Inoculation Theory in the Post-truth Era: Extant Findings and New Frontiers for Contested Science, Misinformation, and Conspiracy Theories

"...applications of inoculation theory to prevalent science misinformation across issues that are clearly consequential and harmful for both society and individuals..."

In the present "post-truth" era, misinformation abounds, scientific facts are increasingly called into question, and trust in science is being eroded. In this context, inoculation theory may have a role to play in addressing contested science beliefs that can foment vaccine hesitancy, COVID-19 conspiracy theories, and other harms. Inoculation theory explains how an attitude or belief can be made resistant to persuasion or manipulation through pre-exposure to weakened forms of challenges. This paper considers the findings of work to date on inoculation theory in the face of threats posed by "alternative facts" and proposes new directions for inoculation theory research.

The paper begins by examining inoculation as a way to proactively fight public misperceptions of science. Described here as the "grandparent theory of resistance to attitude change", inoculation theory has been found to help protect a desirable position on a scientific issue (e.g., that climate change is real and exacerbated by human activity) from misinformation via "prophylactic" inoculation. This process relies on two main mechanisms: (i) forewarnings or threat of a counter-attitudinal attack to motivate resistance; and (ii) a preemptive refutation of the attack to model the counter-arguing process and provide people with content they can use to refute future persuasive challenges. Even when people already hold undesirable positions, "therapeutic" inoculation messages can change those undesirable attitudes and beliefs and then make new attitudes and beliefs more resilient. This review focuses on both prophylactic and therapeutic applications of inoculation theory to science misinformation.

In reviewing scholarly work done to date, the researchers point to what they call "the greatest power of inoculation theory messaging", which is its ability to spread and diffuse over populations not initially exposed to the inoculation message. Studies have demonstrated that inoculation treatments can enhance perceived interest in the topic at hand and increase people's intent and likelihood to talk about societally contested issues. For example, Goldberg and colleagues (2019) found that talking about climate change with family and friends leads to more acceptance of climate science, including by supporting understanding of the scientific consensus on climate change. This social "spreading" of inoculation's protection in the form of post-inoculation talk (PIT) has been compared to (biological) herd immunity.

Having explained key concepts, the researchers explore some of the studies that have used inoculation to better understand how to generate resistance against scientific misinformation about climate change, anti-vaccination beliefs, and other controversial and contested scientific issues. For instance, findings support the applicability of inoculation theory to vaccine hesitancy in that they demonstrate the possibility of intervening against the effects of anti-vaccine conspiracy theories by presenting people with accurate scientific information beforehand. One study involving the human papillomavirus (HPV) vaccine demonstrated that a more general inoculation pretreatment on vaccines can afford protection against multiple counterattitudinal attacks related to the safety and efficacy of the HPV vaccine - supporting the notion that one inoculation message might carry the potential to protect related attitudes in the same manner that vaccines may protect against a range of other viruses.

The researchers note that, while such empirical findings are promising, further research is needed. Four recommendations for inoculation theory scholarship in the post-truth era include:

1. Prophylactic (preemptive) and therapeutic (retroactive) inoculation messaging should be designed and tested across a wide range of scientific issues, and scholars should identify inoculation messaging as such in their work (prophylactic or therapeutic). The type of inoculation matters when clarifying and developing theory.
2. Issues around source credibility - the perceived accuracy, validity, and plausibility of a message - are important in applying inoculation theory to scientific issues, especially when argumentation focuses on scientific consensus and channels of scientific information messaging (e.g., conventional news, government reports). Such efforts could build on the theoretical work that explores issues of inoculation theory and character assassination - that is, pointed attacks on perceptions of a source's competence, character, or the like.
3. Researchers exploring issues of inoculation theory should attend not only to "passive refutations", in which the counter-arguments and refutations are provided to the recipient (usually in the form of a conventional persuasive article), but to active inoculation. In this "learning by doing" approach, participants are asked to actively generate pro- and counter-arguments themselves, which could elicit a more involved cognitive process leading to enhanced resistance. One study built defences through active participation in video games that simulate persuasive arguments on social media.
4. PIT and its science communication applications warrant continued study. Cook et al. (2017) found inoculation effects by helping message recipients identify reasoning fallacies, but more could be learned regarding mapping the spread of talk (e.g., social network topologies) in such cases. That is, one could ask: "Would this message content also spread through talk, and if so, could enhanced critical thinking also spread, both online and offline?"

In conclusion, the researchers point to the timely nature of such investigations in light of "the onslaught of scientific misinformation about COVID-19, from fake cures (e.g., ingesting alcohol) to unfounded conspiracy theories about vaccines....Amidst a worldwide 'infodemic,'...the study and application of inoculation theory has never been more relevant and exciting for social psychologists and communication scholars than it is today."