What is a spaced repetition system? How does it maintain your knowledge?
Spaced repetition makes memorizing things easy.
The human brain quickly forgets information that is not recalled.
Imagine your memory is a battery. When a fact is added, the battery is fully charged. Over time the battery drains it’s power, until the fact is forgotten.
In 1885, psychologist Hermann Ebbinghaus made an observation while studying his ability to memorize facts. The amount of time to forget a fact decreases with each time a fact is encountered. In other words, each time you remember a fact, your memory “battery” drains slower.
This is the basis for Spaced Repetition System.
You recall learned information just before you forget it, at wider and wider intervals of time, such that retention is maintained.
Software such as Anki takes can take care of the timing with algorithms based on scientific studies of the forgetting curve.
Sources and Further Reading:
Article goes in depth in the scientific literature:
https://www.gwern.net/Spaced-repetition#
