Distributed Practice in Verbal Recall Tasks: A Review and Quantitative Synthesis

Author: Nicholas J. Cepeda, Harold Pashler, Edward Vul, John T. Wixted, Doug Rohrer · Type: academic · Status: draft · URL: https://augmentingcognition.com/assets/Cepeda2006.pdf

Licence: APA copyright (Psychological Bulletin 132(3), 354-380, 2006); publicly mirrored PDF; abstract and short quotes citable with attribution, do not republish full text

Summary

The foundational meta-analysis of the spacing effect, synthesizing 839 assessments of distributed practice from 317 experiments in 184 articles on verbal recall. It confirms that spaced study reliably beats massed study and, crucially, that the interstudy interval (ISI) producing maximal retention grows as the retention interval grows: there is no single best gap, it depends on how long you want to remember. It also notes prior reviews found the spacing benefit especially for verbal tasks including foreign-language learning, and that intervals can become too long. This is the deep evidence base under any spaced repetition scheduler, including FSRS-style adaptive interval optimization.

Insights

• The spacing effect is one of the most replicated findings in memory research: this meta-analysis alone covers 839 assessments of distributed practice across 317 experiments in 184 articles. (high, draft) spaced repetition memory meta-analysis

  This review found 839 assessments of distributed practice in 317 experiments located in 184 articles. — Abstract, p. 354

• The optimal gap between reviews increases with how long the material must be retained, which is the theoretical justification for adaptive interval schedulers rather than fixed review calendars. (high, draft) spaced repetition memory product design

  Analyses suggest that ISI and retention interval operate jointly to affect final-test retention; specifically, the ISI producing maximal retention increased as retention interval increased. — Abstract, p. 354

• Prior quantitative reviews found that increasingly distributed practice yields larger effects specifically for verbal tasks such as foreign-language learning, though effects follow an inverse-U so intervals can become too long. (high, draft) spaced repetition vocabulary memory

  Overall, Donovan and Radosevich found that increasingly distributed practice resulted in larger effect sizes for verbal tasks like free recall, foreign language, and verbal discrimination, but these tasks also showed an inverse-U function, such that very long lags produced smaller effect sizes. — Past Quantitative Reviews, p. 355