Why We Don’t Need Highlighters

Mark Enser recently drew our attention to a 2017 blog produced by @WHSmith and research behind using coloured pens in revision. It’s not clear who the author of the blog is but it says,

Studies have shown that colours such as orange, red and yellow are more attention-grabbing compared with colours such as grey or brown. This means that information written or highlighted in these colours have a higher chance of being remembered.

Mark rightly questions what these studies are because there are no references or links in the blog. The blog continues and says,

So, when it comes to revision it’s all about choosing the right colours to help your child remember information. You could encourage your child to highlight important text with a yellow highlighter, or write key phrases or terms using a red pen.

Where does this evidence come from?

I replied to Mark in his Tweet and said that as I understand it research has found that picking out individual phrases in fluorescent yellow, green or pink can actually hinder revision. Highlighting has failed to help students.

It is my view that marking potentially important portions of to-be-learned materials while reading is just safety blanket stuff and helps people feel better. It also makes them feel like they have done the work. As Benedict Carey (2015) says, “highlighting passages is a feel-good waste of time.”

Stationers are bound to promote the use of highlighters because they sell them. They are in business to make money and they have every right to do that. But, it is irresponsible of them to make claims that simply aren’t backed up by research evidence and therefore it can be very misleading especially to gullible customers who won’t have their fingers on the pulses of what works and what doesn’t.

In 2013, Professor Paul Dunlovsky et al published a paper that was a review of over 1000 studies that had been carried out, over a number of years, looking at the 10 most popular revision strategies.

They discovered that 8 out of 10 strategies did not work or worse than that, actually slowed down learning and most studies showed no benefit of highlighting (as typically used) over and above the benefit of simply reading. The authors found that highlighting tended to work better for students who were more adept at identifying the crucial to-be-remembered aspects of a text.

For others highlighting could undermine their comprehension of material. He said, “When students are using a highlighter they often focus on one concept at a time and are less likely to integrate the information they’re reading into a larger whole,”

Dunlovsky (2013) cites one study by Peterson (1992) that shows students who highlighted while reading performed worse on tests of comprehension because they spent less time thinking about connections across concepts.

In their overall assessment, Dunlovsky et al note,

On the basis of the available evidence, we rate highlighting and underlining as having low utility. In most situations that have been examined and with most participants, highlighting does little to boost performance. It may help when students have the knowledge needed to highlight more effectively, or when texts are difficult, but it may actually hurt performance on higher level tasks that require inference making. Future research should be aimed at teaching students how to highlight effectively, given that students are likely to continue to use this popular technique despite its relative ineffectiveness.

Dunlovsky says that getting rid of highlighters isn’t necessary but training students to use them more effectively could be beneficial. They also serve as important comfort blankets.

Dunlovsky found that the two most effective strategies for learning were practice testing and distributed practice. They were found to be of high utility because they benefited students of many different ages and ability levels and enhanced performance in many different areas.

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