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« Want to know what empirically *informed* vaccine risk communication looks like? | Main | How are climate skepticism, disbelief in evolution & vaccine hesitancy related? »

The culturally polarizing effect of the "anti-science trope" on vaccine risk perceptions 

The “ ‘anti-science’ trope” refers to a common theme in ad hoc risk communication that links concern about vaccine risks to disbelief in evolution and climate skepticism, all of which are cited as instances of a creeping hostility to science in the U.S. general public or at least some component of it.

In the last post, I presented evidence, collected as part of the CCP Vaccine Risk Perception study, that showed that the trope has no meaningful connection to fact. 

Those who accept and reject human evolution, those who believe in and those who are skeptical about climate change, all overwhelmingly agree that vaccine risks are low and vaccine benefits high.

The idea that either climate change skepticism or disbelief in evolution denotes hostility to science or lack of comprehension of science is false, too. That’s something that a large number of social science studies show.  The CCP Vaccine Risk study doesn’t add anything to that body of evidence.

But the CCP Vaccine Risk study did examine how differences in science comprehension and religiosity, which interact in an important way in disputes over climate change and evolution, don’t have any meaningful impact on perceptions of vaccine risk perceptions.

In addition to examining whether there was any factual substance to the anti-science trope, the CCP Vaccine Risk Perception study also investigated what the impact of the trope is—or at least could be if it were propagated widely enough—on public opinion.

For that purpose, the study used experimental methods. The experiment had three key elements.

First was a measurement of subjects’ cultural predispositions toward societal risks.

 I’ve actually described the strategy used to do so in several earlier posts.  But basically, the experiment used an “interpretive community” strategy, in which unobserved or latent group predispositions are extracted from subjects perceptions of a host of societal risks that are known to divide people with diverse cultural and political outlooks. This approach, as I’ve explained, furnishes the “highest resolution” for measuring the influence group predispositions might be having on perceptions of a risk on which there is reason to believe the impact might be small.


That analysis identified two cross-cutting or orthogonal dimensions along which risk predispositions could be measured.  I labeled them the “public safety” and “social deviancy” dimensions, based on their respective indicators (various environmental risks, guns, second-hand smoke in the former case; legalization of marijuana and prostitution and teaching of high school sex ed in the latter). 

 Subjects in the diverse 2,300-person sample of U.S. adults could thus be assigned to one of four “interpretive communities” (ICs) based on their score relative to the mean of both of these two “risk perception dimensions”: IC-α (“high public-safety” concern, “low social-deviancy”);  IC-β (“high public-safety,” “high social-deviancy); IC-γ (“low public-safety,” “low public-safety”); and IC-δ (“low public-safety,” “high social-deviancy”).  The intensity of the study subjects' commitment to one or the other of these groups can be measured by their scores on the public-safety and societal-deviancy risk-perception scales.

The second element was exposure of the subjects to examples of “ad hoc risk communication.”

The subjects were assigned to experimental conditions or groups, each of which read a different communication patterned on information in the media or internet.

One of these communications used the “anti-science trope.” Patterned on real-world communications (including ones reproduced in the Appendix to the Report), it was in the form of an op-ed that described disbelief in evolution, climate skepticism, and the belief that vaccines cause autism as progressive manifestations of a mutating “anti-science virus.” As is so for most real-world communications embodying the anti-science trope, the experiment communication displayed an unmistakably partisan orientation and conveyed contempt for members of the public who are skeptical of climate change and disbelieve evolution.

The third element was measurement of the subjects’ perceptions of vaccine risks and benefits.

The study used a large battery of risk and benefit items, which were combined into a highly reliable scale, “PUBLIC_HEALTH” (Cronbach’s α = 0.94), scores of which were transformed into z-scores (i.e., normalized so that increments reflected standard deviations from the mean) and coded so that lower ones denoted relatively negative assessments of vaccines and higher scores relatively positive ones.

In the experiment, then, the risk perceptions of subjects exposed to different forms of “ad hoc risk communication” were compared to the perceptions of survey participants, who were assigned to read a news story unrelated to vaccines and whose members served as the “control” group.

The results . . . .

As previewed in an earlier blog post, the study found that among members of the control group there was no practically meaningful relationship between  vaccine risk perceptions and the cultural risk predispositions measured by the “public safety” and “social deviance” IC dimensions.  IC-αs (“high public-safety,” “low social-deviancy”) scored highest on PUBLIC_HEALTH and IC- δs the lowest.  But the difference between them was trivially small—less than one-third of one standard deviation of the mean score.

