Confirmatory bias in health decisions: Evidence from the MMR-autism controversy

Since Wakefield et al. (1998), the public was exposed to mixed information surrounding the claim that measles-mumps-rubella vaccine causes autism. A persistent trend to delay the vaccination during 1998-2011 in the US was driven by children of college-educated mothers, suggesting that these mothers held biases against the vaccine influenced by the early unfounded claim. Consistent with confirmatory bias, exposures to negative information about the vaccine strengthened their biases more than exposures to positive information attenuated them. Positive online information, however, had strong impacts on vaccination decisions, suggesting that online dissemination of vaccine-safety information may help tackle the sticky misinformation.

Why such differing stances? A review of position statements on home birth from professional colleges

Despite low rates of home birth throughout most Western countries, the topic generates considerable debate. This is reflected by the differing positions on home birth adopted by professional colleges representing obstetricians and midwives. We reviewed position statements of midwifery and obstetric colleges in the UK, USA, Australia, New Zealand, and Canada to explore how the same body of research evidence leads to different positions. Aside from a joint statement from the UK we found widely differing stances, reflecting traditional midwifery perspectives of birth as a physiological process versus obstetric perspectives of potential pathology. We feel the differences in position statements are largely the end product of significant confirmatory bias.

TWEETABLE ABSTRACT

Review of organisational position on home birth suggests bias in literature interpretation.