Scientific and Scholarly Publications

Special thanks to Gwern for organizing and summarizing many of the important scientific contributions to the science of spaced repetition. Here is his summary of spaced-repetition research after extensive review of the scientific literature.

Testing is effective and comes with minimal negative factors

Expanding spacing is roughly as good as or better than (wide) fixed intervals, but expanding is more convenient and the default

Testing (and hence spacing) is best on intellectual, highly factual, verbal domains, but may still work in many low-level domains

The research favors questions which force the user to use their memory as much as possible; in descending order of preference:

  1. free recall
  2. short answers
  3. multiple-choice
  4. Cloze deletion
  5. recognition

The research literature is comprehensive and most questions have been answered – somewhere.

The most common mistakes with spaced repetition are

  1. formulating poor questions and answers
  2. assuming it will help you learn, as opposed to maintain and preserve what one already learned. (It’s hard to learn from cards, but if you have learned something, it’s much easier to then devise a set of flashcards that will test your weak points.)

The critical importance of retrieval for learning “Repeated studying after learning had no effect on delayed recall, but repeated testing produced a large positive effect.”

Test-Enhanced Learning: Taking Memory Tests Improves Long-Term Retention “Testing is a powerful means of improving learning, not just assessing it.”

The Power of Testing Memory: Basic Research and Implications for Educational Practice  “Tests enhance later retention more than additional study of the material, even when tests are given without feedback.”

Test-enhanced learning, Chapter 38 “Test-enhanced learning represents a powerful learning tool that could be utilized to improve medical education. Production tests (e.g. short-answer, free recall or simulation) tend to promote better long-term retention than recognition tests (e.g. multiple choice tests). Use repeated retrieval practice spaced out over time whenever possible, with intervals that are close enough to prevent forgetting but long enough to require some effort to recall.”

Distributed Practice in Verbal Recall Tasks: A Review and Quantitative Synthesis “…spaced (vs. massed) learning of items consistently shows benefits, regardless of retention interval, and learning benefits increase with increased time lags between learning presentations…”

Using Spacing to Enhance Diverse Forms of Learning: Review of Recent Research and Implications for Instruction “Every day students and instructors are faced with the decision of when to study information. The timing of study, and how it affects memory retention, has been explored for many years in research on human learning. This research has shown that performance on final tests of learning is improved if multiple study sessions are separated—i.e., “spaced” apart—in time rather than massed in immediate succession.”

Learning Concepts and Categories Is Spacing the ‘‘Enemy of Induction’’? “Inductive learning—that is, learning a new concept or category by observing exemplars—happens constantly, for example, when a baby learns a new word or a doctor classifies x-rays. What influence does the spacing of exemplars have on induction?…. Surprisingly, induction profited from spacing…”

Is Spacing Really The “Friend of Induction? Yes!


Make It Stick The best review of the science of learning from one of the leading researchers in the field.

Learning How to Learn: How to Succeed in School Without Spending All Your Time Studying; A Guide for Kids and Teens By the creators of the wildly popular free Coursera course Learning How to Learn: Powerful Mental Tools to Help You Master Tough Subjects which has been taken by millions.

Mindshift: Break Through Obstacles to Learning and Discover Your Hidden Potential The latest work from Professor Barbara Oakley

Check out this fantastic compilation of Learning How to Learn Books