History of spaced repetition

Intro

There is a great deal of mythology surrounding the origins of spaced repetition. This article should trace the roots of key ideas behind the concept.

Printable version

• True history of spaced repetition (final version, supermemo.com)
• True history of spaced repetition (wiki transclusion, live updates, supermemo.guru)

Chapters

Chapters that are missing in the printable version are marked with '*' below.

• 1885-1985: Why spaced repetition research kept failing?
• 1885-2018: History of the optimization of repetition spacing
• 1985: The birthday of spaced repetition: July 31, 1985
• 1986: First steps of SuperMemo
• 1987: SuperMemo 1.0
• 1988: Two components of memory
• 1989: First adaptable spaced repetition algorithm: Algorithm SM-4
• 1989: First fast-converging spaced repetition algorithm: Algorithm SM-5
• 1990: Search for a universal memory formula
• 1991: Employing forgetting curves
• 1994: Exponential nature of forgetting
• 1994-1995: SuperMemo Knowledge Machine *
• 1995: First data-driven spaced repetition algorithm: Algorithm SM-8
• 1997: Employing neural networks
• 1999: Choosing the name "spaced repetition"
• 1994-1999: Inevitability of incremental reading *
• 2000: Incremental reading *
• 2005: SuperMemo Algorithm: 30-year-long labor
• 2013: Algorithm SM-15 *
• 2014-2016: Algorithm SM-17 *
• 2018: Recapitulation of history in SuperMemo Algorithm SM-17
• 2018: History of SuperMemo algorithm *
• 2018: Exponential growth in the adoption of spaced repetition

Color codes

Important notes: the most important ideas are marked in yellow. Those are snippets I want you to remember most from my texts. If you do not have time for reading, reviewing those notes will tell you roughly what I want to say. If you disagree, you can dig deeper in the text to figure out my reasoning

Excerpts: mark the most remarkable or influential words taken from other authors. At times, putting things in my own words would not do justice to the original

Personal anecdote. Why use anecdotes?

Personal anecdotes: if you have an impression that my opinions about education are distorted by my own experience, you are right. I have spent all my professional life on self-directed learning, while my 22 years of formal schooling remained a distant memory. With each improvement to my own learning, I recall those early years with less and less respect to the old ways of learning. My personal notes are marked with this colored template. You can skip them without losing on the message, or dig into my own recall to see how my opinions have been shaped or biased

Anecdote. Why use anecdotes?

Anecdotes: some stories from lives of great and/or ordinary people

Motto: some witty idea or quote from a wise man, usually from ages ago. A quote that sets the theme for a chapter. Those witticisms often help us realize that we are re-learning history over and over again. The ancients knew things many people fail to see today

Metaphor. Why use metaphors?

Metaphors: some ideas are best presented in a metaphoric pop-science fashion. If you fully understand the text, skip metaphors. If you don't or if you are skeptical, see if metaphoric approach is more convincing. Metaphors help you build models that facilitate reasoning

SuperMemo insert. What is SuperMemo?

SuperMemo notes: are relevant only to those who care about SuperMemo. You can skip those inserts without missing main points

FAQ question. What are FAQs?

Frequently asked questions (FAQs): Interesting questions you might have about memory, learning, creativity, sleep, etc.

Archive warning: Why use literal archives?

Archive: Archive materials are presented for historic reasons. They may intentionally include wrong hypotheses or models, e.g. to illustrate the progression of thought

Your Help

If you see errors, distortions, inaccuracies or would like to contribute to this article, write to me