Updated August 5, 2026 after a source and claim review.
A student opens a textbook chapter or a PDF intending to highlight only the truly important parts. The first sentence establishes the main problem, so it naturally gets highlighted. The next defines the mechanism and receives the same treatment. A few lines later, an example clarifies the definition, making it seem equally essential. By the bottom of the page, the highlighter has stopped creating contrast. It is simply supplying the background color.
Later, during a study session, the reader scans only those marked passages. The words look correct. The explanation follows a logical path, and the chapter feels manageable, right up until the notes close and explaining the central argument without looking turns out to be surprisingly hard.
You can recognize a sentence without being able to explain the idea behind it. That is where an over-highlighted page often stops being useful. Coloring a page leaves a physical record of what attracted your attention during a first pass. Attention at the moment of reading, however, is not the same as understanding, and it is certainly not the same as later access.
The short version: to highlight a textbook effectively, read to the end of a paragraph before marking anything. Highlight only the language that carries the central claim, definition, mechanism, limitation, or result. Then give the mark a job to do: turn it into a question, add a margin note, or explain the idea from memory. Do that, and the mark becomes the start of a study task. Stop at the color, and you have made the passage easier to find. You have not yet tested whether you can recall it.
To see why an over-highlighted page is such a weak study guide, it helps to ask what highlighting was supposed to accomplish in the first place.
Highlighting works only when it selects
The most useful way to understand highlighting is as a selection technique. Its primary job is to distinguish information judged relevant from the rest of the text.
Visual emphasis depends on contrast. When most of a passage is marked, the reader has not reduced the material or identified a structural hierarchy. The review session inherits the same selection problem as the original reading session. Everything appears important, but the relationships among the ideas remain unclear.
Research supports this narrower account of what highlighting can achieve. In an influential review of ten commonly used learning techniques, researchers evaluated decades of evidence and rated highlighting and underlining as having low general utility. That did not mean the practice never helps. Its benefits were inconsistent across learners, texts, and assessment conditions, especially when compared with retrieval practice and distributed study.
Visible effort does not automatically translate into better outcomes. In a 2024 digital-reading study, university students were assigned to highlight a text themselves, read a version highlighted by the researchers, or read an unhighlighted version; 170 completed the delayed assessment. Across conditions, there was no overall advantage for literal or inferential comprehension or for transfer. Students who highlighted the text themselves spent 32 percent more time than the control group and 36 percent more than the group given pre-highlighted text. Within the self-highlighting group, however, the quality of the selected information was associated with literal comprehension and transfer.
The amount of ink on the page is equally unhelpful as a measure of success. In a study in which 400 adults read passages from a college-level biology textbook, participants highlighted during the initial reading, reviewed the text with those marks visible, and then took a quiz. The amount highlighted was unrelated to quiz performance. The particular pattern of selections carried some information about readers’ understanding; highlighting more did not.
A highlight is also an instruction to your future attention. In an eye-tracking study, highlighting changed where readers returned their gaze during review. Marking peripheral information increased rereading of peripheral information, while processing and recall of central information did not differ across highlighting conditions. A highlight can steer attention toward the wrong material as easily as toward the right material.
Should you highlight a textbook? Yes, if the marks help you locate central ideas and lead to a later act of explanation, comparison, or retrieval. Highlighting is an editorial decision made by the reader, not a memory mechanism.
Familiarity is not the same as learning
The trouble is that making that editorial decision feels remarkably like learning, even when little has changed in what the reader can independently explain.
Highlighting is psychologically convincing because it leaves a visible trace of effort. It makes later reading faster. The selected language becomes increasingly familiar with every pass, and eventually the reader mistakes smooth recognition for independent knowledge.
Rereading produces the same reassuring effect. The words look correct. Nothing seems missing. But highlighting and rereading ask memory a relatively easy question: does this sentence look familiar? An exam, a research meeting, or a blank page asks something harder: can you produce and explain the idea without the sentence in front of you?
That sense of familiarity can be misleading, as we explain in why rereading feels like learning.
This difference becomes visible in a study of retrieval practice with prose passages. Students either continued restudying the material or tried to recall it without looking. Repeated study produced slightly better performance on a test after five minutes. Retrieval produced better retention after two days and one week. The students who restudied also felt more confident about their future memory, despite performing worse on the delayed tests.
