Active Recall vs Re-reading: Which Works Better?

Re-reading is one of the most common ways students revise. In a survey of 177 undergraduates, 84% said they re-read their notes or textbook, and 55% said it was their main strategy. Only 11% said they tested themselves. The trouble is that an exam asks you to produce answers from a blank page, and re-reading mostly practises recognising them.

Recognition and recall

Recognition is a judgement: here is a statement, have I seen this before? Recall is production: here is a question and nothing else, now give the answer.

Recognising a face across a room without being able to produce the name is the everyday version.

Re-reading trains recognition, because the answer is on the page the whole time. Exams, vivas, problem sets and conversations ask for recall.

Why re-reading feels productive

The second pass through a page is smoother than the first: fewer stumbles, less re-reading of long sentences, no surprises. This ease is called processing fluency, and it is easy to mistake for knowing the material.

A 2013 review by Robert Bjork, John Dunlosky and Nate Kornell describes how people's judgements of their own learning are swayed by how fluent the material feels at the time, which leads them to misjudge how much they will remember.

Recall feels worse. You sit in front of a blank page and nothing arrives for several seconds. That discomfort does not mean the method is failing.

What the research shows

In a 2006 study, Henry Roediger and Jeffrey Karpicke had students read short science passages. After the first reading, the students either read a passage again or spent the same time writing down everything they could remember from it, with no feedback.

• Students tested five minutes later recalled the re-read passage slightly better: 81% against 75%.
• Students tested two days later recalled more of the passage they had practised recalling: 68% against 54%.
• Students tested a week later: 56% against 42%, again in favour of recall.

In a second experiment, students who spent four study periods reading a passage were more confident they would remember it a week later than students who read it in one period and then spent three practising recall. A week later, the re-readers remembered 40% of the passage and the recall group 61%, even though the re-readers had been through the text about 14 times and the recall group about 3.

So how confident you feel after an evening of study is not a reliable guide to what you will remember.

Why recall works

Recalling something changes how well you will remember it later. In another study by Karpicke and Roediger, students learned Swahili–English word pairs. In some groups, a word kept being tested after the student had recalled it once. In others, it was dropped from the tests. A week later, the students who kept being tested recalled about 80% of the words, and those who stopped recalled about 35%, whether or not they had kept studying the words. All the groups had predicted they would recall about half.

Recall that takes some effort seems to do more than recall that comes instantly. In one study, word pairs that students had to recall after longer gaps were harder to get during practice and better remembered afterwards.

Trying and failing helps too, as long as you then see the answer. In experiments by Nate Kornell and colleagues, people who tried to answer a question before being shown the answer remembered it better than people who saw the question and answer together, even though their attempts were wrong.

How to practise active recall

The basic method:

1. Read one section of your notes or textbook.
2. Close it and write down everything you can remember, in your own words.
3. Open it and mark what you missed or got wrong.
4. Come back to the parts you missed in a day or two and try again.

For example, if the section is on the rotator cuff, close the book and write down the four muscles and what each one does. Then check. Whatever you left out or mixed up is what you test yourself on next time.

Other ways to do the same thing:

• Turn each heading into a question before you read the section, and answer the questions afterwards without looking.
• Explain the topic aloud until you get stuck. The point where you stall is the next thing to study.
• Cover one column of a table or definition list and recall it from the other.
• When a question gives you options, answer it in your head before you look at them.

The slow parts are writing good questions about a chapter you do not yet understand, and finding the paragraph that settles an answer when you check it. In SymbioLearn, each Concept in a Module has a Quick Quiz written from the Sources you added, and Flashcards where the material suits a front and a back. Every question and card keeps the page, slide or timestamp it came from, so checking an answer opens the passage that settles it.

When re-reading is useful

Reading is how the ideas arrive. You cannot recall something you have never read, and the first pass through a difficult chapter has to be reading.

Re-reading is also well spent straight after a failed recall attempt, because you now know exactly what you were missing.

Re-reading does help a little, more so when the re-reads are spread out. But Dunlosky and colleagues' review of ten study techniques rated it low utility, because it is usually much less effective than testing yourself. The problem is using re-reading as the whole method.

Common mistakes

• Testing yourself once, at the end of term. Recall does more when it is spread out over weeks. The timing is covered in the forgetting curve.
• Reading flashcards instead of testing with them. Say the answer before you turn the card over.
• Skipping the check. Always compare your answer with the source. A failed attempt helps when you then see the right answer.
• Stopping at one correct answer. In the word-pair study above, words recalled correctly only once were mostly forgotten a week later. What helps knowledge last is covered in how to remember what you studied last month.

What to do tonight

1. Take the section you read most recently and close it.
2. Write down everything it said, without looking.
3. Open it and mark what you missed.
4. Put the missed points on a list to try again in two days.

Whatever you could not write down is what you do not know yet, and it is better to find that out now than in the exam. If you would rather have the questions written for you, with every answer linked to the page it came from in your own study material, that is what a Module in SymbioLearn does.