News & Views: Vaccines and Science Denialism

Philip Schmid and Cornelia Betsch recently published an important article in Nature Human Behaviour (https://doi.org/10.1038/s41562-019-0632-4). Titled “Effective strategies for rebutting science denialism in public discussion,” the authors reported their findings related to “debating” science deniers. The majority of their experiments used vaccines as the topic; however, they also included a similarly designed experiment related to climate change to assess whether their findings were replicated using a different topic.

In a “radio show” format, participants heard or read science deniers speak against vaccines or climate change. They were presented with follow-up arguments by science advocates designed to determine the most effective means of countering the misinformation presented by the denialists. Randomized groups heard the following science advocate responses:

• No response
• Topic-specific response addressing misinformation presented by the denialist
• Rhetorical technique response describing techniques the denialist used, for example creating impossible expectations, cherry-picking, using false logic, etc.
• Combined topical misinformation and rhetorical technique response

The study had some interesting, and generally applicable, findings worth considering.

Negative messaging has an effect.

Not surprising, science denialist messaging related to vaccines negatively affected both the attitudes and intentions of listeners. The negative effects were strongest in the group that did not hear any counter arguments, highlighting the importance of responding to negative messages. Interestingly, in the climate change experiment, the same effect was observed related to attitudes, but not intent.

Factual rebuttals or attention to technique can be effective in responding.

The effects of the denialist’s messaging were lessened whether the science advocate addressed the topical misinformation or the rhetorical techniques used by the denialist. This is important when an advocate may not feel confident effectively arguing the facts because they can, instead, point out a denialist’s use of cherry-picked data or logical fallacies. The authors mentioned that a limited number of techniques tend to be utilized across the array of science-based areas in which denialists have sown seeds of doubt. To that end, science advocates who are able to “pull back the curtain” on these practices can effectively diminish their impact. The categories of techniques, described by Diethelm and McKee, include the following:

• Selectivity — Cherry-picking the data and relying on particular papers to present “data” that agrees with the denialist’s point of view
• Impossible expectations — Pointing to the limitations of science to sow the seeds of doubt related to existing data, such as suggesting that the science advocate did not rule out the chance that something could occur when responding to a particular claim
• Conspiracy theories — Promoting the notion that the large group of advocates who agree with the science are involved in a nefarious cover-up or, related, relying on “inversionism,” in which the accusations include self-reflective characterizations and motivations
• Misrepresentations or false logic — Presenting information in a way that inaccurately portrays it or which involves logical fallacies, such those described on the VEC’s related Q&A sheet
• Fake experts — Having spokespersons who appear to have legitimate credentials, but who disregard the evidence and established knowledge, sometimes while simultaneously marginalizing or discrediting actual experts

Using both techniques did not improve the effectiveness of the messages presented by science advocates. Neither did the data suggest a “backfire effect” caused by addressing the misinformation.

Some subgroups are more likely to be affected by a denialist’s messaging than others.

The researchers explored how participants’ confidence in vaccination and their political viewpoints (conservative versus liberal) affected their response to denialist messaging. Those with low confidence in vaccination and those with a conservative viewpoint were more likely to be influenced by the inaccurate information; however, they were also more susceptible to having the effects on intent moderated by either topical or technique-based advocacy messaging. Reversing the effects of attitude changes were demonstrated as well, but they did not differ based on confidence or political viewpoint.

Conclusions

Based on these findings, the authors concluded that it is important to respond to denialists’ claims, but emphasized that advocates can effectively respond either to the content or to the technique used to make the claim. However, they also pointed out that while not responding would offer the worst outcome, in the context of something like a public debate, if the expert’s refusal to participate would result in the event being cancelled, that would be the most effective outcome since the audience would not suffer the negative effects of the misinformation at all. Finally, the authors spoke to the importance of helping audiences gain the skills necessary to detect misinformation proactively, citing studies in school children.

Practical applications

While most providers do not find themselves responding to vaccine hesitancy in public forums, such as radio shows or debates, this study offers some insights that may be applicable outside of these types of situations:

• Address misconceptions.
• Rather than just focusing on content, consider speaking to the techniques being used to misinform.
• Be proactive in helping parents and patients learn how to identify solid information before it is presented to them.

Some VEC resources may be helpful for addressing rhetorical techniques:

• “Evaluating information: What you should know”
• “Logical fallacies and vaccines: What you should know”
  • Both sheets can be shared by photocopying, linking, or quoting applicable subsets of information with appropriate source credit.
• The Vaccine Makers Project also has a vaccine safety lesson for high school students that teaches how to evaluate online information using criteria developed by the World Health Organization’s Vaccine Safety Net program. The website evaluation criteria were also developed into a pocket-sized card for use with the VMP lesson.