Because they are generally politics junkies, readers of this blog are more likely to know what the HPV vaccination debate is about than members of the public, but in case anyone needs some background, here’s the story. The FDA recently approved a vaccine that would inoculate girls and women against infection by the human papillomavirus (HPV). HPV infection is a sexually transmitted disease and is the leading cause of cervical cancer. The CDC recommends vaccination at a relatively young age (11-12), before the onset of sexual activity that can lead to HPV exposure and infection (at which point the vaccine is ineffective). A political debate has started to emerge over whether government (through public schools or other agencies) should mandate HPV vaccination for all young girls.

The HPV-vaccine debate features competing risk claims. Proponents argue that the failure to administer mass vaccinations will lead to continuing widespread infection and correspondingly high rates of cervical cancer. Opponents argue that the vaccination, by eliminating the risk of one common STD, might induce young women to engage in unprotected sex and thus increase their risk of contracting other diseases, including HIV-AIDS. They also raise concerns about potential unforeseen side effects from the vaccination.

Moreover, the policy of mandatory HPV vaccination seems to touch on a variety of issues of cultural import: from premarital sex to parental autonomy, from individual choice to the power of the state to control medical decisions. One might expect, then, that individuals will resolve competing factual claims about the risks of HPV in a manner that affirms rather than threatens their cultural worldviews.

At the same time, the risk of mandatory HPV vaccination -- compared, say, to the risks associated with climate change or gun ownership -- are relatively novel. As a result, many members of the public are unlikely to have an intuitive or emotional response to the issue informed by their cultural affiliations. For that reason, the advent of the HPV vaccination debate struck us -- myself, Don Braman, Paul Slovic, John Gastil, and Geoff Cohen -- as supplying an excellent opportunity to investigate the discrete mechanisms through which culture operates to shape risk perceptions on new issues.

To that end, we constructed a multi-part experimental study. The aim of the first part was to determine whether individuals’ cultural predispositions bias how they process information on a relatively novel risk. We divided 500 subjects into two groups: one that received no information about the policy of mandatory vaccination of school-age girls other than it was being proposed (the “no argument” group); and another that was instructed to read opposing arguments relating to the policy (“argument” group). Both groups of subjects were asked to indicate their beliefs about various facts relating to the policy (including its asserted benefits in reducing the incidence of cervical cancer, its possible unanticipated side-effects, and its contribution to the propensity of vaccinated females to have unprotected sex).

We found that subjects exposed to information polarized along cultural lines relative to ones who were not. Even in the “no argument” condition, so-called individualists (persons who resent government interference with private choice) and hierarchs (persons who hold traditional values) rated the potential risks of the policy as being slightly higher, and the potential benefits lower, than did communitarians (proponents of governmental responsibility for securing collective welfare) and egalitarians (supporters of egalitarian values). But in the “argument” condition, these disparities in risk-benefit perceptions were significantly more pronounced. (These results matched ones we had obtained n a previous experiment involving the risks of nanotechnology, which are even more unfamiliar to most members of the public.)

Next we conducted an experiment to see whether the perceived cultural values of argument advocates would make a difference. We started by creating four culturally identifiable “policy experts”: individuals who, based on their pictures and mock CVs, were perceived by pretest subjects as holding one or another of the worldviews featured in the cultural cognition theory (you might recognize one or more of the ones at right; our subjects didn't -- sorry, guys). We then asked 800 completely new subjects to indicate what they thought about the risks and benefits of the HPV vaccine after reading the balanced arguments, which were now randomly assigned to debating pairs of culturally identifiable experts.

We found that policy advocates’ perceived cultural worldviews can indeed significantly accentuate or mute cultural polarization. Where an egalitarian advocate defended mandatory vaccination and a hierarchal advocate opposed it (“expected alignment” condition), the gulf between egalitarian and hierarchical subjects widened. The same was true of the gap between communitarians and individualists when advocates sharing their identities took the pro- and con- positions, respectively.

But when the advocate-argument alignments were reversed—that is when a hierarchal or an individualist expert defended mandatory vaccination against an egalitarian or communitarian expert who opposed it (“unexpected alignment” condition)—polarization shrunk. Indeed, individualists and communitarians in this “unexpected alignment” condition actually swapped places: now communitarians displayed greater concern for the risks of the HPV-vaccination policy (although the difference between the two groups’ was small and not statistically significant in that condition; in effect, polarization along this dimension had disappeared). Clearly, the cultural identity of advocates is an incredibly powerful mechanism -- one that rivals cultural predispositions – in the processing of information about risk.

The inversion of the alignment between advocate identity and arguments need not be this complete in order to counter polarization. We found that polarization was also small (relative to that in the “argument” and “expected alignment” conditions) among subjects in what we called the “voucher” condition. Each subject in that condition had observed a debate among advocates who both shared that subject’s worldview. Accordingly, only one of the two debating experts in this condition was taking a position contrary to the stance normally associated with his (and the subject’s) perceived values.

We think the diminishment of polarization in the "voucher" condition is important. People in the real world won’t encounter many examples of debates in which there is a radical inversion of the cultural identities of advocates and the cultural resonances of the arguments they are making. But they might well see examples of advocates whose values they share taking unexpected positions in debates with others of their own persuasion. The conservative Governor of Texas, for example, surprised many of his ideological peers when he came out in favor of mandatory HPV vaccinations. When individuals see that even some persons who hold their values are willing to take such a position -- to “vouch” for that position as acceptable for someone with their values to hold -- they are less likely to form the subconscious impression that taking such a view will estrange them from their peers. They are then more likely to consider with an open mind arguments that run against the grain of their cultural predispositions.

Of course, it shouldn’t come as news to anyone that people tend to listen to policy experts they find knowledgeable and trustworthy, particularly on relatively novel issues that turn on uncertain empirical claims. But our study helps to reveal what makes ordinary people find experts credible: an affinity between the experts’ perceived cultural values and their own. This finding too shouldn't come as a shock, yet it's a truth that is consistently missed by many public policy advocates, who tend to assume that all they need to do to persuade the public on some risk issue (global warming, gun control, etc.) is amass reams of evidence from people whose authority derives solely from their technical training and expertise. If those advocates make that same mistake here -- if they don’t take care to assure that public advocates in the HPV vaccine debate are perceived as having appropriate cultural credentials as well as appropriate scientific ones -- they’ll likely be left scratching their heads in bewilderment, and stomping their feet in frustration, once again as their message fails to get through.