It has to do with cartographic clues, cognitive overhead, and--oh, hell, just print it already, would you?!
Do you understand and remember more after reading from a page than reading from a screen? As Ferris Jabr reports for Scientific American, the book itself binds your understanding.
As you read something, you structure out its content in your mind, Jabr says; you're making a map of the meaning of the text. This process is tied to the physical object that you're interacting with: just as you mentally map a trail as you ascend a mountain, your brain plots the line-by-line journey your eyes walk through a book.
This is why, studies suggest, if you're asked to recall a specific piece of information in a text, you'll remember where on the page you were when you read it. Jabr uses a bit of Pride and Prejudice to make the point:
We might recall that we passed the red farmhouse near the start of the trail before we started climbing uphill through the forest; in a similar way, we remember that we read about Mr. Darcy rebuffing Elizabeth Bennett on the bottom of the left-hand page in one of the earlier chapters.
Holding a book grants you a tactile sense of textual topography.
As Jabr notes, you have physical markers like left page facing the right page, the hanging corners, and the shifting of the weight in your hands as you advance from cover to cover. This gives you a sense of narrative context: holding a book, it's obvious where the individual page relates to the whole of the text, which makes it easier to create that mental map of the text's meaning.
For the rest of the story: http://www.fastcompany.com/3009366/leadership-now/you-wont-remember-this-article-or-anything-else-you-read-online-unless-you-pr?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+fastcompany%2Fheadlines+%28Fast+Company%29