Thursday, April 29, 2010

It takes 15-20 exposures to learn a word

In an article on VOA News, Catherine Snow of Harvard's Graduate School of Education gives us some numbers on how many exposures you need to a word before you learn it:
In order to have a high probability of learning a word, you need to encounter it fifteen, twenty times.


  1. I would like to know where she gets that figure from because she just kind of throws it out there. In an interview like this, it is understandable why she does that, but I'd still be interested to see studies.

    I do like that she mentions that seeing the word in a variety of contexts is important. Encountering it flashcards or vocab lists doesn't seem to count according to her take on the issue. I enjoy flashcards sometimes, but still I agree that you will remember a word much better when you learn it in context.

  2. Agreed on all points. It would be nice to see where those numbers come from. If I recall correctly, the data on the SuperMemo site says that you only need about half of that, assuming the repetitions are well timed. Her numbers would make sense if it's exposures to something for which the leaner doesn't know the meaning, with perhaps the first half of those reps needed simply for you to figure out what it means.

  3. In classroom teaching using comprehensible input, we usually aim for 70-80 exposures in novel contexts during the first day of presentation, then regular "refreshers" when the item is presented in the course of input over future lessons. 10-20 isn't nearly enough, especially if the language is not highly similar to English. For a cognate, maybe. For anything else, not really.

  4. @Terry: When you say "the first day of presentation", do you mean in the single class when the word is introduced? 70-80 times in a single class seems like a lot of repetition to me. What you're describing raises a bunch of questions for me.

    Doesn't that make the classes boring? Recalling my typical hour-long classes from high school, if each new word has to be repeated 70-80 times, and there is a certain number of new words, that would mean a lot of time go over the same words, even if each rep is in a novel context.

    Doesn't that also limit the number of vocab you can learn? I've always avoided classes whenever possible, and one of the main reasons was that classes were always so slow. If you're repeating each new word 70-80 times, that would seem to make progress slow.

    Do new grammar rules also need to be repeated 70-80 times?

    Does that number go down for motivated language learners? If you told me to repeat something 70-80 times, I'd think you were crazy because I can certainly learn something in far fewer exposures than that (and certainly not so many in a single day). So somewhere between those classroom practices and where I find myself something changes.

    How are those "refreshers" timed? Is the spacing based on the forgetting curve like spaced-repetition systems?

  5. I guess she out to read this post: Nice review of my post, and great stuff on your blog, congrats!