Active Recall vs Rereading: Why Testing Yourself Works Better

Testing yourself works better than rereading. Pulling an answer out of memory (active recall, or retrieval practice) strengthens that memory more than looking at the material again does, even though rereading feels easier and more productive.

The evidence

In a 2008 study published in Science, Jeffrey Karpicke and Henry Roediger had students learn foreign-language vocabulary. Once a student could recall a word, some kept being tested on it and some only kept studying it. A week later, the students who kept being tested remembered far more. Extra studying of words they had already recalled added nothing.

A 2013 review led by John Dunlosky rated ten common study techniques by how well the evidence supported them. Only two got the highest rating: practice testing and distributed practice (spacing). Rereading, highlighting and summarising were rated low.

Why rereading is so popular

Rereading feels fluent: the material looks familiar, so it feels learned. But recognising something on the page is a different skill from recalling it when the page isn't there, which is what a conversation or an exam asks of you.

Flashcards are active recall

A flashcard shows a prompt and hides the answer, so every review is a small test. The important part is to actually answer before you flip: say the word, or think the full answer, then check. Flipping and nodding along turns a flashcard back into rereading.

Combine it with spacing and you get both of the techniques the 2013 review rated highest. See spaced repetition vs cramming.

References: Karpicke, J. D., & Roediger, H. L. (2008). Science, 319(5865), 966–968. doi.org/10.1126/science.1152408. Dunlosky, J., et al. (2013). Psychological Science in the Public Interest, 14(1), 4–58. doi.org/10.1177/1529100612453266.