Heightening Uncertainty Around Certain Science: Media Coverage, False Balance, and the Autism-Vaccine Controversy

To investigate how balanced presentations of the autism-vaccine controversy influence judgments of vaccine risk, we randomly assigned 327 participants to news articles that presented balanced claims both for and against an autism-vaccine link, antilink claims only, prolink claims only, or unrelated information. Readers in the balanced condition were less certain that vaccines did not cause autism and more likely to believe experts were divided on the issue. The relationship between exposure to balanced coverage and certainty was mediated by the belief that medical experts are divided about a potential autism-vaccine link. We discuss theoretical and practical implications of these findings.