Fig. 1.

Design of bot accounts. We created eight human-like, identical-looking bot accounts (two per each condition) and varied their political partisanship (Republican versus Democrat) as well as the extremity of political partisanship (stronger versus weaker). The bot accounts followed a set of elite accounts matching their political partisanship and retweeted randomly from these accounts every day (this was the same for bot accounts with stronger or weaker political partisanship). Bot accounts with stronger partisanship have a background supporting the Democrat versus Republican candidate and include the name of the candidate as part of their profile names.