Before revision:  We find evidence of bias affecting the news and information to which U.S. Twitter users are likely to be exposed , depending on their own political alignment . Partisan accounts, especially conservative ones, tend to receive more followers,  follow more automated accounts , and find themselves in echo chambers . Conservative accounts are  exposed to more low-credibility content . Liberal accounts are exposed to moderate content shifting their experience toward the political center, while the interactions of conservative accounts are skewed toward the right.
After revision:  We find evidence of bias affecting the news and information to which U.S. Twitter users are exposed depend strongly on the political leaning of their early connections. The interactions of conservative accounts are skewed toward the right, whereas liberal accounts are exposed to moderate content shifting their experience toward the political center . Partisan accounts, especially conservative ones, tend to receive more followers, follow more automated accounts , and find themselves in echo chambers . Conservative accounts are exposed to more low-credibility content . Liberal accounts are exposed to moderate content shifting their experience toward the political center, while the interactions of conservative accounts are skewed toward the right.