Time for an Update

Abstract: Scientific evidence for many effects tends to be ambiguous. Here we investigated how psychological novices update their preexisting beliefs about psychological effects based on ambiguous scientific evidence. Specifically, we investigated various predictors and systematic patterns of belief updating. Participants were presented a series of fictitious hypotheses, accompanied by a series of fictitious study outcomes. For each hypothesis, we assessed participants’ preexisting beliefs and subjective expertise regarding the topic, as well as their posterior beliefs after presentation of scientific evidence. We found a negative effect of subjective expertise and positive effects of trust in psychological science and number of studies investigating an effect on belief updating. We further found evidence for a belief updating pattern according to which participants weight the outcome of the most recent study stronger than that of previous studies. The results advance our understanding of evidence-based belief updating and provide practical implications for science communication.