Psychological Science in the Public Interest , in press Misinformation and its Correction : Continued Influence and Successful Debiasing

The widespread prevalence and persistence of misinformation in contemporary societies, such as the false belief that there is a link between childhood vaccinations and autism, must be of public concern. For example, the myths surrounding vaccinations which led some parents to withhold immunization from their children have demonstrably led to a marked increase in vaccine-preventable disease, as well as unnecessary public expenditure on research and public information campaigns to rectify the situation. We first examine the mechanisms by which such misinformation is disseminated in society, both inadvertently and purposely. Misinformation can originate from rumors but also works of fiction, from government and politicians, as well as vested interests. Moreover, changes in the media landscape and the arrival of the internet have fundamentally impacted the ways in which information is communicated and misinformation is spread. We then move to the level of the individual, and review the cognitive factors that often render misinformation resistant to correction. We consider how people assess the truth of a statement and what makes people believe certain things but not others. We answer the question why retractions of misinformation are so ineffective and why efforts to retract misinformation can even backfire and ironically increase misbelief. While ideology and personal worldviews can be major obstacles for debiasing, there nonetheless are a number of effective techniques to reduce the impact of misinformation, and we pay special attention to these factors that aid in debiasing. We conclude by providing specific recommendations for practitioners to aid in the debunking of misinformation. These recommendations pertain to the ways in which corrections should be designed, structured, and applied in order to maximise impact. Grounded in cognitive psychological theory, these recommendations may help practitioners—including journalists, health professionals, educators, and science communicators—design effective misinformation retractions, educational tools, and public information campaigns. MISINFORMATION AND ITS DISCOUNTING -3 On August 4, 1961, a young woman gave birth to a healthy baby boy in a hospital at 1611 Bingham Street, Honolulu. That child, Barack Obama, later became the 44th President of the United States. Notwithstanding the incontrovertible evidence for this simple fact—from a Hawaiian birth certificate to birth announcements in the papers to the fact that a pregnant woman went into hospital and left it cradling a baby—a group known as “birthers” claimed during the first few years after Obama assumed office that the President was born outside the United States and therefore not eligible to assume the presidency. Even though the claims were met with skepticism by the media, polls at the time showed that a sizable proportion of the public believed these claims (Travis, 2010), including at one point a majority of Republican primary voters (Barr, 2011). In the United Kingdom, a 1998 study suggesting a link between a common childhood vaccine and autism generated considerable fear in the general public concerning the safety of the vaccine. The UK Department of Health and several other health organizations immediately pointed to the lack of evidence for such claims, and urged parents not to reject the vaccine. The media subsequently widely reported the failures to substantiate any of the original claims. Nonetheless, in 2002, about 20-25% of the public continued to believe in the vaccine-autism link, and a further 39-53% continued to believe there was equal evidence on both sides of the debate (Hargreaves, Lewis, & Speers, 2003). More worryingly still, even a substantial number of health professionals continued to believe the unsubstantiated claims (Petrovic, Roberts, & Ramsay, 2001). Ultimately, a significant conflict-of-interest emerged involving the first author of the misleading study, whereupon most co-authors distanced themselves from the study, the journal officially retracted the article, and the first author was eventually found guilty of misconduct, losing his license to practice medicine (Colgrove & Bayer, 2005; Larson et al., 2011). Another particularly well documented case of the persistence of mistaken beliefs despite extensive corrective efforts involves the decade-long deceptive advertising for Listerine mouthwash in the U.S. Advertising for Listerine had claimed for over 50 years that the product helped prevent or reduce the severity of colds and sore throats. After a long legal battle, this claim was found to be deceptive, and the U.S. Federal Trade Commission (FTC) mandated corrective advertising that explicitly withdrew the deceptive claims. The company ran a television ad campaign for 16 months during 1978-1980 retracting cold-related claims using a 5-second disclosure midway through 30-second TV spots. Notwithstanding a $10 million budget, the campaign was only moderately successful (Wilkie, McNeill, & Mazis, 1984). Using a cross-sectional comparison of representative samples at various points during the corrective campaign, a telephone survey by Armstrong, Gural, and Russ (1983) did find a MISINFORMATION AND ITS DISCOUNTING -4 significant reduction in consumers’ belief that Listerine could alleviate colds, but overall levels of acceptance of the false claim remained high. For example, 42% of Listerine users continued to believe that the product was still promoted as an effective cold remedy, and more than half of Listerine consumers (57%) rated the presumed medicinal effects of the product as a key attribute of their purchasing decision (compared to 15% of consumers of a competing product). In summarizing the results, Wilkie et al. (1984) suggested that the campaign was only partially effective, with important misperceptions persisting despite the corrective ad campaign. Those results underscore the difficulties of correcting widespread misinformation in society. These difficulties arise from two distinct factors: First, there are cognitive variables within each person which render misinformation “sticky. ” We focus primarily on those variables in this article. The second factor is purely pragmatic, and relates to the ability to reach the target audience. The Listerine real-life quasi-experiment is particularly informative in this regard because its effectiveness remained limited despite the availability of a fairly large budget to disseminate corrective information. What, then, causes the persistence of erroneous beliefs in sizable segments of the population? Assuming corrective information has been received, why does misinformation continue to influence people’s thinking despite clear retractions? The literature on these issues is extensive and complex, but it permits several reasonably clear conclusions which we present in the remainder of this article. Psychological science has much light to shed onto the cognitive processes with which individuals process, acquire, and update information. To foreshadow, we focus primarily on individual-level cognitive processes as they relate to misinformation. However, a discussion of the continued influence of misinformation cannot be complete without addressing the societal mechanisms that give rise to the persistence of false beliefs in large segments of the population. Thus, it is a matter of individual cognition to understand why one might reject evidence about President Obama’s place of birth; however, to understand why more than half of Republican primary voters expressed doubt about the President’s birth place (Barr, 2011) requires a consideration not only of why an individual clings to misinformation, but also how information—and especially false information—is disseminated through society. We therefore begin our analysis at the societal level: First, we highlight the societal costs of widespread misinformation, and then turn to the societal processes that permit its spread. 1 We use the term “misinformation” here to refer to any piece of information that is initially processed as valid but which is subsequently retracted or corrected. This is in contrast to the literature on so-called “post-event misinformation”, which has been reviewed extensively elsewhere (e.g., Ayers & Reder, 1998, Loftus, 2005) and has focused on the effects of suggestive and misleading information presented to event witnesses after the event. MISINFORMATION AND ITS DISCOUNTING -5 The Societal Cost of Misinformation It is a truism that a functioning democracy relies on an educated and well-informed populace (Kuklinski, Quirk, Jerit, Schwieder, & Rich, 2000). The processes by which people form their opinions and beliefs are thus of obvious public interest, in particular if major streams of beliefs persist that are in opposition to established facts. If a majority believes in something that is objectively incorrect, political and societal decisions will be made and accepted that may run counter to a society’s best interest; if an individual is misinformed, they will likewise make decisions for themselves and their families that may not be in their best interest and can have serious consequences. For example, following the unsubstantiated claims of a vaccination-autism link, many parents decided not to immunize their children, which has had dire consequences both for individuals and societies, with a marked increase in vaccine-preventable disease and hence preventable hospitalizations, deaths, and unnecessary expenditure of large amounts of money for follow-up research and public information campaigns to rectify the situation (Larson, Cooper, Eskola, Katz, & Ratzan, 2011; Poland & Spier, 2010; Ratzan, 2010). This reliance on misinformation differs from ignorance, defined here as the absence of relevant knowledge. Ignorance, too, can have obvious detrimental effects on decision making but, perhaps surprisingly, those effects may be less severe than those arising from reliance