Warnings of misinformation are an increasingly common feature of American political communication. The spread of misleading news through social media platforms during the 2016 U.S. election season provoked widespread discussions of and warnings about political misinformation (Allcott and Gentzkow 2017; Frankovic 2016; Guess et al. 2018a, b; Nyhan 2019; Silverman 2016; Silverman et al. 2016; Silverman and Singer-Vine 2016). In the months prior to the 2016 general election, one in four Americans read a fact-checking article from a national fact-checking website (Guess et al. 2018b, p. 10). Fact-checking organization growth accelerated in the early 2000s, and the number of fact-checking outlets continues to increase in the U.S. and around the world (Graves 2016; Graves et al. 2016; Spivak 2010; Stencel 2019). Due to the increased salience of political misinformation and rise of fact-checking organizations, people often encounter warnings regarding misinformation, but the quality and veracity of these warnings can vary considerably. In this article, we evaluate how invalid warnings of misinformation can lead people to distrust the information’s source, cause people to discard accurate information, and ultimately impede memory.

Valid warnings of misinformation tend to originate from professional third-party organizations, target information that is actually misleading, and reduce the spread and acceptance of misinformation. For example, FactCheck.org, PolitiFact, and the Washington Post’s Fact Checker are all organizations that investigate the veracity of claims made by political figures and news organizations, operate year-round, and view themselves as a distinct professional cohort within journalism guided by rules and norms (Graves 2016). Warnings originating from these organizations tend to be precise and issued neutrally.Footnote 1 Other institutions, such as Facebook, also devote resources to counteract false news through critical changes to algorithms and various policies. Working to retain users’ trust and confidence in their site, Facebook’s warnings of misinformation often seek to correctly identify and reduce the spread of actual misinformation, although these efforts have recently excluded the direct speech of politicians (Funke 2019; Kang 2019; Mosseri 2017).Footnote 2 Irrespective of the source of a warning, the main criterion of whether or not a warning is valid is if it correctly targets misinformation and efficiently counters the effects of misinformation.

In contrast, less valid or invalid misinformation warnings are biased and inefficient. First, warnings of misinformation are biased when they target factual information rather than misinformation. Bias may be inadvertent but some misinformation warnings are intentionally designed to discredit information. Strategic elites may issue warnings of misinformation against news that is factually correct but unfavorable. Recently, the term “fake news,” has been used by politicians and pundits around the world to discount news reports and organizations they find disagreeable in order to control political news and shape public opinion (Tandoc Jr. et al. 2018; Wardle and Derakhshan 2017; Wong 2019).

Second, warnings of misinformation may be less valid because their effects are inefficient and imprecise. In the U.S., President Donald Trump frequently uses the term “fake news” in tweets referencing the mainstream news media, especially in reaction to critical coverage or investigative reporting (Sugars 2019). These and other warnings of misinformation employed by President Trump are often so broadly construed that they could potentially target both misleading and accurate news (Grynbaum 2019a, b). For example, on March 28, 2019, President Donald Trump wrote “The Fake News Media is going Crazy! They are suffering a major “breakdown,” have ZERO credibility or respect, & must be thinking about going legit. I have learned to live with Fake News, which has never been more corrupt than it is right now. Someday, I will tell you the secret!”Footnote 3

While clumsy warnings may be able to counter misinformation, they are less valid because they often incur high unintended casualties. For example, in contrast to warnings that identify specific misleading facts, Clayton et al. (2019) find that general warnings of misinformation shown to people before news exposure reduce the perceived accuracy of both real and false news headlines. Mistrust and rejection of news is beneficial when that news is misleading, but when the mistrust and rejection spills over to real news, the potential drawbacks of misinformation warnings become apparent.

Pennycook and Rand (2017) also uncover other drawbacks of misinformation warnings. An “implied truth effect” emerges when some, but not all, false stories are tagged as misinformation. Those false stories which fail to get tagged are considered validated and seen as more accurate. Even legitimate misinformation warnings, if not fully deployed, can enhance the effects of misinformation in the larger system. Sophisticated organizations seek to employ nuanced and specific fact-checking techniques, but less valid warnings of misinformation continue to be used by both political elites and in broad public conversations on misinformation and the news media. Consequently, it is very important that we continue to investigate both the positive and negative effects of misinformation warnings in the realm of news media and political communications.

