How to Study Effectively: What Cognitive Science Recommends

Most students study by rereading their notes or highlighting their textbooks. Most students are using the least effective techniques available. This is not speculation: Dunlosky and colleagues reviewed ten common study strategies against the available evidence and rated rereading and highlighting as “low utility,” while retrieval practice and distributed practice were rated “high utility” [1]. The gap between what students do and what works is one of the more striking findings in educational psychology. The review examined decades of research across multiple populations and concluded that the two best-supported techniques are among the least used, while the most popular techniques have the weakest evidence.

What works: retrieval practice

Retrieval practice means testing yourself on the material rather than reviewing it passively. Flashcards, practice questions, writing from memory, teaching someone else from memory: any activity that requires you to produce the answer rather than recognize it.

The mechanism is what researchers call the testing effect. The act of retrieving information from memory strengthens the memory trace more than additional study of the same material [2]. This is counterintuitive: it feels like retrieval should be an assessment of learning, not a cause of it. But the evidence is unambiguous. Roediger and Karpicke tested this directly: students who studied a passage once and then practiced retrieval three times retained significantly more after one week than students who studied the passage four times [2]. On the first day, the study-only group performed slightly better. By one week, the retrieval group had a substantial advantage. The crossover pattern is important because it reveals the temporal signature of the testing effect: retrieval does not help immediate performance as much as it helps durable retention.

Karpicke and Blunt extended this finding by comparing retrieval practice against concept mapping, an active study technique that requires organizing information into a visual structure. Retrieval practice produced better performance on both verbatim and inferential test questions [5]. The advantage held even when participants rated concept mapping as more effective. This is notable because concept mapping is already a step above passive reading; it requires genuine engagement with the material’s structure. The fact that retrieval practice outperformed even an active technique suggests that the act of generating information from memory, rather than reorganizing information that is in front of you, is the critical variable.

This last point matters. Students consistently judge rereading as more effective than testing, even when their actual performance shows the opposite [4]. Kornell and Bjork surveyed 472 undergraduates and found that most students relied on rereading as their primary study strategy and believed it to be effective. The fluency illusion, the sense that familiar-looking material is well-learned material, is powerful and misleading. It operates at the level of metacognition: the student’s sense of how well they know the material is systematically biased by how easy the material is to process, not by how well they can actually retrieve it.

What works: spaced repetition

Distributed practice, or spacing, means spreading study over multiple sessions rather than concentrating it in one block. The spacing effect is one of the most robust findings in cognitive psychology, demonstrated across hundreds of studies over more than a century [3].

The mechanism is still debated, but the leading explanation is that each retrieval after a gap requires more effort, and that effortful retrieval produces stronger encoding. The gap allows partial forgetting, and the work of recovering fading information is what strengthens the memory trace. Massed practice (cramming) feels effective because the material is fresh, but the long-term retention is substantially worse. The forgetting that occurs between spaced sessions is not a failure of the method; it is the method.

The optimal spacing interval depends on when you need the material. Cepeda and colleagues’ meta-analysis of 254 studies found that the ideal gap between sessions is roughly 10 to 20 percent of the retention interval [3]. For an exam in 30 days, study sessions spaced 3 to 6 days apart. For material you want to retain for months, wider gaps are better. This principle is what flashcard programs like Anki use to schedule reviews: each successful retrieval lengthens the interval before the next review, and each failure shortens it, maintaining the gap at the point where retrieval is effortful but still possible.

Rawson and Dunlosky investigated the optimal schedule for retrieval practice and found that spacing retrievals to the point where performance begins to drop, rather than overlearning through repeated successful retrievals at short intervals, produced the most efficient retention [6]. Practicing until you get it right once and then spacing the next practice further out is more efficient than drilling the same item until it feels automatic.

What doesn’t work as well as it feels

Rereading creates familiarity without understanding. The material looks recognizable, which the brain interprets as “I know this,” but recognition is far easier than recall. Students who reread perform only marginally better on delayed tests than students who read once [1]. The first reading does most of the work; subsequent readings produce diminishing returns because they maintain the feeling of familiarity without requiring the effortful processing that builds durable memory.

Highlighting is similarly passive. Marking text requires no processing beyond selection, and the evidence for its effectiveness is weak across multiple studies. It can even be counterproductive if it creates a false sense of having engaged with the material [1]. The highlighted passage looks studied, which can reduce the motivation to return to it with more effortful techniques. The physical act of drawing a line does not transform the information in any way that strengthens its encoding.

Summarizing fares slightly better, but only when done from memory rather than by copying from the text. The benefit comes from the retrieval component, not the writing itself. A summary written while looking at the source is reorganization; a summary written from memory is retrieval practice with a note-taking structure, and the difference in retention is substantial.

When these techniques tend not to work

Retrieval practice is least effective when used too early, before any initial understanding has been established. Testing yourself on material you have not yet studied at all produces frustration, not learning. The evidence assumes at least one good initial exposure to the material. A solid first reading or lecture that builds comprehension is the foundation; retrieval practice then strengthens and maintains what that initial exposure created.

Spacing requires planning and discipline that is the opposite of how most students actually operate. The technique works best for factual and conceptual material; for skill-based learning (writing, mathematics), the picture is more complicated because practice effects interact with spacing effects. There is also a practical barrier: spacing requires starting early. A student who begins studying three days before the exam cannot space effectively, because the intervals would be too short to produce the effortful retrieval that spacing depends on. The technique rewards foresight and punishes procrastination, which is one reason adoption is low.

Both techniques feel less effective than they are [4]. Retrieval is effortful and uncomfortable. Spacing means revisiting material when it has started to fade, which feels like you are losing what you learned. Students consistently prefer the techniques that feel good (rereading, highlighting) over the ones that work well (testing, spacing), which is one reason the evidence has been slow to change practice. The metacognitive mismatch is the central obstacle: the techniques that produce the best learning produce the worst feelings of learning, and vice versa.

Practical considerations

Replace rereading sessions with retrieval sessions. After reading a chapter, close the book and write down everything you remember. Then check what you missed. This is more effortful and less pleasant than rereading, and it is substantially more effective [5]. The checking step is important: it identifies gaps, which you can then target in the next retrieval attempt.

Space your study sessions. If you have four hours to study, four one-hour sessions on four different days will produce better retention than a single four-hour session, even though the total time is identical [3]. The distributed approach is not just more effective; it is also more efficient, because each session builds on the effortful retrieval from the previous one.

Combine the two. Use spaced retrieval: test yourself on material at increasing intervals. Flashcard apps automate this, but the principle works with any material and any format. The combination of spacing and retrieval practice is more powerful than either alone, because spacing creates the partial forgetting that makes retrieval effortful, and effortful retrieval is what strengthens the memory.

Trust the discomfort. If retrieval feels difficult, it is working. The effort is the mechanism, not a sign that you are studying wrong [6]. A study session that feels easy and fluent is probably doing less for long-term retention than one that feels halting and uncertain.

If difficulty concentrating is new, persistent, or significantly affecting your life, it’s worth speaking with a doctor. Changes in focus can sometimes reflect sleep problems, mood disorders, or health conditions that are worth addressing directly. This site covers technique, not diagnosis.