UCLA

Concerns about misinformation on the Internet usually focus on the amount of misinformation available, the ease of retrieving it, the speed with which it spreads, or the lack of editorial oversight. Yet none of these would be cause for concern if no one was misinformed. Indeed, what constitutes misinformation is often determined by who believes it. Hence the most important consideration may be a focus on why people believe. To explore this, this study reports results from a qualitative content analysis of online information about vaccine safety—with a particular focus on user comments—supplemented by exploratory interviews. The study examines how people on all sides of the debate use evidence to support their beliefs about vaccine safety. It also reflects upon the relationship between the Internet and those beliefs.

The most common beliefs about vaccine safety are beliefs about toxicity, beliefs about the cumulative effects of vaccines, beliefs about the premise of immunization, and beliefs about the compromised integrity of the medical system. Contrary to popular conceptions, these beliefs do not divide easily into binaries of pro-vaccination and anti-vaccination. Rather, it is as if available beliefs were arrayed in a buffet from which each believer chooses an individualized meal. The selection of beliefs is limited, as the same beliefs recur over and over in the data, yet each believer combines the limited selections into diverse belief profiles.

People justify these beliefs using risk-benefit calculations based in reason and authority, both of which are heavily influenced by personal experience, a kind of evidence that may be more prominent on the Internet than elsewhere. These basic tactics are employed in complex patterns that vary across beliefs, believers and situations. Perhaps surprisingly, while each person uses the tactics in different ways and to different degrees, the same basic tactics are used on all sides of the vaccine safety debate, suggesting a more complicated belief landscape than the popular conception. In turn, this suggests that it is not merely that misinformation affects what we believe, but also that what we believe appears to affect how we understand misinformation.