The Myth

Open any textbook in a university library and you’ll see the evidence: pages of yellow, pink, and green highlights, sometimes so dense that more text is colored than not. Students spend hours with highlighters, carefully marking “important” passages, confident they’re studying effectively.

The assumption behind highlighting is intuitive: marking key information should help you remember it. You’re actively deciding what matters. You’re creating visual emphasis that will draw your eye when reviewing. You’re engaging with the material. It feels like learning.

Why People Believe It

Highlighting feels productive. You’re doing something visible. You’re making decisions. Your textbook looks worked-over and studied. These physical signs of effort create a powerful sense of accomplishment.

There’s also a comforting logic to it. Surely marking what’s important must help? Surely drawing attention to key points must aid memory? The assumption seems so obvious that questioning it feels almost absurd.

But the critical flaw is this: highlighting vs active recall represents two fundamentally different types of cognitive activity. Highlighting is input — you’re marking what you see. Active recall is output — you’re generating what you know. And output is what builds memory.

What Research Actually Shows

The research verdict is clear and consistent: highlighting produces little to no learning benefit compared to simply reading the same material without highlighting.

A landmark 2013 review of learning strategies by Dunlosky and colleagues examined decades of studies and rated highlighting as having “low utility” for learning. The researchers found that students who highlighted text performed no better on later tests than students who just read — and sometimes performed worse.

Why doesn’t highlighting work? The act of highlighting is too passive. You can drag a highlighter across text while barely processing its meaning. There’s no requirement to understand, connect, or retrieve — just to identify. And identification without deeper processing doesn’t create lasting memories.

Highlighting can even hurt learning. When students highlight excessively, they often highlight the wrong things — surface details rather than core concepts. And having highlighted text can create a false sense of mastery: “I marked that, so I must know it.” This familiarity illusion prevents students from discovering their actual gaps.

The Truth: Why Active Recall Works

Active recall — the practice of actively retrieving information from memory without looking at it — is what highlighting wishes it could be. It’s effortful, it’s generative, and it works.

When you close your book and try to remember what you just read, your brain does something fundamentally different than when you highlight. It must reconstruct the information, activating and strengthening the neural pathways that encode that knowledge. Each successful retrieval makes future retrieval easier.

This is called the testing effect, and it’s one of the most robust findings in cognitive psychology. Testing yourself on material produces far better retention than rereading, highlighting, or any other passive strategy — even when you can’t recall everything, even when you get things wrong, even when it feels harder and less pleasant than highlighting.

The Desirable Difficulty Principle

Active recall works precisely because it’s harder. Psychologist Robert Bjork calls this “desirable difficulty” — learning strategies that feel harder in the moment but produce better long-term retention.

Highlighting is easy. Active recall is hard. That’s exactly why active recall works and highlighting doesn’t. Your brain strengthens memories that require effort to access. Effortless exposure — even repeated effortless exposure — creates weak memories that fade quickly.

What This Means for Your Reading

Replace Highlighting with Recall

Instead of highlighting as you read, periodically close the book and ask yourself: What were the main points? What’s the author’s argument? What evidence did they present? The struggle to answer these questions is where learning happens.

If you can’t recall something, that’s valuable information — it tells you exactly what you need to reread and focus on. Highlighting can’t give you this feedback because it never tests whether you actually know anything.

If You Must Highlight, Use It Strategically

Highlighting isn’t completely useless — it can serve as a marker for what you’ll later test yourself on. The key is that highlighting should be the beginning of a study process, not the end of one.

Highlight sparingly — a few key passages per chapter. Then use those highlights as prompts for active recall: cover the highlighted text and try to explain the concept in your own words before checking.

Embrace the Difficulty

When active recall feels hard and highlighting feels easy, remember: that difficulty is the learning. The discomfort of trying to remember something you can’t quite grasp is your brain building new connections. The ease of highlighting is your brain doing almost nothing.

For more evidence-based approaches to retaining what you read, explore the complete Strategies & Retention collection in our Reading Concepts hub.