Building an Anki System for Life

Long-term, systematic question-answering and contemplation with Anki

Epistemic Status: very high, at the time of writing, I’ve done 17,000 card reviews in Anki and practiced 93% of days over the past few years, and I’ve written 1800 cards to populate my SRS, spaced repetition is a habit in my lifestyle, I’ve comprehensively explored research literature on Anki and spaced repetition

Epistemic Effort: medium, most of the content here is from my PKM notes on spaced repetition, Anki, and memory, I added sections on scope and implementation

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“We learn something not only when we connect it to prior knowledge and try to understand its broader implications (elaboration), but also when we try to retrieve it at different times (spacing) in different contexts (variation), ideally with the help of chance (contextual interference) and with a deliberate effort (retrieval)." - Sönke Ahrens, How to Take Smart Notes

In a previous article, I explored the concept of spaced repetition, a powerful learning technique that involves distributing learning sessions across time to optimize long-term knowledge retention.

I discussed how the traditional approach of cramming information before exams fails to promote effective retention. Instead, spaced repetition offers a more efficient method for retaining acquired knowledge. By repeatedly retrieving information in spaced intervals, the forgetting curve is disrupted, leading to enhanced long-term retention.

Building upon the principles of spaced repetition, I will now delve into the topic of spaced repetition systems (SRS). These systems provide a concrete approach to implement spaced repetition in your learning workflow.

By incorporating active recall and adjusting the spacing intervals, spaced repetition systems offer a powerful tool to improve long-term retention and maximize learning outcomes.

I will primarily focus on Anki, the most popular spaced repetition system and the one I’ve personally used for years, and discuss how one can be quite creative with their SRS design, as well as review some research on the impact of Anki on student performance.

What is Anki?

Anki combines the two most effective learning techniques backed by research: spaced repetition and active recall.

The algorithm runs an expanding relative spacing schedule, meaning the interval between cards up for review increases over time. If I wait 2 days to review a card and successfully retrieve the information, then the next time I review the card might be in 4 days. In this case, the spacing interval increases by 100%.

Another unique property of the algorithm is that it takes into consideration how easily the user is able to retrieve information. If the retrieval is relatively easy, then the time until the next review experiences a greater increase, as opposed to a more challenging retrieval which would result in a smaller increase in the spacing interval.

The actual details of how Anki's algorithm works are beyond the scope of this note, but a solid introduction to it is provided by Zach Highley. You can also spend $5 on the Anki Essentials Guide.

The Scope of an SRS

I want to emphasize that an SRS can have any scope you want. Think bigger than what it has historically been used for. When I tell people I use Anki, they sometimes respond “Isn’t that for medical students?” (medical students love to use Anki to study for exams). I reply, “Not at all. I use it to take a daily test on all my knowledge” (which is then typically met by a hilariously confused look on their face).

That’s the scope I set for my SRS–a test for everything.

I test myself on the theses of books I’ve read, math problems, operating the command line on a computer, insights from podcasts, a historical event, a technical concept, Stoic literature, and even my opinions on deeply philosophical questions like, “Why is it important to cultivate more discipline as you become more successful?” (an actual question in my system).

While it’s important to be creative with your SRS scope, you also have to be economical with what you put in it. Of course, I don’t just throw every random fact in there to test myself on it. I am careful to craft meaningful questions that I genuinely think are relevant for me to know or contemplate in the long term.

But don’t let that slow you down when writing questions, you can always suspend a card in Anki if at some point you realize it’s actually not relevant anymore (I do this ALL the time).

So when setting the scope of an SRS, think more about the objective of what questions and prompts you want to interact with on a periodic basis.

• Is this a short-term goal or a long-term goal? (you can have decks for both with different spaced repetition parameters)

• Do I want to contemplate an opinion?

• Do I want to memorize an important fact?

• Do I want to test a skill relevant to my job?

• Do I want to stay prepared for technical job interviews?

One dichotomy that’s worth digging into is that of memorizing vs understanding. I dedicate the next section to dispelling some counterproductive perspectives on flashcards and memorization.

