We conducted preregistered replications of 28 classic and contemporary published findings, with protocols that were peer reviewed in advance, to examine variation in effect magnitudes across samples and settings. Each protocol was administered to approximately half of 125 samples that comprised 15,305 participants from 36 countries and territories. Using the conventional criterion of statistical significance ( p < .05), we found that 15 (54%) of the replications provided evidence of a statistically significant effect in the same direction as the original finding. With a strict significance criterion ( p < .0001), 14 (50%) of the replications still provided such evidence, a reflection of the extremely high-powered design. Seven (25%) of the replications yielded effect sizes larger than the original ones, and 21 (75%) yielded effect sizes smaller than the original ones. The median comparable Cohen’s ds were 0.60 for the original findings and 0.15 for the replications. The effect sizes were small (< 0.20) in 16 of the replications (57%), and 9 effects (32%) were in the direction opposite the direction of the original effect. Across settings, the Q statistic indicated significant heterogeneity in 11 (39%) of the replication effects, and most of those were among the findings with the largest overall effect sizes; only 1 effect that was near zero in the aggregate showed significant heterogeneity according to this measure. Only 1 effect had a tau value greater than .20, an indication of moderate heterogeneity. Eight others had tau values near or slightly above .10, an indication of slight heterogeneity. Moderation tests indicated that very little heterogeneity was attributable to the order in which the tasks were performed or whether the tasks were administered in lab versus online. Exploratory comparisons revealed little heterogeneity between Western, educated, industrialized, rich, and democratic (WEIRD) cultures and less WEIRD cultures (i.e., cultures with relatively high and low WEIRDness scores, respectively). Cumulatively, variability in the observed effect sizes was attributable more to the effect being studied than to the sample or setting in which it was studied.

All people share a need for safety. Yet people's pursuit of safety can conflict when it comes to guns, with some people perceiving guns as a means to safety and others perceiving guns as a threat to safety. We examined this conflict on a U.S. college campus that prohibits guns. We distinguished between people (N = 11,390) who (1) own a gun for protection, (2) own a gun exclusively for reasons other than protection (e.g., collecting, sports), and (3) do not own a gun. Protection owners felt less safe on campus and supported allowing guns on campus. They also reported that they and others would feel safer and that gun violence would decrease if they carried a gun on campus. Non-owners and non-protection owners felt the reverse. The findings suggest that protection concerns, rather than gun-ownership per se, account for diverging perceptions and attitudes about guns and gun control.

We examined whether gun ownership, and more importantly, the reason for owning a gun, is linked to expectations about what will happen if legislation allows guns on one’s college campus. We sent a web-based survey to students, faculty, and staff at a single southeastern United States university in March 2016. We queried respondents about gun ownership and the potential effects of campus carry laws on personal safety and the educational environment. We grouped respondents (N = 11,390) into gun owners who own guns for protection (protection owners), gun owners who own guns for nonprotection reasons (e.g., sport, collecting; nonprotection owners), and nonowners. Nonprotection owners and nonowners responded similarly and were generally distinct from protection owners. However, all 3 groups reported that legalizing guns on campus would harm the academic atmosphere and diminish feelings of safety when having heated exchanges or evaluating student outcomes. Ironically, protection owners acknowledge these harms yet support legislation allowing guns on campus. Regardless of group, our participants anticipated that allowing guns on campus would largely produce undesirable downstream academic consequences. Lawmakers must find ways to mitigate the possible harmful effects on personal safety and the academic environment, and find solutions that satisfy the safety needs of groups who see guns as source versus a threat to safety.

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Heuristic judgment processes appear to contribute to caregivers' proxy risk perceptions of their child's asthma exacerbation risk. Moreover, the display of other, possibly erroneous, judgment phenomena is associated with lower caregiver risk perceptions. Designing interventions that target these mechanisms may help caregivers work with their children to reduce exacerbation risk.