Spacing Effect, Spaced Repetitions, Distributed Practice, etc.

NOTE: This was the first blog post on my blog (all posts from that blog are now incorporated into this blog).


It was about 7 years ago when I was researching the spacing effect that I first got the idea for subscription learning. So, for the first post on the subscription-learning blog, I’m going to explain the “Spacing Effect” research finding.

The basic finding is this: When a learning point is repeated, it will create better remembering if it is repeated after a wider period of time than if it is repeated after a shorter period of time. For example, repeating something after four days will create higher levels of memory retrieval than repeating it after two days. Similarly, a repetition interval of one day will produce more remembering than a repetition interval of half a day. One hour will be better than half an hour. 10 minutes will be better than five minutes, and so forth.

The spacing effect is one of the best ways to support long-term remembering. Indeed, in my list of the 12 most important learning factors (the Decisive Dozen) I’ve found that spacing is one of three learning factors that is particularly potent in supporting remembering.

As Harry Bahrick and Linda Hall (Learning Researchers) put it in the Journal of Memory and Language:

“The spacing effect is one of the oldest and best documented phenomena
in the history of learning and memory research.”

Of course, as with any research on human beings, there are variations, contingencies, and boundary conditions on the spacing effect. Still, it is a very robust finding. And, it should be one of the most important tools in any learning professional’s toolbox.

I wrote a research-to-practice report on spacing back in 2006 and included over 100 research citations. And the research continues to accumulate year after year because the phenomenon is so fascinating. Today there would be dozens of additional studies that could be highlighted. I’ll provide a short list below.

Here is what is so fascinating: Why is it that providing the same exact information to learners, but in one case separating the repetitions more widely in time, will produce profound differences in how well people remember? Why are wider spacings so much more potent than more-narrowly-spaced repetitions?

Different reasons have been proposed by researchers:

  • Wider spacings require more cognitive effort.
  • Wider spacings produce more varied retrieval routes through memory.
  • Wider spacings promote more retrieval failure, and thus encourage better learning practices.

Let me be clear. Subscription learning–as defined–does not require the use of the spacing effect, but compared with other forms of learning, it is most suited to enabling the spacing effect.

Some Recent Research on The Spacing Effect

  • Mulligan, N. W., & Peterson, D. J. (2013). The Spacing Effect and Metacognitive Control. Journal of Experimental Psychology: Learning, Memory, and Cognition. Advance online publication.
  • Goossens, N. A. M. C., Camp, G., Verkoeijen, P. P. J.
    L., Tabbers, H. K., & Zwaan, R. A. (2012). Spreading the words: A
    spacing effect in vocabulary learning. Journal of Cognitive Psychology, 24(8), 965-971.
  • Logan, J. M., Castel, A. D., Haber, S., &
    Viehman, E. J. (2012). Metacognition and the spacing effect: The role of
    repetition, feedback, and instruction on judgments of learning for
    massed and spaced rehearsal. Metacognition and Learning, 7(3), 175-195.
  • Vlach, H. A., & Sandhofer, C. M. (2012).
    Distributing learning over time: The spacing effect in children’s
    acquisition and generalization of science concepts. Child Development, 83(4), 1137-1144.
  • Callan, D. E., & Schweighofer, N. (2010). Neural
    correlates of the spacing effect in explicit verbal semantic encoding
    support the deficient-processing theory. Human Brain Mapping, 31(4), 645-659.
  • Smith, T. A., & Kimball, D. R. (2010). Learning from feedback: Spacing and the delay–retention effect.
  • Journal of Experimental Psychology: Learning, Memory, and Cognition, 36(1), 80-95.
  • Son, L. K. (2010). Metacognitive control and the spacing effect. Journal of Experimental Psychology: Learning, Memory, and Cognition, 36(1), 255-262.