My Comparison Between Anki and SuperMemo

As you probably have read why I switched to SuperMemo, you should know that I’ve transitioned to SuperMemo and no longer use Anki. The content here is partial and completely opinionated (it’s my blog after all), so please take it with a grain of salt. For a more generic (and hence less opinionated) comparison, please read the Comparison Matrix in SuperMemo: First Steps.

Criteria of Comparison

Major Criteria:

1. Incorporation of learning science techniques

2. Learning Tools (Incremental Reading)

3. Platform Support

Secondary Criteria:

4. Subsidiary Support

5. User Interface/User Friendliness

6. Community Support

1. Incorporation of Learning Sciences

From Improving Students’ Learning With Effective Learning Techniques, it is clear that spaced repetition, retrieval practice, interleaved practice are the three big guns for effective and efficient learning. The question is, which SRS has more and a better implementation of these three learning strategies?

A. Spaced Repetition Algorithms

Both Anki and SuperMemo are based on spaced repetition, hence the name Spaced Repetition Software (SRS). Spaced Repetition is the very core of both software. Although they are both the same in nature, the effectiveness and efficiency of the algorithm however, is different.

It’s been 3 months since I’ve written that piece. Nothing has changed. I believe the algorithm in SM-17 is superior than the old one implemented/modified in Anki.

If you have modified any of the Anki’s parameters, any comparison from SuperMemo’s site is not quite applicable. Why? First, changing any parameter in the Anki setting means another modified version of Anki’s modified SM-2. Maybe your modified SM-2 is better or worse than SM-2. I don’t know. Second, the algorithm from Anki’s modified SM-2 is a class of its own. It’s not the same as SM-2. Judging its effectiveness and efficiency against SM-17 based on SM-2 is not applicable.

B. Retrieval Practice

In terms of retrieval practice, there’s nothing to compare in this aspect. Retrieval Practice really is about how you formulate your cards/items to maximize the retrieval practice, rather than the nature of the software. You can do passive re-reading in Anki just as you could in SM. You can use SRS just for spaced re-reading, without any retrieval practice.

C. Interleaved Practice

You may read The Significance of Incremental Reading in SuperMemo: Part II for what I mean by macro- and micro-interleaving.

From Improving Students’ Learning With Effective Learning Techniques, we know that interleaved practice is a better learning technique than massed practice. The discriminative-contrast hypothesis explains:

Interleaved practice helps students discriminate between the different kinds of problems so that they will be more likely to use the correct solution method for each one.

I’m aware that the common definition of “Interleaved practice” means mixing different topics under the SAME subject, not interleaving different subjects together.

Type 1: Micro-interleaving: Interleaving different topics under the same subject:

Algebra, Trigonometry, Calculus. They are all Maths.

Type 2: Macro-interleaving:  Interleaving different subjects together:

Physiology, Maths, Spanish, History

In Anki, it’s harder to do Type 2. If you want to interleave between different decks, there are two options that I’m aware of:

1. Filtered Deck

2. One Giant Deck with a Tagging System

Massed Practice of a Deck but Interleaved Practice of the Deck’s Content

When I was using Anki, I used to organize my decks with sub-decks.

For example,

In Anki, the default behavior is massed practice of decks (you finish one deck then move on to another) but interleaved practice of a particular deck’s content (mixing cards within a deck). For example, when I review the top deck of my Biology deck (with its subdecks), Anki would go through the subdecks alphabetically: When I’m done with Chapter 1, Anki would go to Biology Chapter 2 and so on. This is interleaved practice within chapters (the sub-decks), but massed practice across chapters (they are all Biology)

Interleaving Within Chapters

All the cards in Chapter 1 are mixed, presented according to their retrieval strength and storage strength calculated by the algorithm.

Massed Practice Across Chapters

You go through your review chapters by chapters. You don’t get to review a card from Chapter 3 after reviewing a card from Chapter 1. You have to finish Chapter 1 before moving on.

What is the Problem?

