When students encounter a set of concepts (or terms or principles) that are similar in some way, they often confuse one with another. For instance, they might mistake one word for another word with a similar spelling (e.g., allusion instead of illusion) or choose the wrong strategy for a mathematics problem because it resembles a different kind of problem. By one proposition explored in this review, these kinds of errors occur more frequently when all exposures to one of the concepts are grouped together. For instance, in most middle school science texts, the questions in each assignment are devoted to the same concept, and this blocking of exposures ensures that students need not learn to distinguish between two similar concepts. In an alternative approach described in this review, exposures to each concept are interleaved with exposures to other concepts, so that a question on one concept is followed by a question on a different concept. In a number of experiments that have compared interleaving and blocking, interleaving produced better scores on final tests of learning. The evidence is limited, though, and ecologically valid studies are needed. Still, a prudent reading of the data suggests that at least a portion of the exposures should be interleaved.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Price excludes VAT (USA)
Tax calculation will be finalised during checkout.
Austin, S. D. M. (1921). A study in logical memory. The American Journal of Psychology, 32, 370–403.
Bahrick, H. P., & Phelps, E. (1987). Retention of Spanish vocabulary over eight years. Journal of Experimental Psychology: Learning, Memory, and Cognition, 13, 344–349.
Bird, S. (2010). Effects of distributed practice on the acquisition of second language English syntax. Applied PsychoLinguistics, 31, 635–650.
Bjork, R. A. (1979). Information-processing analysis of college teaching. Educational Psychologist, 14, 15–23.
Bloom, K. C., & Shuell, T. J. (1981). Effects of massed and distributed practice on the learning and retention of second-language vocabulary. The Journal of Educational Research, 74, 245–248.
Carpenter, S. K., Pashler, H., & Cepeda, N. J. (2009). Using tests to enhance 8th grade students’ retention of U. S. history facts. Applied Cognitive Psychology, 23, 760–771.
Carter, J. A., Cuevas, G. J., Day, R., Malloy, C. E., Kersaint, G., Luchin, B. M., et al. (2011). Math Connects Plus: Course 3 (Florida Version). School Education Group (SEG), McGraw-Hill, Glencoe. New York: McGraw-Hill.
Cepeda, N. J., Vul, E., Rohrer, D., Wixted, J. T., & Pashler, H. (2008). Spacing effects in learning: A temporal ridgeline of optimal retention. Psychological Science, 11, 1095–1102.
Cepeda, N. J., Mozer, M. C., Coburn, N., Rohrer, D., Wixted, J. T., & Pashler, H. (2009). Optimizing distributed practice: Theoretical analysis and practical implications. Experimental Psychology, 56, 236–246.
Chi, M. T. H., Feltovich, P. J., & Glaser, R. (1981). Categorization and representation of physics problems by experts and novices. Cognitive Science, 5, 121–152.
Crowley, K., Shrager, J., & Siegler, R. S. (1997). Strategy discovery as a competitive negotiation between metacognitive and associative mechanisms. Developmental Review, 17, 462–489.
Dempster, F. N. (1989). Spacing effects and their implications for theory and practice. Educational Psychology Review, 1, 309–330.
Dunlosky, J., & Lipko, A. R. (2007). Metacomprehension: A brief history and how to improve its accuracy. Current Directions in Psychological Science, 16, 228–232.
Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (in press). Improving students’ learning with effective learning techniques: Promising directions from cognitive and educational psychology. Psychological Science in the Public Interest.
Hall, K. G., Domingues, D. A., & Cavazos, R. (1994). Contextual interference effects with skilled baseball players. Perceptual and Motor Skills, 78, 835–841.
Halpern, D. F. (2008, March). 25 learning principles to guide pedagogy and the design of learning environments. Paper distributed at the keynote address at the Bowling Green State University Teaching and Learning Fair. Bowling Green, OH.
Kang, S. H. K., & Pashler, H. (2012). Learning painting styles: Spacing is advantageous when it promotes discriminative contrast. Applied Cognitive Psychology, 26, 97–103.
Kester, L., Kirschner, P. A., & van Merriënboer, J. J. G. (2004). Timing of information presentation in learning statistics. Instructional Science, 32, 233–252.
Kornell, N., & Bjork, R. A. (2008). Learning concepts and categories: Is spacing the “enemy of induction”? Psychological Science, 19, 585–592.
