Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology

43 Vassar St., Room 46-3037c, Cambridge, MA, 02139

© 2017 by Idan A. Blank

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Going Into Your Mind

The Brain, Revealed. Cutting-Edge Research. For Everyone.


B: how do you study for your exams?
P: I read my notes.
B: And then?
P: I go over them again.
B: How can you be sure that you’ve successfully learned the material?
P: ???
B: Don’t you quiz yourself?
P: …


This is a recent chat my Brother had with his Partner about the latter’s study habits. Simply reading material before an exam struck my brother (and me) as an unnervingly risky strategy. Instead, we study by alternating between reading sessions and circling the living room, where we would try to recite from memory everything we’ve learned so far; such repeated, brief parading culminates in a two-hour trek the night before the exam. This study regime has an intuitive appeal for nerve-rackingly anxious students with floor-level confidence and ominous prophecies of failure, like us. Self-quizzing is how we obsessively monitor learning.


Yet self-quizzing is not hailed by many students. Most professors, too, still view classes as windows of exposure to material, with tests being highly infrequent. Such teaching regimes tacitly assume that testing is merely a tool to measure learning after the latter has taken place – a measurement that does not affect learning itself. However, this assumption is wrong: testing strengthens your memory.


Eight years ago, a team from Purdue University conducted a seminal study on quizzing. In a beautifully elegant experiment, college students were taught Swahili words and their English translations over sessions alternating between “reviewing” (reading “elimu = science”) and “quizzing” (reading “elimu” and having to recall its translation). Critically, different students were assigned to different regimes: in one, all items were read on every review session and tested on every quiz. In the others, once a word had been correctly recalled on a quiz, it was dropped from future quizzes (but remained in reviews), dropped from future reviews (but remained in quizzes), or dropped from both quizzes and reviews. A week later, the students returned to the lab for a final exam. How well do you think they did? 


The researchers found that memory was not influenced by the amount of reviewing, but was instead determined by the amount of quizzing: if items were dropped from quizzes once they were successfully recalled – regardless of whether they remained in reviews or not – students could translate only 35% of Swahili words on the final exam. However, if items were repeatedly tested throughout all four quizzes (even if they were dropped from reviews), performance was more than twice as good, with students translating 80% of Swahili words on the final exam. Quizzing improved scores by four standard deviations – a huge effect! 


While these results are strikingly clear, you might wonder whether they are relevant to college students, who deal with material that is more complex than word-pairs in two languages. Importantly, the greater impact of quizzing compared to reviewing might be due to how active the former is compared to the latter: maybe reviewing engages you with the material too superficially, but elaborative studying could influence memory more strongly than quizzing. Fortunately, the same laboratory at Purdue examined this issue in a follow-up study, using a more realistic setting.


This time, students read two excerpts from science textbooks. After reading one text, students were asked to quiz themselves by typing everything they remembered reading; then, they re-read the text and re-quizzed themselves. After reading the second text, students were instead asked to keep the material visible and use it to create a concept map: a diagram denoting the relationships between concepts in the text. Concept maps, a popular learning strategy, are much more active than a simple review, because they require us to explicitly structure our knowledge and link different ideas. However, unlike quizzing, material for these concept maps was not recalled from memory: students created their maps while looking at the text.


During the learning session, students mentioned somewhat fewer concepts in their quizzes than in their diagrams. Therefore, concept mapping required students to engage more heavily with the material compared to quizzing. Students subjectively agreed with this judgment: they anticipated scores on an exam after concept mapping to be higher than after quizzing. However, when taking a short-answer exam a week later, students remembered and understood material that they quizzed themselves on much better than material for which they created concept maps. Remarkably, the text that was quizzed earlier was understood better even if the final exam asked students to generate a concept map from memory.


Thus, the advantages conferred by self-quizzing are not due to some general engagement with the material; rather, when you access a memory to recall what you have learned, mechanisms that are specific to this process of retrieval cause the memories to strengthen. The implications of this psychological finding are ridiculously easy to implement: start self-quizzing yourself. As Aristotle said: “Exercise in repeatedly recalling a thing strengthens the memory”. 


Yet not all self-quizzes are created equal: more effortful quizzes (recitation from memory) are better than easier ones (solving multiple-choice questions, where the answer only needs to be recognized, not recalled). In addition, post-quiz feedback through reviewing the material is critical; it would help you to both correct errors and increase confidence in accurate knowledge that you were unsure about. Finally, self-quizzing multiple times works best, but make sure you sufficiently space these quizzes – otherwise, quizzing feels like reviewing, and is indeed less effective.


MY TWO CENTS: research suggests that we need to pay close attention to two errors we make during learning. First, when reviewing material, we usually don’t feel that we have mastered it very well and we choose to keep reviewing. So despite being aware of the benefits of self-quizzing, we would postpone this strategy until we have at least moderate confidence in our knowledge. Nevertheless, quizzing early on, even if we get things wrong, is actually helpful. Second, and this is radical, we should keep quizzing ourselves even on material that we think we have already mastered. This is not easy: when we successfully recall something on a quiz, our subjective impression is that we learned it well and can drop it, but we are often wrong.​

CITATION: Karpicke, J. D., & Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865), 966-968; Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772-775.



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