The Conspiracy Mentality Scale

Abstract. Beliefs in conspiracy theories, generally considered to be a unidimensional construct, are associated with negative outcomes. The existing measures of conspiracy theory beliefs have number of shortcomings. We present the development of a novel measure of the tendency to believe in conspiracy theories and report the discovery of a second factor that reflects rational skepticism. In Study 1 ( N = 500) we use item response theory to devise the final items. In Study 2 ( N = 202) we demonstrate the predictive validity of the two factors for different types of conspiracies. In Study 3 ( N = 308) we demonstrate convergent/divergent validity. In Study 4 ( N = 800) we demonstrate construct validity in three countries. Implications for the concept of conspiracy theory and conspiracy theory beliefs are discussed.