Brett LindenbergTo retain information better, practice pulling it out of your memory instead of reading it again. Quiz yourself after each section, spread your reviews over several days, and explain the ideas in your own words. A 2013 review of ten study techniques by John Dunlosky and colleagues gave its top rating to only two of them, self-testing and spaced practice, and rated rereading and highlighting low. Sleep and regular exercise help your brain keep what you practice. To try one recall check now, read the short brief in the video below and answer from memory after the brief disappears.
What does it mean to retain information?
To retain information means to keep it in memory so you can recall and use it later. Merriam-Webster defines this sense of retain as "to keep in mind or memory." Retaining is different from absorbing. You absorb a lecture when you follow it and understand it in the moment. You retain it if you can still explain it next week without your notes.
Memory works in three stages, and a problem at any one of them causes forgetting:
- Encoding is when you take in the information and make sense of it. Attention matters most here.
- Consolidation is when your brain stabilizes the new memory over the following hours and days, much of it during sleep.
- Retrieval is when you find the memory again. Each time you retrieve it successfully, the next retrieval gets easier.
Information retention is the share of what you learned that you can still recall or use after a delay. Teachers and training teams measure it with a quiz days or weeks after the lesson, because a quiz right at the end of the lesson cannot show what fades over the following days.
Why you forget new information so quickly
In the 1880s, the German psychologist Hermann Ebbinghaus memorized lists of nonsense syllables and timed how long relearning each list took later. After 20 minutes, Ebbinghaus needed 58% less time than the first learning took. After one day the saving was about 34%, and after 31 days it was 21%. A 2015 replication by Murre and Dros in PLOS ONE produced a very similar curve.
Ebbinghaus was the only person tested, on syllables with no meaning, so the percentages should not be applied to a course or a book chapter. Claims such as "you forget 70% of what you learn within a day" come from loose readings of this one curve. The shape does hold: you lose the most in the first hours and days, and then forgetting slows down.
Rereading adds a second problem: familiar material feels learned. In a 2006 study by Henry Roediger and Jeffrey Karpicke, students who read a short passage four times expected to remember it better than students who read it once and then practiced recalling it three times. One week later, the rereading group recalled 40% of the passage's idea units, and the recall group recalled 61%.
The best ways to retain information
The table sorts common methods by the strength of the research behind them. The first five rows use the ratings from the Dunlosky review, which judged each technique as high, moderate, or low utility for students.
| Method | What you do | Evidence |
|---|---|---|
| Practice testing (active recall) | Answer questions or write what you remember without looking | High utility (Dunlosky et al., 2013) |
| Spaced practice | Review the same material across several days or weeks | High utility (Dunlosky et al., 2013) |
| Elaborative interrogation and self-explanation | Ask why a fact is true and explain each step in your own words | Moderate utility (Dunlosky et al., 2013) |
| Interleaved practice | Mix different problem types in one session | Moderate utility (Dunlosky et al., 2013) |
| Rereading, highlighting, summarizing | Go over the same text again or mark it up | Low utility (Dunlosky et al., 2013) |
| Chunking and organizing | Group details into a few meaningful units | Based on working-memory research (Cowan, 2001); not rated in the review |
| Memory palace and other mnemonics | Link items to vivid images or places | Large gains for word lists (Dresler et al., 2017) |
| Sleep and exercise | Sleep before and after learning; walk or do other aerobic exercise | Lab and clinical trials (Yoo et al., 2007; Erickson et al., 2011) |
Use self-testing and spacing for everything you need to keep. Add the other methods when the material calls for them.
1. Test yourself instead of rereading
Self-testing, also called active recall or retrieval practice, means you produce the answer before you see it. Each search through your memory strengthens the memory you find. In the Roediger and Karpicke study, one reading plus recall practice beat four readings by 21 percentage points a week later.
Ways to do it:
- Close the book after each section and write down everything you remember. Then open the book and mark what you missed.
- Turn each heading into a question before you read the section, and answer it from memory afterward.
- Use flashcards, and say the answer out loud before you flip the card.
- Do practice problems before you look at worked solutions. Short topic quizzes count too, as long as you answer before you look anything up.
Wrong first answers help too. In experiments by Lindsey Richland, Nate Kornell, and Liche Kao (2009), students who tried to answer questions about an essay before reading it remembered that content better than students who spent the same time reading, even when their first answers were wrong. The benefit depends on seeing the correct answer soon afterward, so check your answers as you go.