Memorizing vs Understanding

"How we perceive the world and how we act in it are products of how and what we remember." - Joshua Foer, Moonwalking with Einstein

Flashcards tend to receive a negative connotation because they are associated with rote memorization, but there are two issues with this point of view.

1. Memorization is vital to learning. Memory forms the bedrock of understanding, and should not have a negative connotation. Understanding a domain requires an initial period of memorizing concepts, and out of that conceptual layer, you start to form connections, integrate the concepts, apply them (do), and arrive at understanding.

2. Flashcards are not for memorization. They can be used for memorization, but can also be used for understanding. It’s up to the user to decide how to use the tool.

The reason information may go "in one ear and out the other" is that the brain lacks the appropriate internal representation of the subject of such information. Memorization allows you to store an interconnected set of facts and concepts in your brain that you can use to contextualize new information. In order to build a network of knowledge, you need to have an initial set of nodes to connect to new incoming nodes, and that's where memory comes in.

Facts are a precondition to understanding, but they are not themselves understanding.

So I make sure to test both memory and understanding in my Anki system.

The line between testing rote memorization and testing understanding is a bit blurry in the center, but here is how I think about it when populating my SRS with content.

• A flashcard is just a prompt or question. It’s like someone asking you a question, and you have to think and provide a response.

• Given a flashcard is just a prompt or question, we can be deliberate about the type of question or prompt based on the learning objective.

• To test rote memorization, you ask closed-ended questions such as “What year did X happen?” or “Name the part of the body that is responsible for X?” There really is only one answer, and thus the domain of answers is finite.

• To test understanding, you ask more open-ended questions that prompt you to explain a concept or solution. For instance, “Explain the concept of supply and demand in economics and how it influences market prices.” This requires a basic factual understanding of what supply and demand are as concepts, but the question builds on those facts to test understanding of how those concepts relate to market prices.

Questions can be whatever you want. They could prompt you to solve a math problem, write a piece of code, or provide an opinion. The more open-ended questions are interesting because my answer will evolve over time as I absorb more knowledge and gain more experience.

For example, I have a very broad question, “What is data science?” (my career), and that’s really just an opinionated question, but I like to prompt myself on a scheduled basis so I think about it and see how my thoughts have changed since X months ago.

I also have a deck I call “Skill Tests” that prompts me to practice a skill to solve a problem or provide an extended explanation of something. These questions can last much longer, anywhere from 10-30 minutes, so I only do one a day, but they truly assess my understanding because there is no way I could memorize such a long and complex response. I even find sometimes I arrive at the answer using a different path than the solution I initially devised.

Cultivating Humility

I find an SRS keeps me well aware of what I think I know that I don’t actually know. There is a concept from psychology called the illusion of explanatory depth. It’s the idea that we overestimate our understanding of a concept such that we can't explain it as well as we think. I like to craft questions that combat this overconfidence bias by prompting me to explain a concept that I feel I truly understand.

Literature Review

As with my pieces on spaced repetition and active recall, I like to present some of the research findings.

Research has shown Anki to be an effective learning tool. A study on the use of Anki flashcards in a college anatomy class found the software reduced self-reported anxiety in a majority of the students and that 83% of students found the flashcards helpful.¹

A paper published in the Journal of Surgical Education found the amount of time orthopedic surgery trainees spent on Anki flashcards had a strong positive correlation with their performance on the orthopedic basic sciences examination.² In fact, 100% of those who used Anki for at least an hour in total passed the exam, which has a national pass rate of 67%.

Additionally, research on retrieval practice in medical students found the use of user-generated Anki flashcards to be a predictor of Step 1 scores.³ In their abstract, the authors state:

"Medical students engage extensively in self-initiated retrieval practice, often with spaced repetition. These practices are associated with superior performance on a medical licensing examination and should be considered for formal support by educators."

Interestingly enough, the same study found the use of Firecracker flashcards (commercially available) not to be a predictor of Step 1 score, which may indicate that user-generated flashcards result in greater retention compared to pre-built decks, or Anki's expanding spaced repetition algorithm is superior in increasing retention.