Highlighting is often followed by selective rereading. The same polished sentence becomes increasingly familiar, but familiarity does not test whether the learner can reconstruct the idea. A paper’s conclusion may look obvious in the abstract while its design, variables, and limitations disappear once the PDF closes.
The highlighter remembers where the sentence is. It does not remember the sentence for you.
Notes are tools, not evidence of understanding
Notes can solve part of this problem, but only if we are clear about what a note is for.
Researchers generally distinguish two functions. The encoding function describes the processing that happens while a learner takes notes. The external-storage function is simpler: notes preserve information so it can be found and reviewed later.
The distinction matters. A copied definition may serve as an excellent external record when you are writing a paper later in the semester. It is not evidence that you can explain the definition without opening the notebook. A meta-analysis of 57 note-taking-versus-no-note-taking studies found that the overall encoding benefit of taking notes without later review was positive but modest. Recording information can help direct attention, but the physical act of writing or typing is not a powerful learning intervention by itself.
The familiar paper-versus-laptop debate can distract from the more useful question. A 2022 systematic review and meta-analysis found no overall performance advantage for longhand or digital note-taking under controlled conditions. Neither medium guarantees meaningful processing. What matters here is whether the learner selects, reorganizes, and later uses the information.
A complete set of notes may be a useful archive. An archive is not the same thing as a trained memory.
A highlight needs a next step
If copying is not enough, the useful question is what the mark should make you do next. A highlight can select information. A note can organize or connect it. A question can ask you to retrieve it.
A common highlighting mistake is deciding too early. A sentence may look essential before the rest of the paragraph reveals whether it states the claim, supports it, qualifies it, or merely gives an example. Read to the end of the paragraph, then decide.
Good candidates include a central claim, a definition you will need later, a mechanism, a limitation, or a result whose exact wording matters.
How much should you highlight? No fixed percentage works across every text. Use a functional test: if this mark disappeared, what specific idea would become harder to locate or reconstruct?
Color coding is optional. If you use several colors, give each one a stable job; otherwise, the palette becomes another layer of decoration.
Notes can then organize the relationships among the selected ideas. Linear notes preserve individual facts while often losing the structure between them. The format should match the material: a comparison table for competing theories, a flow diagram for a process, or a cause-and-effect chain for a mechanism.
In one experiment with fourth graders, students who completed a compare-and-contrast graphic organizer or answered structured questions outperformed a reading-only group on comprehension and memory tests. Ordinary note-taking did not significantly outperform reading alone. The point is not that one diagram always wins. Structured processing asks more of the reader than transcription does.
Notes can also connect new information to existing knowledge. In biology, that might mean explaining why a change in one pathway affects another. In statistics, it might mean writing down not only a formula but the conditions under which its assumptions fail. In history, it could mean connecting an event to a competing causal account.
The most consequential transformation is making the note ask for retrieval.
A copied note states:
Statistical power is the probability of rejecting the null hypothesis when a specified alternative is true.
A retrieval note asks:
What is statistical power, and which four factors usually affect it?
In laboratory experiments using science texts, retrieval practice produced better delayed performance than concept mapping, including on questions that required comprehension and inference. The result does not establish that concept maps are generally inferior. It shows that reconstructing material from memory can support more than verbatim recall under those conditions.
An effective note does not need to contain more information than a poor one. It often contains less source text and more intellectual work.
Focused questions are one reason why flashcards work when the answer remains hidden until the learner makes an attempt.
The best note is not always the one that preserves the most. It is the one that gives you a useful next action.
How to highlight a textbook effectively
Read first. Highlight second. Then make the mark do something: label the passage, turn it into a question, or close the source and explain the idea from memory.
Before reading, write one or two questions the source is expected to answer. For example: How does this method estimate causal effects? Why did the authors reject the previous explanation? A purpose gives you a criterion for relevance. Without one, almost every well-written sentence can look highlight-worthy.
Read a short section before marking anything. At the end of a paragraph or screen, identify the main function of the passage. Mark only the words that would genuinely help you locate or verify the point later. If the whole paragraph seems essential, write a margin label such as “main mechanism” instead of coloring the entire block.