2. Space your reviews over days
Spacing means you come back to the same material after a gap instead of repeating it in one sitting. Cramming can carry you through tomorrow's test, but the same study time split across days leaves a stronger memory. A 2008 study by Nicholas Cepeda and colleagues with 1,354 participants tested how long to wait before a review. For the same total study time, the best gap improved final recall by 64% compared with two sessions back to back. The best gap also grew with the time between the review and the final test.
| Time from review to final test | Best gap between first study and review |
|---|---|
| 7 days | 1 day |
| 35 days | 11 days |
| 70 days | 21 days |
| 350 days | 21 days |
Measured as a share of the test delay, the best gap fell from about 20% to 40% of a one-week delay to about 5% to 10% of a one-year delay. In practice, review new material the next day, again about a week later, and again after a few weeks if you need it for months. Make each review a self-test, not a reread.
You can schedule reviews by hand with the Leitner system, a box method that the German science journalist Sebastian Leitner published in 1972. Cards you answer correctly move to a box you review less often, and cards you miss go back to the first box. Software does the same job for you. Anki is free on desktop and Android, and since version 23.10 in November 2023 it includes the FSRS scheduler as an option. RemNote combines notes and flashcards and includes spaced repetition on its free plan. For a longer walk-through written for certification exams, AZ-204 Fast has a guide to the spaced repetition study method.
Add new cards at a pace you can review every day. Each new card comes back several times, so the daily review load grows faster than the number of new cards suggests.
3. Explain how and why
New facts are easier to find later when they connect to things you already know. The Dunlosky review gave a moderate rating to two ways of making those connections. Elaborative interrogation means asking why a stated fact is true. Self-explanation means explaining each step of a solution or process to yourself while you study it.
Preparing to teach has a similar effect. In a 2014 study by John Nestojko and colleagues, students who expected to teach a passage recalled more of it, and organized their recall better, than students who expected a test, although none of them actually taught. A popular version is often called the Feynman technique: explain the topic in plain words as if to a beginner, notice where you get stuck, reread only that part, and explain it again.
4. Mix related problem types
Interleaving means you mix different kinds of problems in one practice session instead of finishing all of one kind before you start the next. In Rohrer and Taylor's 2007 study, students practiced finding the volume of four kinds of geometric solids. A week later, students who had practiced the kinds mixed together scored 63% on the test, and students who had practiced each kind in a block scored 20%, even though the block group did better during practice. Mixing helps most when the hard part is choosing the right method, as in math problems or troubleshooting.
5. Break material into chunks
Working memory, where you hold and work with information right now, is small. Nelson Cowan's 2001 review put its limit at about four chunks, fewer than the "seven, plus or minus two" that George Miller described in 1956. A chunk is a group of details you handle as one unit, such as reading 555-867-5309 as three groups instead of ten separate digits.
To chunk a topic, sort the details under a few headings before you try to memorize anything. Learn one group, test yourself on it, and then add the next. A one-page outline or a sketch that links each group to the main idea shows the structure at a glance.
Memory techniques for lists and facts
Memory techniques, also called mnemonics, help when you must remember items in a fixed order or facts with no logic to hang them on. They do little for understanding, so pair them with self-testing.
The memory palace (method of loci)
Picture a route you know well, such as a walk through your home. Place a vivid image of each item at a stop along the route. To recall the list, walk the route in your mind. In a 2017 Neuron study led by Martin Dresler, people with no memory training practiced this method in 30-minute sessions over six weeks. Their recall of a 72-word list rose from 26 words to 62 words, and they still recalled more than before training when retested four months later.
Acronyms, first-letter cues, and rhymes
Make a word or a sentence from the first letters of the items, or set the facts to a rhyme. These cues take seconds to build and work well for short lists. The keyword mnemonic, which links a foreign word to a similar-sounding image, received a low utility rating in the Dunlosky review, so do not rely on it as your main study method.
How to improve memory with sleep and exercise
Sleep and exercise affect how well your brain stores what you practice.
You need sleep both before and after learning. In a 2007 study from Matthew Walker's lab, published in Nature Neuroscience, students who had been awake for 35 hours remembered new images 19% worse on average than students who had slept, and as much as 40% worse in some results. A 2010 review by Susan Diekelmann and Jan Born describes how sleep after learning helps consolidate new memories. An all-nighter before an exam cuts into both stages.
