Learning about Spaced Repetition, SuperMemo, Org-drill, et al.

I have been reading a bunch of articles on the SuperMemo site (including the original thesis of P. A. Wozniack, the creator of SuperMemo). I initially started off trying to understand the algorithms SM2,5 and 8 which org-drill implements, but reading the articles has given me a lot of general background and theory on how memory works, and why SuperMemo is as effective as it is (for those who stick with it). This blog post is an attempt to summarize and capture what I have read in all those articles, and not get lost in them. I would recommend reading the thesis and the suggested reading there, yourself, but if you really don't want to – this blog post + the summary in here, and here would be a good alternative.

  • Memory works by repetition. Each time you recall a fact, the time it takes for the memory to fade increases. Spaced repetition is the idea of repeating items, just when you are about to forget them – trying to optimize the time spent on learning, as well as the retention of learned material.
  • Prioritization of the items we need to learn is key to being able to stick to Spaced repetition. Beginners tend to be over-enthusiastic about the technique and fill up their system with stuff that they don't really care about. Applicability of the knowledge you are trying to gain, is a good test for whether or not it goes into your system.
  • Each version of SuperMemo comes with a slightly modified (on most occassions, improved!) algorithm. SM2, SM5, … refer to these algorithms. Org-drill currently supports only sm2,5 and 8. It may be worth looking at sm15/16 and seeing if it can be implemented and is worth doing. In any case, using any of these is way better than not using Spaced repetition at all.
  • Understanding what we are trying to learn goes a long way in helping memory. It is, therefore, good to start with basic material. People have been surprised by how easily the advanced stuff fell into place, once they had the basics covered.
  • Keep items in the system simple. Stick to the minimum information principle. Keeping it simple, doesn't mean you leave out on learning the complex stuff; instead break it into simpler components. Simpler items has the following advantages:
    • Simple is easier to remember.
    • Simpler items are easier to schedule. You get more resolution to figure out what the problem areas are.
    • Simple makes brings in redundancy automatically. And redundancy is good for memory, just like it is for managing hardware failure.
  • Keep learning fun! Don't make review sessions a chore. Think about the material you are reviewing. Edit/delete/improve items based on your reviews, then and there. Stay active.
  • It is useful to add a link to the source of the items added to your system, considering that you wish to use the system over a long period of time (ideally, the rest of your life!)
  • Prioritize, add examples, appeal to your emotional state, link to existing knowledge, use images. Anything else that works for you! Use all of these techniques, that work well and you probably already use in everyday life, in the items you add to your system, to make them easier to recall.
  • Being physically fit and healthy is important for being so mentally. Exercise, sleep, eat well, avoid caffeine.
  • Try incremental reading, as an input source of items into your memory system.