Before last week, every time Valdis Krebs mapped the reading habits of those buying political books through Amazon.com, he found a few volumes read by both the left and the right .
Krebs used data from Amazon to discover the patterns among readers of the top-selling political books. He would find the other books that readers of, say, Liberal Fascism , would buy from Amazon. As he accumulated data, Krebs found that most books were connected to others. People who bought Liberal Fascism also bought The Obama Nation .
The pattern was always the same. There was one group of readers who bought conservative books and another that supported liberal authors. The maps Krebs made of Americans' book-buying patterns pictured two swarms: liberals on one side and conservatives on the other.
There were always one or two books in the middle-books both sides read, connector books between readers who otherwise had little in common. In Krebs' first map in 2003, the connector book was What Went Wrong , Bernard Lewis' book on the Islamic world. The books in the middle would change with the times, but there was always something both sides were reading in common .
Until last week.
Krebs did another run on his Amazon book project, and the swarms flew onto the page, left and right, but the connectors were gone. The two sides read nothing in common. Readers came to the week before the election isolated, separated by walls made out of books.
Krebs' map is worth a few minutes of study. You can see there are fewer books on the red side. That doesn't mean conservatives are buying fewer books, just that they are concentrating their purchases among fewer titles. And look at the book on the bottom left of the red web- Rules for Radicals , Saul Alinsky's book on community organizing. (Conservatives are studying their opponent.) There's a separate cluster of readers of Obama books, people who aren't connected to any of the Bush-bashing books clustered nearby. There are no books about McCain that seem to interest either the left or the right.
Given a choice, people will go to places where their beliefs are reinforced. In a recent study of Yahoo Finance discussion boards, three University of Texas business professors found that stock-pickers cluster. Those who think Apple is going up talk to each other on one thread. Those who think GE will fall even more find their way to the same little spot on the Web. Technology doesn't help people find new ways of thinking or seeing the world -- even when it might be in their financial interest. We still hunker down with those who hold our opinions.
(See " Melting-Pot or Homophily? : An Empirical Investigation of User Interactions in Virtual Investment-Related Communities," by Hsuan-Wei Michelle Chen, Bin Gu, and Prabhudev Konana.)
Morningside Analytics has developed its Political Video Barometer to discover the YouTubes being linked to by liberal and conservative bloggers. Who'd a-thunk the Batman vs. Penguin debate would be a liberal clip (linked to by 82 liberal bloggers but only 14 conservatives)? The 2001 Obama radio interview , in which the candidate talked about the "redistribution of wealth," was linked to by 262 conservative columnists but only 20 liberals.
When the YouTube videos are charted , they swarm, too: liberal YouTubes in one group and conservative videos in another.
And that's the way we live, in more ways than are imaginable. Full-size pickup drivers support John McCain at the same rate as white evangelicals (66 percent), according to a survey by Kelley Blue Book. Seven out of 10 Mini Cooper owners back Barack Obama.
We read apart, live apart, watch apart, blog apart, and drive apart; we are one country that lacks any shared experiences or, it seems, common purpose.