spaced repetition

A learning technique involving study at increasing intervals, aimed at improving recall rates while reducing required study time. Some variation of this is used by learning applications like Anki or SuperMemo as well as online learning platforms like Duolingo.

Wikipedia has more details. See also distributed practice effect, which lists some related terminology.

Title Type Date Names Characters Series
The Spacing Effect: A Case Study in the Failure to Apply the Results of Psychological Research JournalArticle 1988 Frank N. Dempster
A Trainable Spaced Repetition Model for Language Learning JournalArticle 2016-08 Brendan Meeder, Burr Settles