Spaced Practice for Skill Learning
By Cindy Nebel
Psychologists often breakdown memory into different types. Long-term memory can be divided into two different types: explicit memories and implicit memories. Explicit memories are memories for events and facts. They are memories that we can easily think and talk about. Implicit memories are a bit different. Implicit memories include procedural (muscle) memories as well as some other types of automatic processing.
The primary focus of most of the things on our site is the acquisition and retention of factual information, which would fall into the explicit memory category. When we talk about spaced practice, we often talk about studying in small sessions over the course of time instead of studying in one long session.
Sometimes when we talk about the six strategies for effective learning, we get a little push-back from educators who state that they don’t want their students to simply memorize information, but to understand it. Thankfully, the six strategies do promote understanding. We also sometimes hear that we are talking about learning facts, but that is not useful in other areas, such as art. But again, we’ve talked about the usefulness of the strategies in lots of other subjects (and even for dressage!).
Today I want to talk a little bit more about how we can use one of the strategies, spaced practice, to improve learning of implicit memories – of skills. While teaching a course on Learning last week, I told the students about a classic study showing that spacing works not only for explicit learning, but also for skill learning. Here is that study:
Baddeley and Longman (1) trained postal workers on a new typing task that sorted mail. At the time, this was a very practical matter. Going from hand sorting to mechanical sorting would require training up to 10,000 new postal workers, so doing this in the most efficient way was key. They started out by training 72 workers in sessions that were either 1 or 2 hours long, either 1 or 2 times/day until all of the groups had worked on the training for 60 hours. So the group who training for 1 hour 1 time/day had trained for 60 days, but the group that trained for 2 hours 2 times/day had only trained for 12 days. Note that each group received the same amount of training and that they were paid the same amount to do that training.
Below, you can see the results of part of that study. This shows the number of hours that it took for each group to learn the new typing skill. Those that practiced for 1 hour once/day took considerably fewer hours to learn the new skill than did those who practiced for 2 hours twice/day. In fact, the fastest person in the latter group took 2 hours longer than the slowest person in the former group.
So how well did they learn it? The figure below shows the average number of correct keystrokes/minute for individuals in each group. Once again, the 1 hour once/day group performed much better than the 2 hours twice/day group.
Altogether, the four groups spent the same amount of time attempting to learn the new skill, but the group that spread out that training actually took less time to become proficient and were faster at the system when they had learned it.
For their employers, this is a clear win. The company will spend less time training employees who will be better at their jobs after, saving the company even more money. Clearly, spaced practice is the most money-saving strategy for learning new skills.
When I taught this in my class, I immediately threw this back to the students. If spaced practice is so clearly superior for both explicit and implicit memories, why don’t people use it? The answer is that it doesn’t actually feel easier. Spaced practice feels more difficult, but to my students who have many competing demands (most of them have full time jobs and many of them have children and other family obligations), any process that reduces the amount of time that they have to spend on a task is worthwhile.
One of my students asked, “But, do I have to spend hours studying every night?! I don’t have time for that.” My answer was, “Absolutely not. If you have 20 minutes, or even just 5, you will still benefit from taking a little time to open up your notes, cover up a page, try to retrieve everything from that section, and then check to see how well you did.” And remember, even the group that practiced twice a day, but only for an hour at a time did better than the group that practiced for two hours twice per day. Even a little bit of spacing can make a big difference.
So whether you’re trying to learn how to tie your shoes, a new musical instrument, a new task at work, or new information, give yourself the time to do it. Practice a little bit each day and you will perform better than if you try to do too much in any one sitting.
(1) Baddeley, A.D., & Longman, D.J.A. (1978). The influence of length and frequency of training session on the rate of learning to type. Ergonomics, 21, 627-635.