New MIT Sloan research finds Americans are more receptive to counter-partisan messages than previously thought

Party loyalty and partisan motivation may interfere less with Americans’ thinking than previously believed, MIT behavioral researchers Ben M. Tappin, Adam J. Berinsky, and David G. Rand report in new research published in the journal Nature Human Behaviour.

The study, which looked at how Democrats and Republicans react to persuasive messaging that doesn't align with their party leader’s position, challenges the view that party loyalty distorts how Americans process evidence and arguments.

“Our results are clear and unequivocal: Learning the in-party leader’s position on an issue certainly did influence partisans’ attitudes — but it did not cause the partisans to ignore or discount arguments and evidence that ran counter to the leader’s position,” said Rand, the Erwin H. Schell Professor and Professor of Management Science and Brain and Cognitive Sciences at the MIT Sloan School of Management.

Rather, respondents seemed to integrate the leader cues and the countervailing persuasive messages as “independent pieces of information” in determining whether they agreed or disagreed with various policy issues, he said.

Evidence versus cues from the left and right

The study was conducted in September 2021 and more than 5,000 American partisans — Republicans who voted for Donald Trump in 2020 or Democrats who voted for Joe Biden in 2020 — completed a survey spanning 24 policy issues including affirmative action, assisted suicide, the death penalty, estate tax, foreign aid, tariffs on Chinese imports and restrictions at the US border, among others.

In the study, respondents gave their opinions on several of the policy issues on a seven-point scale running from “strongly disagree” to “strongly agree.” Before giving their opinion, they were either shown a cue about the position of their party leader on the issue; a message with arguments and evidence that went against their leader’s position; both the cue and the message; or neither the cue nor the message.  

For instance, some respondents were asked whether the military should be allowed to use techniques such as waterboarding to gain information from a suspected terrorist. For those respondents who were Trump-voting Republicans and were assigned to see a persuasive message, they then read a paragraph that cited a 2014 Senate report in which the CIA concluded that such techniques rarely provided reliable intelligence or got suspects to cooperate. The message concluded, “The question then becomes: is it worth violating international law by torturing people — who are effectively innocent until proven guilty by a jury — for mainly useless information? The answer is No. America is better than that.” 

This particular example contradicted Trump’s position that such techniques are justified. In 2017, Trump said he believes waterboarding works, stating, "We have to fight fire with fire." Critically, informing respondents that Trump supports waterboarding did not cause them to ignore or discount the persuasive message. 

In fact, exposure to the message caused respondents to shift their attitudes towards the message, and this attitude change was a similar size even when they knew that their favored party leader took the opposite position. This pattern of results was consistent across a wide range of policy issues, as well as across demographic groups and different types of partisan cues.

“We found no evidence that countervailing cues from favored party leaders meaningfully diminished partisans’ receptivity to persuasive arguments and evidence — in contrast to what one would expect if party loyalty distorted partisans’ information processing,” said Tappin, a postdoctoral researcher at MIT Sloan and lead author on the study.

“These findings contrast with the notion that party loyalty overrides people’s values and interferes with, distorts, or otherwise limits their processing of counter-partisan messages,” added Rand. “If such interference and distortion does occur, our findings suggest that it is relatively minor, uncommon or may be avoided with ease.”

Not blinded by party loyalty

The authors noted that their results highlight a distinction between two key questions in political psychology: to what extent do party cues influence people’s attitudes, and why do they exert their influence? While there is relative consensus on the first question — party cues reliably influence people’s attitudes, sometimes by a great deal — the second question remains unsettled. Their new paper found that party cues are influential not because of blind loyalty to the party leader, but rather because they contain useful information (which is then weighed against countervailing information).

The range of issues and arguments in the latest study was larger than previous work but, by necessity, still limited; the authors write that different persuasive messages containing alternate arguments and evidence might have produced different results. They also point out that in their study the party leaders’ positions were not supported by justifications and talking points from the partisan media, as they often are in the real world. 

The researchers believe that the messages might have worked by appealing to people’s values and identities other than those of their party — and that party loyalty could not override the relevance of these other factors. “People have various identities and motivations that are not reducible to their party,” Tappin concluded.