Time for an Update: How does Ambiguous Scientific Evidence Change our Beliefs About the World?

Scientific evidence for many effects tends to be ambiguous, that is, some studies show an effect and others do not. In this study, we investigate how people update their prior beliefs based on ambiguous scientific evidence. We aim to identify general patterns or strategies of belief updating. We focus on three potential strategies: An uncertainty-weighting strategy (Behrens et al., 2007; Hogarth & Einhorn, 1992) where people update their beliefs less the higher the uncertainty of evidence, a unidimensional strategy (Nassar et al., 2010) where people update their beliefs more the more the evidence differs from their prior beliefs, and a weight-last-stronger strategy (see e.g., Hogarth & Einhorn, 1992) where people weight the evidence from the latest study stronger than that of previous studies. Further, we aim to assess the impact of subjective expertise (which may be an indicator of the strengths of prior beliefs), trust in (psychological) research and the breadth of information (the number of studies investigating an effect) on belief updating.