We conducted an experiment via Mechanical Turk (MTurk) (October 22-23, 2020; N = 1,483) exposing subjects to Facebook and Twitter memes based on real disinformation in order to test the efficacy of using source alerts to reduce the tendency of social media users to believe, like, share, and converse offline about pseudonymous disinformation related to the 2020 presidential election. We find that source alerts can reduce belief in the meme’s claim and mitigate social media users’ tendency to spread the disinformation online and offline, but the effects vary by the partisanship of the user, the type of social media, and the specificity of the alert.  The findings advance our understanding of the theoretical promises and limitations of source alerts as a means of combating the belief in and spread of disinformation online. Specifically, our findings suggest that tech companies should continue to invest in efforts to track and warn users of disinformation and to expand their current practices to include country-of-origin tags. Our findings come short of suggesting a one-size-fits all solution, however, as we highlight the importance of considering partisanship as a confounding factor, as well as the importance of considering the nuances of competing social media environments.

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