As a measure of the practical difference in these scores, the predicted probability of agreeing that the “benefits of obtaining generally recommended childhood vaccinations outweigh the health risks” was estimated to be 84% (± 3%, LC = 0.95) for a typical IC‑α and 74% ( ± 4%) for a typical IC‑δ.

This was consistent with the findings of the Vaccine Risk Perception study's survey component generally, which found that there is broad-based consensus, even among groups that are bitterly divided on issues like climate change and evolution, that vaccine benefits are high and their risks low.  As of today, at least, vaccine risks are not culturally polarizing.

But that could change, the experiment results suggested.

This very modest difference in the perceptions of subjects displaying the IC-α  and IC-δ risk disposition widened significantly among their counterparts in the “anti-science trope” condition. Exposure to the “anti-science” op-ed also drove a wedge between subjects displaying the IC-β (“high public-safety,” “high social-deviancy) and IC-γ (“low public-safety,” “low social-deviancy”) dispositions, groups whose scores on the PUBLIC_HEALTH scale were indistinguishable in the control.

The practical significance of the difference can be illustrated by examining the impact of the experiment on the predicted probability of agreement with the item measuring “confidence in the judgment of the American Academy of Pediatrics that vaccines are a ‘ safe and effective way to prevent serious disease.’ ” Subjects responded to this item immediately after reading a statement issued by the AAP on vaccine testing and safety. The predicted probability that a subject with a typical IC-δ disposition would indicate a positive level of confidence dropped from 73% (± 4%, LC = 0.95) in the control to 64% (± 7%, LC = 0.95) in “anti-science”; the gap between the predicted probability of a positive assessment by a typical IC-δ and a typical IC-α grew 14% (± 9%) in the two conditions. The gap between the typical IC-β and both the typical IC-α (7%; ± 7%, LC = 0.95) and typical IC-δ (6%; ± 6%, LC = 0.95) grew, too, but by a more modest level. As one would expect, similar divisions characterized responses to other items in the PUBLIC_HEALTH scale.

There was no similar decrease in the predicted probability that a typical IC-δ would express a positive level of confidence in the other experiment conditions, one of which which featured a composite news story proclaiming an impending public health crisis from “declining vaccine rates,” and another of which a communication patterned on a typical CDC press release that conveyed accurate information on the high and steady level of vaccine rates in the U.S. in the last decade.  But as discussed in a previous post, subjects in the “crisis” condition, not surprisingly, grossly overestimated the degree of parental resistance to universal immunization—an effect that could negatively affect reciprocal motivations to contribute to the public good of herd immunity.

It is important to realize that the polarizing impact of the “Anti-science” op-ed resulted both from the positive effect it had on the vaccination attitudes of IC-α subjects and the negative effect it had on IC-δ ones. The overall effect of the “Anti-science” treatment was negligible.

The practical importance of the result, then, turns on the significance attached to the intensified levels of disagreement among subjects of diverse outlooks.

Previous CCP studies, including one involving controversy over the HPV vaccine, suggest that the status of a putative risk source as a symbol or focus of cultural contestation is what disrupts the social processes that ordinarily result in public convergence on the best available evidence relating to societal and health risks.

If this is correct, then any influence that intensifies differences among such groups should be viewed with great concern.

The "anti-science trope," in sum, is not just contrary to fact.  It is contrary to the tremendous stake that the public has in keeping its vaccine science communication environment free of reason-effacing forms of pollution.

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Reader Comments (6)

I wonder what the effect is of tropes like that the theory that ACO2 has the potential to significantly affect the climate is a "hoax?" Or the trope that climate scientists are only interested in pursuing funding and destroying capitalism?

Off-topic, Dan - I thought you might find this of interest if you haven't seen it:

February 1, 2014 | Unregistered CommenterJoshua


on an old topic—did you think of mentioning as an example of humor in the pro-Science™ science-communication camp? If only you had, you might have won the debate...oh well. ;-D

February 3, 2014 | Unregistered CommenterBrad Keyes

I finally had a chance to thoroughly read your blog and the underlying article. Let me say that I'm gobsmacked as I read the conclusions. It may turn my world on its head, but I do have to make a few comments.

As one of the targets of your article, I would like to point out a few things.

