This blog post, written by Dr. Terry Flynn and Tim Li, is based on a research paper by Ullrich K. H. Ecker, Ph.D., University of Western Australia; Stephan Lewandowsky, University of Bristol; 

Key Findings

  • Providing more evidence against an ambiguous claim can be more effective at reducing misperceptions, but only if the evidence is relevant.
  • A larger number of counterarguments (four to six) may be equally or more effective than a smaller number at reducing belief in an ambiguous claim, depending on the strength of the counterarguments.

Implications for Public Relations

Communicators are often advised to be concise and focus on fewer key points when trying to refute misinformation. The findings from this study however suggest that presenting more evidence against a claim can actually be more effective at reducing belief in it, as long as the evidence is relevant. Public relations professionals should provide as many counterarguments as possible and be clear and concise by presenting them in an easily accessible manner and removing irrelevant information.


Previous research in the area of persuasion suggests that presenting too many arguments can be counterproductive to the end-goal of changing someone’s attitude or belief. Excessive information may be too difficult to process in a timely fashion and be ignored. It may also be met with skepticism or reactance, especially if it creates the impression of bias, which may result in a stronger belief in the opposite direction. Ecker and colleagues assessed the impact of argument quantity in the context of misinformation, asking if countering false claims is better accomplished with a less-is-more approach or a more-is-more approach.

In a series of three experiments, the authors presented participants with ambiguous claims and various quantities of strong, weak, or irrelevant counterarguments. Compared to a small number of counterarguments (two), a larger number of counterarguments (four to six) was equally as or more effective at reducing belief in an ambiguous claim, depending on the strength of the counterarguments. Irrelevant counterarguments, those that are tangentially related to the general topic but do not address the issue at hand, did not contribute to belief reduction. However their inclusion also did not appear to hinder the effect of relevant counterarguments.  There was also no evidence of an overload backfire effect, where the increased number of counterarguments leads to stronger claim belief.

These findings suggest that providing more evidence against a claim leads to stronger belief reduction, as long as it is relevant. More information helps individuals understand an issue and revise their beliefs accordingly. However, a more-is-more approach may not always be effective or appropriate, like when claims are aligned with someone’s worldview or are internalized as part of their identity. Attempts to refute those claims are usually met with counterarguing to protect against what is viewed as a threat to sense of self, which may further entrench misinformed beliefs.

Blog post compiled by Dr. Terry Flynn and Tim Li of McMaster University.


Ecker, Ullrich K. H., Lewandowsky, Stephan, Jayawardana, Kalpana, & Mladenovic, A. (2018). Refutations of Equivocal Claims: No Evidence for an Ironic Effect of Counterargument Number. Journal of Applied Research in Memory and Cognition, (8)1, 98-107.

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Heidy Modarelli handles Growth & Marketing for IPR. She has previously written for Entrepreneur, TechCrunch, The Next Web, and VentureBeat.
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