Social Media, Interest Groups, and Perceptions of Public Opinion

How does social media use by interest groups influence political decision-making? While digital advocacy is central to how firms, citizens, and organized interests seek to shape policy, its effectiveness remains poorly understood. This study examines a novel pathway of influence: how interest groups shape politicians’ perceptions of public opinion. We conduct survey experiments in Denmark, the UK, and Norway with elected representatives and representative samples of citizens, using real advocacy social media content. We explore mechanisms by analyzing how politicians’ perceptions of the groups sending messages condition the impact of different versions of advocacy material on their estimates of public sentiment. Moreover, by comparing politicians’ estimates with actual opinion data, we identify potential biases in how decision-makers interpret societal views. As a benchmark, we also test the impact of the same content on citizens, focusing on policy attitudes, intended behavior, and perceptions of public opinion. The findings illuminate how interest groups strategically use digital tools to shape political attitudes and the perceptions guiding decision-making, shedding light on the mechanisms through which online communication mediates representation.