Will’s History of Spacing Out on Learning


As you know, if you’ve dabbled into my work for a few years, I’ve closely followed the research finding, “The Spacing Effect,” both from a research perspective and a practical perspective. Indeed, I was one of the first in the workplace learning field to recognize its practical significance, which I wrote about as early as 2002. In 2006 I published the research-to-practice report entitled Spacing Learning Over Time, which should — if there was justice in the world (LOL) or viable trade organizations (OUCH) — be enshrined in the Learning and Development Hall of Fame. Snickers are welcome. Taza Chocolate even better. A few years ago, still wanting to advocate for the practical use of the spacing effect, I began speaking about Subscription Learning at conferences and I developed a website (SubscriptionLearning.com) to encourage folks in the learning field to utilize the spacing effect in their learning designs. SubscriptionLearning.com is being retired in 2017, as it is no longer needed. Blog posts from the website are incorporated in this blog.

I am grateful to the enlightened organizations who have supported my work over the years and specifically to the individuals who continue to encourage the reading of the 2006 research report. Feel free to share yourself.

Now in 2017, I am grateful to another organization, Learning Technologies (in the UK) who is sponsoring me to speak on the spacing effect at their conference starting in a few weeks. As part of my efforts, I am developing a new presentation and I am updating my research compilation on the spacing effect. Stay tuned to this blog as I’m likely to share a few of my findings as I dig into the research.

Indeed, the research on spacing is some of the most interesting I’ve studied over the years. The first thing that fascinates is that there is so much damn research on the spacing effect, also referred to as spaced learning, distributed practice, and interleaving. In 1992, Bruce and Bahrick counted up the number of scientific studies on spacing and found over 300 articles at that time. Every year, there are more and more scientific articles published on spacing. By my rough count of journal articles cited on PsycINFO (a primary social-science database), over the last three years there have been 31 new articles published on the spacing effect (7 in 2014, 14 in 2015, and 10 in 2016).

One of the main reasons that so many research articles are published on the spacing effect is that the phenomenon is so intriguing. Why would spacing repetitions over time produce so much more remembering than giving the learners the exact same repetitions but simply massing them all at once or spacing them with less time in between? Freakin’ fascinating! So researchers keep digging into the complexities.

Harry Bahrick and Lynda Hall announced in 2005 that, “The spacing effect is one of the oldest and best documented phenomena in the history of learning and memory research.” And, just last year in a scientific review article, Geoffrey Maddox wrote, Because of its robustness, the spacing effect has the potential to be applied across a variety of contexts as a way of improving learning and memory.”

Stay tuned, as I hope to be be spacing my research compilations over time…


Bahrick, H. P., & Hall, L. K. (2005). The importance of retrieval failures to long-term retention: A metacognitive explanation of the spacing effect. Journal of Memory and Language, 52, 566-577.

Maddox, G. B. (2016). Understanding the underlying mechanism of the spacing effect in verbal learning: A case for encoding variability and study-phase retrieval. Journal of Cognitive Psychology, 28(6), 684-706.

Thalheimer, W. (2006, February). Spacing Learning Events Over Time: What the Research Says. Available at: http://work-learning.com/catalog.html.