A Randomized Controlled Study on the Effectiveness of Plain Language Summaries of Psychological Meta-Analyses

Abstract: Plain language summaries (PLSs) are easily comprehensible summaries of scientific articles. They translate research findings for nonexperts to foster laypersons’ understanding of scientific evidence. We examined whether PLSs of psychological meta-analyses improve laypersons’ understanding of scientific evidence in a general population sample. Moreover, to develop guidance on writing PLSs, we varied four PLS characteristics: The number of effects reported, information on conflicts of interest (COI), information on publication bias, practical relevance statements. In an online study, 2,451 participants read two PLSs. Preregistered hypotheses were partly supported: Laypersons preferred PLSs over scientific abstracts, and PLSs facilitated knowledge acquisition; detrimental effects existed for PLSs reporting a higher number of effects on user experience, but not on knowledge acquisition; COI statements affected epistemic trustworthiness. Contrary to our predictions, we did not find significant effects of publication bias and practical relevance statements on subjective outcomes. However, PLSs educated laypersons on the concept “publication bias.”