How to remember what you read: test yourself, do not reread

Many of us read a good book, underline beautiful sentences and a month later can barely remember what it was about. It is not the book's fault, nor our memory's. It is the way we learn.

The 2006 experiment

The psychologists Henry Roediger and Jeffrey Karpicke gave 120 students short science texts to read, such as one about the Sun and one about sea otters. After a first reading, the students either read the text again, or wrote down everything they remembered, without looking and without feedback.

They were then tested after 5 minutes, after 2 days or after a week:

• After 5 minutes, those who reread remembered a little more (81% versus 75%).
• After 2 days, those who were tested remembered more (68% versus 54%).
• After a week, the difference was clear: 56% versus 42%, in favour of testing.

The most surprising finding: the students who reread were more confident that they would remember the text. Rereading gives a feeling of familiarity, because the text looks known. But recognising something when you see it is not the same as recalling it when it is not in front of you.

Memory grows stronger not when you put information in, but when you take it out.

Spaced practice

The second strong finding concerns timing. A large meta-analysis by Nicholas Cepeda and colleagues (2006), covering hundreds of experiments, showed that the same amount of study time gives better results when it is spread over several sessions with breaks in between than when it is done all at once. The right gap depends on how long we want to remember something: for an exam in a week, a day between sessions is enough; for something we want to keep for months, the gaps should be longer.

A method for readers

1. Read a chapter or an article. Without hurrying, once.
2. Close it and write three to five sentences on what you remember: the main idea, one example, one thing that surprised you.
3. Check. Open the text and see what you forgot or misunderstood.
4. After two or three days, try again without opening it: what do I remember now? Then check again.
5. After a week or two, one last time. Or, even better, explain it to someone else.

This method takes more effort than rereading, and it feels harder. That difficulty is not a sign that it is not working; researchers call it a "desirable difficulty". It is precisely the effort of recalling that strengthens the memory.

On lexoshpejt you can try it right away: after each article, close the page and tell yourself the three things you learned. If you cannot remember them, you have not failed. You have just found what is worth reading again.