Supplementary Material I and II - Overview of the 24 Experimental Conditions, German Lay Friendly Research Summaries and Translated Versions in English for Indicators of Trustworthiness in Lay Friendly Research Summaries – Scientificness Surpasses Easiness

Lay readers’ trust in scientific texts can be shaped by perceived text easiness and scientificness. The two effects seem vital in a time of rapid science information sharing, yet have so far only been examined separately. A preregistered online study was conducted to assess them jointly, to probe for author and text trustworthiness overlap, and to investigate interindividual influences on the effects. N = 1467 lay readers read four short research summaries, with easiness and scientificness (high vs low) being experimentally varied. A more scientific writing style led to higher perceived author and text trustworthiness. Higher personal justification belief, lower justification by multiple-sources belief, and lower need for cognitive closure attenuated the influence of scientificness on trustworthiness. However, text easiness showed no influence on trustworthiness and no interaction with text scientificness. Implications for future studies and suggestions for enhancing the perceived trustworthiness of research summaries are discussed.