When I review this way, I know that I’m in Biology Chapter 1 and that primes me to recall materials related to Chapter 1. This undermines the power of your retrieval practice. Recall is made easier by priming. All the cards are related, so it’s likely one card will help you recall the answer for the next card. Your working memory from a card you review 2 minutes ago will help this next card. This type of massed practice will help you fly through your review like a rapid-fire fashion, but it doesn’t help with long-term retention and your performance during exam.

Back in high school, my Biology teacher would dish out sorted practice questions. These are sets of practice questions with all similar topics grouped together. So set A is all related to photosynthesis, set B digestive system, set C central nervous system. When I was doing these practice paper sets, I could easily and immediately see the similarities and difference between Q1 and Q2 and so on.

But all those previous questions and solutions were actually hurting my ability to come up with the solutions on my own. These insight was only made possible when questions were presented in such close succession. Being shown “the way” by the previous 10 similar questions, I couldn’t generate the solutions on my own. This is like having a guide to help you walk through the forest vs. having to walk through it on your own.

The value of doing Q1 is high, but the value after Q1 drops exponentially. Why? With such massed practice, answers almost automatically pop into consciousness. I might be exaggerating but I hope you get the idea.

PS: This is one example of well-intentioned teachers helping students during practice but actually hurting their exam performance.

So if you have an Anki deck/sub-deck “Biology: CH 22”, the questions and solutions are presented too closely that undermines the interleaving effect.

From The causes and consequences of reminding.

The goal of understanding is the construction of an integrated representation that combines an input with prior knowledge.

With this deck, you are most likely retrieving relevant information you just saw a few minutes ago, rather than knowledge from long-term memory.

Although longer intervals decrease the probability of reminding, they increase the mnemonic potency of reminding. That is, because more laborious retrieval enhances memory more than easy retrieval, difficult reminding enhances memory more for the reminded (i.e., retrieved) event than does easy reminding.

Thus, the product of reminding can reveal a trade-off between likely and potent retrieval: if the reminding cue is too late, little reminding occurs and consequently little benefit accrues; if reminding is too soon, reminding occurs but the benefits are minimal.

1. Filtered Deck

I tried to fix this massed practice problem with a custom deck. It turned out it was quite complicated:

1. Doing a custom deck will affect the behavior of the algorithm (see Anki manual). The algorithm setting in the filter deck will affect the respective home decks' algorithm. I never figured out how the relay of cards from home deck to custom deck works

2. Concerned with the behavior of filter deck: What if I forgot to clear the filter deck after done?

3. I had a hard time providing a string that was catered to my need

These were all the concerns I had when trying to use a filter deck. I think there was a bug with the relaying of cards from custom deck that it’s now fixed in 2.1? Regardless, I was always paranoid of messing up the algorithm, so I was reluctant and never got to use the filter deck function.

Update:

In 2.1 the new scheduler solves this problem: “When a deck has children, reviews are taken from all children decks at once, instead of showing each deck’s review cards one by one.” see here.

In 2.0, these can be fixed with add-ons:

1. You can use the add-ons Filter Safety for the reset problem.

2. You can use the add-ons Advanced Previewer or Remove “study ahead” penalty (and sort by earliness) × for the learn ahead problem.

3. You can use the the add-on sched_filter_dailydue which ‘Adds the search term “is:today” to the filtered deck creation dialog which includes the following cards all cards due for today, according to each deck’s review limit and all new cards “due for today”, according to each deck’s new card limit’.

2. One Giant Deck with a Tagging System

I resorted to using tags to organize my decks and cards.

This way, I could put everything into the same deck to interleave across subjects. But:

1. I always forgot to tag a bunch of cards before moving them to the main deck, and they were forever lost in the main deck. There were times when I wanted to locate all the cards from a chapter, say, Biology Chapter 22, and it turned out I forgot to tag them. I had to look through the main deck (with thousands of cards) and select them one by one, which was extremely time-consuming not sometimes just impossible.

2. Hard to organize. When I wanted to later add some more cards to Biology Chapter 22, I had to remember to tag them with the correct tag.

My point is, the default behavior of Anki doesn’t support macro-interleaving. The supposed use is micro-interleaving, not macro-interleaving.