After each meaningful section, add one transformation. Write a one-sentence summary from memory. Formulate a question. Sketch a relationship. Compare the point with an earlier concept. One transformation is enough. The aim is not to produce a flawless visual artifact.
Then close the source briefly. Hide the original and reconstruct the main claim, the supporting logic, and one remaining uncertainty. Compare your reconstruction with the source and correct the note. Opening the source first converts the exercise back into recognition.
In two experiments with online lectures, short memory tests between lecture segments reduced reported mind-wandering and improved learning of the lecture content compared with restudy or no interim test. The useful takeaway is narrow: building retrieval into a lecture can change both attention and learning in that setting.
To make the system sustainable, separate source notes from review prompts. A source note holds the exact definition, citation, quotation, and method. A review prompt asks you to explain the concept without the definition sitting beside it. That separation prevents the note from permanently containing the answer next to the question.
For a research paper, the useful unit is the argument, not the highlighted sentence. A compact template can make that argument easier to reconstruct:
- Question: What problem or hypothesis is being addressed?
- Method: What did the researchers compare or measure?
- Result: What changed, and how strong or uncertain was the result?
- Limit: What can the design not establish?
- Connection: Which other paper, theory, or project does this alter?
- Recall prompt: What should you be able to answer without reopening the PDF?
For a fuller guide to reconstructing the evidence and argument, see how to read a research paper.
For a busy day, compress the routine. Choose one source, write one guiding question, create three or four prompts, and spend two minutes recalling the main argument without looking. Better note-taking does not require doubling your study time. It requires moving some time away from passive coloring and toward active reconstruction.
That leaves a fairly narrow job for a learning tool. Quizpace can turn learner-provided material into flashcards and quizzes that move a study session from rereading toward retrieval and checking. It cannot decide which passages matter, repair an explanation that never made sense, or do the remembering for you.
A tool can bring the question back. It cannot supply the effort of answering before the source is reopened.
The problem is stopping at highlighting
The point is not to ban the highlighter. It is to stop treating the mark as the end of the study process.
A page that has gone almost entirely yellow is not proof that the study session was wasted. It is a record of a first pass through the material. The visual cue makes information easier to locate, but highlighting everything removes the selectivity that gave the technique its purpose.
Notes help most when they reorganize, connect, question, and test the material. No medium compensates for the absence of those mental operations. Familiarity during rereading is convincing, but it is not the same as retrieval.
Keep the highlighter. Just make sure the next step asks more of you than remembering which sentence was yellow.
References
- Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students’ learning with effective learning techniques: Promising directions from cognitive and educational psychology. Psychological Science in the Public Interest, 14(1), 4–58.
- Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772–775.
- Kobayashi, K. (2005). What limits the encoding effect of note-taking? A meta-analytic examination. Contemporary Educational Psychology, 30(2), 242–262.
- Mason, L., Ronconi, A., Carretti, B., Nardin, S., & Tarchi, C. (2024). Highlighting and highlighted information in text comprehension and learning from digital reading. Journal of Computer Assisted Learning, 40(2), 637–653.
- Ponce, H. R., Mayer, R. E., Loyola, M. S., & López, M. J. (2020). Study activities that foster generative learning: Notetaking, graphic organizer, and questioning. Journal of Educational Computing Research, 58(2), 275–296.
- Roediger, H. L., III, & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255.
- Szpunar, K. K., Khan, N. Y., & Schacter, D. L. (2013). Interpolated memory tests reduce mind wandering and improve learning of online lectures. Proceedings of the National Academy of Sciences, 110(16), 6313–6317.
- Voyer, D., Ronis, S. T., & Byers, N. (2022). The effect of notetaking method on academic performance: A systematic review and meta-analysis. Contemporary Educational Psychology, 68, 102025.
- Winchell, A., Lan, A., & Mozer, M. C. (2020). Highlights as an early predictor of student comprehension and interests. Cognitive Science, 44(11), e12901.
- Yeari, M., Oudega, M., & van den Broek, P. (2017). The effect of highlighting on processing and memory of central and peripheral text information: Evidence from eye movements. Journal of Research in Reading, 40(4), 365–383.