The dominant theme of ad hoc risk vaccine risk communication warns of a ““growing wave of public resentment and fear” that has induced a “large and growing number” of “otherwise mainstream parents” to refuse to vaccinate their children.
As discussed in the last post, this trope is not based on fact: there hasn't been an “erosion in immunization rates”; on the contrary, coverage for all recommended childhood vaccines has held steady at 90% (the HHS "healthy person" target) or above for over a decade.
And while there's zero evidence of a " “growing crisis of public confidence” in vaccines at present, emphatic assertions that there is one can be shown to induce misunderstandings and confusion inimical to the willingness of people to make voluntary contributions to public goods--like the herd immunity associated with universal immunization.
A secondary theme of ad hoc risk communication is the "anti-science" trope. This claim links "growing" concern over vaccine safety to disbelief in evolution and skepticism toward climate change, all of which are depicted as evidence of a creeping hostility to science in the general public.
The CCP Vaccine Risk Perception study found this assertion, too, to be both contrary to fact and antithetical to maintaining the existing, broad-based public consensus in favor of universal immunization.
Below is a section of the Report that presents survey evidence on the relationship between vaccine risk perceptions, on the one hand, and climate change skepticism, disbelief in evolution, and science comprehension generally, on the other. Tomorrow I'll post material relating to the Study's experimental component, which illustrates the potential of the "anti-science trope" to generate cultural conflict over vaccines.
A. Some benchmarks: evolution and climate change, science comprehension and religiosity.
As emphasized, the aim of the survey component of the study was to evaluate the nature of the general public’s perception of childhood vaccine risks. Is there a shared or dominant affective orientation toward vaccine safety in the U.S. public? Or do childhood vaccines provoke mixed and opposing reactions—and if so, among whom?
Meaningful answers to these questions require an intelligible reference point with which to compare the survey responses. Dispute over universal vaccination laws—provisions that make immunization a condition of school enrollment, subject to medical or religious and in some states moral-objection “exemptions”—are frequently likened to conflicts over acceptance of mainstream science, including the teaching of evolution in public schools and the adoption of policies to mitigate the environmental impact of climate change. Associated with religious, cultural, and political divisions, the intensity and character of these conflicts can be used to help assess the intensity and character of any divisions of opinion observed on childhood vaccine risks.
The study measured study participants’ beliefs about both evolution and global warming. On evolution, subjects responded to an item from the National Science Foundation (2012) “Science Indicators” battery, which is conventionally used to measure science literacy. That item instructs respondents to respond to the statement “Human beings, as we know them today, developed from earlier species of animals.” In line with many public opinion polls (e.g., Newport 2012), 56% of the survey respondents classified this statement as “true,” and 44% as “false.”
On climate change, 52% of the survey respondents indicated that they believe scientific evidence supports the proposition that the earth’s temperature has been increasing in “the last few decades” as a result “of human activity such as burning fossil fuels.” Thirty percent indicated that they did not believe there was “solid evidence” of increasing global temperatures over the “past few decades,” while another 18% indicated that they believed there was “solid evidence” of warming but that the cause was “mostly. . . natural patterns in the earth’s environment,” as opposed to “human activity.” These figures, too, are in line with recent national opinion surveys (Silver 2013).
Irrespective of their responses to these items, however, the overwhelming majority of survey respondents agreed with the proposition that the “health benefits of obtaining generally recommended childhood vaccinations outweigh the health risks” (BALANCE). Eighty percent of the respondents who believe in human-caused climate change agreed with this proposition. So did 81% of those who believe the earth’s temperature has increased as a result of “natural patterns,” and 73% of those who believe the earth’s temperature has not increased in recent decades. Eighty percent of the respondents who believe in evolution and 77% who do not (a difference smaller than the survey margin of error) likewise indicated that they agree the benefits of childhood vaccinations outweigh their risks (Figure 5).
