Spaced repetition is one of the most efficient ways to learn new things. (For research citations, see 'Study methods', here.)

The best way to practice spaced repetition is to install Anki to your phone, since you have your phone with you all day long.

I have an Android phone, so here's my 60-second guide to getting started with Anki on Android:


  1. On your Android phone, open 'Market.'
  2. Search for 'Anki'.
  3. Install the 'AnkiDroid Flashcards' app.
  4. In your app drawer, run 'AnkiDroid'.
  5. It will prompt that you don't have any decks downloaded. Tap 'Download deck' and choose 'Shared decks.'
  6. It will take a while to bring up the list of decks available online. Search for 'Less Wrong' and you'll see the deck called 'Less Wrong Sequences.' Download it.
  7. Go back to the AnkiDroid main screen, choose 'Load other deck.' Choose 'Less Wrong Sequences.'
  8. Set your options for 'New cards per day', 'session limit (minutes)', and 'session limit (questions)', then tap 'Start Reviewing.'
That's it!
(This full process will take longer than 60 seconds because of download speed, but will probably require only 60 seconds of interaction with the phone.)


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25 comments, sorted by Click to highlight new comments since: Today at 3:20 PM

Spaced repetition is one of the best ways to learn new things. (For research citations, see 'Study methods', here.)

IMO, you do have citations there, but no real background. I flatter myself that is a good discussion for those not already familiar with SRS.

I started using Anki daily around 3 weeks ago. I made myself a 'general' deck for inputting whatever random things I want to have in my memory. I've put in some simple mathematical definitions and productivity stuff like Czikzsentmihalyi's list of identifying features for flow. I'm planning on trying to read Penrose's The Road to Reality, Lawvere's Conceptual Mathematics and Gelman's Bayesian Data Analysis and making cards of the memorizable stuff like formulas and definitions and see how that goes.

The phone is no good for writing new cards, so you'll want the deck on a PC as well, and then you'll be wanting an easy way to synchronize between the two. An ankiweb account does this very nicely. Of course you can just manually pass the .anki deck file between the phone and the PC as well.

I've also picked up premade decks for the Lojban language gismu root words (gismu by frequency), the pubilic Heisig Kanji deck and a hiragana/katakana deck. I've set these to add 10 new words/symbols per day. Textbook stuff is hard to understand by just grabbing some other person's deck, but basic foreign language vocabulary is much more context-free, so it's easy to do with the premade decks. (It's a good idea to have read through Heisig's mnemonic guide for the kanji before drilling them though.) After a week of drilling the hiragana, I can now recognize most of the alphabet without aid. AnkiDroid also has a whiteboard function which lets you draw the kanji/kana before showing the answer, which is quite handy.

Doing the vocabulary stuff feels quite effortless now, more like playing a casual game than doing work. The SRS takes care of boring stuff like figuring out what needs reviewing and keeping track of the materials, and I just need to come up with weird mnemonics for stuff.

Anki has support for embedded Latex, and doing mathy stuff will probably involve using it sooner or later. You need a PC with Latex installed to generate bitmap files for the cards from the formula markup. The phone can't do this, so you'll need to transfer the PC-generated formula images over.

Anki on PC supports having your media in a Dropbox account. Dropbox support is apparently forthcoming for AnkiDroid. In the meanwhile, you'll want an Android program that downloads entire Dropbox folders, like dropboxdownloader and manually download the png directory from your Dropbox account.

The generated formulas are also likely to have too large a DPI for an Android device. I got the Configure latex plugin for Anki from Anki's Download plugin menu command, and edited the DPI value in file plugins/Configure to 100 from 150. (The settings line looks like latex.latexDviPngCmd = ["dvipng", "-D", "100", "-T", "tight"] after editing.)

I tried fiddling with the latex plugin on my computer, but still can't get the latex to show up on my phone - I see either boxes or boxes with question marks in. Any idea how to fix this?

Check your phone with a file manager application. Is there a directory AnkiDroid/ on the sd-card of the phone with the same set of png-files generated from the latex as there is on the PC?

