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What makes for compelling science? Evidential diversity in the evaluation of scientific arguments

Kary, Arthur, Newell, Ben R., Hayes, Brett K.
Global environmental change 2018 v.49 pp. 186-196
cognition, global warming, public health
Despite overwhelming scientific evidence, many members of the public remain skeptical about anthropogenic global warming. Hence, we examined how the presentation of factual scientific evidence affects lay evaluations of scientific claims. Taking inspiration from cognitive research on inductive reasoning, two studies examined the impact of evidential diversity on acceptance of claims in the domains of climate change and public health. Participants were presented with scientific claims based on competing evidence options and were asked to choose the best and worst form of evidence for each claim. The diversity of the available evidence was manipulated across three dimensions; geographical (evidence from two geographically near or far nations), socio-cultural (evidence from two culturally similar or dissimilar nations), and temporal (evidence drawn from two different periods or the same period). In both studies, diverse evidence on the geographical and socio-cultural dimension increased perceived support for scientific claims, but the relative impact of these dimensions differed between domains; geographical diversity had a larger effect on claims about climate change; socio-cultural diversity had a larger effect on claims about health. On the temporal dimension, recent non-diverse evidence (i.e. from the same recent period) increased perceived support for scientific claims more than diverse evidence. These results may have important implications for the communication of complex scientific evidence to a lay audience.