Source alerts can reduce the harms of foreign disinformation

Social media companies have begun to use content-based alerts in their efforts to combat mis- and disinformation, including fact-check corrections and warnings of possible falsity, such as “This claim about election fraud is disputed.” Another harm reduction tool, source alerts, can be effective when a hidden foreign hand is known or suspected. This paper demonstrates that source alerts (e.g., “Determined by Twitter to be a Russian government account”) attached to pseudonymous posts can reduce the likelihood that users will believe and share political messages.