When you try to recall some detail from memory, that act strengthens your memory of that detail. When exploited as a learning activity, this is called “retrieval practice.”
Experiment has demonstrated this effect even when the correct answer is not provided (though Retrieval practice may be less effective without feedback), and even when the test-taker is given “open-book” access to find a correct answer. The effect has been demonstrated in many fields and at many age levels.
This suggests a significantly different role for tests. In typical classrooms, teachers and students imagine that learning happens during lectures, or while reading the material. The tests are there to assess that learning. But in fact, the tests themselves are an important part of the learning process.
Retrieval practice leads to more durable long-term memory than simply studying material by e.g. re-reading, despite the fact that students will be less successful during practice itself (Roediger, 2006). Related: Desirable difficulties, after Bjork.
It also seems to lead to more durable memory (Karpicke and Smith, 2012) and improved learning performance in general (Karpicke and Blunt, 2011) relative to Elaborative encoding-based practice alone.
The testing effect is generally measured to be more pronounced for production tests (short answer, essay) than for discrimination (multiple choice / true-false) (e.g. Kang et al, 2007). This may be due to the Generation effect.
A few cites to follow up on here from Agarwal, P. K., Nunes, L. D., & Blunt, J. R. (2021). Retrieval Practice Consistently Benefits Student Learning: A Systematic Review of Applied Research in Schools and Classrooms. Educational Psychology Review.:
n.b. that Pan, S. C., & Rickard, T. C. (2018). Transfer of test-enhanced learning: Meta-analytic review and synthesis. Psychological Bulletin, 144(7), 710–756 find a medium-large effect (d=0.58) for transfer across initial and final test formats
Agarwal, P. K., Nunes, L. D., & Blunt, J. R. (2021). Retrieval Practice Consistently Benefits Student Learning: A Systematic Review of Applied Research in Schools and Classrooms. Educational Psychology Review.
Pan, S. C., & Rickard, T. C. (2018). Transfer of test-enhanced learning: Meta-analytic review and synthesis. Psychological Bulletin, 144(7), 710–756, focused specifically on Retrieval practice and transfer learning
Branwen, G. (2009). Spaced Repetition for Efficient Learning. Retrieved December 16, 2019, from https://www.gwern.net/Spaced-repetition
Roediger, H. L., & Karpicke, J. D. (2018). Reflections on the Resurgence of Interest in the Testing Effect. Perspectives on Psychological Science, 13(2), 236–241. https://doi.org/10.1177/1745691617718873
Roediger, H. L., & Butler, A. C. (2011). The critical role of retrieval practice in long-term retention. Trends in Cognitive Sciences, 15(1), 20–27. https://doi.org/10.1016/j.tics.2010.09.003
Unpublished master’s thesis, Purdue University]]
* Following the claims in van Gog, T., & Sweller, J. (2015). Not New, but Nearly Forgotten: The Testing Effect Decreases or even Disappears as the Complexity of Learning Materials Increases. Educational Psychology Review, 27(2), 247–264, the author ran several experiments intended to validate the Testing effect for a complex problem-solving activity (solving Poisson probability problems). Mostly just reproducing Yeo, D. J., & Fazio, L. K. (2019). The optimal learning strategy depends on learning goals and processes: Retrieval practice versus worked examples. Journal of Educational Psychology, 111(1), 73–90 with larger sample sizes.