How memory works, and how to study so it sticks

The problem with cramming#

Most of us study by rereading. We go through a chapter, highlight the important lines, and read the highlights again the night before the test. It feels productive, because the material looks familiar. Familiarity, though, is not the same as being able to remember it.

Memory research over more than a century points to a different approach, built on two simple ideas: space your study out over time, and practise pulling information out of your head instead of putting it back in. This article explains where those ideas come from, what the best-known experiments found, and how to turn them into a routine you can follow.

The forgetting curve#

In the 1880s, the German psychologist Hermann Ebbinghaus ran an unusual experiment on himself. He memorised lists of meaningless syllables, so that prior knowledge could not help him, and tested how much he remembered after different delays. He published his results in 1885 in a book called Über das Gedächtnis ("On Memory").

He found that forgetting is fastest at the start. A large part of what you have just learned fades within hours or days, and then the loss slows down. The pattern is often drawn as a falling curve, now called the forgetting curve.

Two lessons follow. First, forgetting is normal, and not a sign that you are bad at learning. Second, the best moment to refresh a memory is just before it fades, because a successful reminder makes the memory last longer.

Idea one: spacing#

The spacing effect is one of the most reliable findings in the psychology of learning. If you study the same material in several shorter sessions spread over days or weeks, you remember it better than if you study for the same total time in one block.

Why does it work? One common explanation is that when you return to something after a gap, it is harder to recall, and that effort strengthens the memory. When you study the same thing twice in a row, it is still fresh and the second pass takes little effort, so it adds little.

A practical schedule for something you want to remember long-term looks like this:

First study session: learn the material.
Review after a day.
Review after about a week.
Review after about a month.
Review again after a few months, if you still want to keep it.

The exact intervals are not magic. What matters is that the gaps grow. Many flashcard programs automate this and are usually called spaced repetition software.

Idea two: retrieval practice#

The second idea is that trying to remember is itself a powerful way to learn. This is called retrieval practice or the testing effect.

A well-known experiment was published in 2006 by Henry Roediger and Jeffrey Karpicke in Psychological Science. Students read short prose passages. Some then studied a passage again, while others took a free-recall test on it, writing down what they could remember, with no feedback.

The results were revealing:

Straight after studying, the students who had re-read the passage recalled more than the students who had been tested.
Two days later, and a week later, the pattern reversed. Students who had been tested remembered more.

That reversal is the key point. Rereading gives a pleasant feeling of fluency in the short term, but testing leads to better memory in the long term. The authors concluded that testing is a powerful way to improve learning, not just to measure it.

Turning this into a study routine#

Here is a routine based on both ideas. It works for exams, languages, professional certifications, or just things you want to know.

1. Learn it once, actively#

Read or listen, and as you go, write short notes in your own words. Put the main ideas into questions: "Why did this happen?" "What are the three steps?" Questions will become your practice material.

2. Close the book and recall#

When you finish a section, close the book and write down everything you remember, without peeking. Then open the book and check. The gaps you find are exactly where to focus.

3. Make cards or question lists#

Turn the key points into questions with answers on the back, on paper cards or in an app. Keep each card to one fact or idea. Cards that are too long are hard to review quickly.

4. Space the reviews#

Review the cards after a day, then after a week, then after a month. Move cards you answer easily into longer gaps, and keep the hard ones close.

5. Mix topics#

When you review, shuffle topics instead of finishing one before starting the next. Mixing is harder and feels less smooth, but it trains you to choose the right idea for the question, which is what a test or real life asks of you.

6. Sleep and breaks#

Sleep plays a part in storing new memories, so a long night before an exam is a poor trade. Short breaks during study also help you stay focused.

What to avoid#

Highlighting as the main strategy. It is easy and feels busy, but by itself it rarely leads to learning.
Rereading the same page repeatedly. The growing familiarity can trick you into believing you know it.
Studying only what is easy. Retrieval is most useful on the things you find hard.
Waiting until the last night. A few short sessions across weeks do more than one long session.

Using this outside school#

Spacing and retrieval work for adults as well as students. Learning a language, preparing for a certification, remembering names, or keeping up with what you read can all use the same ideas. A simple way to start is a notebook of questions. After reading a book or article, write three questions about it, and answer them from memory a week later.

A realistic note on expectations#

These methods feel harder than rereading, and that is part of why they work. If studying feels a little difficult, you are probably doing it right. Do not judge a method by how smooth it feels in the moment. Judge it by how much you can remember next month.

Sources#

Ebbinghaus, H. (1885). Über das Gedächtnis: Untersuchungen zur experimentellen Psychologie. Leipzig: Duncker and Humblot.
Roediger, H. L., and Karpicke, J. D. (2006). "Test-Enhanced Learning: Taking Memory Tests Improves Long-Term Retention." Psychological Science, 17(3), 249 to 255.