No, though actually there are other media folders for different decks than the one I wanted to use, which it seems work fine, so I will delete and re-add this deck. Thanks.

sequences are too conceptually complex for SRS to work well with. On the other hand the Biases and Fallacies deck is fantastic material.

Does anyone have a list of decks of interest to Less Wrongers?

Go to File > Download > Shared Deck.

Search for "less wrong".

You should have Divia's deck for the Mysterious Questions sequence come up.

That's the one I mention in the original post, but I suspect there are others.

Oops! I already have Anki running, so I only skimmed the original post, and I must've missed it. Plus, I've heard of Divia's deck from an alternate source (IRC), so it wasn't intentional redundancy.

Other than Divia's deck, the one Nazgulnarsil is talking about is available by searching for "List of Cognitive Biases and Fallacies". I'm not aware of any others.

On a related note, the titles of your Anki posts seem incomplete. It might be good to mention the LW-specific deck, since you make it part of the instructions and because it could be a major incentive to start using Anki for some of the people here.

  1. On your Android phone, open 'Market.'
  2. Search for 'Anki'.
  3. Install the 'AnkiDroid Flashcards' app.

Only makes a slight difference, but you can also install apps via the Market website, so you can give a direct link to the AnkiDroid Flashcards app. However, it does depend on the version of Android you're running for remote installs.

Spaced repetition is one of the best ways to learn new things.

I'd qualify that with "most efficient", but probably not the most enjoyable, and it doesn't work for learning to understand conceptually complicated or nuanced stuff better. For these reasons, it's better to read three textbooks on the same topic (that use different presentation, and are on different levels of difficulty) than to memorize all the formulas or definitions.

Having just worked through one statistics course with Anki, and having worked through parts of one machine learning and one algorithms course, I disagree. Anki is great for learning conceptually complicated material, because such material tends to be composed of a large number of elements that build on each other. For the more complicated parts to make sense, you need to remember and comprehend all of the less complicated parts that it builds on. Spaced repetition helps ensure you really do remember all of them.

I also find that memorizing various formulas is actually very useful for one's comprehension. In order to remember a large number of them, you have to think about their contents: "I think the formula went... no, wait, that doesn't make sense, so what would?" In effect, you learn to quickly rederive the formulas each time you're prompted about them, until finally you know them so well that you don't need to think about them.

Doing it this way, you also start to notice when you don't really understand how a formula works. The formula looks like this, but why? You start to think about it on and off over a span of several days, or you might go looking for the answer. Some of the formulas used in the statistics course I did involved using concepts which were never really explained within the course itself, which started bothering me. So I looked them up on Wikipedia, and after having looked up those concepts, made new cards about them. This gave me a broader understanding about the topic than I'd have gotten from the course itself.

(Some of those new cards I made involved getting to the old to-be-memorized formula from the new knowledge I'd picked up. For instance, I edited a "the formula for judging a hypothesis about the variance of a normally distributed variable" card to a "from the knowledge that the chi squared distribution is a distribution of the sum of squares of n normally distributed variables, derive the formula for judging a hypothesis about the variance of a normally distributed variable" card.)

I also find this to be more enjoyable than the traditional process. Previously, if I was reading some conceptually advanced text, I had to spend a lot of effort into both understanding it and remembering it. Now it's enough that I understand it well enough to make Anki cards out of it. On this "knowledge extraction pass", I don't need to worry too much about whether or not I understand some particular formula or algorithm. That will come later. I just enter it into a card, though frequently I do need to think about it somewhat in order to make sure that the answers and questions I'm typing make sense. Then when I'm actually memorizing the cards, it doesn't feel like it took a lot effor either, because the knowledge comes in small-sized chunks (even if they actually do connect to a lot of other information). Somehow this tricks my brain into learning vast amounts of information without it ever seeming like work.

