I find my mind tends to wander when I read dead-tree books.

Interesting. I have the opposite problem My mind tends to wander when reading stuff on the internet. To truly comprehend what I see on my computer screen, I have to print it and read it from a piece of paper.

Perhaps this is because I need to highlight passages and make notes in the margins. If it was easy to do this with anything I read on the internet, maybe my ability to comprehend from the computer screen would be just as good?