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Schnall, Benton, and Harvey (2008) hypothesized that physical cleanliness reduces the severity of moral judgments. In support of this idea, they found that individuals make less severe judgments when they are primed with the concept of cleanliness (Exp. 1) and when they wash their hands after experiencing disgust (Exp. 2). We conducted direct replications of both studies using materials supplied by the original authors. We did not find evidence that physical cleanliness reduced the severity of moral judgments using samples sizes that provided over .99 power to detect the original effect sizes. Our estimates of the overall effect size were much smaller than estimates from Experiment 1 (original d = −0.60, 95% CI [−1.23, 0.04], N = 40; replication d = −0.01, 95% CI [−0.28, 0.26], N = 208) and Experiment 2 (original d = −0.85, 95% CI [−1.47, −0.22], N = 43; replication d = 0.01, 95% CI [−.34, 0.36], N = 126). These findings suggest that the population effect sizes are probably substantially smaller than the original estimates. Researchers investigating the connections between cleanliness and morality should therefore use large sample sizes to have the necessary power to detect subtle effects.

Johnson, Cheung, and Donnellan (2014a) reported a failure to replicate Schnall, Benton, and Harvey (2008) 's effect of cleanliness on moral judgment. However, inspection of the replication data shows that participants provided high numbers of severe moral judgments – a ceiling effect. In the original data percentage of extreme responses per moral dilemma correlated negatively with the effect of the manipulation. In contrast, this correlation was absent in the replications, due to almost all items showing a high percentage of extreme responses. Therefore the parametric statistics reported by Johnson et al. (2014a) are inconclusive regarding the reproducibility of the original effect. Direct replications are prone to error when reviewers only judge similarity of methods, but not resulting data and conclusions. It is my conclusion that preventable problems can arise if publication decisions are made without independent post-data peer evaluation.