Short answer
Negative ones. In the month before the 2015 and 2017 UK general elections, posts that criticised or attacked drew about 20% more interactions than other posts on the same page.
What the evidence shows
- The study links a hand-coded dataset of 1,205 posts from the Labour and Conservative pages and the pages of Cameron, Miliband, May and Corbyn to the interactions each received, comparing posts within the same page.
- The negative-orientation result (95% CI 4% to 39%) holds in every check and on seven of the eight pages, with more comments and shares in particular.
- Humour (60% more) and celebrities (37% more) went with large increases, as did posts showing the page's own leader, asking for the vote or asking people to share (14% to 16%), but these depend on the Labour and Corbyn pages.
Caveats
The posts are a coded sample from two elections and eight pages, and the study corrects for multiple testing; the other associations are less secure.