Testing effect

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, 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.

Versus other study activities

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.



Basic Research and Implications for Educational Practice. Perspectives on Psychological Science, 1(3), 181–210. https

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

Primary research






* Experiment comparing concept mapping (invoking Elaborative encoding) vs. retrieval practice (invoking Testing effect) on memory. Like Karpicke and Smith (2012), this paper is also interested in whether the effects of retrieval practice seem to be due to elaborative encoding, or whether there’s some other process going on.

  • [[Karpicke, J. D., & Smith, M. A. (2012). Separate mnemonic effects of retrieval practice and elaborative encoding. Journal of Memory and Language, 67(1), 17–29.

* Is the Testing effect produced by Elaborative encoding? When you review prompts in a Spaced repetition memory system, you give yourself an opportunity to form new connections based on your current context and the different thoughts you have during the review session.

  • [[Karpicke, J. D., & Zaromb, F. M. (2010). Retrieval mode distinguishes the testing effect from the generation effect. Journal of Memory and Language, 62(3), 227–239.

* Are the Testing effect and the Generation effect simply the same thing? They’re often equated, and indeed, I’d equated them in my own notes. This paper describes a series of experiments which attempt to demonstrate that a different underlying mechanism drives the two phenomena, and that retrieval practice has a greater impact on memory than generation.

  • Preparing for FOO Camp talk 2020
  • [[Roediger, H. L., & Karpicke, J. D. (2006). The Power of Testing Memory: Basic Research and Implications for Educational Practice. Perspectives on Psychological Science, 1(3), 181–210.

* A thorough review paper on the Testing effect. This paper covers the history of experiment on the test in laboratory settings and more practical classroom settings and reviews some more recent research by the authors.

  • [[Rohrer, D., Dedrick, R. F., Hartwig, M. K., & Cheung, C.-N. (2020). A randomized controlled trial of interleaved mathematics practice. Journal of Educational Psychology, 112(1), 40–52.

* Interleaved practice creates a natural context for the Spacing effect and Testing effect: