Fernbach et al. (2013) found that political extremism and partisan in-group favoritism can be reduced by asking people to provide mechanistic explanations for complex policies, thus making their lack of procedural-policy knowledge salient. Given the practical importance of these findings, we conducted two preregistered close replications of Fernbach et al.'s Experiment 2 (Replication 1a: N = 306; Replication 1b: N = 405) and preregistered close and conceptual replications of Fernbach et al.'s Experiment 3 (Replication 2: N = 343). None of the key effects were statistically significant, and only one survived a small-telescopes analysis. Although participants reported less policy understanding after providing mechanistic policy explanations, policy-position extremity and in-group favoritism were unaffected. That said, well-established findings that providing justifications for prior beliefs strengthens those beliefs, and well-established findings of in-group favoritism, were replicated. These findings suggest that providing mechanistic explanations increases people's recognition of their ignorance but is unlikely to increase their political moderation, at least under these conditions.
Keywords: attitude change; open data; open materials; political extremism; political psychology; preregistered; replication.