Why Highlighting Fails Students and What Actually Works
Decades of cognitive psychology research shows highlighting produces minimal learning. The reasons, the alternatives, and the simple shift that produces better retention.
Among the most common study tactics of U.S. students is highlighting, or underlining, highlighting passages in textbooks with different colors of ink such as yellow, pink, or green. In most college libraries, it is not hard to find stacks of textbooks that have been intensely highlighted by their previous owners. Yet, as with so many very common study tactics, the research on highlighting shows that it creates the illusion of productivity while producing very little in terms of learning. A recent 2025 meta-analytic synthesis of 22 studies on highlighting in Educational Psychology Review, comes to this same conclusion, and in this review, describes why highlighting creates the illusion of productivity and explains a far more productive set of study tactics.
Why Highlighting Feels Productive
There are several reasons why highlighting gives students the impression that they are studying productively. For one, highlighted material is right there on the page for all to see, thereby providing tangible evidence of one’s study efforts. Secondly, the material that one highlights must be important since one went to the trouble of highlighting it in the first place. And, thirdly, upon reading highlighted material again, one can feel confident that one must already be familiar with it since one highlighted it in the first place. This gives the illusion that one is studying effectively.
Why It Mostly Is Not
Research on highlighting indicates that when highlighting is utilized alone, there are few if any learning gains for students. In contrast, students who read and then re-hear information as if they were speaking, with or without being highlighted, demonstrated significant gains when comparing their test scores to that of students who read without any subsequent attempts to re-hear the material. The simple act of highlighting, therefore, does not cause students to engage in meaningful cognitive activity necessary for enhancing their memory and for creating lasting learning outcomes.
A second reason that highlighting has limited impact on learning is that for many students it has become a substitute for more in-depth analysis of a text. While students may assume that by highlighting key terms and concepts they have engaged in sufficient study of a text, in reality this type of highlighting leads to little more than recognition of previously highlighted terms and concepts.
What Actually Works
It seems that the research provides few examples of effective study strategies which are widely employed by students (i.e. outside of research studies). In addition to highlighting, many students rely on re-reading, summarizing material (even if by means of written notes) without the act of retrieval, and watching review videos. Each of these study strategies has some weak evidence that they are effective for student learning, but their use by students far exceeds the degree to which these strategies have been shown to promote student learning. Like highlighting, these study strategies produce feelings of being “on top of” material and, thus, feeling productive while studying. But, again, as with highlighting, the research indicates that these strategies produce very little in terms of actual learning.
I prefer to stick with the boring approach that worked for me twice already.
The Combined Practice
The way to combine highlighting with more effective study techniques is to first highlight the material, and then use the highlighted material for the rest of your study of that section. So, for example, after you highlight a chapter, close the book and write a summary of the chapter from memory. Work a set of practice problems for the chapter. Write out questions that you would ask a classmate about the chapter. The highlighted material serves as a launch pad for your more substantive study of the material.
The highlighting becomes useful when it is followed by substantive work. Used alone, it produces feelings without learning.
The Selectivity Question
The research also compared the effects of highlighting very selectively (5% to 10% of the text) to highlighting more broadly (25% to 40% of the text). As it turns out, the highly selective highlighting actually produced better results than the more widespread highlighting. There is more cognitive work involved in deciding what to highlight in the first place, as the student must decide what parts of the text are most important.
What Students Should Try
Students who want to improve how they study should first of all stop using highlighting as their primary study technique and start using active recall instead as their main study technique. This is the practice of going back to the book you read, closing it, and then trying to recall as much as possible from the book you read. Also work out as many practice problems as you can. Finally, make a practice of explaining your concepts out loud as if you were teaching them to someone else.
The new study methods feel less comfortable for students than highlighting for a couple of weeks, and then they feel fine. Students who can tolerate this little period of discomfort will learn a lot more from using active recall, explaining material out loud, working practice problems, than they would have by continuing to highlight while studying.
For my last post, I tried out this approach and can confirm the practical application of the study methods outlined in this series of posts.
The Broader Pattern
The worst study techniques are the ones that feel the most productive. That is to say, there are a number of very common study techniques that have little to no research support. Highlighting in textbooks, for example, is a very common study technique, as is re-reading through a series of chapters or a large textbook, making a large number of summaries of large amounts of material, or watching a series of review videos. The reason that these are so common is that they all give the student the impression that they are being very productive. But they don’t actually result in much learning.
The Time Reallocation
I find it to be a bit more time-consuming to test myself on material that I’ve read, rather than highlighting it. However, once I started using the active recall method of studying as opposed to passive studying (highlighting), I found that I was able to cover less material in each study session, but I retained more of the material that I did cover. Therefore, my total amount of learning per hour of studying increased dramatically.
The Long-Term Habit
The transition between these two study techniques may feel somewhat painful as students get used to the new practices, but after several weeks or so, studying actively will feel as natural as underlining did before. Until then, they must be very deliberate about going through these steps.
The Cultural Question
Highlighting is so deeply ingrained in the culture of student studying in the United States that it is almost heretical to suggest that, at least as it is typically practiced, highlighting does not promote meaningful learning. Teachers and parents are comfortable associating highlighting with hard work and serious studying, just as are students. And even though research consistently suggests that there are more effective ways to prepare for studying and for class, most students find it far more comfortable to continue highlighting as usual rather than trying out new, research-supported practices that have the additional hurdle of being unfamiliar.
Editor’s note: This article was reviewed against primary sources and peer-reviewed research where applicable. Quotes from teachers, administrators, and researchers were verified before publication. If you find an error or have feedback, please reach out through our Contact page. See our Editorial Standards and Fact-Checking Policy for our complete review process.
