“I Share Your Sentiment”—A Longitudinal Study of Facebook Post Sentiment and Sharing

This study examines how Norwegian political parties used negative, positive or neutral sentiment on Facebook over a 10-year period (2016–2025) and how such sentiment affected the sharing of their posts. Drawing on a full population of posts from all major parliamentary parties, the study investigates (a) whether negative sentiment increases over time, (b) how sentiment varies with party ideology and incumbency status, and (c) how positive and negative sentiment relate to sharing overall and at the party level. Demonstrating an approach using large language models in combination with human annotation for sentiment analysis, the study finds that while positive sentiment remains dominant, negative sentiment has increased over time, especially among challenger and left-wing parties. Extremist parties on both the far-left and far-right post more negative content, but this does not consistently translate into higher sharing. Overall, negative posts tend to receive more shares, but this advantage appears to weaken over time, suggesting strategic adaptation and possible audience fatigue.