According to a report published in December 2009 by the Global Information Industry Center, Americans consumed information outside of work for about 1.3 trillion person/hours in 2008, for an average of almost 12 hours, 100,500 words and 34 gigabytes for an average person on an average day. The report analyzed consumption of more than 20 sources of information from old fashioned (paper newspapers and books) to new (computer games, satellite radio, and internet video).
The study defined "information" as flows of data delivered to people. So "information" includes video, with 1.3 zettabytes (a million million gigabytes) from television and about 2 zettabytes from computer games. Radio and TV dominate as sources of information, for about 60 percent of the hours expended in consuming information. But computers have had a huge effect on information consumption. Before widespread use of computers, information was usually consumed passively (with the exception of telephone). Reading as a means of consuming information was hit hard by TV. But reading as a source of information tripled from 1980 to 2008 because reading is how we consume information on the internet.
A 2005 study about reading behavior in the digital environment by Ziming Liu (available online in the Journal of Documentation) concludes that screen-based reading is different than reading text on paper. People reading on screen tend to spend more time browsing and scanning, and reading more selectively. They spend less time on in-depth, concentrated reading.
I've noticed a difference for myself between reading the screen and reading text on paper. The screen is the best for fast access to a wide range of related information. But, when I need to break down complicated information and really learn it for long term use, the screen is no match for paper. I had thought my longing for paper and a squeaky yellow highlighter to go with it was nothing more than habit-- an old-fashioned vestige of the way I learned to consume information. But scientists who research how we consume information by reading are beginning to learn about intrinsic differences in the two modes. The trick seems to be matching the mode to the text. The screen is great for Facebook, but not so much for Ulysses.