Abstract
In this article, we test and compare several message-based nudges designed to promote civil discourse and reduce the circulation of harmful content such as hate speech. We conducted a large pre-registered experiment (N = 4,081) to measure the effectiveness of seven nudges: making descriptive norms, injunctive norms, or personal norms salient, cooling down negative emotions, stimulating deliberation or empathy, and highlighting reputation. We used an online platform that reproduces a social media newsfeed and presented the nudge as a message when entering the platform. Our findings indicate that none of the nudges significantly impacts participants' engagement with harmful content. At the same time, nudges making descriptive norms salient selectively increase participants' overall engagement with relatively harmless content. Additionally, making injunctive norms salient increased the likelihood of liking harmless posts. Exploratory text analysis also reveals that highlighting reputation leads to more substantial and coherent comments on harmful posts. These results suggest that nudges that activate norm considerations represent a promising approach to promoting civil discourse and making social media a safer and more inclusive space for all.