LeBlanc, K., & Simon, D. (2008). Mixed practice enhances retention and JOL accuracy for mathematical skills. Paper presented at the 49th Annual Meeting of the Psychonomic Society, Chicago, IL.
Mayfield, K. H., & Chase, P. N. (2002). The effects of cumulative practice on mathematics problem solving. Journal of Applied Behavior Analysis, 35, 105–123.
McCabe, J. (2011). Metacognitive awareness of learning strategies in undergraduates. Memory & Cognition, 39, 462–476.
Metcalfe, J. (2000). Metamemory: Theory and data. In E. Tulving & F. I. M. Craik (Eds.), Oxford handbook of memory (pp. 197–211). London: Oxford University Press.
Metcalfe, J., Kornell, N., & Son, L. K. (2007). A cognitive-science based programme to enhance study efficacy in a high and low-risk setting. European Journal of Cognitive Psychology, 19, 743–768.
Mitchell, C. J., Nash, S., & Hall, G. (2008). The intermixed-blocked effect in human perceptual learning is not the consequence of trial spacing. Journal of Experimental Psychology: Learning, Memory, and Cognition, 34, 237–242.
Reynolds, J. H., & Glaser, R. (1964). Effects of repetition and spaced review upon retention of a complex learning task. Journal of Educational Psychology, 55, 297–308.
Robinson, D. H., Levin, J. R., Thomas, G. D., Pituch, K. A., & Vaughn, S. R. (2007). The incidence of “causal” statements in teaching and learning research journals. American Educational Research Journal, 44, 400–413.
Rohrer, D. (2009). The effects of spacing and mixing practice problems. Journal for Research in Mathematics Education, 40, 4–17.
Rohrer, D., & Pashler, H. (2007). Increasing retention without increasing study time. Current Directions in Psychological Science, 16, 183–186.
Rohrer, D., & Pashler, H. (2010). Recent research on human learning challenges conventional instructional strategies. Educational Researcher, 39, 406–412.
Rohrer, D., & Taylor, K. (2007). The shuffling of mathematics practice problems boosts learning. Instructional Science, 35, 481–498.
Schwartz, B. L., Son, L. K., Kornell, N., & Finn, B. (2011). Four principles of memory improvement: A guide to improving learning efficiency. International Journal of Creativity and Problem Solving, 21, 7–15.
Seabrook, R., Brown, G. D. A., & Solity, J. E. (2005). Distributed and massed practice: From laboratory to classroom. Applied Cognitive Psychology, 19, 107–122.
Siegler, R. S. (2003). Implications of cognitive science research for mathematics education. In J. Kilpatrick, G. W. Martin, & D. E. Schifter (Eds.), A research companion to principles and standards for school mathematics (pp. 119–233). Reston: National Council of Teachers of Mathematics.
Siegler, R. S., & Shrager, J. (1984). Strategy choices in addition and subtraction: How do children know what to do? In C. Sophian (Ed.), The origins of cognitive skills (pp. 229–293). Hillsdale: Erlbaum.
Skinner, B. F. (1933). The rate of establishment of a discrimination. The Journal of General Psychology, 9, 302–350.
Slavin, R. E. (2002). Evidence-based education policies: Transforming educational practice and research. Educational Researcher, 31(7), 15–21.
Son, L. K., & Kornell, N. (2010). The virtues of ignorance. Behavioral Processes, 83, 207–212.
Taylor, K., & Rohrer, D. (2010). The effect of interleaving practice. Applied Cognitive Psychology, 24, 837–848.
Vlach, H. A., Sandhofer, C. M., & Kornell, N. (2008). The spacing effect in children’s memory and category induction. Cognition, 109, 163–167.
Wahlheim, C. N., Dunlosky, J., & Jacoby, L. L. (2011). Spacing enhances the learning of natural concepts: An investigation of mechanisms, metacognition, and aging. Memory & Cognition, 39, 750–763.
Willingham, D. T. (2002). Allocating student study time: Massed vs. distributed practice. American Educator, 47, 37–39. Summer.
I thank Pooja Agarwal and one anonymous reviewer for their comments on an earlier version of this review. This work was supported by the Institute of Education Sciences, U.S. Department of Education, through Grant R305A110517 to the University of South Florida (PI: D. Rohrer). The opinions expressed are those of the author and do not represent views of the Institute or the U.S. Department of Education.