Highlighting feels like studying. Cognitive science says it is not. In a landmark review of study techniques, Dunlosky et al. (2013) rated highlighting as one of the least effective methods available, alongside re-reading. Both create familiarity with the text without forcing your brain to retrieve anything, and retrieval is where learning actually happens.
You finish a chapter and the page is glowing yellow. You feel accomplished. You put the textbook or the quarterly report down, confident the information is safely stored in your mind. Then the exam begins, or the Monday morning board meeting starts, and you cannot remember a single specific detail.
Highlighting is a mechanical action disguised as a cognitive one. Here is what the research actually says about how to keep what you read, and why the techniques that work feel worse than the ones that don’t.
Why highlighting fails the memory test
When you drag a pen across a page, your brain experiences a false sense of mastery. Brown, Roediger and McDaniel’s 2014 book Make It Stick established that highlighting and re-reading create fluency with the text, which we frequently mistake for actual learning. Because the words become familiar to your eyes, you assume they are available to your memory.
They are not.
The average student re-reads a chapter three or four times before a test. That is hours per week spent on a technique that produces only marginal gains in retention. The rehearsal feels like progress because the material becomes easier to read. What it does not do is make the material easier to recall without the page in front of you.
If you have ADHD, this problem compounds. Highlighting gives your hands something to do, which can soothe hyperactivity, but it does nothing to alleviate the working memory bottleneck that causes neurodivergent readers to lose information moments after reading it. The physical motion of the pen substitutes for the cognitive work of retrieval. It is comforting. It is not learning.
What the research says actually works
Dunlosky and colleagues reviewed ten commonly-used study techniques in their 2013 report for Psychological Science in the Public Interest. Only two received a high utility rating. Both involve testing yourself rather than reviewing material passively.
The first is practice testing, also called active recall. Instead of re-reading your notes, you close the book and try to answer questions about what you just read. The second is distributed practice, more commonly known as spaced repetition. You test yourself on the material at gradually widening intervals rather than in one exhausting session.
The 80% vs 35% retention gap
Karpicke and Roediger’s 2008 study in Science put a number on the gap. Students who repeatedly tested themselves on a set of material recalled approximately 80% of it a week later. Students who only studied the text recalled about 35%. Same material. Same total study time. More than twice the retention from the group that quizzed themselves.
| Technique | Dunlosky (2013) rating | Where measured, 1-week retention |
|---|---|---|
| Highlighting | Low utility | Not shown to improve on baseline reading |
| Re-reading | Low utility | ~35% (Karpicke & Roediger, 2008) |
| Summarisation | Low utility | Depends heavily on the reader’s summary skill |
| Practice testing (active recall) | High utility | ~80% (Karpicke & Roediger, 2008) |
| Distributed practice (spaced repetition) | High utility | Sustained retention across weeks and months |
The struggle of trying to remember something is not a sign that the technique is failing. It is the mechanism by which the memory is formed. Karpicke and Roediger called this “the testing effect”, and the effect has been replicated across dozens of studies since.
The problem with doing it yourself
The traditional method involves writing your own flashcards and reviewing them at expanding intervals. This is highly effective. It is also exhausting.
A typical chapter of a textbook yields fifty to eighty potential flashcards. Writing them by hand takes longer than reading the chapter did in the first place. Most students and professionals attempt this once, feel the weight of the admin, and abandon the system within a week. The technique is proven; the manual overhead is what kills it.
Anki, the free flashcard app that many students eventually find, uses the SM-2 spaced repetition algorithm and produces excellent results. It also requires you to build every card yourself. For a reader who is already fighting for attention through an ADHD-shaped day, or for a professional trying to keep up with quarterly reports, that overhead is often the difference between doing it and not doing it.
Skip the flashcard admin, keep the retention
Accruva reads your document and generates the flashcards, quizzes, and summaries automatically. The SM-2 algorithm handles the review scheduling. You do the actual learning. Free on every tier.
Get Accruva freeWhere this leaves you
Three concrete changes will do more for your retention than any highlighter ever will.
Close the book before you feel ready
Try to reconstruct the argument in your own words. The gaps you notice are the information you actually needed to study. This is the reading equivalent of what athletes call “training under fatigue”: the discomfort is the point.
Space your reviews out
Same-day review is nearly worthless for long-term memory. Reviewing at day 1, day 3, day 7, and day 14 will lodge material into memory more deeply than reviewing five times on the day of the exam. This is what the SM-2 algorithm was designed to schedule automatically, and it is the reason spaced-repetition tools work.
Work with your brain rather than against it
If highlighting is soothing your hands, keep the highlighter for the emotional regulation, but do not confuse it with a study technique. The actual study happens when you close the book and try to remember.
If you want the reading part to feel less exhausting so you have energy left for the retrieval part, our breakdown of the reading techniques that actually work covers the mechanics of that side. And if you want a baseline of your current speed to measure improvement against, the reading speed test takes two minutes.
Frequently asked questions
Why do I forget what I read so quickly?
Is highlighting ever useful?
Is re-reading completely useless?
What is spaced repetition, in one sentence?
Does active recall work for ADHD readers?
How does Accruva handle flashcards?
Is Accruva only for students?
Highlighting will feel productive tomorrow morning. Quizzing yourself will feel awkward. In two weeks, you will remember which one worked.
Ross Proudfoot, founder of Accruva
Reading shouldn’t feel like a fight with your own brain.
Accruva is the free reading app for ADHD, dyslexia and neurodivergent minds. Five modes, AI study tools, and every accessibility feature free.
