  While social media make it easy to connect with and access information from
anyone, they also facilitate basic influence and unfriending mechanisms that
may lead to segregated and polarized clusters known as "echo chambers." Here we
study the conditions in which such echo chambers emerge by introducing a simple
model of information sharing in online social networks with the two ingredients
of influence and unfriending. Users can change both their opinions and social
connections based on the information to which they are exposed through sharing.
The model dynamics show that even with minimal amounts of influence and
unfriending, the social network rapidly devolves into segregated, homogeneous
communities. These predictions are consistent with empirical data from Twitter.
Although our findings suggest that echo chambers are somewhat inevitable given
the mechanisms at play in online social media, they also provide insights into
possible mitigation strategies.
