School Library Journal has a link to a study titled Student Comprehension of Books in Kindle and Traditional Formats by Michael Milone from Renaissance Learning that indicates there’s no real difference between ebooks and traditional paper books when it comes to kids’ reading comprehension.
Since it’s only one study by a private company, I think it needs to be closely read and evaluated and additional unbiased studies conducted.
And only fiction books were considered. Picture books were not part of the study.
However, it is interesting reading.