Dispositional pessimism selectively predicts engagement with system-blame conspiracy theory around COVID-19 on social media

Understanding why some individuals engage with conspiracy theories online remains a central challenge in misinformation research. In this study, we analyzed data from 2,506 U.S.-based Twitter users linked to over 7.7 million of their social media engagements, focusing on six COVID-19-related conspiracy theories. Using machine learning classification of ecologically valid behavioral tracking and multilevel modeling, we investigated whether self-reported dispositional optimism and pessimism, along with experimentally measured judgment bias, could predict interest in conspiracy-related content. Our results revealed that dispositional pessimism was selectively associated with engagement with one of the six conspiracy theories examined - specifically, the narrative that “ The virus and response to it are aimed at creating economic instability and benefiting large corporations .” The remaining five theories showed no such association, and neither dispositional optimism nor judgment bias predicted engagement with any of the six narratives. These findings suggest that dispositional pessimism may increase susceptibility to conspiracy theories that emphasize systemic threats, while leaving others unaffected. This underscores the role of affective-cognitive dispositions in shaping engagement with conspiratorial narratives and real-world digital behavior.