Can professional or AI fact-checking protect trust in journalism from political attacks? The complex roles of source, transparency, ideology, and the machine heuristic

Trust in mainstream news media in the United States has declined to a historic low, partly due to political influencers attacking journalism on social media as a form of identity performance. This study examines whether fact-checking can defend trust in journalism against such attacks by exploring the roles of fact-checker source (AI vs. human), transparency, political ideology, and belief in the machine heuristic. An online experiment (N = 526) found that identity congruence with the political influencer significantly shaped perceptions of post accuracy, fact-checker credibility, trust in the targeted news outlet, and sharing intentions. Attributing the fact-check to AI did not enhance its effectiveness than human, even among strong machine heuristic believers. However, providing transparency about the fact-checking process reduced partisan gaps in perceived fact-checker credibility. Theoretical and practical implications are discussed.