  Social media platforms are like giant arenas where users can rely on
different content and express their opinions through likes, comments, and
shares. However, do users welcome different perspectives or only listen to
their preferred narratives? This paper examines how users explore the digital
space and allocate their attention among communities on two social networks,
Voat and Reddit. By analysing a massive dataset of about 215 million comments
posted by about 16 million users on Voat and Reddit in 2019 we find that most
users tend to explore new communities at a decreasing rate, meaning they have a
limited set of preferred groups they visit regularly. Moreover, we provide
evidence that preferred communities of users tend to cover similar topics
throughout the year. We also find that communities have a high turnover of
users, meaning that users come and go frequently showing a high volatility that
strongly departs from a null model simulating users' behaviour.
