biostudies-literatureGranados Samayoa JANational Science Foundatione0275502https://www.ebi.ac.uk/biostudies/studies/S-EPMC9604008biostudies-literatureUnknown17(10)A primary focus of research on conspiracy theories has been understanding the psychological characteristics that predict people's level of conspiracist ideation. However, the dynamics of conspiracist ideation-i.e., how such tendencies change over time-are not well understood. To help fill this gap in the literature, we used data from two longitudinal studies (Study 1 N = 107; Study 2 N = 1,037) conducted during the COVID-19 pandemic. We find that greater belief in COVID-19 conspiracy theories at baseline predicts both greater endorsement of a novel real-world conspiracy theory involving voter fraud in the 2020 American Presidential election (Study 1) and increases in generic conspiracist ideation over a period of several months (Studies 1 and 2). Thus, engaging with real-world conspiracy theories appears to act as a gateway, leading to more general increases in conspiracist ideation. Beyond enhancing our knowledge of conspiracist ideation, this work highlights the importance of fighting the spread of conspiracy theories.PloS oneA gateway conspiracy? Belief in COVID-19 conspiracy theories prospectively predicts greater conspiracist ideation.PMC9604008BCS-2031097Moore CALadanyi JTGranados Samayoa JAFazio RHRuisch BCBoggs STfalseA gateway conspiracy? Belief in COVID-19 conspiracy theories prospectively predicts greater conspiracist ideation.A primary focus of research on conspiracy theories has been understanding the psychological characteristics that predict people's level of conspiracist ideation. However, the dynamics of conspiracist ideation-i.e., how such tendencies change over time-are not well understood. To help fill this gap in the literature, we used data from two longitudinal studies (Study 1 N = 107; Study 2 N = 1,037) conducted during the COVID-19 pandemic. We find that greater belief in COVID-19 conspiracy theories at baseline predicts both greater endorsement of a novel real-world conspiracy theory involving voter fraud in the 2020 American Presidential election (Study 1) and increases in generic conspiracist ideation over a period of several months (Studies 1 and 2). Thus, engaging with real-world conspiracy theories appears to act as a gateway, leading to more general increases in conspiracist ideation. Beyond enhancing our knowledge of conspiracist ideation, this work highlights the importance of fighting the spread of conspiracy theories.2022-01-01T00:00:00Z20222025-04-19T12:04:04.161Z2025-04-19T12:04:04.161ZS-EPMC96040083628827610.1371/journal.pone.0275502