Paper beats computer screens
The results clearly demonstrated that those who had read on computer screens had understood less than those who read on paper. Perhaps surprisingly, this disparity was encountered with both the fiction and the factual prose.
This may interesting for anyone who tends to remember the position of words on a page:
An obvious difference between PC screens and paper is that paper is material. You can feel the weight, texture and thickness of a pamphlet or a book. You can see where it begins and ends. You can quickly leaf through the pages with your fingers.
This perceptible, direct experience gives you a mental map of the entire text. The brain has an easier task when you can touch as well as see.
Previous research has demonstrated that a mental map is particularly important if the text is long. Lengthy texts call for quicker navigation. You need to be able to leaf back and forth through different parts of the text to see, review and comprehend relationships and contexts.
See also Take Notes by Hand to Remember Better.