His map showing how the titles are connected by buyers reveals a readership — or at least a book buyership — as fiercely polarized as the national electorate is said to be. On the left is a cluster of several dozen liberal polemics (the blue nodes) linked by a dense thicket of crisscrossing gray lines. On the right is a nearly identical cluster of conservative tracts (the red nodes). Connecting the blue and red sides of the map are just a few gray lines and gray nodes, all politically moderate or nonpartisan titles, including “Sleeping With the Devil” by Robert Baer, “Bush at War” by Bob Woodward and “All the Shah’s Men” by Stephen Kinzer, a cultural correspondent for The New York Times.
Mr. Krebs, who got similar results when he conducted the same experiment last year, calls this pattern the “echo chamber” effect: for the most part, he found, buyers of liberal books buy only other liberal books, while buyers of conservative books buy only other conservative books. This finding appears to buttress the argument made by Cass Sunstein, a law professor at the University of Chicago, in his influential study “Republic.com” (Princeton University Press, 2001) that contemporary media and the Internet have abetted a culture of polarization, in which people primarily seek out points of view to which they already subscribe.
[…] Even with the bridging books, the average distance between the map’s left and right clusters is still four links — or in network theory parlance, “four degrees” — Mr. Krebs said. Given that the clusters represent ideological extremes, he reasoned that if he expanded his book sample to include nonpolitical best sellers like “The Da Vinci Code” and “The South Beach Diet,” the distance between left and right would be reduced. To his surprise, that turned out not to be the case, though what, if anything, this means he is not entirely sure.
Ernest raises all the right questions about the conclusions (and points to the actual study) in Republic.Press. Of course, there’s still the interesting question of, in an age of intrusive legislation into reading habits, just how easily the researcher was able to do this work using online resoursces like Amazon’s reading lists…..