Less is More: Highlighting as Learning Strategy

 Original blog in Dutch by Tim Surma, Gino Camp & Paul Kirschner (translated and reworked by Paul and Mirjam)

Henry Green, a British novelist talking about his craft, wrote: “The more you leave out, the more you highlight what you leave in.” This might be very true when it comes to highlighting as a learning strategy.

Sometimes learners have to deal with large amounts of content, for example in books or articles. It’s usually the teacher’s job to emphasise which parts of the text are key. (S)he can do this by using advance organizers and by intermittently focusing the learners’ attention on foundational concepts and skills (e.g., prompting; also see our previous blogs on spaced practice and what makes a top teacher). No matter what the teacher does, learners still need to discern the key things in a text themselves. They usually do this by using their favourite study mate: the highlighter!


This blog explores highlighting as a learning strategy. What empirical proof is there about its (in)effectiveness? What guidelines do we need to give to learners to help them optimally use highlighting as a learning strategy? These questions, have, for example, been explored by Miyatsu, Nguyen, and McDaniel (2017) and Dunlosky, Rawson, Marsh, Nathan, and Willingham (2013).

Highlighting has minimal effect, despite its potential

Highlighting is a very simple strategy which doesn’t require much more than the learner reading the text and deciding what needs to be highlighted and then highlighting it. The question is, to what extent such an easy-to-apply strategy have the desired effect?

Despite a low effectiveness score in various review studies (e.g., Dunlosky et al, 2013; Marxen, 1996), highlighting seems to have potential to be a good learning strategy. After all, salient attention cues in texts are beneficial for readers. For example, we know that underlined text, capitalised words, marked text, etcetera, are better remembered by readers. This effect is often described as the isolation effect (Hunt, 1995). In one study, learners were asked to answer questions on articles published in Scientific American. Within the first group, five statements were highlighted, while in the control group nothing was highlighted in the text.

The test scores related to the given statements were higher for the intervention group (statements were highlighted), in comparison to the control group where there was no highlighting (Cashen & Leicht, 1970). These results suggest that highlighting increases the reader’s attention and because of that, the highlighted text is better processed. This is called ‘intentional learning’, or in other words, purposeful learning of something that is specifically emphasised. This is similar for techniques like asking (adjunct) questions or making learning objectives explicit before reading a text. By helping the learner to find focus, these parts of a text are better coded and remembered.

The opposite of intentional learning is ‘incidental learning’. This is learning something that hasn’t been made explicit through emphasis, questions, or learning objectives; that is, the rest of the text. It isn’t clear if intentional learning happens at the expense of incidental learning with regards to the parts that are not highlighted. Research results here are ambiguous (Marsh & Butler, 2013)

Although highlighted text draws a learner’s attention to the highlighted parts, researchers run into a shortcoming of highlighting as a learning strategy. As is the case with almost every tool or technique, its effectiveness depends upon whether it is used properly. The challenge with a technique as highlighting is that learners need to decide how much text they need to highlight as well as which parts they should highlight. This turns out to be a problem!

  • Learners often tend to either highlight too much or too little text. Too much highlighting has two disadvantages: first, learners don’t have to think that much about which paragraphs they mark (they just keep highlighting) and second, there’s no longer an isolation effect. In other words, when everything’s highlighted, it’s no longer ‘isolated’, or, more cherries than cake. Too little highlighting also doesn’t lead to the isolation effect as hardly anything is isolated. So, the amount of highlighting is important.
  • When learners were given the freedom to highlight as much or little of the text, there was no advantage to the strategy.
  • Learners with more prior knowledge of a topic benefit more from highlighting as a learning strategy (Klare, Mabry& Gustafson, 1955). Also, for young children it turns out to be very difficult for them to select important parts in a text in the first place so, as a consequence, they’re also not able to highlight effectively.

highlight 2.png

The biggest challenge with highlighting as a learning strategy, not surprisingly, is that learners need to decide which text needs to be highlighted.

But that’s not all! Researchers concluded that there are even more limitations to highlighting to support learning.

  • Learners restudy a highlighted text too quickly, only focusing on the highlighted parts (e.g., Hoon, 1974). This is an example of intentional learning at the expense of incidental learning.
  • Highlighting focuses attention on individual, separated concepts, instead of paying attention to connections between concepts. That’s why highlighting might be less suitable for learning things where connections between parts need to be made (Peterson, 1992).
  • There also doesn’t seem to be any advantage for highlighting when learning more complex content and there was also no difference between learning texts of different lengths (Peterson, 1992).
  • Finally, learners seem to think they’ve learned a text, even if they’ve only highlighted parts. Kind of like “I’ve highlighted it and I’m done studying”. Highlighting in itself doesn’t mean that they’ve processed the text. However, learners seem to think that highlighting equals learning. Unfortunately, of course, that’s not the case.