1. I am one of literally 100-200 blogs that focus on the anti-vaccination movement. About 10-20 hit the top of Google rankings for key word searches for vaccine information, with mine being one of them.
2. Over that top 20 blogs, they range from very motherly (meaning it's a regular mom talking positively about vaccines) through medical bloggers through science journalists to me. I take a unique perspective of being harsh, snarky, and a bit condescending to the antivaccination world.
3. My niche is really to attack the truly anti-science memes and tropes that are pushed by the anti-vaccination community. I've refuted the "vaccines cause autism" meme dozens of times. Moreover, my audience is really other pro-science people, so people tend to use my articles as a reference when information is needed.

That all being said, I guess I've observed so much anti-science attitude from hardcore vaccine deniers, it's hard for me to accept what you've written, though I am big evidence based skeptic, and what you present appears to show that my observations may be on the extreme edge.

Maybe if we take a large group of people who don't vaccinate, some don't do so for personal reasons that have nothing to do with science. The aren't actively anti-science, just passively accept their observations and research as good enough backing to not vaccinate. The graphs that show little different between vaccine acceptance and the other science denialism like evolution and global warming was shocking. I have always assumed that they are in the same crowd.

You've given me a lot to think about. I might not change that much in my writing, because I've tended to focus on the anti-science memes in the antivaccination movement. I've concluded, long ago, that there is really no debate about vaccines. The science is solidly behind the safety and efficacy of vaccines, so it almost becomes difficult for me to see how anyone could deny that without being the same as a creationist or global warming denier.

On Twitter, you volunteered to guest blog about this topic, and I would love if you did. My audience is, oddly, medical/science professionals and people who are just generally pro-science. Of course, I have a small number who just hate everything I write, but they keep reading it. Just contact me by the email I left here. This has really opened my eyes.

February 3, 2014 | Unregistered CommenterSkeptical Raptor


thanks for thoughtful comments.

I'd be happy to do guest post at your site; I was actually inviting you to do a guest post here! Invitation remains open.

One thing your comments makes me realize is that I've likely framed some of my points poorly.

For sure I don't mean to be saying that those who propagate the claim that vaccines cause autism & the like shouldn't be deemed "anti-science." I suppose one could try to figure out whether they are 'science literate' or trust scientists in general etc., but that seems beside the point. The people actively advancing those claims are misrepresenting the best available evidence; and they also are interfering with ability of others to recognize, & avail themselves of the benefits of, the same. Those are genuinely evil things to do. It's certainly justifiable to be angry at them & to condemn them.

What I am focusing on is the position that there is some sort of public opinion link between "climate skepticsm," "disbelief in evolution" & "vaccine hesitancy."

There isn't: members of the public who are climate skeptics & those who are climate believers, those who say "don't believe" & those who say "do believe" when asked about evolution -- they all overwhelmingly hold a positive view about childhood immunizations.

What's more, the asserted link is advanced as part of a broad-based indictment of a *moral* or cultural orientation that is being ridiculed as "anti-science& & blamed for various social harms.

When societal risks and like facts become entangled in group rivalries of that sort, positions on them are transformed into symbols of membership in & loyalty to the groups in question. That condition compromises the ability of those on both sides to reason & also frustrates their common interest in being able to make accurate assessments about how private actions & public policies interact w/ the states of affairs they value (their interest in that is the same, even if they don't value the *same* states of affairs!).

It is certainly possible to advocate, passionately & even angrily, against misleading people about vaccine safety without smearing a rival cultural group as being responsible for such conduct. I featured a *great* example of a writer who did that -- & who avoided the factually insupportable, & also boringly trite, "growing distrust"/"eroding vaccination rates" trope too -- in my blog post today (or yesterday, I guess).

So if you understood me to be saying that there's a problem in being critical -- even snarky! -- per se toward those making anti-vaccine arguments, I must have failed to present my points as clearly as I should have.

It's also very possible that for one reason or another I am reading you in a manner that doesn't match your own intentions.

I think it would be useful for us to continue & extend this exchange -- so we can both be clear on the points we agree on & the ones that, even after discussion, we don't. Then w/ respect to the latter, we can figure out why & what sorts of evidence would help us to sort that out.

Indeed, whatever particular matters we disagree about will never be of great consequence if we do in fact agree that this is how to proceed in general.

Thanks again for the comments, & look forward to more conversation.

