Does Highlighting Help You Learn? What the Research Says

Open almost any secondhand textbook and you will find the same thing: whole pages glowing yellow. Highlighting is close to universal. It feels like studying, it looks like studying, and it leaves visible proof that you did something. The awkward question is whether it actually helps you remember.

The short answer from the research is: not much, by itself. The longer answer is more useful, because it explains why, and what to do instead if you love your highlighter.

What the big review found

In 2013, the psychologist John Dunlosky and colleagues published a large review in Psychological Science in the Public Interest titled "Improving Students' Learning With Effective Learning Techniques." They examined ten common study techniques and rated each for overall usefulness, based on how well the evidence held up across different learners, materials and situations.

Two techniques earned the highest rating: practice testing, which is retrieving information from memory, and distributed practice, which is spreading study over time. Highlighting and underlining, along with rereading and summarisation, were rated as low utility. The authors did not say these techniques never help anyone. Their judgement was that the evidence for broad benefit was weak, and that students would generally get more from their time by using the stronger methods.

That nuance matters. Low utility does not mean harmful or useless in every case. It means that, as most people use it, highlighting is a poor return on study time compared with the alternatives.

Why highlighting feels so effective

If highlighting works so poorly, why does it feel so good? Two related ideas explain most of it: fluency and familiarity.

Fluency is the ease with which you process something. Text you have read and marked before becomes easier to read the second time, and your brain tends to interpret that ease as a sign of knowledge. Familiarity is the sense that you have seen something before. Both are real signals, but they are signals about recognition, not recall. Recognising a sentence on the page is far easier than producing its idea from memory when the page is closed.

This mismatch is a version of what researchers call the illusion of knowing, the gap between how well we think we understand something and how well we actually do. We cover it in depth in the illusion of knowing. Highlighting feeds that illusion beautifully: a page full of colour looks like a page you have mastered.

• Highlighting is passive: you choose what looks important, but you do not have to explain, connect or retrieve it.
• It can focus attention on isolated facts rather than on how ideas fit together.
• Over-highlighting makes everything look important, which defeats the purpose of marking anything.
• Rereading highlights later mostly rebuilds familiarity, which is the same weak signal again.

When highlighting can actually help

There is a fair case for keeping the highlighter, as long as you change its job. Highlighting works best as a sorting tool, not a learning tool. On a first pass through difficult material, marking a small number of key ideas can help you find what to review later. The value comes from what you do with those marks afterward.

Being selective also helps. Deciding that only one or two sentences per page deserve a mark forces a small act of judgement: what is the main claim here? That judgement is more effortful than painting every line, and effort of the right kind is generally where learning happens.

What works better

Retrieval practice

Retrieval practice means closing the material and trying to pull the information out of your own memory before checking. It is the technique Dunlosky's team rated most highly, and it works partly because the act of retrieving strengthens the memory itself. The full protocol is in our retrieval practice guide.

Spacing

Spreading review over several days, rather than cramming it into one evening, tends to produce more durable memories. Forgetting a little between sessions makes the next retrieval more effortful, and that effort pays off. See spaced repetition explained for how to schedule it simply.

Elaboration

Elaboration means explaining why something is true and how it connects to what you already know. Asking yourself "why would that be?" or "how does this relate to the last chapter?" turns a highlighted fact into part of a web of meaning, which is much easier to recall later.

An upgrade path for highlighter lovers

You do not need to throw out your favourite habit. You can promote it from the main event to the opening act.

1. 1Read a section once without highlighting anything, just to get the shape of it.
2. 2On a second pass, highlight no more than one or two key ideas per page.
3. 3In the margin or a notebook, turn each highlight into a question. "Mitochondria produce cellular energy" becomes "What do mitochondria do, and why does the cell need them?"
4. 4Close the book and answer your questions from memory. Check, and mark the ones you missed.
5. 5Revisit the missed questions in two or three days, then again about a week later.
6. 6When you review, answer the question before you look at the highlight, never the other way around.

Building recall checks into everyday learning

The same principle applies outside formal study. After reading an article or a chapter for interest, try writing down the three main points from memory before looking back. It takes a couple of minutes and usually reveals how much was recognition rather than recall.

Disclosure: MindSnap is our app. It is built around two-minute lessons drawn from five flagship story collections, Art, History, Psychology, Philosophy and Economics, plus unlimited further topics, and it includes short recall checks inside lessons so you answer from memory rather than simply rereading. It is not a full spaced repetition system, and dedicated flashcard tools do that job more thoroughly. The point is the same in any tool: test yourself, then check.

The takeaway

Highlighting is not a crime. It is just a weak learning strategy dressed up as a strong one. Use it to find what matters, then do the harder, more rewarding work of pulling those ideas out of your own head, more than once, over time. The page will look less colourful. Your memory will be in better shape.