Here's a description of the underlying theory, courtesy of a user of the new Anki FSRS algorithm:
ClarityInMadness wrote:Level 1: Baby Version
FSRS uses a model of memory called DSR - Difficulty, Stability and Probability of Recall, or Retention, or Retrievability if you are Piotr Wozniak, although in his terminology "recall" and "retrievability" are different things...look, trying to come up with a good naming convention can be hard.
R is the probability that a user will recall a particular card on a particular day, given that card's repetition history. It depends on how many days have passed since the last review and on S. What's important is that every "honest" spaced repetition algorithm must be able to predict R, one way or another (even if it doesn't use memory stability). Otherwise it cannot possibly determine which intervals are optimal.
S is memory stability, it is defined as the amount of time, in days, during which R decreases from 100% to 90%. Higher is better. For example, S=365 means that an entire year will pass before the probability of recalling a particular card will drop to 90%. Estimating S is the hardest part, this is what FSRS is all about.
D is difficulty. Unlike the other two variables, difficulty has no precise definition and is calculated using a bunch of heuristics that are not based on a good understanding of human memory. Difficulty is just stuff that goes down if you press "Easy", and goes up if you press "Hard" or "Again".
This model was originally proposed by Piotr Wozniak, the creator of SuperMemo, and a few years ago u/LMSherlock
published a paper where he used this model.
FSRS is a fancy new scheduler in Anki which tries to schedule your cards so that you achieve a particular, desired failure rate—10%, in the above example. This goal here, I believe, is to learn a fixed set of facts in the minimum possible amount of time. And I think this goal makes sense for things like conjugation tables, or for medical students learning the names of the cranial nerves.
But there's a hidden underlying assumption here, and it's a doozy: All facts are equally important to learn right now. Or even worse, this approach assumes that the hardest-to-learn facts are worth a much larger portion of your effort, when compared to facts that you can learn with a modest effort.
And in many cases, I think this is actually a significant mistake. At any given point in the learning process, some things are worth the effort to learn, and some things are better postponed until later. In emergency medicine, there's an idea called "triage". After a major disaster, you often have limited resources, and you want to save as many people as possible. So patients are sorted into four groups:
- Green tag / Minor: These patients are medically stable and usually walking under their own power. No treatment.
- Yellow tag / Delayed: These patients need help, but they can wait an hour or two.
- Red tag / Immediate: These patients need help immediately.
- Black tag / No Further Treatment: These patients are not breathing, even after an attempt to clear their airway. Or they're breathing, and perhaps you could theoretically save them if you had a skilled trauma surgey team and an operating theater. But you don't have either.
The key takeaway: Anki defaults, and particularly FSRS, are optimized for when you don't plan to triage cards.
There are several techniques you can use to tirage cards:
- Grade cards gently, and add hints to make the next review easier.
- Aggressively suspend any card that feels frustrating.
- Set a low "leech threshhold" and configure Anki to suspend leech cards. These are the cards you fail repeatedly.
- Use Hard instead of Again. This is a super-common workaround. It also completely breaks FSRS scheduling, because FSRS is going to optimize until it gets a 10% failure rate.
But why not just... let those cards go? There are plenty of other things you could be learning right now. So let's do card triage. Yes, this is a bit of grim metaphor.
- Green: You either know this already, or you will learn it easily enough by osmosis. No need to make a card. If you do make a card, you can just hit the Easy button a few times and you won't see it for years.
- Yellow tag / Red tag: This material is difficult enough that you probably won't pick it quickly by osomosis (or at higher levels, it's rare enough that you won't see it often). But if you invest a modest amount of effort, Anki will help you learn it.
- Black tag: You cannot reasonably learn this card right now with the resources you have, not without sacrificing many yellow- or red-tagged cards.
So this is what I mean when I keep saying "I treat Anki as an amplifier, not as a list of specific facts to learn." The idea of culling difficult cards—or just passing them along despite technically "failing" them—is a key part of the process.
And as an extra bonus, cutting the difficult and miserable cards can make Anki surprisingly fun. Most of the awfulness of Anki is caused by cards that shouldn't be there in the first place.
(None of this necessarily applies to things like "the conjugation table of ser." It's perfectly reasonable to decide to just learn the entire table, including the hard bits.)
And a video. After all that, let's do a video! This is the song I'm learning now. As my kids would say, "it's a bop."
Notice the lyric at 0:15: Ya no me busques, aquí estoy "Don't search for me, I'm here." If anyone ever told you Spanish was a strictly phonetic language, they're exaggerating. As far as I can tell, that's actually being pronounced Ya no me busquəs‿aqu'estoy or "sac'estoy". As a student of French, I am thoroughly used to this sort of thing. And since I occasionally use chuis for je suis, I have forfeited all right to complain. Not that I'll that stop me.