Implementation

Anki Configuration

Here is the Anki configuration I use for my master deck, which is the one I use for long-term knowledge retention.

Extensions

One of the advantages of Anki is the plethora of add-ons you can use. Here are the add-ons in my personal SRS:

• AnkiConnect - An API that allows other systems to create cards in Anki, I use this for my Obsidian integration.

• Custom Background Image - Customize the background image of the Anki system (I’ve got a mathy background since a lot of my questions are on mathematics).

• Image Occlusion - An add-on for testing visual memorization, it allows you to mask parts of an image.

• Review Heatmap - Data visualization of your historic reviews by day.

Obsidian Integration

I don’t use any pre-built decks. Everything is hand-crafted, and all of my Anki cards are created from within Obsidian. You have to install the Obsidian Anki plugin and the AnkiConnect add-on for this to work.

I like this setup because it allows me to write and modify cards from within my PKM system. My typical workflow is to flesh out a note on a topic, and then “Ankitize” that note (a verb I came up with to describe the process of crafting meaningful questions to test myself on the salient information in that note). My standard note template has the Anki Deck syntax already defined at the bottom, and I have templates for all card types.

If I write a lot of Anki cards (3+), I will roll them out to my SRS gradually over time. That’s because I want to spread the tests out over time rather than get hit on the same topic all at once. It’s pretty simple to do this. I just prefix the card template with a backslash “\” so that the Obsidian_to_Anki plugin won’t pick it up, I add an “_unlock” tag, and then I search for the “_unlock” tag to see all the notes that still have Anki cards to be released. I try to keep the daily count to 20 cards in my primary deck, so if I have less than 20, I’ll release some cards from my vault until I hit 20.

Tag Structure

Anki makes use of tags to categorize your cards. This makes it easy to do a custom study, where you test yourself on specific topics by selecting the relevant tags, but you can use it for any organizing principle. I use tags for topic categorization and marking cards that I learned in graduate school. Tags can also be hierarchical, so you can nest lower-level tags under higher-level tags if you want different levels of granularity.

Workflow

Anki is an essential part of my learning workflow. Almost any learning activity ends with me writing Anki cards to ensure I revisit the information or skill in a systematic way.

• I like to keep my Master deck around 60 seconds per card.

• My Skill Tests deck has much longer response rates, anywhere from 1 minute to 25 minutes.

• I aim to hit about 20 cards from Master every day, and 1 card from Skill Tests every day.

• Anki is a morning habit for me, it’s part of my morning routine.

• To enhance learning, consider doing 10 minutes of meditation afterward or a cold shower.

• I’ve practiced 93% of the days since 2021. I miss 7% of days due to vacation or abnormal circumstances.

Statistics

Anki has a very nice stats tab that visualizes the state of your system. I like to look at the Card Count pie to see the breakdown of my cards by state.

Conclusion

In conclusion, Anki is a powerful spaced repetition system that combines the effectiveness of active recall and expanding relative spacing. The flexibility and customizability of Anki allow for scalable learning, as the spacing between reviews increases over time, accommodating the addition of new cards without sacrificing retention.

I also discussed how flashcards are not just for memorization but can also be used for understanding. Memorization is important for building a foundation of knowledge, which allows for contextualizing new information.

I have a lot more writings in the works on the topic of building systems to improve cognitive performance, so stay tuned :)

References

1. Rana, T., Laoteppitaks, C., Zhang, G., Troutman, G., & Chandra, S. (2020). An Investigation of Anki Flashcards as a Study Tool Among First Year Medical Students Learning Anatomy. The FASEB Journal, 34(S1), 1–1.

2. Anton Lambers, Adrian J. Talia. (2021). Spaced Repetition Learning as a Tool for Orthopedic Surgical Education: A Prospective Cohort Study on a Training Examination. Journal of Surgical Education.

3. Deng, F., Gluckstein, J., & Larsen, D. (2015). Student-directed retrieval practice is a predictor of medical licensing examination performance. Perspectives on Medical Education, 4(6), 308–313.