Brain Science: Overcoming the Forgetting Curve

Written By

Art Kohn

April 10, 2014

In last month’s column we admitted the painful fact that our employees quickly forget most of what they learn. And while forgetting depends on many factors, research shows that, on average, students forget 70 percent of what we teach within 24 hours of the training experience (Figure 1). This is a “dirty secret of training” because while we all know it is true, training organizations spend 60 billion dollars a year on training programs knowing full well that most of that knowledge will quickly disappear.

And we wonder why we do not get a lot of respect.

Figure 1:
The forgetting curve, training’s dirty secret

Forgetting is usually an active, adaptive, and even desirable process. After all, most of the things we remember (like where we set our glasses), are only of short-term importance, and after a day or so the brain needs to suppress such time-limited memories in order to free space for information that may be of more immediate value.

The problem is that if you remember, say, 50 things in a day, your brain does not automatically know which of these bits of information will be useful to you in the long run. As a result it sometimes purges the baby right along with the bathwater.

Coping with the forgetting curve

The good news is that while forgetting is a pervasive process, it is not random. In fact, it is possible to signal the brain that a particular piece of information is important and that it should retain it. Professor Henry Roediger and his laboratory at Washington University in St. Louis are doing the pioneering work in this area. Henry is a prolific researcher, one of my personal heroes, and his research provides us with strategies for signaling the brain to retain particular pieces of information.

In brief, Dr. Roediger’s research shows that when you force a learner to recall information in the hours and days after training, then they are much, much more likely to retain that information in the long run. Let’s look at a couple of experiments that illustrate this point.

In the first, study, students studied a series of pictures and were told to remember as many of them as possible. Afterward, they let one group leave the lab while they gave a second group a brief booster quiz during which they simply wrote down as many pictures as they could recall; they gave a third group three successive opportunities to recall the pictures. Note that they did not give these latter two groups any additional study time—they simply asked them to recall the photos. One week later, all of the students returned to the lab for a comprehensive recall test. As you can see in Figure 2, the opportunity to recall the pictures immediately after the training significantly increased the chances that they remembered the information a week later.

Figure 2:
The opportunity to recall pictures immediately after training significantly increased the chances that they remembered the information a week later 

A clever researcher might criticize this experiment by pointing out that the students who took the practice tests had, in effect, more study time and this caused them to recall more pictures. To address this concern, Dr. Roediger conducted another experiment where a group of students read essays on science topics. Afterward, half of the students had a chance to reread the text and half of the students spent about the same amount of time answering a series of booster questions that asked them to recall material from the passages.

Several days later, the researchers gave all of the students an exam over the materials. The results showed that those students who read the material and took a booster quiz did significantly better than those students who read and then reread the material. This was true when they conducted the exam two days after studying and even truer when they did the exam one week after studying (see Figure 3).

Figure 3:
More evidence that when you force a learner to recall information in the hours and days after training they are far more likely to retain that information in the long run

These two experiments, along with perhaps two hundred more dating back to 1909, clearly demonstrate that opportunities to recall information in the days and weeks after training dramatically improve the long-term retention of material.

Use it or lose it

Why do booster opportunities cause the brain to retain information? One explanation, based on the idea mentioned above, is that your brain wants to retain information that is useful to you and purge information that is not. And so, if you happen to call that information into your mind in the hours and days after training, your brain tags that information as important and is more likely to retain it. If you use it, you won’t lose it!

So what do these results mean for corporate and industrial training? In short, if you provide your learners with booster events in the hours and days after training you can reshape their forgetting curve. For example, if you provide employees with a leadership seminar on Monday, you can expect that most of this information will be lost within a week. However, if you provide a booster event, such as a multiple-choice questionnaire, it causes the learner to recall the information, which will reset the learner’s forgetting curve (see Figure 4). Furthermore, strategically providing a series of these booster events will reset the forgetting curve each time and will maximize long-term retrieval (Figure 5).

Figure 4:
A booster event “re-sets” a learner’s forgetting curve

Figure 5:
A series of booster events maximizes long-term retrieval

An important note here is that these booster events improve retention for the entire learning experience, and not just for the particular topics in the quiz question. This “halo effect” means that just a few booster experiences can enhance the retention of the entire training session.

A strategy for moving forward

Booster training provides an amazing opportunity to enhance the ROI of our training programs. Let’s take our heads out of the sand and not allow the forgetting curve to flush away 70 percent of our training. We can do better.

So here is a mantra to yell over the top of your cubicle. If your goal is to produce long-term retention, and if your goal is to produce behavior change, then what you do after training is more important than what you do during training. If you do nothing, people will forget most of your training. However, if you provide them with a series of booster experiences, you will signal the learner’s brain that that particular information is important and, in turn, they will be far more likely to remember it.

The details of boostering matter a lot, and next month we will look at the optimal ways to author and deliver them. See you then.

Digging deeper

Dr. Henry Roediger is one of the masters of memory research, and if you have a serious interest in this discipline, here are some more resources to explore:

This is the website for Dr. Roediger’s laboratory at the Washington University in St. Louis.

These two articles, “Benefits of Testing Memory. Best Practices and Boundary Conditions,” and “The Power of Testing Memory” provide the research foundation that will help you understand the forgetting curve and how you can cope with it.

Finally, by the time you read this article, Dr. Roediger will have released his new book entitled Make It Stick: The Science of Successful Learning. It is awesome.

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