"The more time people spend before the computer screen or any screen, the less time and desire they have for two human activities critical to a fruitful and demanding intellectual life: reading and conversation. The media invade, and in many instances destroy altogether, the silence that promotes reading and the free time required for both solitary thinking and social conversation." -- Susan Jacoby, The Age of American Unreason (New York: Pantheon, 2008), p.247.
I was explaining to a prospective student for the fall at The King's College why I do not permit the use of laptop computers in my classroom. She was surprisingly agreeable to this policy, and I found her reason illuminating.
She told me that relationships among her peers are mediated by screens, whether computers and cell phones. Their social life centers on Facebook and MySpace. They communicate via text messaging and cell phone. Consider all the 14 year olds walking around constantly on the phone. One way or another, they're distant when they do not have to be. Face to face relationship is one of the most precious goods in life--when it is done right. A kiss between two people is a particularly intimate face to face relationship. God's promise to his redeemed people is that they will see him one day "face to face" (I Cor. 12). But it is disappearing among those of the emerging generation.
This self-imposed distance between close friends is changing the nature and quality of human relationships. In electronically mediated relationships, people are more careless in what they say, and in particular they are bolder in what they say to the opposite sex. They say things they would never say "to your face." People of the rising generation are socially more awkward and have a more difficult time sustaining a friendship. Marriage will be even more difficult than it has been for previous generations.
You might find Maggie Jackson's recent book, Distracted, on the effect of email on one's attention span, interesting.
An older and more philosophical writing (and more difficult to find) is George Grant's essay with the intentionally ironic title, "The computer does not impose on us the ways it should be used" (in Beyond Industrial Growth, Abraham Rotstein ed. Toronto: University of Toronto Press, 1976. 117-31).