Dynamics of collective minds in online communities

How communities respond to diverse societal challenges, from economic crises to political upheavals, is shaped by their collective minds - shared representations of ongoing events and current topics. In turn, collective minds are shaped by a continuous stream of influences, amplified by the rapid rise of online platforms. Online communities must understand these influences to maintain healthy discourse and avoid being manipulated, but understanding is hindered by limited observations and the inability to conduct counterfactual experiments. Here, we show how collective minds in online news communities can be influenced by different editorial agenda-setting practices and aspects of community dynamics, and how these influences can be reversed. We develop a computational model of collective minds, calibrated and validated with data from 400 million comments across five U.S. online news platforms and a large-scale survey. The model enables us to describe and experiment with a variety of influences and derive quantitative insights into their magnitude and persistence in different communities. We find that some editorial influences can be reversed relatively rapidly, but others, such as amplification and reframing of certain topics, as well as community influences such as trolling and counterspeech, tend to persist and durably change the collective mind. These findings illuminate ways collective minds can be manipulated and pathways for communities to maintain healthy and authentic collective discourse amid ongoing societal challenges.