Highlighting and Underlining: Why the Most Popular Study Method Barely Works (and What to Do Instead)

Walk into any university library during finals week and you will see the same scene: students hunched over textbooks, neon highlighters in hand, painting page after page in yellow, pink, and green. Highlighting feels productive. It looks like studying. The pages start to glow with effort. And yet, decades of cognitive science research keep arriving at the same uncomfortable verdict — highlighting is one of the least effective study techniques you can use.

If you have been highlighting your notes, your textbooks, and your printed lecture slides under the assumption that all those colored streaks were building memory, this article is going to be a hard read. The good news is that the fix is simple, takes the same amount of time, and will actually move your exam score.

What the Research Actually Says About Highlighting

In 2013, a team of psychologists led by John Dunlosky published one of the most cited studies on student learning techniques in Psychological Science in the Public Interest. They reviewed ten common study methods and ranked each one by how much research supported it. Highlighting and underlining received the lowest rating: low utility.

The reason is not that highlighting damages learning. The reason is that it does almost nothing to build the kind of memory you need on test day.

Several controlled experiments have compared highlighters to other techniques:

• A 1983 study by Fowler and Barker found that students who highlighted text performed no better on recall tests than students who simply read the same passage without marking it up.
• Research from Peterson (1992) showed that highlighting often produced worse outcomes when students were asked to apply concepts to new situations, because the act of marking encouraged shallow processing.
• A 2013 follow-up by Dunlosky's team confirmed that highlighting does not improve performance on inference questions — the kind that dominate college and standardized exams.

The pattern is clear. Highlighting can give you a small boost when the test asks you to recall the exact sentences you marked. The moment the question requires you to connect ideas, apply a principle, or explain a concept in your own words — which is what most exams actually demand — the benefit disappears.

Why Highlighting Feels Like It Works (When It Doesn't)

Cognitive scientists have a name for this gap between perceived learning and real learning: the illusion of fluency. When a passage looks familiar, your brain interprets that familiarity as understanding. Highlighted pages are extremely familiar. You see your own pen marks, you recognize the rhythm of the colors, and the material feels processed. It is not.

Three specific problems show up again and again in the research:

1. Highlighting is passive. When you drag a marker across a sentence, the cognitive work involved is identification (this looks important), not retrieval, not elaboration, not reorganization. Memory research is unambiguous on this point — passive exposure builds far weaker memory traces than effortful processing.
2. Students highlight too much. Studies of student note-taking consistently find that learners highlight 20 to 50 percent of what they read. Once everything is marked, nothing stands out. The signal-to-noise ratio collapses, and the highlights stop functioning as a study aid at all.
3. Highlighting interferes with how the brain encodes meaning. When you mark isolated sentences, you fragment the structure of the argument. You end up remembering disconnected phrases instead of the relationships between ideas — and exam questions are almost always about relationships.

The student who reads carefully without any highlighter in hand is, on average, learning more than the student who is marking up every other sentence.


When Highlighting Can Help (the Narrow Use Case)

Before throwing every highlighter in your desk drawer, it is fair to acknowledge the conditions under which marking text does provide a small benefit:

• You highlight extremely sparingly — fewer than 10 to 15 percent of the text, and only the single most important phrase per paragraph.
• You return to the highlighted material and do something with it — you write summary notes, build flashcards, or quiz yourself on the marked sections.
• You are studying for a test that genuinely rewards verbatim recognition — for example, a vocabulary quiz or a list of dates.

In other words, highlighting is fine as a bookmark. It is a way of flagging material you intend to process later. The problem starts when students treat the highlighting itself as the study session.

What Actually Works: Evidence-Based Replacements

If you remove highlighting from your routine, you need something to put in its place. Here are five techniques that research consistently ranks far higher in effectiveness — and the good news is that none of them take more time than highlighting does.

1. Active Recall (the Single Best Replacement)

Active recall means closing the book and forcing yourself to retrieve information from memory before checking your answer. After reading a section, look away from the page and ask yourself: What were the three main points? What examples did the author use? How would I explain this to someone who has never read it?

A 2011 study published in Science by Karpicke and Blunt found that students who used active recall outperformed students who reread material by an average of 50 percent on conceptual questions one week later. The technique is so effective that some researchers consider it the single most important study habit a student can build.

