Brain Science: Overcoming the Forgetting Curve

In last month’s column we admitted the painful fact that ouremployees quickly forget most of what they learn. And while forgetting dependson many factors, research shows that, onaverage, students forget 70 percent of what we teach within 24 hours of thetraining experience (Figure 1). This is a “dirty secret of training” becausewhile we all know it is true, training organizations spend 60 billion dollars ayear on training programs knowing full well that most of that knowledge willquickly 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 desirableprocess. After all, most of the things we remember (like where we set ourglasses), are only of short-term importance, and after a day or so the brainneeds to suppress such time-limited memories in order to free space forinformation 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 willbe useful to you in the long run. As a result it sometimes purges the babyright along with the bathwater.

Coping withthe 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 particularpiece of information is important and that it should retain it. Professor HenryRoediger and his laboratory at Washington University in St. Louis are doing thepioneering work in this area. Henry is a prolific researcher, one of mypersonal heroes, and his research provides us with strategies for signaling thebrain to retain particular pieces of information.

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

In the first, study, students studied a series of pictures andwere told to remember as many of them as possible. Afterward, they let onegroup leave the lab while they gave a second group a brief booster quiz duringwhich they simply wrote down as many pictures as they could recall; they gave athird group three successive opportunities to recall the pictures. Note that theydid not give these latter two groups any additional study time—they simplyasked them to recall the photos. One week later, all of the students returnedto the lab for a comprehensive recall test. As you can see in Figure 2, theopportunity to recall the pictures immediately after the training significantlyincreased the chances that they remembered the information a week later.

Figure 2: The opportunity to recall pictures immediately aftertraining significantly increased the chances that they remembered the informationa week later 

A clever researcher might criticize this experiment bypointing out that the students who took the practice tests had, in effect, morestudy time and this caused them to recall more pictures. To address thisconcern, Dr. Roediger conducted another experiment where a group of studentsread essays on science topics. Afterward, half of the students had a chance toreread the text and half of the students spent about the same amount of timeanswering a series of booster questions that asked them to recall material fromthe passages.

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

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

These two experiments, along with perhaps two hundred moredating back to 1909, clearly demonstrate that opportunities to recallinformation in the days and weeks after training dramatically improve the long-termretention of material.

Use it orlose it

Why do booster opportunities cause the brain to retaininformation? One explanation, based on the idea mentioned above, is that yourbrain wants to retain information that is useful to you and purge informationthat is not. And so, if you happen to call that information into your mind inthe hours and days after training, your brain tags that information asimportant 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 industrialtraining? In short, if you provide your learners with booster events in thehours and days after training you can reshape their forgetting curve. Forexample, if you provide employees with a leadership seminar on Monday, you canexpect that most of this information will be lost within a week. However, ifyou provide a booster event, such as a multiple-choice questionnaire, it causesthe learner to recall the information, which will reset the learner’sforgetting curve (see Figure 4). Furthermore, strategically providing a seriesof these booster events will reset the forgetting curve each time and willmaximize 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 improveretention for the entire learning experience, and not just for the particulartopics in the quiz question. This “halo effect” means that just a few boosterexperiences can enhance the retention of the entire training session.

A strategyfor moving forward

Booster training provides an amazing opportunity to enhancethe ROI of our training programs. Let’s take our heads out of the sand and notallow the forgetting curve to flush away 70 percent of our training. We can dobetter.

So here is a mantra to yell over the top of your cubicle. If your goal is to produce long-termretention, and if your goal is to produce behavior change, then what you doafter training is more important than what you do during training. If you do nothing, people will forgetmost of your training. However, if you provide them with a series of boosterexperiences, you will signal the learner’s brain that that particularinformation is important and, in turn, they will be far more likely to rememberit.

The details of boostering matter a lot, and next month we willlook 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 moreresources 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 helpyou 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.