Update:

1. For tags the add-on Hierarchical Tags is recommended. Tag entry is much easier with the add-on hierarchical tags subtag_completer so that you get suggestions for tags even if the string you entered doesn’t match the beginning of a used tag.

Interleaved Practice of Decks and Decks' Content

On the other hand, in SuperMemo, the default behavior is macro-interleaving: interleaved practice of all subjects and their content.

In SM, you’re pretty much FORCED to do the macro-interleaving rather than micro-interleaving. The default setting will interleave everything you have in SM.

Anki is micro-interleaving while SuperMemo is macro-interleaving:

Anki: Throwing fruits, such as apples, oranges, watermelons into the blender.

SuperMemo: Throwing fruits, vegetables, potatoes, eggs, honey into the blender.

Yes, you can tweak the setting to do subset learning/review, but it’s not encouraged. Heck, the function to only learn new items from a subset is even removed from a later iteration of SM so that you can’t just interleave across a subject.

Which Type Is Better, Micro-Interleaving or Macro-Interleaving?

I believe macro-interleaving is equally, if not more, beneficial than micro-interleaving. Macro-interleaved practice means that there is more spacing between content from the same subject. The lag effect tells us there is an advantage of spacing with longer lags over shorter lags.

In Anki, you are reviewing in a massed practice fashion: Finish the Maths deck, then Spanish deck, then Physiology deck. Although the content of your Maths deck is interleaved, e.g., mixing triangles, circles, quadrilaterals, you are still doing Maths. Everything is still about Maths. You are staying in the Maths-ville. A village is analogous to a prepackaged schema in working memory.

Meaning of prepackaged schema? From The causes and consequences of reminding.

When you face a situation that you’ve faced many times before, you’ll access a schema that already contains the relevant prior knowledge, inferences, and slots for understanding that particular situation.

You may think of the prepackaged schema as that cluster of neurons to solve all the Math questions in that deck. When you’re doing Maths in a Math deck in Anki, you don’t have to RE-ACCESS and RELOAD that prepackaged schema because it’s already in your working memory.

Micro-interleaving (Massed practice of all triangles –> all circles –> all quadrilaterals) is staying in the Maths-ville.

Macro-interleaving (Interleaving all subjects) is walking back and forth between Maths-ville, Physiology-ville and Spanish-ville.

Are your exercising your ability to retrieve the answers in micro-interleaving? Yes, but not as much as you would with macro-interleaving.

For Mathematics, it is harder to blindly regurgitate the answers when all the solids are mixed; it’s even harder when all the solids are interleaved among other subjects. Without a clear (or at least enough) understanding between the relationships of different solids, the distinctive features of different solids, there is no way you can retrieve the correct solutions for different solids. “I’ve just seen a question similar to this. Maybe that solution should be applicable?” is not quite possible when the similar questions are spaced so far apart across subjects.

On the other hand, in SuperMemo, since it interleaves everything (Maths, Spanish, Physiology), you stay in the Maths-ville for a question, then jump to Spanish-ville for a vocabulary item, then Physiology-ville for an anatomy question.

The “jumping back and forth between different subjects” is paramount. You want to RE-ACCESS and RELOAD a particular piece of information as much as possible. Doing so is a form of desirable difficulty. Desirable difficulty is all about finding encoding or retrieval activities that will make studied materials accessible after a delay. The act of “finding the correct route from Spanish-ville to Maths-ville” is significant. You have to reload all relevant materials from long-term memory to working memory. If you stay in Maths-ville, all those relevant materials are easy to find, if not readily available, in the working memory.

Mini Conclusion

Learning under conditions that force you to retrieve from long-term memory is superior. Macro-interleaved practice in SuperMemo provides stronger encoding and retrieval activities than micro-interleaved in Anki.

2. Learning Tool: Incremental Reading

It’s an unfair comparison. Incremental Reading is a feature of SuperMemo, then it’s obvious that Anki wouldn’t have it.

