How to study effectively, according to the research

In 2013, Dunlosky, Rawson, Marsh, Nathan and Willingham reviewed ten widely used study techniques and rated how useful each one is, based on the evidence available (Dunlosky et al., 2013). The result often surprises students, because the most popular methods are also the lowest rated. A survey of 177 students found that most of them reread their notes or textbook, and relatively few quiz themselves (Karpicke et al., 2009).

The table below lists the ten techniques and the rating of each. Two stand out clearly, practice testing and distributed practice. Three sit in the middle. Five are rated low, including rereading and highlighting. These ratings tell you which technique held up best under scrutiny. They give you an order of priority when time is short.

In the study by Roediger and Karpicke, students read a text once and then quizzed themselves three times. One week later they remembered 61% of the ideas, against 40% for students who had reread the text four times (Roediger and Karpicke, 2006). This technique is called active recall, and you will find the details in Active recall, why quizzing yourself beats rereading.

In practice, you close your notes, try to answer a question, rewrite a definition or redraw a diagram from memory, and then check. The effort of retrieving is what counts. A 2014 meta-analysis also found that recall tests give a bigger benefit than recognition tests, such as multiple choice (Rowland, 2014). Before finals, that means answering practice questions from your course with the book closed instead of reading the chapter a fourth time.

The meta-analysis by Cepeda and colleagues, 839 measures drawn from 317 experiments, concluded that spacing beats massing (Cepeda et al., 2006). In another study with more than 1,350 people, the ideal gap between two sessions was about 20 to 40% of the delay before the test when the test was a week away (Cepeda et al., 2008). For an exam in 10 days, that means a second session 2 to 4 days after the first.

With vocabulary flashcards, spacing worked better for 90% of participants, yet 72% thought after the first session that massing worked better (Kornell, 2009). So the feeling misleads you. Rawson and Dunlosky advise recalling an item correctly 3 times in the first session, then relearning it 3 times at widely spaced intervals (Rawson and Dunlosky, 2011). You will find the details in Spaced repetition, how long to wait between two reviews and, for the night before an exam, in Does cramming the night before an exam work?.

Elaborative interrogation, self-explanation and interleaved practice get a moderate utility rating (Dunlosky et al., 2013). That is not a bad score, and these techniques make a good complement once you already quiz yourself. Interleaving means mixing problem types instead of grouping them. In math, it improved results on a delayed test (Rohrer and Taylor, 2007). In practice, that means mixing the kinds of problems in one homework set instead of doing ten of the same type in a row. See Does interleaving, or mixed practice, really help you study?.

Another result points the same way, although it is not one of the ten techniques. Participants who studied a text expecting to teach it produced fuller, better organized recall, even though nobody actually taught (Nestojko et al., 2014). This is the idea behind Does learning by teaching work? What research says about the protégé effect. So you can explain your course out loud, as if someone had to understand it after you.

Summarizing, highlighting or underlining, keyword mnemonics, mental imagery for text and rereading all get a low utility rating (Dunlosky et al., 2013). Low does not mean useless. It means other methods held up better against the evidence. The trap is that these methods give you a feeling of mastery. In the study by Roediger and Karpicke, the students who reread were the most confident they would remember, yet they had forgotten the most one week later (Roediger and Karpicke, 2006).

If you like highlighting or rereading, keep them as a first step, then move quickly to quizzing yourself. The dedicated pages cover each case, Why rereading your notes is not enough and Is highlighting your notes actually useful?. A good habit for finals or AP prep is to turn each highlighted passage into a question, then ask it to yourself the next day without looking.