The Spaced Repetition Snowball: How to become overwhelmed by learning vocabulary

There are few people out there today, who don’t see the value of spaced repetition for learning vocabulary in languages. In fact, it can actually be used to learn anything. However, lately I’ve discovered a few traps with spaced repetition that I thought would be of use to other language learners.

In case you are unfamiliar with spaced repetition it was first described by Hermann Ebbinghaus in a detailed study published in 1885. The study showed that spacing out the learning process greatly aided the long-term recall rate. Today the results of the study are most popularly used in learning vocabulary for foreign languages, but it works for everything.

There’s also a significant amount of writing on the topic. The most recent I’m aware of is Fluent Forever by Gabriel Wyner, and although his book is a comprehensive guide to learning foreign languages, a large deal of the book is spent on how to do spaced repetition, or flash cards, the best way.

Association technique

The most common way to approach vocabulary learning, also shared by other language learners, involves taking a foreign word and then using association to make it stronger in your memory. Usually you would combine a vivid image, that in someway related to both the foreign word but also the translation.

An example could be the Russian word for to burn, romanised would be “GARET” (гореть.) When I saw that word I instantly thought of a cigarette burning. So now when my brain attempts to recall how to say to burn, it will think of the cigarette and then make the connection.

There are a few problems with this traditional approach. First of all it might be difficult to make up associations with certain foreign words, particularly if you like me, lack a certain creativity. Luckily other users on popular flashcard platforms such as Memrise often provide some for you. If you are using more independent systems like Anki or others, you might be left to your own creative devices.

The other problem is that it is very time consuming. Mr. Wyner describes in detail how every word he wants to learn needs to be part of a story and the flashcards themselves need to be images rather than words. As he points out, humans are quite visual and the memory of an image lasts longer than a memory of words.

However, I don't not fully understand whether the positive benefits of taking so long per word, outweighs the amount of repetitions one could otherwise do if one just blasted through, or used any quick association that came to mind, like my cigarette example above.

At the end of the day learning vocabulary is a numbers game. The more words we learn, the more we can understand in the language. That is fairly self-explanatory. My personal opinion is that I would rather spend less time designing each word, and spend more time working on the repetitions. The first few repetitions are usually harder, particularly in very different languages like Russian, but by the time I’ve repeated the word 5 or more times it sticks…and quite well too.

Now, of course another caveat is that the effect on the long term memory is also a topic of uncertainty. It’s a well-known fact that words, or pieces of information, enter the long-term memory and is thus difficult to get rid of. However, it does happen. We do forget things, and things might move from an active to a passive part of the long-term memory. Meaning, we can understand the information when presented with it, but we couldn’t come up with it if asked directly.

This often happens in language learning, where the words are flowing between the two memories and thus a language learner might be disappointed at his or her ability to produce the foreign vocabulary, but present them with a text of equal difficulty and they have no problem understanding what it says.

The question is then, are words better stored in long-term memory using the association techniques or is the quality of our memories simply a function of how many times we’ve had it repeated? I can’t say for sure, but as a non-creative person with a below-average patience I’m just going with the, get as many repetitions as possible solution for now.

The Vocabulary Snowball

Another unforeseen problem of spaced repetition is the concept of the vocabulary snowball. When we start learning languages we want to be effective and learn a lot of new words every day, while also tending to the words that we recently learned. I recently did a challenge to see how many new words of vocabulary in Russian I could add per day, without it overwhelming me. I started at 70, which means I had to review all the previously learned words and then learn 70 new ones.

Predictably it was madness. But the reason why was not what I expected. Learning 70 new words per day wasn’t actually a problem for me. The problems started a few days in, when vocabulary from the previous days started to show up for review. It wasn’t long until I had a mountain of 300+ words I had to review before getting on with my 70 new ones.

And you might say, well reviewing is quick! But no, in reality reviewing is much slower than learning. First of all you are likely to have forgotten a fair bit of the words you are reviewing. In my case I consistently forgot 25-30% of the words in my short-term memory. So for every word in this 25-30% bracket I had to re-learn them, meaning 4 new repetitions including how to type them. If I mistyped them (remember this is Russian, a completely foreign script) I would also have to repeat them 4 more times.

This means that 300 words would require around 600 repetitions. This takes a lot longer than 280 repetitions that it takes to add 70 new words to your short-term memory. Of course that assumes you get it a 100% right during the learning, which is sometimes hard to do but even allowing for mistakes and typos learning new words is a lot easier than reviewing old ones.

This was unexpected to me.

And of course the more words you learn, the bigger this proverbial snowball will get. Memrise uses an ever changing algorithm to determine the right time for the words to come back for review. Apparently, according to Memrise the best time to review a word is JUST when you were about to forget it.

This means that, as you are adding new words of vocabulary, the review snowball is getting bigger and bigger and as words return for review, they are starting to clash with other words that require reviewing. Meaning that although you still maintain the 70 words per day, the review pile is going to continue to grow at a very high rate.


The lesson I’ve learned from this is that starting a new language project with vocabulary goals that are too ambitious, will mean that I will be absolutely overwhelmed within just a few days. This could be one of the reasons people fail and give up on learning languages, because they simply get overwhelmed by the amount of vocabulary reviewing they need to do.

So I cut my goal in half, 35 a day. And guess what, it was still too ambitious! Don’t get me wrong, if you enjoy doing spaced repetition for hours and hours a day, and have that time to spare – no problem! Even 70 might be doable for you. But if you like me have trouble focusing on learning vocabulary for long periods of time, and have a ton of other commitments then you might just make the same realisation as me.

I think, for the hobby, part-time language learner, spending more time per word, but trying to learn maybe 20-25 words per day is more than fine. This means that the review snowball doesn’t grow out of control, and you don’t risk having to spend extra time per word, because it was left too long in the review queue. Remember that the optimum time to review a word is just before you forget it, not right after.

In conclusion, I’d like to say that I’m a huge fan of spaced repetition and if done correctly, conservatively and consistently adding thousands and thousands of new vocabulary every year is not difficult. Learning more vocabulary is a compound effect where the more words you know, the more you will understand. Not only of the context the words are in, but you will also understand more of a technical point of view, how the vocabulary is constructed, how the endings work and so on and so forth.

I do all my spaced repetition on Memrise and you can follow me on there by clicking this link, I’d love to follow you back as well. The more people the better!

You can also see my spreadsheet for my Russian Memrise at the end of 2014. I decided to do this, to boost my feeble vocabulary efforts of 2014. However, as I explained in the text, I wouldn’t recommend this “power”-approach. Much better to settle on a modest goal, that you can consistently achieve. As you can see in the spreadsheet I consistently failed my 70>35>30 goals. Note: It's worse than usual at the moment because I'm travelling. Hopefully I can make a comeback when I return to Denmark soon.

I hope you enjoyed this article on spaced repetition, what’s your take on it? How do you learn vocabulary and what is the critical number for you? Please leave your comments below.