First, there is an Incremental Reading addon for Anki. Though I’ve never tried it (yet) so I can’t vouch for its validity. I included IR as a criterion because it is a very important feature in reading and learning, as I explained it in The significance of Incremental Reading Part I and The significance of Incremental Reading Part II. Besides, IR is an application of spaced repetition so I hope it’s not too out of line to include this as a criterion.

3. Platform Support

No Cross-platform Support in SuperMemo

SM is only available in Windows. You have to use it on a Windows machine (laptop/desktop). So, no reps on your phone while waiting in line or just to kill time.

Rich Cross-platform Support in Anki

Anki supports pretty much all the platform there is. Heck, it even has support for Windows phone. Desktop Anki is great: It has add-ons for extra functionality; Ankimobile is beautifully crafted by Damien, the creator of Anki; the Ankidroid is managed by another team of Anki users and it provides more than enough functionalities to do your reps on mobile.

Synchronization

In Anki, the most brilliant thing is, you can sync your account across all your devices and platforms. So when you’re done making flashcards on the desktop, you can hit sync immediately, leave home and review your newly crafted cards during commuting.

On the other hand, SuperMemo doesn’t have any synchronization feature. If you want to use SM across Windows devices, you have to back up your collection, zip it, put it in a USB or cloud, then re-import the whole collection to another device. This can get very annoying as your collection grows. Even if you had a Surface Go, who would want to spend 5 minutes every time exporting and importing collection through a USB just to do your reps for 20 minutes during commute?

This round

Anki wins all the way in terms of platform support. No support for Mac in SuperMemo and this alone drive away a lot of potential users. It is a deal breaker for a lot of people. Of course, if I were only allowed to a MacBook, I would install a virtual machine to install Windows just to use SM, but I doubt anyone without being this die-hard about SM would do this.

4. Subsidiary Support

By subsidiary support I mean extensions, addons.

Due to the open-source nature of Anki, there are a wide range of addons you can use to add extra funtionalities to Anki. For example, Night Mode for doing your reps late at night; AwesomeTTS so that you can add TTS inside Anki; The possibilities are limitless. There are over 500 addons for Anki; new and exciting addons are constantly coming out. If you can code in Python, you can even make your own addons to suit your specific needs. Heck, the source code of Anki in on Github. If you can, you can modify your Anki any way you want.

On the other hand, SuperMemo is proprietary. There is no addon support. You can’t change a thing in SuperMemo. For example, I get used to immediately jumping to the next card after grading in Anki. In SuperMemo, after rating, you have to press spacebar to move on. Fortunately, I built a simple AutoHotKey script to do this.

5. User Interface/User Friendliness

To begin with, I don’t think the UI design should be a major criterion, hence it falls under the secondary criteria. Is it really important enough so that you will abandon one over the other because of the UI?

Users complain that SuperMemo has a steep learning curve. They are right. SuperMemo has been optimized to make a life of a pro easy.

The user interface is almost universally recognized as “ugly”. Some people care but I don’t. Ultimately, what’s important is “how efficient and effective this software can help me learn”, not how nice the UI is. I know the UI throws a lot of people off. I do wish I could eliminate some extra buttons like the email and help button. But they are too minor. Besides, it’s easy to mistake the lack of features with elegance or simplicity.

Anki, on the other hand, is more alinged with principles of user interface design. At least when I first used Anki, I didn’t have to Google how to add mp3, but I had to when I switched to SM.

6. Community Support

The community support is proportional to the number of users. I think for every 500 Anki users, there is only 1 SM user. So if everyone is willing to ask your question, you would have 500 replies for Anki and only 1 for SuperMemo.

The r/Anki is very welcoming; there are a lot of active members discussing various topics related to Anki and learning in general. The official support fourm is equally welcoming and active.

SuperMemo Google Group is mostly dead; Fortunately, this Discord channel is the most active platform I’ve visited. By the way, I’ve started r/super_memo. There is also a r/supermemo. They are managed by two different groups of SuperMemo users. Feel free to ask any question there.

Comparion Table

Closing Remarks

Everything is drawn from my 5 years of Anki experience and 8 months of SuperMemo use. I hope the critiera I picked could highlight the major difference between Anki and SuperMemo.