A new study led by an international team of scientists has investigated how people evaluate whether information is true or false, and how this evaluation is affected by source credibility.
For the purposes of the study, published today in Royal Society Open Science, participants rated their belief in statements from the campaign trail of Donald Trump— described by many as perhaps the most polarising political figure of recent times.
Professor Stephan Lewandowsky from the School of Experimental Psychology and the Cabot Institute at the University of Bristol was one of the researchers who led the project.
He said: "Individuals have limited time to comprehend complex topics and people may use perceived credibility of political figures as a shortcut when evaluating whether information is true or false.
"Even in ideal circumstances false information continues to influence memory and reasoning even after credible corrections. We focused upon the impact of source credibility on the assessment of information veracity, and the extent that false information could be corrected."
Using statements from the campaign trail of Donald Trump, participants rated their belief in statements either directly attributed to Trump ("the MMR vaccine causes autism") or unattributed statements ("vaccines cause autism – how much do you believe this statement to be true").
After rating the extent to which they believed each item on a 0-10 scale, participants received an explanation as to whether the items were true or false. Participants re-rated their belief in the items either immediately or after a one week delay.
It was found that participants’ opinion of Donald Trump did indeed influence how valid they initially perceived information to be. If information was attributed to Trump, Republican Trump supporters believed it more than if it was presented without attribution, whereas the opposite was true for Democrats.
Additionally, it was found that information that came from Trump was less accurately recalled than unattributed information even after credible fact-check explanations were provided.
Finally, although Trump supporters reduced their belief in misinformation items following corrections, they did not change their voting preferences.
People thus use political figures as a heuristic to guide evaluation of what is true or false, yet do not necessarily insist on veracity as a prerequisite for supporting political candidates. This study suggests that spreading misinformation did not hinder President Trump’s candidacy, as even if misinformation was exposed, this did not reduce voting preferences or positive feelings.
Professor Lewandowsky added: "The term ’post-truth’ was virtually unknown prior to 2016, and it has shot to prominence in the media during the last 12 months as political discourse has become more and more dissociated from evidence and facts.
"During the US Presidential campaign last year, independent fact checkers judged nearly three quarters of Donald Trump’s statements to be misleading or outright false.
"Since he assumed office, President Trump has made 140 false or misleading claims, suggesting that ‘post-truth’ politics is poised to become ’normal.’
"Our study was conducted during the primaries and we found that even though people of all stripes—including Trump supporters—are sensitive to corrections and believed Mr Trump’s false statements less after they had been corrected, that shift in belief was not associated with a reduction in feelings towards Mr Trump or the intention to vote for him among his supporters. People seem to be unconcerned with the factual status of politicians’ utterances."