In this study, we investigate the potentially negative side effects of invalid, retrospectiveFootnote 4 misinformation warnings. To do this, we replicate and expand a relatively understudied area of research traditionally applied to the area of eyewitness testimony in the field of social cognition. Specifically, we investigate the tainted truth effect, which proposes that misdirected warnings of post-event misinformation can disadvantage memory of an original event by discrediting factual information and causing it to be discarded at the time of memory assessment (Echterhoff et al. 2007; Szpitalak and Polczyk 2011).

Drawing on Szpitalak and Polczyk’s (2011) study on the tainted truth effect, we replicate and extend their three primary research questions to a political context. We first ask, after viewing a political event, how does later exposure to information and misinformation in a news article describing the event alter individuals’ memory and recognition of the details from the original event? Second, when individuals are retrospectively exposed to a valid warning that the news article contained misinformation, are they able to discard the misinformation and remember the correct original event information? Third, do people discard accurate data when exposed to an invalid warning of misinformation? While all three research questions work together to build a picture of individual memory and information processing, the third question regarding the potential drawbacks of misinformation warnings, formally referred to as the tainted truth effect, is the focus of our research. Finally, building on Szpitalak and Polczyk’s three primary questions, we also consider the mechanisms and nuances of misinformation warnings, that is, how these warnings influence the credibility of the warning’s target and the certainty of memory.

From these questions, we derive a series of particular expectations. First, in the absence of a misinformation warning, we expect that individuals’ memories of the original event will be strongly influenced by a post-event description, that is, a related news article. Receiving misleading (or accurate) post-event descriptions in a news article will decrease (or increase) respondents’ ability to recognize original event details.

Hypothesis 1a (Misinformation Effect)

Exposure to misleading information in a post-event description is expected to reduce memory recognition of the original event.

Hypotheses 1b (Information Effect)

Exposure to accurate information in the post-event description is expected to increase the memory recognition of the original event details.

Second, respondents who are exposed to misinformation in the news article but are later warned about misleading information should recognize original event details and misinformation better than respondents who were exposed to misinformation without a warning.

Hypothesis 2a (Warning and the Memory Performance)

Exposure to a valid retrospective misinformation warning will increase the ability to correctly recognize original event details.

Hypothesis 2b (Warning and the Misinformation Recognition)

Exposure to a valid retrospective misinformation warning will reduce the incorrect recognition of misinformation as original event information.

Third, warnings of misinformation are expected to taint all information that is associated with the news article. Therefore, misinformation warnings, even when completely invalid (in the case where no misinformation is in the post-event description), should lead individuals to also reject accurate information that is associated with the news article and result in reduced memory accuracy compared to individuals who are not warned.

Hypothesis 3 (Tainted Truth Effect)

Exposure to an invalid or imprecise retrospective misinformation warning will reduce the ability to correctly recognize original event details.

Finally, we expect trust to be fundamentally damaged by misinformation warnings. First, when warned of misinformation, individuals should be less trusting of their own memory and feel more uncertain about their responses. Second, warnings of misinformation should erode trust in the origins of the information and should lead people to view the news source as less credible.

Hypothesis 4a (Warning and Information Uncertainty)

Exposure to a misinformation warning will increase memory uncertainty.

Hypothesis 4b (Perceived Credibility)

Exposure to a misinformation warning will reduce the perceived credibility of the post-event description that is targeted by the warning.

We find evidence that retrospective, invalid misinformation warnings taint news and lead individuals to view the news as less credible. Increased skepticism produced by invalid misinformation warnings leads individuals to discard information that was in fact accurate, as predicted by the tainted truth hypothesis, and these invalid warnings are also associated with more memory uncertainty. In addition to the tainted truth effect, we find valid warnings help people reject misleading information, but we do not find that individuals are able to fully overcome the effect of misinformation and remember all of the correct information. Our findings generally align with the few studies that have previously examined this topic. However, our use of a diverse subject pool and political context reveals more muted effects and insights into the influence of misinformation warnings on memory, memory uncertainty, and the perceived credibility of news that has been discounted by misinformation warnings.