The testing effect is a well-known psychological phenomena whereby people remember things better if they are tested on them. The benefits don't stem just from getting feedback on right or wrong answers - although that can help too. It appears that the process of retrieving information from memory actually helps it to be consolidated. In other words, a test can make the memory more secure and less likely to be forgotten.
So what role should tests play in the learning process? This phenomenon can certainly be applied to self-testing during revision; students who do this appear to get better grades (see Hartwig & Dunlosky, 2012). Self-questioning of a text has also been linked to superior recall and understanding compared to re-reading (Pressley et al., 1990).
More broadly, questioning can help to pique curiosity - leading to the surprising finding that even being tested before you have been taught the information can boost subsequent attainment (the 'pretesting effect').
However, testing can play a much broader role in the classroom than just revision activities. Memory research in this area suggests that retrieval of information plays a fundamental role in the way a new memory forms.
A key research study
A 2006 study by Henry Roediger III and Jeffrey Karpicke has become a classic in this area, and is highly illuminating to teachers. They compared memory for a text after studying (S) it and/or being tested (T) on it. They found that study opportunities followed by a test where students wrote down everything they could remember (S-S-S-T) was led to better recall than being given an additional study opportunity (S-S-S-S). More surprisingly, a single reading followed by three tests (S-T-T-T) was best of all, even though no feedback was given on any of the tests.
An additional point to note from the Roediger and Karpicke study is that the advantage was only shown after a 1 week delay - if recall was assessed after just a few minutes, the study-only conditions were better. This is important, as it suggests that testing helped to prevent forgetting in long-term memory; participants in the S-S-S-S condition forgot far more (52%) than those in the S-S-S-T condition (28%), with participants in the S-T-T-T condition forgetting least of all (14%).
A huge amount of research has been done on this area over the past 10 years or so since the Roediger & Karpicke paper, many of them using educationally relevant materials. Benefits that were first established in psychology labs have been shown to apply to real world learning situations such as a middle school science classroom (e.g. McDaniel et al, 2011).
It is easy to measure the testing effect with simple facts or word lists, and the extent to which the benefit extends to more complex materials has been questioned (e.g. van Gog & Sweller, 2015; see also Karpicke & Aue, 2015). However, the effect has been shown with a wide range of real-world tasks including texts, and Smith et al (2010) found that being tested on material from a passage also improved later knowledge of items that had not been tested (in comparison to a re-reading control condition), suggesting that it does promote integrated understanding. Overall, the current research seems to suggest that most teachers and learners in most learning situations would benefit from increasing the level of retrieval used, i.e. the amount that learners have to actively recall things from memory, and that this should be preferred to re-reading or re-teaching as a learning strategy.
Indeed, the research into retrieval practice can prompt a new way of thinking about learning as a whole - that although initial exposure to material and ideas is clearly necessary, that the actual learning takes place when we retrieve and use the information. Otherwise, forgetting can be quite rapid. Nevertheless, this area of psychology is still developing and it is important to keep an eye on new findings and possible boundary conditions as they emerge.
Despite its name, the testing effect does not just apply to tests - and more recently, researchers have tended to prefer the term 'retrieval practice' rather than testing effect (e.g. Karpicke et al, 2014), because retrieval is a key process in learning, while the term 'testing' tends to imply assessment. Of course, setting a class test is just one way of prompting students to retrieve information from memory; other methods could include:
- Direct verbal questioning
- Writing notes from memory
- Using flashcards
- Writing essays
- Group discussion
The key factor in all cases is that information is actively retrieved rather than passively heard or re-read - a principle that can be applied to any subject discipline. A straightforward method for a teacher who uses Powerpoint would be to insert slides with short questions, either at the end or throughout (see Weinstein et al, 2016, for a discussion of the relative efficacy of interspersing question slides v's testing at the end).
It is also relatively easy to pair retrieval practice with other evidence based interventions, such as distributed learning. Roediger & Pyc (2012) described both retrieval practice and distributed learning as 'low-hanging fruit' in terms of possible educational interventions - in comparison to the millions that are spent on technological innovations, they are quick, easy and cheap to implement.
Overall, a large body of research suggests that integrating more opportunities for retrieval practice into our teaching will improve learners' long-term retention of facts and understanding of concepts.
See also: Memory in education - a mission statement
Further reading (for teachers): Learn how to study using retrieval practice; Learning how to learn - practicing retrieval.
Hartwig, M. K., & Dunlosky, J. (2012). Study strategies of college students: Are self-testing and scheduling related to achievement?. Psychonomic Bulletin & Review, 19(1), 126-134.
Karpicke, J. D., & Aue, W. R. (2015). The testing effect is alive and well with complex materials. Educational Psychology Review, 27(2), 317-326.
McDaniel, M. A., Agarwal, P. K., Huelser, B. J., McDermott, K. B., & Roediger, H. L. (2011). Test-enhanced learning in a middle school science classroom: The effects of quiz frequency and placement. Journal of Educational Psychology, 103, 399–414.
Pressley, M., Tanenbaum, R., McDaniel, M. A., & Wood, E. (1990). What happens when university students try to answer prequestions that accompany textbook material?. Contemporary Educational Psychology, 15(1), 27-35.
Richland, L. E., Kornell, N., & Kao, L. S. (2009). The pretesting effect: Do unsuccessful retrieval attempts enhance learning?. Journal of Experimental Psychology: Applied, 15(3), 243.
Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning taking memory tests improves long-term retention. Psychological Science, 17, 249-255.
Roediger, H. L., & Pyc, M. A. (2012). Inexpensive techniques to improve education: Applying cognitive psychology to enhance educational practice. Journal of Applied Research in Memory and Cognition, 1(4), 242-248.
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.
Weinstein, Y., Nunes, L. D., & Karpicke, J. D. (2016). On the placement of practice questions during study. Journal of Experimental Psychology: Applied, 22(1), 72.