Does Highlighting Help Studying? What 36 Studies Found

Open any used textbook and you will see it: pages glowing yellow, sometimes every line. So does highlighting help studying, or does it only make reading feel productive? The honest answer is in between. Highlighting is not useless, but it is weak on its own, and the way most students do it removes most of the small benefit it has.

Below is what the research says, why the effect is small, and a simple method that keeps your highlighter but adds the part that actually builds memory.

The best summary comes from a 2022 meta-analysis in Educational Psychology Review by Ponce, Mayer and Méndez. They pooled 36 published articles with 85 effect sizes, from studies run between 1938 and 2019. When students did their own highlighting, the average effect on memory was 0.36 and the effect on comprehension was 0.20, which was not a reliable improvement.

Two details matter more than the averages. First, text that an instructor had already highlighted helped more, with an effect of 0.44 on both memory and comprehension. Second, self-highlighting helped college students (0.39) more than school students (0.24). Choosing what to mark is a skill, and beginners mark the wrong things.

An earlier review of ten common techniques reached a similar verdict. It placed highlighting in the low utility group next to rereading, because the benefits are small and inconsistent, while practice testing and spaced practice were rated high.

• It is passive at the key moment. Dragging a pen over a sentence takes almost no thought once you decide to mark it.
• Over-marking cancels the signal. If 60% of the page is yellow, the highlight no longer tells you what matters.
• It rewards rereading. Most students later review by rereading their highlights, which is the same familiarity trap as rereading notes.
• It splits ideas apart. Highlights catch definitions and numbers but miss the because and therefore that link them.

Active learning is a family of methods, not one trick. Active recall is the core. Asking why a fact is true, known as elaborative interrogation, is another. The common thread is that your brain has to generate something instead of recognizing it.

A worked example

Say an economics chapter has this sentence: When the price of a good rises, quantity demanded falls, all else equal. A typical student highlights it and moves on. With the method above, you also write in the margin: What happens to quantity demanded when price rises, and what does all else equal rule out? Tomorrow you cover the text and answer. If you cannot explain the second half, you just found a gap the highlighter would have hidden.

This works with any layout. If you take Cornell notes, the cue column is made for these questions. If you read with SQ3R, the recite step is where your highlights get tested.

Keep it to two or three colors and write the key on the inside cover. The benefit comes from the decision you make, not from the ink. If picking colors takes longer than reading, drop it and spend the time on questions instead.

On screen, the same rules apply. Digital highlights are even easier to overdo because there is no cost to marking. Copy your highlights into one place, rewrite each as a question, and quiz yourself from that list.

1. Marking on the first read. You do not know yet what the paragraph is for. Wait until the end of the section.
2. Highlighting examples instead of the rule. The example helps you understand, but the exam usually asks for the principle behind it.
3. Treating marked pages as finished. A yellow page is a to-do list, not a sign that you learned it.
4. Reviewing by rereading the yellow parts. Turn them into questions and answer with the page covered.
5. Never checking your choices. Compare your marks with the chapter summary or the learning objectives. If they do not overlap, adjust what you select next time.

So, does highlighting help studying? Treat it as a sorting step. It helps you find the ten sentences worth testing. The testing is what makes them stick, so make sure every study session ends with the page closed and you answering questions, not with one more pass of the highlighter.

If you only have twenty minutes, skip the highlighter entirely. Read the section, close the book, write the three main points from memory, and check them. That short loop gives you more than an hour of careful marking, and it tells you exactly what to review next.