Designing and building effective sales onboarding programs is all about finding ways to flatten a steep learning curve.

But it’s just as important to think about how to flatten an equally steep forgetting curve.

Research shows people forget up to 80 percent of what they’ve learned within a month of training. That’s why reinforcement is critical. Spaced repetition is one way to keep employees thinking about new concepts until it’s burned into long-term memory.

What do I mean by spaced repetition? You probably already know about repetition. You do it when you meet someone new and you repeat their name over and over again so you don’t forget it.

With spaced repetition, you repeat the information over and over again but instead of all in a row you spread it over time. Think of those flashcards you probably used to study for some big exam in school. Now imagine setting up a schedule where you review those cards a day after the lesson. If you answer a question correctly, you place the card in a stack to revisit a week from now. If you answer incorrectly, you put it in another stack to review tomorrow.

Why does this work? Your brain might seem like a video recorder or computer but it actually operates differently. It’s constantly recording information you might only use in the short term (if at all) — like today’s weather, the color of the car that just drove by, or what that passerby on the phone just said.

Because the brain gets constantly bombarded with new information, it evolved to dump off lots of it quickly to avoid overload. Unfortunately, it also dumps off the information you need. The trick to keeping intact that valuable information you just learned in a training session is to use it so you don’t lose it.

Here, simple repetition isn’t as effective for sales onboarding reinforcement as spaced repetition. That’s because it takes almost no effort to recall something immediately after you’ve learned it. But, recalling something you learned over a longer interval is tougher. In general, the harder your brain works to retrieve a given memory, the more likely you’ll be able to recall it later.

To implement spaced repetition using old-school methods, you might ask your sales reps to practice flashcard drills for a couple minutes a day for product knowledge or common objections. If you’ve got modern learning technology, you could automate this process. Tools enable you to quiz reps with mobile friendly flashcards on a personalized basis using machine learning.

The quizzes challenge them to recall key training facts for a couple minutes a day based on each individual’s mastery level. When the rep delivers a correct answer, intelligent algorithms shuffle the deck so they see that material less often. The software gradually decreases the number of review sessions as the knowledge moves into your rep’s long-term memory— so they never waste time reviewing material they’ve already mastered.

It’s normal for employees to forget some of what you teach them. Offer them follow-up drills strategically spaced to reinforce lessons better. Also, adapt those lessons to focus on the subjects they need to review most. You’ll soon find yourself hacking the brain and overcoming the forgetting curve that once diminished the investment you made in your reps’ sales onboarding training.