The Effect of Brooding About Societal Problems on Conspiracy Beliefs: A Registered Report

Abstract

This Stage 2 Registered Report concerns the relationship between rumination, a repetitive style of negative thinking, and conspiracy beliefs (Stage 1 protocol: https://osf.io/y82bs, date of in-principle-acceptance: 23/05/2023). Based on four pilot studies, we tested in a fifth, registered study whether brooding, a particularly dysfunctional form of rumination, contributes to conspiracy beliefs using a repeated-measures within-person experiment (N = 1,638). Mean difference scores (conspiracy beliefs at T2 minus conspiracy beliefs at T1) were significantly greater in the brooding condition than in the control condition. However, we could neither confirm that this effect was larger than the specified smallest effect size of interest of d = 0.20, nor conclude that it was too small to be of interest (i.e., smaller than d = 0.20). We explored how reflection, an analytic form of rumination, impacted conspiracy beliefs. We further discuss implications for theories about the formation of conspiracy beliefs, and efforts aimed at preventing or reducing unfounded conspiracy beliefs. Hopefully, this article sparks a discussion among conspiracy belief researchers about how smallest effect sizes of interest could be determined in a principled way based on real-world outcomes.