How to Study Effectively: Evidence-Based Memorization Techniques

Students and professionals spend hours studying, but not all study methods produce the same results. A 2013 review in Psychological Science in the Public Interest, led by cognitive psychologist John Dunlosky of Kent State University, evaluated ten widely used learning techniques against the available experimental evidence and sorted them into high, moderate and low utility categories.

The two techniques with the strongest evidence

Practice testing, also called retrieval practice, means actively recalling information from memory instead of simply looking at it again — for example, closing the book and trying to write down what a flashcard's answer is before checking it. According to Scientific American's reporting on the underlying research, one experiment found students remembered 35% of word pairs they had been tested on a week earlier, compared with only 4% of pairs they had merely reread. A separate experiment cited in the same report found 80% recall for items that had been repeatedly tested versus 36% for items that were only restudied.

Distributed practice — spacing study sessions apart instead of cramming them into one sitting — was the other technique rated high utility by Dunlosky and colleagues. Scientific American reported that a meta-analysis covering 254 studies found average test scores of 47% after spaced study compared with 37% after massed (crammed) study. The ideal gap between sessions depends on how long the information needs to be retained: the same report cited research suggesting roughly 12 to 24 hours between sessions when the goal is to remember something for a week, versus 6 to 12 months of spacing when the goal is retention over five years.

The Australian Education Research Organisation (AERO), a government-affiliated research body, reaches a similar conclusion in its practice guide on spacing and retrieval: there is no single 'optimal' interval, but separating study sessions by at least one day outperforms concentrating all learning into a single session.

Putting retrieval and spacing into practice

1. Turn notes into questions rather than statements, and quiz yourself on the questions without looking at the answer first.
2. Use flashcards or short self-made quizzes, and mark items you get wrong so they come back sooner than items you got right.
3. Revisit the same material more than once, with at least a day between sessions rather than reviewing it all at once.
4. Mix question types during a single review session — combine factual recall questions with higher-order or conceptual questions, as AERO's guide recommends.
5. Treat low-stakes self-quizzing as part of studying itself, not just as a way to check what you already know — the act of recalling strengthens the memory.

Techniques with moderate, less settled evidence

Three other techniques were rated moderate utility by Dunlosky and colleagues: elaborative interrogation (asking yourself 'why' a fact is true), self-explanation (explaining a step or concept in your own words as you study), and interleaved practice (mixing different types of problems instead of practicing one type repeatedly before moving to the next). Scientific American's account of the research notes that in one study, mixing problem types for calculating geometric volume made students 43% more accurate on a test a week later than practicing one problem type at a time.

These three techniques showed benefits across a range of ages and subjects, but the review's authors said the supporting evidence was less extensive than for practice testing and distributed practice, so their effectiveness could not be rated as highly.

Techniques rated low utility

Despite being among the most common study habits, summarization, highlighting/underlining and rereading were rated low utility in the same review. The Association for Psychological Science, which published a summary of the findings, quoted Dunlosky saying he found it surprising that 'rereading and highlighting seem to provide minimal benefits' given how widely students rely on them. Scientific American's report adds that highlighting 'has failed to help U.S. Air Force basic trainees, children and remedial students, as well as typical undergraduates' in controlled studies, and that rereading — used by 84% of surveyed undergraduates in one cited survey — performs poorly compared with more active strategies such as retrieval practice.

Key takeaways

• Self-testing (retrieval practice) and spacing out study sessions have the strongest research support among the ten techniques Dunlosky and colleagues reviewed.
• Interleaving problem types, explaining material in your own words, and asking 'why' questions have moderate support and can be combined with testing and spacing.
• Highlighting, rereading and summarizing are the most commonly used study habits but showed the weakest results in controlled studies.
• Spacing works best when sessions are separated by at least a day; the exact ideal gap grows the longer you need to remember the material.