US Military use a Spaced Repetition System in the form of a flashcard app (retrieval practice)
Jeopardy! winners who publicly stated they used Retrieval Practice / Spaced Repetition System “Anki flashcards”:
Spaced Repetition:
1. “There is considerable evidence, gathered in a variety of settings and across many different types of materials and procedures, that spaced repetitions are a highly effective means of promoting learning.” Dempster, F. N. (1989). Spacing Effects and Their Implications for Theory and Practice. Educational Psychology Review
2. According to Donovan and Radosevich’s meta-analysis of spacing studies, the effect size for the spacing effect is d = 0.42. This means that the average person getting distributed training remembers better than about 67% of the people getting massed training. Donovan, J. J., & Radosevich, D. J. (1999). A meta-analytic review of the distribution of practice effect: Now you see it, now you don't. Journal of Applied Psychology
3. “The spacing effect—that is, the benefit of spacing learning events apart rather than massing them together—has been demonstrated in hundreds of experiments, but is not well known to educators or learners.” Kornell, Nate. (2009). Optimising learning using flashcards: Spacing is more effective than cramming. Applied Cognitive Psychology.
4. Bahrick, H. P., & Phelps, E. (1987). Retention of Spanish Vocabulary Over 8 Years. Journal of Experimental Psychology: Learning, Memory, and Cognition. In this study, subjects who practiced recalling the words with the longest interval between practice sessions performed the best after 8 years. This shows that Spaced Repetition with expanding intervals is not only more practical, but also superior in terms of efficacy.
Active Recall / Retrieval Practice
1. One week after learning new words in Swahili, students who’d used Retrieval Practice remembered on average ~80% of the vocabulary, versus ~35% for the students who had reviewed the words more traditionally. Karpicke, Jeffrey & Roediger, Henry. (2008). The Critical Importance of Retrieval for Learning. Science (New York, N.Y.)
2. The effect works for people of all ages: this study verifies that the testing effect (aka Retrieval Practice) in older adults has similar effect size as younger. Meyer & Logan 2013, “Taking the Testing Effect Beyond the College Freshman: Benefits for Lifelong Learning”
3. “Over the last century hundreds of studies have demonstrated that testing is an effective intervention to enhance long-term retention of studied knowledge and facilitate mastery of new information, compared with restudying and many other learning strategies” Yang, Chunliang & Luo, Liang & Vadillo, Miguel & Yu, Rongjun & Shanks, David. (2021). Testing (quizzing) boosts classroom learning: A systematic and meta-analytic review. Psychological Bulletin.
4. “More than a decade of research has supported a robust consensus: Acute stress impairs memory retrieval. […] Participants who learned by restudying demonstrated the typical stress-related memory impairment, whereas those who learned by retrieval practice were immune to the deleterious effects of stress.” Smith, A. M., Floerke, V. A., & Thomas, A. K. (2016). Retrieval practice protects memory against acute stress. Science.
5. “Repeated study of previously recalled items did not benefit retention relative to dropping those items from further study. However, repeated recall of previously recalled items enhanced retention by more than 100% relative to dropping those items from further testing. Repeated retrieval of information is the key to long-term retention.” Karpicke, Jeffrey & Roediger, Henry. (2008). The Critical Importance of Retrieval for Learning. Science (New York, N.Y.).
7. The findings are rock-solid: the following is an extremely thoughtful, carefully conducted meta-analysis about the effects of Retrieval Practice: Agarwal, P.K., Nunes, L.D. & Blunt, J.R. Retrieval Practice Consistently Benefits Student Learning: a Systematic Review of Applied Research in Schools and Classrooms. Educ Psychol Rev
8. Finally, the idea is centuries old. Consider the following statement: ‘Exercise in repeatedly recalling a thing strengthens the memory’. Although this quotation sounds as though it could come from a recent piece of research, it is actually from Aristotle’s classic treatise on memory—De Memoria et Reminiscentia. It seems, once again, that scientific research merely confirms what philosophers had posited hundreds of years ago.