Home > Education > If your text book looks like the offspring of a rainbow, YOU’RE DOING SOMETHING WRONG!

If your text book looks like the offspring of a rainbow, YOU’RE DOING SOMETHING WRONG!

Your friends at Sharpie want you to 'highlight what's right'!

Your friends at Sharpie want you to ‘highlight what’s right’!

All students love to highlight. It’s easy, requires little time, and feels manageable. Though this study method may feel productive, does it actually enhance learning?

In a recent review of the literature, Dunlosky et al. (2013) reference several studies that show the potential benefits but overall disadvantages of highlighting.

Evidence that highlighting is a no-go:

Here is one of the experiments that have tested the effectiveness of highlighting. The study consisted of 3 groups: the control (students who just read the designated text), active highlighters (those who were free to highlight as much text), and the passive highlighters (those who read only the highlighted portions by active highlighters).
After this phase, the three groups reviewed the material one week later for 10 minutes. They were then tested on the material. The results showed that the control group performed better than the passive/active highlighting groups.
Even though the control condition was most effective, the advantage that active highlighters had over the passive group was that highlighting requires extra processing of the material. The highlighting groups answered particularly well on questions concerning text that was highlighted. This is known as the isolation effect. Studies show that “marked text promotes later memory for the marked material” (Dunlosky et al., 2013). The problem with the isolation effect is that information not highlighted is neglected during evaluation.

More problems with highlighting:

The quality of the highlighting is a variable that can affect the effectiveness of this study strategy. There is a lot of variability of what information is or isn’t considered important by students. Students are also not aware of what an appropriate amount of highlighting is. Over-highlighting makes marked text less defined. Studies show that if students only underline a key sentence per paragraph, recall is higher compared to the no-underlining control group (Dunlosky et al., 2013). Thus, less highlighting might help recall.
However, a persistent problem with highlighting is students’ unawareness of what the critical concepts are. In one study, when critical concepts were already highlighted for students, exam scores increased. But when students highlighted material themselves, it was difficult for them to distinguish what was or wasn’t critical. In regards to comprehension, studies show that underlining is detrimental to making later inferences. Overall, underlining draws attention to individual concepts (facts) but does not facilitate the big-picture concepts. Further studies have shown that underlining is more associated with concepts that may be on a multiple-choice exam.

What conditions give highlighting a fighting chance?:

The effectiveness of highlighting can be dependent upon prior knowledge of material. Studies show that students who previously had knowledge of the topic benefited more from active highlighting than those who had no prior knowledge. In one study, the potential to highlight effectively was measured when given the incentive to highlight well. Half of the students tested were told that they would receive a 5-dollar bonus for effectively highlighting key terms. The ones with this incentive benefited during testing versus the ones who did not receive a monetary bonus. This shows that people have the capacity to highlight effectively (Dunlosky et al., 2013).

I don’t want this blog to leave you thinking, “My life is a lie! How can I as a moral being ever highlight again knowing that it won’t enhance my learning?!” We all like to highlight. The pretty colors make us feel good about ourselves. So don’t feel guilty about using this study technique; instead, be open to other study methods along with improved methods of highlighting. Experiments show that proper training on highlighting improved performance on test scores. So there is hope! The nutshell of this blog: limit highlighting to only key terms, think about the important concepts/the big picture, and most importantly, don’t turn your paper into rainbow offspring.

If you want to review the original paper to learn more about effective study strategies, you can go here.

You can also check out other blog posts by following the tags “Testing Effect” and “Academics” or looking at the “Education” category.


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.

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  1. December 2nd, 2013 at 18:35 | #1

    I think this would be an interesting study to compare to a different study where students were told to write in the text versus highlighting it. I would think that writing in the text would improve the persons understanding or memory for those specific details since they paid attention to them, but I wonder if it would have a similar effect like the isolation effect. Writing in the text, like highlighting correctly would be a desirable difficulty, one that you would have to really think about to actually do well. Thus you would probably remember the information attended to better. But this study makes a good point about only knowing the information highlighted instead of the big picture (isolation effect). I think it would be interesting to see what is more effective for studying; or have a study that took even more study techniques similar to writing in the text or highlighting and tested their effectiveness in different situations.

  2. aspencer
    December 2nd, 2013 at 20:11 | #2

    I really enjoyed your post; it reminded me of a colorful version of metacognition. The challenge with highlighting seems to be not only knowing how well you know the information, but how good you are at deciding what information to select. Since most of us do some sort of highlighting, I was wondering how well participants in the study though they knew the material. I had some other additional questions:
    How were participants trained in proper highlighting and why did that make their ability to remember the information from their readings better? How does underling and annotation a regular pen affect retention? How do color coding different types of material effect retention? Is there no effect or is the practice of connecting material to other material with colors help?