Also, learning more and more cards triggers in me the same kinds of reward mechanisms that are activated by gathering experience and leveling up in video games, which helps make it feel more enjoyable. On some occasions, I've been known to go through a day's cards, be disappointed that I ran out of them, and then work ahead in a book just so I could make myself new ones to memorize. Partially because of this, I've picked up a habit of entering the content of any non-fiction book I read into Anki cards.

The role of Anki cards that force you to remember where a formula came from and why is usually played by the deeper material that builds on the earlier material. The trick is to reinforce understanding of the earlier material every time you use it, instead of relying on a reference or trusting the textbook. There certainly is a bit of an art to learning from textbooks on one reading.

On the other hand, adding a spaced repetition deck for the new material to your schedule permanently could keep the material from fading from memory in the long run, something that's hard to manage otherwise if you don't use the material regularly.

There certainly is a bit of an art to learning from textbooks on one reading.

Sounds more like magic to me. I've seen research quoted recently that indicated people retain only about 2% of a book after a month of reading it through once.

Edit: Further elaboration, prompted by the downvote:

How do you reinforce understanding of earlier material without referring back to it?

And if you do refer back to it, can it still be called one reading?

Plus, If you periodically expose yourself to the same information multiple times, it's not much different from using a SRS, though one could claim it's less efficient, especially in the long run.

The sentence I quoted seemed to be making a claim for eidetic memory, hence my skepticism.

How do you push content to Anki effectively? I've been thinking about using it to study too, for example scientific papers (with lots of equations), but copying content by hand seems to be tedious... I also thought about converting them to images and then slicing them up, but that doesn't seem to be the best choice for a small phone screen. Or how do your decks look like?

A sample deck made up of my "psychology", "operating systems" and "machine learning" tags.

Note that some of those cards are old, and pretty bad: e.g. I have a card saying "name three things that villain hysterias have in common". I should have broken that up to three separate cards, each of which listed two of those things and told me to fill in the third. And that's what I've done with some of the later cards. It's also worth noting that I probably did too many operating systems cards when studying for that exam - while I aced it, it was so much work that I've been reluctant to touch Anki afterwards, and currently have around 700 due cards...

cool thanks! It's nice to have a look at a real-world example too... (btw do you do the breaking-up of cards by hand or using some plugin?)

Meanwhile, I started experimenting with using screenshots from pdf fiiles (equations, mainly) and dropping them into anki cards. It seems to work well so far and it's faster than I thought (though I haven't yet tried actually studying them, not to speak of doing it on a phone...)

(btw do you do the breaking-up of cards by hand or using some plugin?)

Entirely by hand.

What sorts of "new things" are we talking about? Can you use this to (for instance) teach yourself how to do hard things? Examples of things I consider hard. Second quantization. Programming. Writing novels people want to buy.

One basic problem I've noticed when trying to do new, hard things is that I have great trouble gathering the unfamiliar concepts needed to work with the thing to my mind. There's a novice level where a thing is hard, and I can't work on the thing without having a bunch of reference material at hand, since I can't recall a suitable number of prerequisite elements from memory. This was most of my experience with nontrivial university studies. Then there's the level where you do have the basic stuff pretty much loaded to your head, but the thing is still hard because it just plain requires insight and cleverness.

SRS is supposed to help with the first level of problem. I've got no idea what second quantization involves, but I'd assume being able to perfectly recall from memory the formulas on the wiki page would be some help with it. Programming does tend to involve clever things, but you could cram language syntax, standard library APIs, design patterns and other code idioms with SRS, and would probably have a lot easier time with the hard stuff.

Writing novels probably has the largest ratio of needing to be clever to leveraging fixed crunchy bits. You could drill in some Strunk & White equivalent to help with language, but that would probably be a pretty marginal help. Suppose you're doing some sort of background research for a historical novel or something though, SRS could help you get that stuff committed to memory. Also just having a lot of stuff recallable and combinable at will would probably help in coming up with plots.

Did it, cheers! The name of the app I found in the market was:

AnkiDroid flashcards (Nicolas Raoul)

Is the name of the App AnkiDroid flashcards?