Exercise has trial evidence too. In a 2011 trial by Kirk Erickson and colleagues in PNAS, 120 adults aged 55 to 80 walked for 40 minutes three days a week for a year. Their hippocampus, a brain region central to memory, grew by about 2%, while it shrank by about 1.4% in a comparison group that did stretching. The walking group also improved on a spatial memory test. The trial studied older adults, so treat it as evidence for that group.
How to retain information when studying
This routine combines the methods above. It works for a textbook chapter or a recorded lecture.
- Before you start, skim the headings and summary, write a few questions you expect the material to answer, and try to answer them.
- Study one section at a time. At the end of each section, close the source and write what you remember.
- Check what you wrote against the source and mark the gaps. Make flashcards or practice questions for the gaps only.
- End the session with one recall sheet that covers everything you studied.
- The next day, answer your flashcards and questions again before you study anything new.
- About a week later, test yourself again with questions mixed from different sections.
- Before the exam or deadline, do mixed practice from all units instead of rereading the whole book.
The recall steps replace rereading instead of adding to it. Expect the sessions to feel harder than rereading. In the Roediger and Karpicke study, the students who reread felt more confident and remembered less.
How to absorb and process information better
You cannot retain what you never took in, so the encoding stage deserves attention too.
When you read, preview the section first, read with a question in mind, and stop at the end to recall the main points. Write notes in your own words instead of copying sentences, so you process the meaning as you go.
After a meeting or a call, write the decisions and next steps from memory before you look at anyone's notes. Then compare. The gaps show what you did not take in.
Videos and recorded lectures make it easy to drift. In a 2013 PNAS study, Karl Szpunar, Novall Khan, and Daniel Schacter split a 21-minute statistics lecture into four segments. One group answered short test questions between segments. That group reported mind wandering on 19% of attention checks, compared with 39% and 41% in the two groups without tests, and remembered more of the lecture on the final test. When you watch a lesson on your own, pause every few minutes and say what you just learned before you continue.
How to build retention into training videos
If you make training or course videos, you can put recall practice inside the lesson so learners do not have to remember to do it. This is the problem we work on at Mindstamp, and the research above maps to specific settings:
- Place a question right after each key point. Mindstamp questions pause the video, and you can require an answer before playback continues, so the recall happens while the context is fresh.
- Ask one question before you teach a concept, and let the explanation that follows act as the feedback. This applies the pretesting result from the Richland study.
- Turn on Repeat Until Correct so a wrong answer shows Try Again, or send a wrong answer back to the explanation with Change Time. The help article on scores and retries explains both settings.
- Show the source and then remove it before you ask, as the active recall demo at the top of this page does, so the learner has to recall instead of reading the answer from the frame.
- Check the per-learner report for the questions most learners miss, and re-teach those points.
- About a week later, send a short follow-up video with a few recall questions. Mindstamp does not schedule spaced reviews for you, so send the link from your LMS or by email.
If your LMS tracks completions, Mindstamp can export the video as a SCORM package that sends completion and score to a compatible LMS. For quick checks beyond a final exam, see our guide to assessing learning. For the workplace version of this topic, read our knowledge retention strategies for corporate training, and for more ways to keep learners working during a lesson, our list of active learning strategies.
Common questions about retaining information
What is the best way to retain information?
Test yourself on the material, and repeat the test over several days. Practice testing and spaced practice were the only two of ten techniques that earned a high utility rating in the 2013 Dunlosky review. For concepts, add explanations in your own words, and protect your sleep.
How long does it take to see results?
Recall practice pays off within days. In the Roediger and Karpicke study, the gap between the two groups showed up on a test one week later. Spacing needs at least two sessions, so plan a review for the next day and another a week or more later.
Can you improve your memory as an adult?
Yes, for the material you practice. Adults in the Dresler study more than doubled their recall of a word list after six weeks of memory palace training, and older adults in the Erickson trial improved on a spatial memory test after a year of walking.
Why do I forget what I read right after I read it?
Usually the text felt familiar, but you never tried to recall it. Recognizing a page is much easier than producing its content from memory. Close the text after each section and write what you remember. A blank page shows you the gap while you can still fix it.
Do I need an app for spaced repetition?
No. Index cards and a few boxes work. Apps such as Anki and RemNote save time because they schedule each card for you, which matters once you have hundreds of cards.
How do I help a team retain training?
Build recall into the training itself: questions during the lesson, feedback right after each answer, and a short follow-up quiz a week later. Our post on using interactive video for training and education shows how that looks in a video lesson.
