There has been much speculation about what makes Donald Trump’s supporters tick. But new psychology research suggests outside observers may be prone to error when trying to understand their motivations. The study, published in the journal Cognition, found that people tend to overestimate the importance of attributes with extreme values.

“People frequently make assumptions about why others make the choices they do. Sometimes it’s trivial and all in good fun — for instance, guessing why someone chose to wear a wild outfit, or wondering what could have ever possessed them to date the person they did. But sometimes it’s far more consequential,” said study author Kate Barasz, a professor at IESE Business School.

“After the 2016 U.S. presidential elections, we watched as much of the nation fixated on the question of what had possibly motivated Trump voters. There was rampant speculation that all Trump voters had been disproportionately compelled by his immigration policy, and therefore all must be racist xenophobes.”

“We wondered whether this generalized inference was accurate — or whether (all political leanings aside), we may be seeing a more basic cognitive heuristic at work. So we tested it, in both a political and non-political context.”

In seven studies, which included more than 2,000 participants, the researchers examined the potential cognitive process that may have shaped inferences about Trump voters. They found that non-Trump voters tended to believe that Trump’s most extreme positions were the reason people voted for him.

The researchers found that Clinton voters perceived Trump’s immigration policy to have been more important to his supporters than Trump voters reported it to have been.

This tendency to overemphasize the extreme was found for non-political issues as well. People who viewed the weather in Ft. Lauderdale as more extreme were more likely to assume that people moved there because of the extreme weather.

“Sometimes other people choose things that have a really extreme feature — think reading glasses in a fluorescent shade of green, or a city with exceptionally great weather, or a presidential candidate with an unusually extreme stance on immigration. The more extreme the feature, the easier it is — and the more confident and likely we are — to assume we know what motivated that choice,” Barasz told PsyPost.

“But that isn’t always the case: sometimes extreme features cause us to have a blind spot in our judgment. We infer more than we can and should, and become insensitive to other factors that also (or instead) could have motivated the choice.”

The study has some limitations — as all research does.

“Our research investigated how observers make inferences about other people’s choices; we don’t focus on the decision-maker’s perspective, so we can’t answer questions like when and why people are likely to be motivated by extreme features,” Barasz explained.

“In addition, we highlight how observers’ automatic inferences can — but do not always — lead to erroneous assumptions. Certainly some decision-makers are, indeed, uniquely motivated by extreme features; however, we don’t know who these decision-makers are. Nor do we have data about the frequency or likelihood of the error.”

“Our major conclusion is that observers are prone to over-inferring when they encounter extreme features,” Barasz added. “Accordingly, we offer that people could be more aware of this heuristic’s existence — and its possibility for error.”

The study, “I know why you voted for Trump: (Over)inferring motives based on choice“, was Kate Barasz, Tami Kim, and Ioannis Evangelidis.