How Much Evidence Is Enough? Biased Thresholds in Judgments of Scientific Conclusions

Abstract People are biased in their consumption of scientific information. The current research investigated conclusion thresholds, testing the hypothesis that more scientific evidence is needed to arrive at a non-preferred than a preferred conclusion. Participants read brief summaries of scientific studies exploring the nature of homosexuality (Study 1; N = 126) and air safety that supported either the Democratic or the Republican position on the issue (Study 2; N = 311). Participants read summaries until a conclusion could be made about the evidence. Supporting the hypotheses, participants read fewer study summaries when the results of those studies supported their preferred conclusion than when they did not. Recommendations focus on how the scientific community and science journalism can address this bias.