The effects of scientific messages and narratives about vaccination.

A fundamental challenge complicates news decisions about covering vaccine side effects: although serious vaccine side effects are rare, less severe ones do occur occasionally. The study was designed to test whether a side effect message could induce vaccine hesitancy and whether that could be countered by pro-vaccine messages about vaccine safety. A large (N = 2,345), nationally representative experiment was conducted by randomly exposing participants to one of six videos about the measles, mumps, and rubella (MMR) vaccine edited from news programs produced during the 2019 measles outbreak in the United States. The design was a 2x3 factorial crossing the presence or absence of a hesitancy-inducing narrative message with a pro-vaccine science-supporting message (i.e., no message, science-supporting expert message, or pro-vaccine narrative message), leading to a total of six conditions. A general linear model was used to assess the effects of these videos on respondents' (1) vaccine risk perceptions, (2) policy views on vaccination, (3) willingness to encourage others to vaccinate their children, and (4) intention to send a pro-vaccine letter to their state representative. Findings indicated that the science-supporting expert message about vaccine safety led to higher pro-vaccine evaluations relative to other conditions [e.g., b = -0.17, p < .001, a reduction in vaccine risk perceptions of 0.17 as compared to the control]. There was also suggestive evidence that the hesitancy-inducing narrative may limit the effectiveness of a science-supporting expert message, although this finding was not consistent across different outcomes. When shown alone the hesitancy-inducing narrative did not shift views and intentions, but more research is needed to ascertain whether exposure to such messages can undercut the pro-vaccine influence of science-supporting (expert) ones. All in all, however, it is clear that science-supporting messages are effective and therefore worthwhile in combating vaccine misinformation.

Misleading Claims About Tobacco Products in YouTube Videos: Experimental Effects of Misinformation on Unhealthy Attitudes.

BACKGROUND: Recent content analyses of YouTube postings reveal a proliferation of user generated videos with misleading statements about the health consequences of various types of nontraditional tobacco use (eg, electronic cigarettes; e-cigarettes). OBJECTIVE: This research was aimed at obtaining evidence about the potential effects of YouTube postings about tobacco products on viewers' attitudes toward these products. METHODS: A sample of young adults recruited online (N=350) viewed one of four highly viewed YouTube videos containing misleading health statements about chewing tobacco, e-cigarettes, hookahs, and pipe smoking, as well as a control YouTube video unrelated to tobacco products. RESULTS: The videos about e-cigarettes and hookahs led to more positive attitudes toward the featured products than did control videos. However, these effects did not fully translate into attitudes toward combustive cigarette smoking, although the pipe video led to more positive attitudes toward combustive smoking than did the chewing and the hookah videos, and the e-cigarette video led to more positive attitudes toward combustive cigarette smoking than did the chewing video. CONCLUSIONS: This research revealed young people's reactions to misleading claims about tobacco products featured in popular YouTube videos. Policy implications are discussed.

Associations of Topics of Discussion on Twitter With Survey Measures of Attitudes, Knowledge, and Behaviors Related to Zika: Probabilistic Study in the United States.

BACKGROUND: Recent outbreaks of Zika virus around the world led to increased discussions about this issue on social media platforms such as Twitter. These discussions may provide useful information about attitudes, knowledge, and behaviors of the population regarding issues that are important for public policy. OBJECTIVE: We sought to identify the associations of the topics of discussions on Twitter and survey measures of Zika-related attitudes, knowledge, and behaviors, not solely based upon the volume of such discussions but by analyzing the content of conversations using probabilistic techniques. METHODS: Using probabilistic topic modeling with US county and week as the unit of analysis, we analyzed the content of Twitter online communications to identify topics related to the reported attitudes, knowledge, and behaviors captured in a national representative survey (N=33,193) of the US adult population over 33 weeks. RESULTS: Our analyses revealed topics related to "congress funding for Zika," "microcephaly," "Zika-related travel discussions," "insect repellent," "blood transfusion technology," and "Zika in Miami" were associated with our survey measures of attitudes, knowledge, and behaviors observed over the period of the study. CONCLUSIONS: Our results demonstrated that it is possible to uncover topics of discussions from Twitter communications that are associated with the Zika-related attitudes, knowledge, and behaviors of populations over time. Social media data can be used as a complementary source of information alongside traditional data sources to gauge the patterns of attitudes, knowledge, and behaviors in a population.

Debunking: A Meta-Analysis of the Psychological Efficacy of Messages Countering Misinformation.

This meta-analysis investigated the factors underlying effective messages to counter attitudes and beliefs based on misinformation. Because misinformation can lead to poor decisions about consequential matters and is persistent and difficult to correct, debunking it is an important scientific and public-policy goal. This meta-analysis ( k = 52, N = 6,878) revealed large effects for presenting misinformation ( ds = 2.41-3.08), debunking ( ds = 1.14-1.33), and the persistence of misinformation in the face of debunking ( ds = 0.75-1.06). Persistence was stronger and the debunking effect was weaker when audiences generated reasons in support of the initial misinformation. A detailed debunking message correlated positively with the debunking effect. Surprisingly, however, a detailed debunking message also correlated positively with the misinformation-persistence effect.

Avoiding the boomerang: testing the relative effectiveness of antidrug public service announcements before a national campaign.

OBJECTIVES: This study examined the relative perceived effectiveness of 30 antidrug public service announcements (PSAs) and assessed the extent to which judgments of effectiveness are related to judgments of realism, amount learned, and positive and negative emotional responses. METHODS: Data were obtained from 3608 students in grades 5 through 12 in 10 schools. The ethnically diverse sample was 50.8% male. Students in 5 experimental conditions viewed sets of 6 antidrug PSAs and filled out a brief evaluation questionnaire following each PSA. Those in the control condition viewed a non-drug-related television program. RESULTS: The relative perceived effectiveness of the 30 PSAs varied considerably. Sixteen were rated as significantly more effective, and 6 as significantly less effective, than the control program. Relative rated effectiveness was highly related to realism (r =.87), amount learned (r =.88), negative emotion (r =.87), and positive emotion (r = -.35). CONCLUSIONS: Evaluative research is necessary to prevent broadcast of PSAs that could have a negative impact. PSAs should point out the negative consequences of drug use behavior rather than telling adolescents to "just say no."