Thursday, 25 October 2007

The secret to remembering material long-term

The secret to remembering material long-term is not to cram and over-learn but rather to periodically review what you’ve studied. That’s according to Doug Rohrer and Harold Pashler who have identified an intriguing relationship between how long to leave it before returning to previously studied material, and the ultimate duration for which you want to remember it for.

The technical definition for ‘over-learning’ is any time you spend continuing to study material which you have already mastered. So, for example, once you’ve correctly recalled a list of French vocab without any errors, any additional time you immediately spend learning that vocab is over-learning. The evidence shows that time spent over-learning is only beneficial over the short-term. For example, one study found over-learning was advantageous when tested a week later, but not when tested four weeks later.

According to Rohrer and Pashler, if your aim is long-term retention, time spent over-learning would be better spent reviewing material at a later date. Just how much later depends on how long you want to remember the material for. Their research suggests the optimal time to review material is after a period which is 10 to 30 per cent of the time for which you want to remember it for. Reviewing too soon, or too near the later test will be associated with poorer learning. For instance, one study that tested retention after ten days (always measured from the second ‘review’ session) found that from a range of 5 minutes to 14 days, the optimal time for review was after one day. Another study that looked at retention over 6 months, found the optimal time for reviewing material was one month.

The researchers say their observations have implications for the design of textbooks. For example, most maths books tend to end each chapter with numerous problems prompting over-learning of that chapter’s material. It would be more effective if a variety of problems were posed at the end of each chapter so that students were continually reviewing material studied in earlier chapters.

Rohrer, D. & Pashler, H. (2007). Increasing retention time without increasing study time. Current Directions in Psychological Science, 16, 183-186.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.


Anonymous said...

In fact, some mathematics textbooks - my high school used the "Saxon Method" - teach using this principle. It was generally considered unsuccessful, in part because there was no continuity between daily lessons. Each day visited a different topic (algebra, geometry, trigonometry, or what have you). For the marginal students, the problems devolved into rote memorization of techniques rather than a deep understanding of the material. I presume this is because different students require different amounts of practice to go on to the next step. As much of the day's problems concern previous problems, students were not forced to understand the concept underlying each day's lessons to reasonably complete the problem sets.

Unknown said...

The approach you describe doesn't sound like the same thing these authors are suggesting. Of course it is important that students are given time to properly learn and understand new concepts. They aren't suggesting that a new topic is taught each day. They're just saying that rather than having all the same kinds of problems at the end of each textbook chapter (which relate to that chapter's material), it would be beneficial if there were also some problems that related to chapters dealt with earlier in the school term or year - in other words, giving students a chance to review and renew previously mastered techniques and knowledge (bearing in mind the research shows this is beneficial for long-term learning).

Anonymous said...

Hi. I always forget the material that i study. Say i study a question i can understand the meaning and every thing is alright but if after sometime i try to recall it. Then i cant! Please give me the cause and help me how to overcome it?!

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