For those interested, this is basically the theory of law professor Cass Sunstein in his book Republic.com. He calls this problem the "daily me," the idea being that content can become too personalized to one's views, resulting in irrationally extreme perspectives on those views and their correctness.

I would recommend the book, and also the numerous criticisms of his theory (that prompted him to partially retract his argument in the second edition), easily found online.

A book? Yes, a book! Go out and stare at a fixed-content display for a while.