The Cambridge Analytica scandal shed light on the ways social media advertising could potentially be used to influence electoral outcomes. With traditional advertising, political campaigns can only reach broad audiences —such as newspaper subscribers, or viewers of a certain television show—and their spending is strictly regulated. But with social media advertisements, political parties and their supporters can fine-tune their messages to highly specific audiences, without the rest of the country knowing what information their friends and neighbours are receiving.

Key findings - Facebook election ads:

• The Liberal Party outspent the Conservatives on Facebook. They also chose more narrowly targeted ads compared to the Conservatives’ “broadcast”-style strategy.
• The highest-spending partisan third-party group, by far, was Canada Proud.
• Troublingly, we found at least two advertisers purporting to show “fact checks” that were actually partisan advertisements.

Key findings - survey:

• Canadians do not seem to prefer positive ads to negative ads. Negative ads do drive up negative perceptions of the party that is targeted, but also of the party that pays for the ads.
• Positive political ads appear to reduce affective polarization—dislike of parties or their supporters on the other end of the political spectrum simply because they belong to an opposing group.