The Critical Thinking About Conspiracies (CTAC) Test: Development and Validation

How should we measure people's vulnerability to unreasonable conspiracy theories? This is a key question for those designing interventions that aim to limit the spread of inaccurate beliefs. We argue that existing approaches are either too specific (measuring belief in a known conspiracy theory) or too general (measuring broad beliefs about the world). We developed the critical thinking about conspiracies (CTAC) assessment, where participants critically assess fictional conspiracies. Across five studies (N = 3977), we separately validated an 8-item brief version and a 15-item long version of the CTAC. Both versions have a two-factor solution, where the ability to correctly appraise implausible and plausible conspiracy theories is distinct but interrelated components. The CTAC demonstrates convergent validity with conspiracy ideation and cognitive reflection. The CTAC can be easily administered online and takes approximately 5–10 min to complete.