Effect Sizes Reported in Highly Cited Emotion Research Compared With Larger Studies and Meta-Analyses Addressing the Same Questions

We assessed whether the most highly cited studies in emotion research reported larger effect sizes compared with meta-analyses and the largest studies on the same question. We screened all reports with at least 1,000 citations and identified matching meta-analyses for 40 highly cited observational studies and 25 highly cited experimental studies. Highly cited observational studies had effects greater on average by 1.42-fold (95% confidence interval [CI] = [1.09, 1.87]) compared with meta-analyses and 1.99-fold (95% CI = [1.33, 2.99]) compared with largest studies on the same questions. Highly cited experimental studies had increases of 1.29-fold (95% CI = [1.01, 1.63]) compared with meta-analyses and 2.02-fold (95% CI = [1.60, 2.57]) compared with the largest studies. There was substantial between-topics heterogeneity, more prominently for observational studies. Highly cited studies often did not have the largest weight in meta-analyses (12 of 65 topics, 18%) but were frequently the earliest ones published on the topic (31 of 65 topics, 48%). Highly cited studies may offer, on average, exaggerated estimates of effects in both observational and experimental designs.