Sunday, February 14, 2010

spaced repetition (SRS) and language learning, do they go together?

What is an SRS?

SRS stands for Spaced Repetition Software. This should not be confused with flashcards. With flashcards, the learner is in control. With an SRS, the software is in control. The learner will review or test the information when the software decides. To understand why, we must look at the next question.

What is Spaced Repetition?

Spaced repetition is a learning technique that incorporates increasing intervals of time between subsequent review of previously learned material.  This means that between each review the amount of time increases. For example, the time between the 1st review and the 2nd review might be 1 day, and then the 3rd review comes after 5 days, and the 4th review happens 10 days later.

Deciding the intervals is the job of the Spaced Repetition Software. Every day, it will tell the user which items are up for review. The review is actually a test and the learner should provide accurate feedback to the SRS so that it may decide when to schedule each item for a subsequent review.

If the learner tells the SRS that the item was easy to recall, then the SRS will increase the interval for that item. If the learner states that the item could not be remembered, then the SRS may decide to restart the interval process for that item, basically treating it as a brand new item.

What is The Forgetting Curve?

Basically, the Forgetting Curve is the weakening of a memory over time.  If a language learner memorizes the translation of a word, that memory will naturally become harder to recall as time passes.

What is the connection between SRS and The Forgetting Curve?

In my understanding, the purpose of using the SRS is to efficiently manage the review of information. The SRS will schedule the review of each item before it is completely forgotten but not too soon. The theory seems to go that the review of learned material too early is a waste of time.  Language learners are led to believe that they can save time. Most enthusiastic language learners would like to use the saved time to learn more words in an effort to reach the  number of known words required to break past the fluency threshold as soon as possible.

SRS and Vocabulary Learning

SRS has been touted by many language learners blogging about language learning tools. It seems to be the way to go. Never forget a new word! Just put it in your SRS and you'll be constantly reminded of it.

But does SRS really work for language learning?

The ability to recall information has its strong times and its weak times. Perhaps it depends on the time of day, how refreshed or tired one feels, or whether one is in a good mood or a bad mood. I'm suggesting that there are reasons why you may have not been able to recall an item in your SRS. But what do you do? How do you know if you've really forgotten a word or if it was just not a good time to be testing yourself?

Why does the learner remember the ones he got right? Does he know why certain items are easy and certain ones are hard to remember? I'm suggesting that there are reasons why you can recall some vocabulary items easier than other items.

Is language learning just about building up a vocabulary?

The short, and hopefully obvious answer is No. What will you do with an extra 1,000 words if you don't use them? Oh, you say you are reading in your target language? You say you are speaking? You say you are writing? You say you are listening?

Every time you use your new words for reading, listening, writing, or speaking, you are reviewing them! Your vocabulary is not sitting in your SRS waiting 6 months until you see them again. Those words are coming up and refreshing your mind in many ways which you cannot control.

So why would a learner need an SRS? If you haven't seen those words between SRS-decided intervals, you are either not doing enough or those words are not important. You can't tell me that before you are fluent in your target language, you are trying to learn words that native speakers only use once or twice a year. Words are meant to be used. Words are not meant to sit around in your private collection until you grace them with your presence.

The idea behind the SRS is to not review words more than necessary, but the idea behind language learning is to get as much exposure to the language as possible. Am I the only one who sees the opposing ideologies?

Words you need to remember are naturally spaced.

A good language learner exposes herself to the language as much as possible. The words she needs to remember the most are used the most often. Words she uses everyday are never forgotten. More exposure to the words strengthens them.

An SRS gives you less and less exposure to the words. That is not going to strengthen them. It only allows the words to remain forever weak. Those words might as well be forgotten.

SRSing creates a hostile environment.

Reports from users of SRS have come in over the years. The most often cited complaint is the backlog of items needing to be reviewed. Methods of coping with SRS problems have been devised.

Additionally, just using an SRS takes time away from real language learning activities. Time is needed to find words or sentences for the SRS. Then time is needed to enter them. And of course, every day, time is need for review.

So what purpose does an SRS best serve?

An SRS is good for items which you would not naturally run across.  Basically for useless information. Whatever you know you are not going to get exposure to would be a good candidate for entering into an SRS. If you want to remember the capitals of 200 nations, put them in your SRS. However, if you are the ambassador to the United Nations, I would not show them this if I were you.


So what was my point in this post? If you are learning a language, your exposure to it should override any benefit that an SRS could possibly provide. If you are a successful user of an SRS, you are probably successful because of what you do outside of your SRS use. If you were not successful before using the SRS, it may be that the SRS has prompted you to do more reading or vocabulary study or listening or whatever. Your exposure to the language in between SRS reviews is helping you to recall those words correctly. The SRS is really redundant.


  1. Hard to argue with this, Keith. I've been getting away from the SRS more and more lately, because it can really be a drag and kill my motivation. It just might be time to pull the plug.

  2. The order of the characters is wrong on the clock. The child character should be at 12.

  3. Good point, Keith. It's an argument I haven't seen so far, but it's valid. Another thing that annoys me about SRS (and flashcards) is that it emphasizes translation instead of comprehension (as you would in watching a movie).

  4. I agree to a certain extent. Obviously, words that you see very often (the 1,000-3,000 most frequent words) are occur naturally enough that you don't need to put them in SRS. But words that occur less frequently just aren't seen frequently enough to learn naturally unless you are consuming a ridiculous amount of input. If you don't live in a country of the target language and have a job, family, etc. learning via SRS is much more efficient. Otherwise, you end up forgetting the words and having to relearn them, which is obviously a huge waste of time. In addition, one doesn't just have to learn words; learning grammatical structures and sentences is also possible. If you just want to reach an intermediate level, I agree SRS isn't necessary.

  5. "is that it emphasizes translation instead of comprehension"

    Translation--after a point? or ever depending on your approach--is not helping, no matter the media or tool (just like watching a movie with L1 subs). Many people who advocate SRS use monolingual cards.

    I don't use SRS much, but when I do, I notice the repeat exposure to words helps me recognize them when they come up again, or come to mind when the context is right for use.

  6. Mono or bilingual cards, it doesn't really matter. When you memorize a word, it doesn't involve you in using language as language but as body of facts.
    One common belief about language learning is that to learn a language is to learn a body of facts. In Chemistry class you learn facts such as a carbon atom can form four bonds with other atoms. In German class you learned facts such as the first person singular present tense form of möchten is möchte and facts such as the word meaning "dog" is hund. Learning a language is seen as learning hundreds or thousands of facts about grammar and vocabulary.

  7. I wholeheartedly agree! I think that most SRS or flashcards are a waste of time and not fun. If I want to remember a word ahead of it's natural time, then I use a mnemonic story.

    I wrote a quick blog post about the apparent rise of interest in SRS and falling interest in mnemonics here:

  8. Hey Keith

    I guess it comes down to the fact that SRS works for some people, and not for others.

    While I agree that exposure to the target language is a great goal, my own experience is that using SRS I learn many more words per day, and this equips me better for when I'm exposed to the target language.

    I've tried with and without - and my own experience is *materially* better *with* the use of SRS on a daily basis (not just to revise, but also to learn).


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