During my first semester of college, I took an introductory course on cognitive psychology. The course, taught by John R. Hayes of Carnegie Mellon University, covered basic principles of learning and cognition, memory, and quite a bit on problem solving (try Google-ing “tower of Hanoi”). We used a very good little book on the subject written by Hayes. I was determined to do well in the class, as I intended to major in psychology.
The book had a bright yellow cover and thick pages filled with text, figures and tables, and the occasional cartoon. At the same time I picked up the book in the College Bookstore, I bought a thick yellow magic marker. Why? Like generations of students before me, I planned to highlight or underline key points, terms, definitions, and the like in order to know what to study when I later reviewed what I had read.
I remember starting my underlining campaign. When I finished chapter 1, I flipped back through the pages and gazed contentedly at the highlighted text. There was a lot of it marked. Really quite a lot. On some pages I had highlighted 80 or 90% of the words, missing only a few as, ands, thes, and buts. The next week, when I tackled chapter 2, I was less earnest (some might say I became more judicious) in my yellow marker use; I curbed my enthusiasm. But, I still did some highlighting—just the facts, I thought. When chapter 3 rolled around, I realized that underlining likely was not all that helpful. I was spending more time deciding what to highlight than I was actually thinking about the meaning of what I was marking; in short, I wasn't learning much.
I quit cold turkey and never again underlined or highlighted texts with a yellow marker. I still have the book but not, happily, the marker.
I didn’t know (though I guess I suspected) that highlighting is not a very effective method for learning and retaining material. A wonderfully detailed review of effective (and not so effctive) learning techniques appeared in the January 2013 issue of Psychological Science in the Public Interest. John Dunlosky and his colleagues review the available research on highlighting/underlining—and there is more available than you might imagine—and they conclude that the activity is of little practical use to learning. In fact, they claim it can be a problematic activity because it keeps students from using other, more helpful learning techniques. Teaching students to highlight more effectively and selectively may help, but of course, the whole appeal of highlighting is that no training or extra work is needed—you underline or highlight as you read. So, the bottom line—forgive me—is that the technique is not worth students' time.
Here’s the problem: Lots of people—smart people, legions of college and high school students past, present, and future, law students cramming for bar exams, you name the group—sincerely believe that the yellow (or worse, light blue) crutch will help them to learn what they need to know for whatever test (standardized or other) that looms on the horizon. Changing minds can be hard to do because people generalize from their own experience, which they don’t necessarily evaluate thoroughly or critically. Pallid facts (underlining doesn't work) are just not as motivating as personal testimonials or feelings that well-honed (if faulty) study practices are helpful.
As I write this blog on a flight to Chicago, I am sitting across the aisle from a fellow more or less my age who is busily highlighting a book. I refrain from telling him (though I want to be helpful) that in all likelihood the highlighting and underlining is for naught. (He is also listening to an MP3 player while highlighting—music, too, is not a big help when it comes to retaining information—I am hoping he is listening to white noise.) I regularly tell my students, especially first year students, that highlighting is not studying and that more dynamic methods, such as self-quizzing, practice exams or quizzes (many psychology text books provide these in the book or online), creating flashcards of terms or ideas, and even re-writing notes (with some elaboration of content) are significantly better approaches with proven track records.
As a psychology professor, I often see students in our psychology lounge or the library underlining or highlighting their work with abandon. And I will often see students take out copies of readings that are highlighted in iridescent colors—sometimes 2 or 3 to indicate different levels of importance—from stem to stern. Convincing students that highlighting is not effective will not be easy—it’s an ingrained activity that provides comfort, but it turns out it’s the same intellectual comfort available by whistling past the graveyard. So, if you are a teacher or a student or know a student, offer the suggestion that there are better and more effective ways to learn simple or challenging material than highlighting. In other words, draw a line in the proverbial sand (ouch!) in order to increase awareness about the drawbacks of this classic collegiate habit.