Despite widespread political conspiracy theories about Presidents Barack Obama and George W. Bush, a majority of partisans continue to distance themselves from such beliefs. Even so, the ideological biases that drive conspiratorial thinking may be hard to overcome. In this study, we examine the unintentional endorsement of conspiratorial beliefs as revealed in movement dynamics. We track the cursor movements of Republicans and Democrats as they click target regions on their computer screens, ostensibly providing bias-free opinions (e.g., clicking “FALSE” upon reading “Barack Obama was born in Kenya”). However, during these response movements, we find inhibition and movement attraction to regions of the screen where a competitor response is located (e.g., “TRUE” for the “birther” conspiracy). These dynamics are not present for general conspiracies or political knowledge items. Though both Republicans and Democrats show evidence of implicit biases, changes in the strength of competition also reveal key asymmetrical differences.