February 4, 2014 | Unregistered Commenterdmk38

Thanks for looking into this.

Science aside, I think it's helpful to remember that these people aren't followers of and believers in logic. Most ordinary people use common sense. It's a fact-validation system that those of us who follow science tend to forget about, and how it works.

But it's vital if we're to tackle this problem.

Let me put it this way. I don't want to have to learn car mechanics every time I need something done. I'll find a friend who can do it that I trust, or I'll use a reputable company. If a big chain of mechanics were caught and fined for selling dodgy tyres, I wouldn't wait, scanning the news to find out whether the CEO or manager responsible had been fired, and looking up the reputation of the new one. I'd find somebody else to do it because trust is important when you don't have time to learn yourself.

Whether the anti-vaxxers are anti-science is irrelevant. Whether they're lefties or right-wingers is also irrelevant. What's relevant is that they've lost their faith in science. Seems a silly thing to say, but it's true.

Us science people DO need faith from time to time. We need faith in our car mechanics, in our banks, in our bosses. Nobody can know everything, so sometimes we all have to deal with people we trust, rather than go learning everything.

Can we be trustworthy scientists, and show that we're on THEIR SIDE? That we do care about their kids' health. That we mistrust corporate science as much as they do, and we also wouldn't trust a politician as far as we can throw them. Especially with science!

Can we establish this fact with them first, before we go shouting at them, or en masse insulting them?

I think a massive PRO-vax campaign that concentrates on building trust in this area would work better than flinging facts and figures at people. If I suspect my mechanic of ripping me off, him smugly waffling technical details about drive-shafts and carburettors isn't going to help ONE BIT. Neither will flinging the Haynes Manual at me and telling me to "do some research". If I get insulted, that's going to make things worse.

I believe this is the campaign we should be having:-

Independent quietly pro-vaccination science bloggers writing articles slamming corporate and government science, while ALSO slamming the insulting nature of the anti-anti-vax movement, and building trust in people as a voice of reason, and answering questions politely and with empathy.

"Yes, I understand why you don't trust corporate science. I don't either. No real scientist does. But all of us independent scientists and academics around the world have checked the facts for ourselves and we agree on this ONE thing. But you can trust us to be vigilant with every paper Merck puts out, because we acknowledge that profit can, has, and will no doubt again, corrupt the good name of science."

February 10, 2015 | Unregistered CommenterKarl

Hi Dan,
Way late to the game on this, but hopefully this project is still interesting to you. A couple questions/comments:

1. The largest negative shift you see in your results is in the "deltas." Even in the control condition (Fig 19), the deltas seem non-significantly shifted to the left of the other groups in measures of vaccine confidence. If this is true, and if the delta designation is determined by beliefs on other controversial issues, then this implies that vaccine confidence (and the negative shift driven by science trope) does indeed correlate with social/political stances on other hot-ticket issues. Which is contrary to your conclusions and doesn't square with my understanding of your z-score plots. Comments?
2. I thought it was notable that the negative shifts that result from science trope actually appear to be smaller than the positive shifts in the alphas (at least, on the PUBLIC_HEALTH scale; the scores on the other scales are at ceiling for the alphas so it's hard to say). Betas and gammas look the same, but in opposing directions, so they cancel each other out. No one would agree that increased polarization is a good thing, but I wonder if the *net* result of enhancing vaccine acceptance in the population, even if driven by alphas, could be considered a benefit of science trope.
3. In your other blog post, you show that vaccination beliefs are, on the whole, the same in conservatives vs. liberals. But what if you look at it the other way? If you bin the population according to vaccination beliefs, do those who are most strongly anti-vax have a particular political leaning? I'm very eager to hear your response on this one.
4. I've read in a couple of your articles the reassurances that "the overwhelming majority of the U.S. population is pro-vaccine." I live in Colorado, where compliance with the childhood MMR vaccine is 80-85%. That could be considered an "overwhelming majority" by some standards, but it still falls frighteningly short of the levels required for herd immunity. Moreover, vaccine compliance is required (to varying degrees) by the public school system in many states, so nation-wide vaccination rates may not be reflective of vaccination attitudes. And I am sure that you already know that anti-vaccination attitudes have "hot spots" that may not be readily apparent in nation-, or even state-, wide summary statistics.

Very interesting work. Thanks for posting.

April 6, 2016 | Unregistered Commenterkkw

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