What Is the Testing Effect?

The testing effect is the finding that being tested on something helps you remember it better than studying it again. A quiz is not just a measurement; it is a learning event. The effect is strongest at long delays: rereading may win on a test five minutes later, but testing wins a week later.

The key studies

The idea is old. Arthur Gates (1917) found that students who spent much of their study time reciting from memory learned more than those who only read, and Herbert Spitzer (1939) showed that quizzing thousands of schoolchildren soon after reading reduced forgetting. The modern version comes from Henry Roediger and Jeffrey Karpicke:

• Roediger & Karpicke (2006). Students studied short prose passages. Some reread them; others took recall tests. On a test five minutes later, rereaders did better. One week later, the order flipped. In one experiment, students who studied once and took three tests recalled about 61% after a week, against about 40% for those who studied four times.
• Karpicke & Roediger (2008). Students learned 40 Swahili–English word pairs. Continuing to test items after they were learned produced about 80% recall a week later; dropping them from testing left about a third. Continuing to study them made little difference.

The effect has since been replicated with vocabulary, maps, science concepts and classroom material, and across age groups.

Testing effect vs retrieval practice vs active recall

These terms are closely linked, and mixing them up is common:

• The testing effect is the observation: tested material is retained better.
• Retrieval practice is the strategy educators recommend because of that observation.
• Active recall is the everyday technique name for the same strategy, typically flashcards or self-quizzing.

Note also that "test" here does not mean an exam. Any act of retrieval counts, including a flashcard, a cloze sentence or simply trying to remember a meaning before looking it up again.

A vocabulary example

Why testing helps

• Retrieval strengthens memory directly, making future retrieval easier.
• It creates more retrieval routes, as you search through related knowledge.
• It improves later study (test-potentiated learning): after a failed attempt, the correct answer is encoded better.
• It corrects overconfidence. Students consistently predict that rereading will work better than it does.

How to use the testing effect for words

1. After reading, close the text and list the new words you remember, with meanings.
2. Use flashcards in both directions, word to meaning and meaning to word.
3. Check every answer; feedback adds to the benefit.
4. Repeat tests across days instead of within one session. Testing and spacing reinforce each other.
5. Keep quizzes short and low-stakes so they become a habit.

Wordie's recall mode is a simple form of this: you try to recall a saved word's meaning, reveal it, and rate yourself. For a fuller discussion, read the testing effect explained, and see why flashcards alone fail for the limits.

Common misconceptions

• "Testing only measures learning." It also produces learning.
• "Multiple choice is enough." Recognition tests help, but recall tests usually help more for long-term retention.
• "Getting it wrong is harmful." Errors followed by feedback are fine; leaving errors uncorrected is the problem.

Sources: Gates, A. I. (1917). Recitation as a factor in memorizing. Spitzer, H. F. (1939). Studies in retention. Journal of Educational Psychology. Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning. Psychological Science. Karpicke, J. D., & Roediger, H. L. (2008). Science.