So this is one of those dangerously vague listicles designed to get you to click and think that things are settled when they aren't even vaguely, like that one time the AP decided that flossing was useless not because there are studies suggesting it does nothing, but because there's a lack of studies that do something, therefore stop flossing. Take it from the tippy-tippy top:
Ready? Now throw it away, because highlighters don't really help people learn.
So that link isn't to a study, it's to a monograph that gives an overview of like five different learning techniques. It says shit like this:
To understand any benefits specific to highlighting and underlining (for brevity, henceforth referred to as highlighting), we do not consider studies in which active marking of text was paired with other common techniques, such as note-taking (e.g., Arnold, 1942; L. B. Brown & Smiley, 1978; Mathews, 1938). Although many students report combining multiple techniques (e.g., L. Annis & Davis, 1978; Wade, Trathen, & Schraw, 1990), each technique must be evaluated independently to discover which ones are crucial for success.
So what did they learn?
...nothing. For starters, the authors of the monograph struggled to find any studies that treated the data the way they liked it. Then they describe a whole bunch of studies in which the test is whether you learn better highlighting your own text or having it highlighted for you. And... well here. Check this out.
For example, Cashen and Leicht (1970) had psychology students read Scientific American articles on animal learning, suicide, and group conflict, each of which contained five critical statements, which were underlined in red for half of the students. The articles were related to course content but were not covered in lectures. Exam scores on items related to the critical statements were higher when the statements had been underlined in red than when they had not. Interestingly, students in the underlining condition also scored better on exam questions about information that had been in sentences adjacent to the critical statements (as opposed to scoring worse on questions about nonunderlined information). The benefit to underlined items was replicated in another psychology class (Leicht & Cashen, 1972), although the effects were weaker.
Okay, that says the exact opposite of "highlighters don't really help people learn." So where did the monograph go with it?
However, it is unclear whether the results from either of these studies would generalize to a situation in which students were in charge of their own highlighting, because they would likely mark many more than five statements in an article (and hence would show less discrimination between important and trivial information).
This test data is invalid because it doesn't answer our particularly arbitrary understanding of "highlighting" so...
On the basis of the available evidence, we rate highlighting and underlining as having low utility.
Because fuck you, that's why.
So this is literally NPR writing a gotcha article with dubious claims to make you go "whoa" and embarrass yourself at parties even worse than you already have with your unflossed teeth.
My wife gives the fuckers money. I swore off the bastards when they argued in 2000 the economy must be turning around because more rich people were buying Lear jets.