Objective:   Strengthening of antivaccination movements in recent decades has coincided with unprecedented increases in the incidence of some communicable diseases. Many intervention programs work from a deficit model of science communication, presuming that vaccination skeptics lack the ability to access or understand evidence. However, interventions focusing on evidence and the debunking of vaccine-related myths have proven to be either nonproductive or counterproductive. Working from a motivated reasoning perspective, we examine the psychological factors that might motivate people to reject scientific consensus around vaccination. To assist with international generalizability, we examine this question in 24 countries. Methods:   We sampled 5,323 participants in 24 countries, and measured their antivaccination attitudes. We also measured their belief in conspiracy theories, reactance (the tendency for people to have a low tolerance for impingements on their freedoms), disgust sensitivity toward blood and needles, and individualistic/hierarchical worldviews (i.e., people’s beliefs about how much control society should have over individuals, and whether hierarchies are desirable). Results:   In order of magnitude, antivaccination attitudes were highest among those who (a) were high in conspiratorial thinking, (b) were high in reactance, (c) reported high levels of disgust toward blood and needles, and (d) had strong individualistic/hierarchical worldviews. In contrast, demographic variables (including education) accounted for nonsignificant or trivial levels of variance. Conclusions:   These data help identify the “attitude roots” that may motivate and sustain vaccine skepticism. In so doing, they help shed light on why repetition of evidence can be nonproductive, and suggest communication solutions to that problem.

For the first time in a century, incidences of some communicable diseases—such as measles, mumps and pertussis—are on the increase in the United States (World Health Organization, 2017). Many commentators lay the blame for this epidemiological outbreak on an increase in anti-immunization activism, and the associated drop in immunization rates in some communities (Betsch, Renkewitz, Betsch, & Ulshöfer, 2010; van Panhuis et al., 2013). As a...