  3. December 2nd, 2013 at 21:01 | #3

    This was a really interesting study. I definitely found it counterintuitive that highlighting could actually lead to decreased overall memory. As someone who buys most of her textbooks used, I find a lot of them usually come with lots of highlighting and underlining. I always assume whoever had the textbook before me knew which sections were important and that’s why they highlighted them. In hindsight, it makes sense that the person who had the book last was probably just as clueless as I am and so my reading their highlighted sections as the “important parts,” could be detrimental to my overall recall.
    I think there is definitely a lot more research that could be done in this area because “proper” highlighting techniques weren’t really specified.

  4. December 3rd, 2013 at 12:44 | #4

    I really appreciated reading this article because I had always wondered what the significance of highlighting would be. Growing up, my mom always told me how she studied in high school, which was to read through whatever it was once while highlighting in yellow. She would then re-read, using a pink highlighter so she would end up with the most important parts highlighted in orange (with both yellow and pink). I always thought that this was an interesting way to go about reading because it helped pick out what seemed meaningful two times around. However, after reading more on the topic, I’ve come to realize that it probably isn’t that helpful. Sure, it could help distinguish the key points in a paper, but I don’t think it helps memory. I tried my mom’s method in high school and saw no difference in my grades or memory of the information. This makes a lot more sense to me now that I have read this post and article.

  5. December 3rd, 2013 at 14:53 | #5

    I loved the picture that accompanied this post! This is exactly how many of my high school textbooks looked like… unfortunately! I loved to highlight the important facts, however I found that I had highlighted practically the entire book! I definitely agree with your point: “A persistent problem with highlighting is students’ unawareness of what the critical concepts are.” As I thought everything was important, I highlighted everything, detracting from the critical concepts. Additionally, I think it is interesting when you noted that highlighting does not facilitate big-picture concepts. By focusing only on the highlighted content, we bury ourselves in the details and lose sight of the bigger picture.

  6. December 3rd, 2013 at 20:54 | #6

    Very interesting blog post! The isolation effect makes sense once you think about it. Highlighting draws out attention away from the other words on the page. I remember earlier in the year our psych class learned how our attention capacity is limited. If the highlighted portion is drawing our attention away from possibly useful information for a test, I can see how highlighting would be a detrimental study tactic.
    I personally like highlighting because it forces me to actually pay attention to what I am reading. I have to think about every sentence/idea presented and decided whether or not it is important enough to highlight or underline. I sometimes also take notes while I’m reading a chapter from a textbook for the same reasons. After reading your blog post though it would seem that the isolation effect would also apply to note taking because you are paying closer attention to a specific sections/ideas in the text and not others.
    Interesting study! Since finals are just around the corner this is a great blog post to read. I guess the moral to take from this study is that you should not only focus on the details but also the big picture. There are many different types of study tactics out there and it would be a good idea to use more than just one when studying for a test.

  7. December 3rd, 2013 at 23:28 | #7

    I liked your post. Even though I buy a lot of highlighters, I never use them because I end up highlighting everything, which is clearly not effective. Before talking this class, I always thought that highlighting somehow forced you to concentrate on what you are reading. However, highlighting is subjective, and is just like recycling information. At the end you are not making any effort to thoroughly learn the information. Therefore, this post makes sense since highlighting is not a reliable indicator in measuring how much you understand the information. Given the isolation effect, you highlight the things that make sense to you, and miss the whole point of the presented information.

  8. December 9th, 2013 at 15:27 | #8

    An important point is also that the more time you give yourself to study, the more opportunities you have to use more and diverse strategies!

  9. Tara Nguyen
    March 16th, 2014 at 00:40 | #9

    Interesting post for sure! I actually never believe that highlighting/underlining aids memory. The only reason I highlight/underline text is that it will be easier for me to find a piece of information in the future.

    You wrote that highlighting increases processing of the highlighted text. However, I think highlighting may divert our attention from the text itself. According to capacity framework models of attention, which points out that attention is limited, highlighting can take up some attentional capacity, and thus reduces the amount left for our processing of the text.

    As for the isolation effect, I wonder if it applies to different types of text or different text contents. For example, suppose you were reading a piece of Math text, which is usually full of definitions and formulas, and you decided to highlight the formulas only. Later on a test, you were asked to compute something using the formulas in the text you had read. According to the isolation effect, you would be very likely to remember the formulas only. However, to know how to use them, you’d have to know what the letters and symbols in the formulas meant, that is, you’d have to also remember the definitions in the text even though you had not highlighted them. So it seems like the isolation effect doesn’t apply to this situation.

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