In addition to those potential disadvantages, mindless and endless highlighting can also be detrimental in that it can prevent learners from focusing on other, more productive strategies like retrieval practice. However, through combining marking with other proven learning strategies, we can help learners increase highlighting’s effectiveness.

How to use highlighting in an effective manner?

It should be obvious by now: The quality of the highlighting is critical to whether it is an effective strategy. With the following additional support, highlighting can become more useful.

  • Teach learners to distinguish between the wheat and the chaff. Highlighting without being able to separate what is important from what isn’t is pretty useless. When learners were taught to identify various text structures (Where’s the most important information? Which key words does the text provide?), they were way better able to highlight key points or ideas instead of details (Meyer, Young, & Bartlett (1989/2014). What’s also true, is that experts (with more vocabulary and prior knowledge) are better at this (e.g. Meyer & Rice, 1989).
    This isn’t unique to highlighting. While summarising a text that you’ve read can be a very effective strategy to retrieve what you’ve learned from memory (the so-called retrieval effect, see our blog here), it doesn’t work if the learner can’t / hasn’t learned how to write a good summary.
    So, first things first: Learners need to know how to separate the wheat from the chaff.
  • Encourage learners to highlight the right amount of text. In studies where learners were asked to highlight less, better results ensued (Rickards & August, 1975). In other words, learners develop a better strategy if they’re told only to highlight one sentence per paragraph, instead of large chunks of text as this forces them to read carefully and process the text more deeply since to do this they need to make comparisons, weigh alternatives, etcetera to make an informed decision on which sentence is most important.
  • Tell learners that they can only highlight after they’ve read the full text once. Having done this, let them then rephrase the most important parts and ask them to highlight those. The good news is that learners can be taught how to do this during a short training either in small groups or via a lecture to the whole class.
  • Teachers can point out important phrases or paragraphs and ask learners to highlight them. Having done this, they can then discuss with their students why these parts are important and why and which other parts are not important.
  • Combine highlighting with other effective learning strategies. When learners are confronted with a phrase or paragraph with highlighted words, they can first try to remember what was explained in the part they originally highlighted. This way, they use highlighted texts in a similar way to a Cornell method (see this blog) to remember essential information.
  • To promote the isolation effect, books can best highlight the important paragraphs themselves.

Takeaway: Under most conditions, highlighting is a non-effective learning strategy, especially in the way it’s used by most learners. However, for learners with a relatively large amount of prior knowledge on a certain topic, it can help them to remember key information. For novice learners with less prior knowledge, highlighting will often cause problems in choosing what is important and what isn’t. Only when learners receive the right training, in combination with other effective learning strategies, can they benefit from highlighting. Future research needs to figure out how we can help learners learn how to effectively highlight, given the fact that most of us, when we’re trying to learn something, will continue to apply this popular technique (despite its relative ineffectiveness!)

Now go print this blog and highlight it! 🙂


Cashen, V. M., & Leicht, K. L. (1970). Role of the isolation effect in a formal educational setting. Journal of Educational Psychology, 61, 484–486.

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, 4–58.

Hoon, P. W. (1974). Efficacy of three common study methods. Psychological Reports, 35, 1057–1058.

Hunt, R. R. (1995). The subtlety of distinctiveness: What von Restorff really did. Psychonomic Bulletin & Review, 2, 105–112.

Klare, G. R., Mabry, J. E., & Gustafson, L. M. (1955). The relationship of patterning (underlining) to immediate retention and to acceptability of technical material. Journal of Applied Psychology, 39, 40–42.

Miyatsu, T., Nguyen, K., & McDaniel, M. A. (2018). Five popular study strategies: Their pitfalls and optimal Implementations. Perspectives on Psychological Science, 13, 390-407.

Marsh, E. J., & Butler, A. C. (2013). Memory in educational settings. In D. Reisberg (Ed.), Oxford handbook of cognitive psychology (pp. 299-317). Oxford, UK: Oxford University Press.

Marxen, D. E. (1996). Why reading and underlining a passage is a less effective study strategy than simply rereading the passages. Reading Improvement, 33(2), 88-96.

Meyer, B. J. F., & Rice, G. E. (1989). Prose processing in adulthood: The text, the reader, and the task. In L. W. Poon, D. C. Rubin, & B. A. Wilson (Eds.), Everyday cognition in adulthood and late life (pp. 157–194). New York, NY: Cambridge University Press.

Meyer, B. J. F., Young, C. J., & Bartlett, B. J. (2014). Memory improved: Enhanced reading comprehension and memory across the life span through strategic text structure. New York, NY: Psychology Press. (Original work published 1989).

Peterson, S. E. (1992). The cognitive functions of underlining as a study technique. Reading Research and Instruction, 31, 49–56.

Rickards, J. P., & August, G. J. (1975). Generative underlining strategies in prose recall. Journal of Educational Psychology, 67, 860–865.



7 thoughts on “Less is More: Highlighting as Learning Strategy

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s