In 2006, Henry Roediger and Jeffrey Karpicke gave college students short passages to learn. Some students read a passage four times. Others read it once and then tried three times to write down everything they could remember, without looking.
| Group | Recall after 5 minutes | Recall after 1 week |
|---|---|---|
| Read it 4 times | 83% | 40% |
| Read once, recalled 3 times | 71% | 61% |
Five minutes later, the readers did better. But a week later, the group that had practiced recalling remembered far more. The readers had forgotten about half of what they knew; the recallers had kept most of it.
Key idea
Retrieval practice: trying to recall something, before you look, makes the memory stronger. This is called the testing effect.
Why it works
Each time you pull a memory out, you strengthen the path to it. Rereading puts the information in front of you, so your memory doesn't have to do the work.
Worked example: Worked example
Which plan uses the testing effect for learning ten science words?
- Plan A: read the list five times.
- Plan B: read it once, then cover the meanings and try to say each one, checking after each try.
- Only Plan B asks the memory to do the work.
Answer: Plan B.
Common mistake
Thinking a test only measures. In these studies, the test itself was the study session that worked best.