Date of Award

August 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mass Communications

Advisor(s)

T. Makana Chock

Keywords

Counter-rumor, Health misinformation, Persuasion, Rumor, Social media, Vaccination

Subject Categories

Social and Behavioral Sciences

Abstract

This study examined the effects of the counter-rumor on changes in the belief about the anti-vaccination claim, anxiety associated with the rumor, intentions to vaccinate a child and share the rumor. Particularly, we tested whether argument strength, source expertise, as well as the recipient’s previously held attitude toward vaccination, could affect these outcomes. First, the pilot tests were conducted to check source expertise (N = 161) and argument strength (N = 74; N = 73) and select sources and messages used in the experiment. A 2 (argument strength: strong vs. weak) x 2 (expertise source: high vs. low) between-subjects factor experimental design was employed, and we conducted an online experiment (N = 400) set up in the Qualtrics. Participants were recruited via Prolific, a crowdsourcing website. The results showed that attitude toward mandatory vaccination had an impact on the change in the belief about the anti-vaccination claim. We also found that source expertise had a significant impact on the change in anxiety. Those who read the counter-rumor from CDC reported greater decrease in their anxiety than those who read the counter-rumor from a layperson user. This finding suggests that heuristic processing occurs in the reception of the anti-vaccination rumor and the counter-rumor that refutes the claim, such that people are less likely to feel anxious about the anti-vaccination rumor when they receive the counter-rumor from high expertise source.

Furthermore, the results showed a significant interaction between argument strength and source expertise on the change in vaccination intention. When participants read the counter-rumor from CDC, they reported greater increase in their intention to vaccinate a child in response to the strong argument than they did in response to the weak argument. On the contrary, when they read the counter-rumor from a layperson user, the opposite pattern appeared, such that they reported greater increase in their vaccination intention in response to the weak argument than they did in response to the strong argument. This finding reveals that cue-message congruency plays a crucial role in increasing the effectiveness of the counter-rumor and promoting behavioral change. The theoretical implications of the current findings are discussed in light of cognitive dissonance theory, the dual-process model of information processing, and online rumor literature. The practical implications of the findings are further discussed with regard to designing strategies and interventions that mitigate the harmful consequences of health-related rumors.

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Open Access

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