Many Labs 2: Investigating Variation in Replicability Across Samples and Settings

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 highpowered 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.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP

Neural mechanisms underlying the effects of emotional arousal on memory

Emotional events (e.g., seeing a snake while hiking) typically stay in the memory longer and in more detail than neutral ones (e.g., seeing a bird while hik-ing). This emotion-induced memory enhancement has been attributed to the amyg-dala’s modulation on other brain regions, such as the medial temporal lobe and visual cortices. In line with this amygdala modulation hypothesis, previous brain imaging research revealed enhanced amygdala activity when encoding and retriev-ing emotional stimuli compared with non-emotional stimuli. However, emotion does not always enhance memory. Indeed, researchers have long been aware that emotion sometimes enhances and sometimes impairs memory. Yet, the underlying mechanisms of the opposing effects of emotion are relatively unknown. For example, if the amygdala’s modulation on other brain regions is critical in the emotion- memory interaction, how does it result in the enhancement effects for some aspects, while impairing other aspects of memory? In this chapter, we argue an alternative possibility: that norepinephrine released by the locus coeruleus under arousal plays a critical role in the complex effects of emotion on memory