  A group of heterogeneous players gathers information about an uncertain state
before making decisions. Each player allocates his limited bandwidth between
biased sources and the other players, and the resulting stochastic attention
network facilitates the transmission of news from sources to him either
directly or indirectly through the other players. The limit in the bandwidth
leads the player to focus on his own-biased source, resulting in occasional
cross-cutting exposures but most of the time a reinforcement of his
predisposition. It also confines his attention to like-minded friends who, by
attending to the same primary source as his, serve as secondary sources in case
the news transmission from the primary source to him is disrupted. A mandate on
impartial exposures to all biased sources disrupts echo chambers but entails
ambiguous welfare consequences. Inside an echo chamber, even a small amount of
heterogeneity between players can generate fat-tailed distributions of public
opinion, and factors affecting the visibility of sources and players could have
unintended consequences for public opinion and consumer welfare.