The replacement is simple — instead of highlighting a sentence, close the book and try to restate it from memory. Then check.

2. Practice Questions Before You Read

This sounds backwards, but research from the field of pretesting shows that attempting questions before you have read the material primes your brain to encode the answers more deeply when you encounter them. Students who pretest before reading typically score 10 to 15 percent higher on later tests than students who read first and test second.

Open the chapter, look at the end-of-chapter questions, write down a guess for each one, and then read. Your brain will be hunting for the answers as you go, which is far more active than passively scanning for sentences to highlight.

3. The Two-Pass Read

If you really want a written record of what mattered in a chapter, use this method:

• First pass: Read the entire chapter without any pen, marker, or note-taking. Just read for understanding.
• Second pass: Close the book. From memory, write a one-page summary of what the chapter said. Only then go back and check what you missed.

This single change replaces both highlighting and rereading with retrieval practice — the technique that the research keeps identifying as the top performer.

4. Self-Explanation

Self-explanation means pausing every few paragraphs and asking yourself: Why is this true? How does this connect to what I already know? What would change if this were false?

A meta-analysis of 64 self-explanation studies found that students who used the technique scored about 0.6 standard deviations higher on transfer tests than students who did not — a substantial effect by educational research standards. Self-explanation builds the kind of deep, connected understanding that highlighting cannot.

5. Spaced Practice with Active Retrieval

Take the questions you generated through self-testing and revisit them on a spaced schedule — one day later, three days later, one week later, two weeks later. Each retrieval session strengthens the memory and makes future recall faster and more reliable. Spaced retrieval is, by a wide margin, the technique with the strongest evidence base in cognitive psychology.


A Practical Example: One Hour of Study, Two Approaches

To make the difference concrete, here is what one hour of study looks like under the old highlighting approach versus an evidence-based approach.

Highlighting approach (what most students do):

• 50 minutes reading the chapter and highlighting key sentences in two colors.
• 10 minutes flipping back through the highlighted pages, feeling like you have studied.
• Memory durability after 7 days: low. Most material lost.

Evidence-based approach (same 60 minutes):

• 5 minutes scanning the chapter headings and writing down 5 to 7 questions you expect the chapter to answer.
• 25 minutes reading the chapter without any pen.
• 15 minutes closing the book and writing a summary from memory, plus answering your initial questions.
• 10 minutes converting your summary into 8 to 12 active-recall flashcards.
• 5 minutes self-testing on the flashcards.
• Memory durability after 7 days: much higher, with material that survives into exam week.

Same hour. Very different outcomes.

How to Phase Out Highlighting Without Going Cold Turkey

If highlighting is a habit you have used for years, switching overnight is hard. Here is a phased approach that works for most students:

Week 1: Keep highlighting, but limit yourself to one phrase per page. After each chapter, close the book and write a one-paragraph summary from memory. Check what you missed.
Week 2: Stop highlighting on the first read. Read each chapter through, then go back and underline only the sentences you cannot recall on a second pass. The act of testing what you remember replaces the act of marking.
Week 3: Drop the highlighter entirely. Replace it with index cards or a flashcard app. After each section, write one question and one answer on a card. Build your stack of cards as you read.
Week 4 and beyond: Use the cards on a spaced schedule. Most students find that within a month, the new method feels just as natural as highlighting did, with one critical difference — the test scores start moving.

What This Means for Your Next Exam

If you have a major exam in the next few weeks, the most useful change you can make right now is to stop treating highlighting as studying. The hand motion and the colored marks create a feeling of effort that is not matched by the underlying memory work.

Replace passive marking with effortful retrieval. Read the material once with full attention. Close the book. Force your brain to reproduce what it just read, in your own words, on a blank page or on flashcards. Test yourself again the next day and the next week.

This is not about working harder. It is about working in a way that the human memory system was actually built to use. Highlighting feels productive because it is visible. Active retrieval feels harder because the work happens inside your head — but that is exactly why it sticks.

The next time you reach for a highlighter, ask yourself a different question first: Could I close the book right now and explain what I just read? If the answer is yes, you do not need the highlighter. If the answer is no, you do not need the highlighter either — you need to read the section again, then close the book and try once more.

That single shift, repeated across a semester, is the difference between studying that feels good and studying that actually shows up on your exam.