats rereading by half again a week on.In the classic experiment, students who tested themselves after one reading remembered far more a week later than students who reread, even though the rereaders felt more confident; free recall works as well as multiple choice.
- Easy while the page is open is fluency, not memory; the closed-book test is the gauge.Judgements of learning made while the material is visible are inflated: students predicted rereading would beat testing and were wrong, and learners preferred blocked practice and were wrong.
- Mix related topics in one session; it feels harder and tests better than blocking them.Students who practised shuffled maths problems scored far higher on a later test than those who did them in blocks, and learners shown painters' styles interleaved identified new paintings better while insisting blocking had worked.
Sources
Every study this guidebook rests on, in the order it is first cited.
- 1
Dunlosky J, Rawson KA, Marsh EJ, Nathan MJ, Willingham DT (2013). Improving students' learning with effective learning techniques: promising directions from cognitive and educational psychology. Psychological Science in the Public Interest.
- 2
Adesope OO, Trevisan DA, Sundararajan N (2017). Rethinking the use of tests: a meta-analysis of practice testing. Review of Educational Research.
- 3
Rowland CA (2014). The effect of testing versus restudy on retention: a meta-analytic review of the testing effect. Psychological Bulletin.
- 4
Cepeda NJ, Pashler H, Vul E, Wixted JT, Rohrer D (2006). Distributed practice in verbal recall tasks: a review and quantitative synthesis. Psychological Bulletin.
- 5
Roediger HL, Karpicke JD (2006). Test-enhanced learning: taking memory tests improves long-term retention. Psychological Science.
- 6
Karpicke JD, Blunt JR (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science.
- 7
Bjork RA, Bjork EL (2020). Desirable difficulties in theory and practice. Journal of Applied Research in Memory and Cognition.
- 8
Cepeda NJ, Vul E, Rohrer D, Wixted JT, Pashler H (2008). Spacing effects in learning: a temporal ridgeline of optimal retention. Psychological Science.
- 9
Latimier A, Peyre H, Ramus F (2021). A meta-analytic review of the benefit of spacing out retrieval practice episodes on retention. Educational Psychology Review.
- 10
Kornell N, Bjork RA (2008). Learning concepts and categories: is spacing the "enemy of induction"? Psychological Science.
- 11
Mazza S, Gerbier E, Gustin MP, et al. (2016). Relearn faster and retain longer: along with practice, sleep makes perfect. Psychological Science.
- 12
Credé M, Kuncel NR (2008). Study habits, skills, and attitudes: the third pillar supporting collegiate academic performance. Perspectives on Psychological Science.
- 13
Richardson M, Abraham C, Bond R (2012). Psychological correlates of university students' academic performance: a systematic review and meta-analysis. Psychological Bulletin.
- 14
Robbins SB, Lauver K, Le H, Davis D, Langley R, Carlstrom A (2004). Do psychosocial and study skill factors predict college outcomes? A meta-analysis. Psychological Bulletin.
- 15
Okano K, Kaczmarzyk JR, Dave N, Gabrieli JDE, Grossman JC (2019). Sleep quality, duration, and consistency are associated with better academic performance in college students. npj Science of Learning.
- 16
Hershner SD, Chervin RD (2014). Causes and consequences of sleepiness among college students. Nature and Science of Sleep.
- 17
Ophir E, Nass C, Wagner AD (2009). Cognitive control in media multitaskers. Proceedings of the National Academy of Sciences.
- 18
Sana F, Weston T, Cepeda NJ (2013). Laptop multitasking hinders classroom learning for both users and nearby peers. Computers & Education.
- 19
Ariga A, Lleras A (2011). Brief and rare mental "breaks" keep you focused: deactivation and reactivation of task goals preempt vigilance decrements. Cognition.
- 20
Koriat A, Bjork RA (2005). Illusions of competence in monitoring one's knowledge during study. Journal of Experimental Psychology: Learning, Memory, and Cognition.
- 21
Donovan JJ, Radosevich DJ (1999). A meta-analytic review of the distribution of practice effect: now you see it, now you don't. Journal of Applied Psychology.
- 22
Rohrer D, Taylor K (2007). The shuffling of mathematics problems improves learning. Instructional Science.
- 23
Brunmair M, Richter T (2019). Similarity matters: a meta-analysis of interleaved learning and its moderators. Psychological Bulletin.
- 24
Walker MP, Stickgold R (2004). Sleep-dependent learning and memory consolidation. Neuron.
- 25
Rasch B, Born J (2013). About sleep's role in memory. Physiological Reviews.
- 26
Van Dongen HPA, Maislin G, Mullington JM, Dinges DF (2003). The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep.
- 27
Harkin B, Webb TL, Chang BPI, Prestwich A, Conner M, Kellar I, Benn Y, Sheeran P (2016). Does monitoring goal progress promote goal attainment? A meta-analysis of the experimental evidence. Psychological Bulletin.
This summarises research for healthy adults. It is not medical advice and does not replace a professional.