Study participants also responded to items measuring both their religiosity and their knowledge of and facility with scientific evidence. The former was assessed with a scale that aggregated self-reported church attendance, frequency of prayer, and “importance of God” in the respondents’ lives (α = 0.86). Subjects’ “science literacy” was assessed with 11 items from the NSF’s Science Indicator battery, which is conventionally used to study public understanding of science in the U.S. and abroad (NSF 2012). In addition, subjects completed a ten-item version of the Cognitive Reflection Test (Frederick 2005; Toplak, West & Stanovich 2013), which assesses the motivation and capacity to consciously interrogate one’s views on the basis of available information, a critical-reasoning disposition integral to forming evidence-based beliefs (Toplak, West & Stanovich 2011).
The NSF and CRT items formed a reliable scale (Cronbach’s α = 0.82), which can be interpreted as measuring a “science comprehension” aptitude (Kahan, Peters et al. 2012). Consistent with previous studies (Pennycook 2012, 2013; Shenhav, Green & Rand 2011; Gervais & Norenzayan 2012), there was a modest negative correlation between the religiosity and science comprehension (r = -0.26, p < 0.01).
Religiosity and science comprehension also were meaningfully—but not straightforwardly—associated with the study subjects’ positions on evolution and climate change. Science comprehension was modestly associated (r = 0.28, p < 0.01) with belief in evolution and weakly associated with belief in human-caused climate change (r = 0.10, p < 0.01) for the sample as a whole (including both survey and experiment subjects). But the impact was moderated by subjects’ religiosity: among those low in religiosity, higher science comprehension substantially increased belief in evolution and in human-caused global warming; among those high in religiosity, however, higher science comprehension had next to no impact on belief in evolution and substantially reduced belief in human-caused global warming (Figure 7).
The interaction between religiosity and science comprehension is not surprising. Science literacy and critical reasoning dispositions have been found to magnify cultural and ideological predispositions toward global warming (Kahan, Peters et al. 2012; Kahan 2013b). So it stands to reason that they would have the same impact on predispositions associated with religiosity, which plays a comparable role to shared cultural and political outlooks in the web of social relationships that orient individuals toward what is known by science. “Belief in evolution” is not a reliable indicator of either a scientifically literate understanding of evolutionary mechanisms (Schtulman 2006; Bishop & Anderson 1990) or the species of science literacy measured generally by the NSF Science Indicators. Rather, how one responds to the question “do you believe in human evolution” indicates a form of identity that features religiosity (Roos 2012). It is perfectly plausible that the significance of “disbelief” in evolution as an expression of personal identity would be unaffected by science knowledge—or possibly even reinforced by habits of mind associated with critical reasoning. Indeed, experimental evidence supports this inference (Lawson & Worsnop 2006).
These relationships—which are integral to making sense of the salience and ferocity of societal conflict over climate change and over evolution—were absent from the views of the survey respondents toward childhood vaccines (Figure 7). Both science comprehension (r = 0.12, p < 0.01) and religiosity (r = -0.14, p < 0.01) displayed only weak relationships with the battery of items that formed the PUBLIC_HEALTH scale. There was an interaction between religiosity and science comprehension in the survey respondents’ scores on the scale, but it was small in size and, more importantly, moderated only the intensity of the positive orientation that subjects of varying levels of religiosity expressed toward childhood vaccines (App. 1, Table 1).
A more detailed examination of the participants’ responses to the various survey items follows. Unsurprisingly, there is unanimity on none. Nevertheless, understood in relation to contested societal issues that feature conflict among large and readily identifiable societal groups, the uniform and uniformly supportive margins of agreement reflected in survey responses is of fundamental interpretive significance. As will become even more apparent, in probing the nature of opposition to universal childhood immunization, one is necessarily assessing the attitudes of a segment of the population that is small in size and that defies identification by the sorts of characteristics associated with recognizable cultural styles in American society.
To download Vaccine Risk Perceptions and Ad Hoc Risk Communication: An Empirical Assessment, click here.