David Broockman was quoted in Vox:
Groups that want to defeat President Donald Trump have already spent a decent chunk of money making and airing negative ads making the case Trump should not be reelected. A new survey experiment by political scientists David Broockman and Joshua Kalla suggests that this is probably a mistake. People have already heard a lot about Trump, and neither pro-Trump nor anti-Trump ads are very effective at shifting people’s perceptions of him.
Broockman and Kalla conducted a large experiment in early 2020 to test whether this gap in background level of information makes a difference. They found that it did. They took a sample of 291 messages — some pro-Trump, some anti-Trump, some pro-Biden, and some anti-Biden — and subjected a very large sample of 131,742 people to a random selection of two messages each out of the 291.
The full article is available here.