Independent Learning: ‘Desirable Difficulties’ part 2

In the last post we looked at the importance of retrieval and the testing effect. In this week’s post we will look at spaced learning and interleaving as ways of enhancing the long term retention of learning.

In 1885 Herman Ebbinghaus conducted a series of experiments on himself to test memory and recall. He studied the memorisation of random syllables, such as “WID” and “ZOF” by repeatedly testing himself after various time periods and recording the results. He plotted these results on a graph creating what is now known as the “forgetting curve”.


The Forgetting Curve.

His research indicated that total recall (100%) for him was achieved only at the point of learning. Following that, the retention of what had been learned fell away very quickly:

  • Within 20 minutes 42% of the memorised list was lost.
  • Within 24 hours 67% of what he learned had vanished.
  • A month later 79% had been forgotten.

Typically students study a unit or topic for a term (massed practice) are tested on that and then move on to a new unit only to revise that material leading up to an exam. This often takes the form of revisiting material the week or even night before in the form of cramming.

Put aside the fact that this kind of approach can lead to severe stress around exam time, cramming the night before the GCSE exam might yield good results in the short term but will probably not lead to the kind of long term retention of knowledge required for the independent study of subjects in the 6th form and beyond.

It is common sense that when we want to learn information, we study that information multiple times. The schedules by which we space repetitions can make a huge difference, however, in how well we learn and retain information we study. The spacing effect is the finding that information that is presented repeatedly over spaced intervals is learned much better than information that is repeated without intervals (i.e., massed presentation). This effect is one of the most robust results in all of cognitive psychology and has been shown to be effective over a large range of stimuli and retention intervals from nonsense syllables (Ebbinghaus, 1885) to foreign language learning across many months (Bahrick, Bahrick, Bahrick & Bahrick, 1993).

Another way of thinking about the delivery and revisiting of topic material and of engendering long term retention of knowledge is through the process of interleaving where instead of delivering topics through massed practice, material is spaced out and interleaved with each other to induce regular forgetting and retrieval. This process is usually more difficult for students in the short term and requires greater responsibility and independence but leads to great gains in the long term, one reason why Bjork refers to this as a’desirable difficulty.’


What does this look like in the classroom?

There are a variety of ways to harness these benefits. Here are a series of examples from some practitioners are redesigning curricula in extraordinary new ways including this advice from Joe Kirby (who was taught by our very own Tom Wayman):

Over the last decade, eleven cognitive psychologists have taken over a hundred years of laboratory research and applied it to classrooms and subject curricula. Here’s what they recommend:

  • Use frequent quizzing: testing interrupts forgetting

  • Roll forward into each successive quiz questions on work from the previous term.

  • Design quizzing to reach back to concepts and learning covered earlier in the term, so retrieval practice continues and learning is cumulative.

  • Frequent low-stakes quizzes in class helps the instructor verify that students are in fact learning as well as they appear to be and reveal the areas where extra attention is needed. Cumulative quizzing is powerful for consolidating learning and concepts from one stage of a course into new material encountered later.

  • Simply including one test retrieval practice in a class yields a large improvement in final exam scores, and gains continue to increase as the frequency of testing increases.

  • Effortful retrieval makes for stronger learning and retention. The greater the effort to retrieve learning, *provided that you succeed*, the more learning is strengthened by retrieval.

  • In virtually all areas of learning, you build better mastery when you use testing as a tool

  • One of the best habits to instill in a learner is regular self-quizzing.


Further discussion:

– Is spacing and interleaving more pertinent to some subjects than others?

–  Would teaching students to harness the benefits of independent self quizzing improve wellbeing in the long term?

Further reading:

Improving Students’ Learning with Effective Learning Techniques: Promising Directions from Cognitive and Educational Psychology. Dunlosky, Rawson, Marsh, Nathan & Willingham 2011.  

Repeated Retrieval Is the Key to Long-Term Retention. Karpicke & Roediger 2007

Retrieval practice is critical in long-term retention. Roediger & Butler 2010

Test-enhanced learning: Taking memory tests improves long-term retentionRoediger & Karpicke 2006

Retrieval practice with short-answer, multiple-choice, and hybrid testsSmith & Karpicke 2013

Repeated Testing Produces Superior Transfer of Learning Relative to Repeated Studying Butler, 2010