The Joan Ganz Cooney Centre surveyed 1 577 parents on how much time their 2- to 10-year-old kids spent with educational content on "screen media" such as televisions, computers and video games.
Sixty-two percent of children had access to either an e-reader, a tablet or both - but only 49% of them used the devices for reading, either alone or with their parents, the study found.
And when they did read, it was typically for about five minutes a day - compared with about half an hour with printed books.
Parents considered 44% of the screen media used by their children to be educational - representing 56 minutes out of two hours and seven minutes' viewing a day.
Fifty-seven percent thought their child had learned "a lot" from educational media about reading and mathematics - but only 19% thought that much had been learned about science.
Named for one of the founders of the Children's Television Workshop, the studio behind Sesame Street, the Joan Ganz Cooney Centre promotes literacy skills while researching digital learning for youngsters.
It posted its study on its website.