Reading on a computer screen or other digital screen affects comprehension. Research studies are beginning to shed light on why… and highlight the unique rewards of reading on paper.
Studies reveal how sensitive we are to context when we learn.

In a 2014 paper “The pen is mightier than the keyboard” published in the journal of the Association of Psychological Science by Pam A. Mueller of Princeton University and Daniel M. Oppenheimer of the University of California, Los Angeles looked at how laptop note taking is less effective than longhand note taking for learning.
Authors Mueller and Oppenheimer stated:

“Prior studies have primarily focused on students’ capacity for multitasking and distraction when using laptops. The present research suggests that even when laptops are used solely to take notes, they may still be impairing learning because their use results in shallower processing. In three studies, we found that students who took notes on laptops performed worse on conceptual questions than students who took notes longhand. We show that whereas taking more notes can be beneficial, laptop note takers’ tendency to transcribe lectures verbatim rather than processing information and reframing it in their own words is detrimental to learning.”

The advantages of paper over computer screens extend beyond learning and into our everyday reading. A recent article in the Scientific American argues that people read more slowly, less accurately, and less comprehensively on screens than they do on paper. It cites Maryanne Wolf of Tufts University who argues, “there is a physicality in reading… maybe even more than we want to think about.

Tufts argues that our brain regards letters as physical objects and we therefore perceive text as a physical landscape. This explains why we often visualize where in a text a piece of information appeared when we try to recall it e.g. “I remember reading that on the top left of the page”.

Reading on a computer screen or e-reader doesn’t allow us to experience this physical landscape in the same way that reading a paper book does. The tactile experience and physicality of paper helps us to navigate and engage with the text in a much more significant and immersive way – and this aids our comprehension of it.

This argument was explored in length in a 2013 paper “Reading linear texts on paper versus computer screen: Effects on reading comprehension” published in the International Journal of Educational Research. Its authors, Anne Mangan, Bente Rigmor Walgermo, and Kolbjorn Bronnick, found that students who read in print scored significantly more in reading comprehension tests than those who read the same text on a screen.