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Distributing tests over time helps learning facts and concepts and applying them. A recent meta-analysis supports the use of this learning strategy and suggests that it does not matter if the time between tests remains stable or increases until the final test, the important thing is that the tests are separated in time.

Distributing study and retrieval practice (testing) in time benefits learning, but are there better and worse schedules for study and test? In a recent article, Alice Latimier, Hugo Peyre, and Franck Ramus of the University of Paris published a meta-analysis of studies that looked at the educational benefits of spacing out episodes of retrieval practice. The conclusion is that spacing retrieval of the same content increases learning, regardless of how one plans that spacing.

The fact that retrieval practice—testing the information to be learned—benefits learning is already a well-established idea. Recent meta-analyses have shown that this strategy improves the learning of complex topics, both in classrooms and in the laboratory, and at various levels of education and areas of study. If retrieval practice is combined with the distribution of retrieval moments in time, that is, if we introduce intervals between tests on similar content, instead of studying or testing the content in block, retrieval practice seems to become even more powerful.

One of the explanations for the success of spacing is the increased difficulty of retrieval: this leads to the student having to make a greater effort to remember the content to be learned, which, in turn, makes their retrieval more active, helping them to remember the content better and create more links between contents, improving understanding. Another explanation could be that changing contexts (mental states, environment, etc.) in which retrieval occurs, if spaced, creates more recovery tracks that can be used in the future.

Despite these well-established benefits, there were still two questions that needed to be clarified:

  1. what are the benefits of spacing retrieval practice?
  2. Is it better to expand the spacing (increase the spacing progressively until the final test, for example: tests on the same content are initially spaced a day, then a week, then a month) or maintaining a uniform spacing (for example, all tests spaced a week)?

To answer these questions, Latimier and his colleagues did this meta-analysis. To maximize the relevance of their results in educational contexts, the researchers focused only on studies with semantic and verbal stimuli (including math problems) and excluded studies that involved perception or motor skills. After searching scientific databases for articles published until 2017 that included spacing manipulations and allowed answering the aforementioned questions, Latimier and colleagues were able to find 29 studies for their meta-analysis. Of these, they extracted 39 comparisons of interest relating to the first question and 54 relating to the second.

Results indicated that spacing retrieval practice clearly leads to greater learning than massed retrieval practice (blocked contiguous tests). The average aggregate effect of this difference is considered high. However, there are no differences between expanding or standardizing the spacing between tests. Latimier and colleagues also examined factors that may contribute to different spacing outcomes. This analysis revealed that when participants were exposed more than four times to the same content, expanding the spacing was slightly more beneficial than keeping it uniform. The reported results were not influenced by other factors, such as the level of education of the participants, the type of tests used, providing feedback, or the type of material studied.

What do these results mean for practice? Testing students frequently and temporally spacing their exposure to the same content or tests appears to be a powerful strategy for increasing learning. And how this spacing is implemented does not appear to be very important. Nevertheless, the authors of this study draw attention to the need for more experiments with different spacing schedules between both study and test, to assess whether there are spacing schedules more beneficial than others. For now, it seems that as long as there is spacing, learning can improve.


Adesope, O. O., Lavin, T., Thompson, T., & Ungerleider, C. (2010). A systematic review and meta-analysis of the cognitive correlates of bilingualism. Review of Educational Research80(2), 207-245.

Agarwal, P. K., Nunes, L. D., & Blunt, J. R. (2021). Retrieval Practice Consistently Benefits Student Learning: A Systematic Review of Applied Research in Schools and Classrooms. Educational Psychology Review, 1-45.

Bjork, R. A., & Allen, T. W. (1970). The spacing effect: Consolidation or differential encoding?. Journal of Verbal Learning and Verbal Behavior9(5), 567-572.

Hattie, J. (2008). Visible learning: a synthesis of over 800 meta-analyses relating to achievement. Routledge.

Latimier, A., Peyre, H., & Ramus, F. (2021). A meta-analytic review of the benefit of spacing out retrieval practice episodes on retention. Educational Psychology Review33(3), 959-987.

Rowland, C. A. (2014). The effect of testing versus restudy on retention: a meta-analytic review of the testing effect. Psychological Bulletin140(6), 1432.


Ludmila D. Nunes is the Senior Director for Science Knowledge and Expertise at the American Psychological Association (APA). She holds a PhD in Psychology from the University of Lisbon, and has conducted research in human memory and learning at Washington University in St. Louis, Purdue University, and the University of Lisbon. In addition to her research, she has taught classes in Cognitive Psychology and Human Memory at Purdue University, has been a reviewer for several scientific publications, and a science writer.

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