By Leo Babauta

We’ve all done something that researchers call “massed study”: we cram for a few days for a test, we memorize a set of facts (vocabulary words, state capitals, multiplication tables) by repeating the list a whole bunch of times.

And when we really put ourselves into massed study, we feel like we’re learning.

Unfortunately, it’s a bit of an illusion. It turns out that this feeling of making progress is false, because we forget about 80% of what we learn. Cramming for a test, repeating something over and over until you remember it … it leads to doing well on a short-term test the next day, but over the longer term, you begin forgetting it immediately and rapidly.

So what’s a better way? Well, for some of you this won’t be a revelation, but it’s worth talking about: spaced repetition.

Basically, that means it’s better to take a list of foreign vocabulary words (or phrases), and study them in sessions that are spaced out — let’s say 10 minutes a day for two weeks, rather than two hours in one day.

Let’s talk briefly about why this works, and then how you can put it into practice in your daily study sessions.

Why This Works

What’s most important is that it does work, and has been shown to work in research over and over. But here are a couple of the reasons that researchers think spaced repetition works:

  1. When an item enters your memory, it isn’t just inserted into a memory slot — your brain makes connections between the item and other things in your memory. So when you study something on Monday, some of the connections your brain is making with that thing include the smell of baked bread coming from your kitchen, or the sound of that bird chirping annoyingly outside. But when you study on Tuesday, there’s the smell of spaghetti sauce and the sound of the neighbor mowing the grass. These different connections you make in multiple study sessions help strengthen the remembering.
  2. Each time you study, you have to recall the previous study sessions a bit. That means you’re associating the current session with past sessions, making even more connections, and are doing the hard work of retrieving your previous memories. This hard work turns out to be valuable in learning. But when you study something all at one time, you don’t have to do that hard work because you were exposed to previous items just a minute ago.

There’s more to it than that, but the bottom line is that our memories aren’t just a bucket that we can dump information into. We make mental connections, based on a mental model we have of what we’re learning, based on other things we’ve learned before, based on visual, audio and other physical sensations, and much more. Spaced repetition is a way to enrich those connections from multiple angles.

Spacing Out Repetitions, and Retrieval

It’s great to space out your learning, but ideally, you repeat things you’ve already been exposed to … for example, if you are given the phrase for “How are you?” in Spanish (“¿Cómo estás?”) … you don’t just learn it once. You should be given it again soon after you first learn it, before you forget — let’s say in 10 minutes. Then again a little while later — let’s say a day.

Then, as you remember something better than you did at first, you should be exposed to it less often. Let’s say every 2 days, then every 4 days, then every 8 days, and so on. If you realize you don’t really remember something, you can start repeating it a little more often — let’s say every 4 days instead of every 8 days. Early researchers used a series of index card boxes to keep track of when you should study an item (move the card to the “every 4 days” box if you know it well, for example) … but today you can use computer flashcard programs to keep track of when you should study something (I recommend Anki).

Also, here’s a trick:

Combine spaced repetition with the Power of Retrieval.

How do you do that? Well, instead of just exposing yourself to a lot of information all at once, space out the information and force yourself to retrieve previous information you learned in earlier sessions. That means don’t just read, but recall. Don’t just watch videos, actually put it into practice.

How to Use Spaced Repetition in Your Learning

The method you use will depend on what you’re learning, but here are some ways you might use spaced repetition retrieval:

  1. Flashcards. If you add information you’re learning to flashcards as you learn them, then study the flashcards a bit each day, you’ll be spreading out your learning over time and forcing yourself to recall the information as you go. Again, I recommend Anki, because it can be used on any operating system (even your phone) and it automatically figures out when you should study a card again based on how easy it was for you to remember it.
  2. Regularly practice a skill. If you’re learning a sport, martial art, sketching, guitar … it’s not enough to watch a video of a beginner skill and then try it once or twice. You have to practice it regularly until it becomes second-nature. So a good idea is to do drills or other kinds of basic practice on a regular basis, once every day or two until you feel it’s ingrained in you. Then every week or two (depending on how good you are at it), review the basics.
  3. Create a review/practice schedule. One thing I’ve started doing is making several lists for review/practice: daily, every other day, every 4 days, every week, every two weeks, every month, etc. Each list is spaced out (roughly) twice as long as the list on top of it. If I’m just learning something, it goes on the daily list for practice every day until it becomes easy. Then it goes on the every other day list for review, and so on as I master it more and more. It’s not enough to study it once or twice — I need to keep practicing it, probably forever, if I don’t want to forget.

There are some study areas, like programming for example, where doing basic drills might not be useful. That’s because the work itself is the practice — writing a program involves lots of basic skills, and you gain new skills slowly by working on more and more advanced programs. But even as you’re working on advanced programs, you’re working on the basic skills as well, so the spaced review is built into the work. But even then it’s useful to think about what skills you don’t use that often that you might review on a regular basis.

Action step: Think about how you might use spaced repetition & retrieval in your learning sessions, and implement it today.