Robert Keith Collins, a professor of American Indian studies at San Francisco State University, said he found students' performance on tests improved dramatically when captions were switched on during videos.
The finding suggests captions can be beneficial for all students, not just the disabled, he said.
"Not only were students talking about how much having the captions helped them as they took notes, their test scores went up," Collins said.
During the first year of a 2-year case study, he showed videos without captions to establish a baseline of student comprehension, then in the second year turned on the captions and began to see improvement in comprehension and grades.
"During the baseline year, there were a lot of Cs. In the second years, they went from Cs, Ds and Fs to As, Bs and Cs. It was really significant improvement," he said.
"We're living in an age where our students are so distracted by technology that they sometimes forget where they should focus their attention when engaged with technology or media," he said. "Turning on captions seems to enable students to focus on specific information."