Most claims about quizzes are some version of “quizzes make you smarter.” The research supports something narrower and more useful: trying to recall something strengthens your memory of it more than looking at it again. That finding, known as the testing effect or retrieval practice, has been replicated across decades of studies. Most of the real benefits of quizzing follow from it, and so do the limits. This piece covers what’s well established, what depends on how you quiz, and what isn’t supported.

1. Recalling beats rereading

In experiments published in Psychological Science, Roediger and Karpicke (2006) had students study short prose passages and then either take recall tests on them or restudy them the same number of times. On a test five minutes later, restudying came out slightly ahead. On tests two days and a week later the result reversed: the students who had been tested remembered substantially more.

A 2008 study in Science by Karpicke and Roediger made the size of the gap concrete. Students learned 40 Swahili–English word pairs. Once a pair had been recalled correctly, some students kept being tested on it while others only kept studying it. A week later, the students who had kept being tested recalled about 80% of the pairs. Those who had stopped being tested recalled between a third and 36%, even the group that had restudied every pair in every round.

The effect isn’t confined to a few laboratory tasks. Rowland’s (2014) meta-analysis in Psychological Bulletin, which pooled comparisons of testing and restudying across many studies, found a reliable overall advantage for testing, though its size varied from study to study.

2. Quizzing shows you what you don’t know

In the 2008 word-pair study, students were asked how many pairs they expected to recall a week later. Whichever way they had practised, they predicted about half. Their actual results ranged from about a third to about four-fifths. In the 2006 prose experiments, restudying likewise made students more confident about how much they would remember, and that confidence was misplaced.

Rereading produces a feeling of familiarity that is easy to mistake for knowing something. A quiz replaces the feeling with a result. In practice, the questions you get wrong, or get right only by guessing, are the study list for your next session.

3. Spacing multiplies the benefit

Quizzing yourself once helps. Quizzing yourself on the same material on several different days helps much more. Cepeda and colleagues’ (2006) review of the spacing effect pooled 839 assessments from 317 experiments in 184 articles and found that spreading practice out over time consistently beat massing the same amount of practice together. A follow-up study (Cepeda et al., 2008) found that the best gap between sessions depends on how long you need to remember something: the longer you need it, the longer the gaps should be.

A workable routine is to come back to material the next day, then a few days later, then a week or two after that. It doesn’t need to be precise to help.

4. Feedback turns wrong answers into learning

A reasonable worry about multiple-choice quizzes is that they show you wrong answers, and you might later remember a wrong option as true. That does happen. Butler and Roediger (2008), in Memory & Cognition, found that feedback deals with most of the problem: students who were told the correct answers after a multiple-choice test, either straight away or later, recalled more correct answers on a later test and repeated fewer of the wrong options than students who got no feedback.

Question format matters too. Kang, McDermott and Roediger (2007) compared short-answer and multiple-choice practice tests. When feedback was given, practising with short-answer questions, where you have to produce the answer yourself, led to the best later recall. For more on how test format affects learning, see multiple choice vs free recall.

5. It builds understanding, not just recall of facts

Retrieval practice is sometimes dismissed as rote memorisation. Karpicke and Blunt (2011), at Purdue University, tested that in a study published in Science. Students read science texts and then either practised recalling what they had read or built concept maps with the text in front of them. On a test a week later, the retrieval group did better, including on questions that required drawing inferences rather than repeating facts.

6. Mixing topics helps, even though it feels harder

Working through one topic at a time feels smoother than switching between topics, and that smoothness can mislead. Rohrer and Taylor (2007) had students practise maths problems either in blocks of one type or mixed together. Students solved more problems during practice when the problems were blocked, but a week later the students who had practised with mixed problems did better. A mixed general-knowledge round works on a similar principle: you have to work out what kind of question you’re facing before you can answer it.

Where the evidence is weaker

Some common claims about quizzes go beyond what the research shows.

“Quizzes make you smarter in general.” The testing effect strengthens memory for the material you’re tested on. It isn’t evidence that quizzing raises general intelligence. A major review of commercial brain-training programmes (Simons et al., 2016) found good evidence that people get better at the tasks they practise and little evidence that those gains carry over to unrelated everyday abilities.

“Every correct answer gives you a dopamine hit that locks the memory in.” Reward does affect memory, but this is a large simplification. A well-designed quiz can be more enjoyable, which gets people to practise more often. The practice is what does the work.

“More quizzing in one sitting is always better.” Twenty questions on each of three separate days will usually do more for long-term memory than sixty questions at once, for the spacing reasons above.

How to get the benefits

  1. Cover the answer and commit. Say or write your answer before you check. Recognising the right answer when you see it is not the same as recalling it.
  2. Read the correct answer, especially when you guessed. Feedback is what stops wrong answers from sticking.
  3. Come back to the same material. The next day, a few days later, then a week or two after that.
  4. Mix subjects. A mixed round is harder, and that’s part of why it works.
  5. Keep the stakes low. The research is about practice quizzes. Nothing needs to ride on the result for them to work.

To try it now, a mixed general knowledge round shows the correct answer after every question. Our guide on how to study effectively turns these findings into a complete study routine.

Sources

  • Butler, A. C., & Roediger, H. L. (2008). Feedback enhances the positive effects and reduces the negative effects of multiple-choice testing. Memory & Cognition, 36(3), 604–616.
  • Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T., & Rohrer, D. (2006). Distributed practice in verbal recall tasks: A review and quantitative synthesis. Psychological Bulletin, 132(3), 354–380.
  • Cepeda, N. J., Vul, E., Rohrer, D., Wixted, J. T., & Pashler, H. (2008). Spacing effects in learning: A temporal ridgeline of optimal retention. Psychological Science, 19(11), 1095–1102.
  • Kang, S. H. K., McDermott, K. B., & Roediger, H. L. (2007). Test format and corrective feedback modify the effect of testing on long-term retention. European Journal of Cognitive Psychology, 19(4–5), 528–558.
  • Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772–775.
  • Karpicke, J. D., & Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865), 966–968.
  • Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255.
  • Rohrer, D., & Taylor, W. P. (2007). The shuffling of mathematics problems improves learning. Instructional Science, 35, 481–498.
  • Rowland, C. A. (2014). The effect of testing versus restudy on retention: A meta-analytic review of the testing effect. Psychological Bulletin, 140(6), 1432–1463.
  • Simons, D. J., Boot, W. R., Charness, N., Gathercole, S. E., Chabris, C. F., Hambrick, D. Z., & Stine-Morrow, E. A. L. (2016). Do “brain-training” programs work? Psychological Science in the Public Interest, 17(3), 103–186.