Extremely rare but vivid threats often loom large in the human mind. Most people wildly overestimate the number of shark attacks or plane crashes for example. Even when reassured of our statistical safety, many of us still tense up on an airplane runway or while swimming in the ocean.

Psychologists who study human decision-making understand this tendency well. We all contend with a proverbial catalog of cognitive biases — systematic errors in thinking that influence our decisions. Common examples include confirmation bias, which means we seek out evidence that confirms our beliefs and ignore information that challenges them; the sunk cost fallacy, where we continue to do something that is no longer worth the effort simply because we’ve already invested in it; and the availability heuristic, where we overestimate the probability of events based on how easily they come to mind.

But one cognitive bias that scientists are just starting to understand is the psychology of overestimating perceived threat. This error in our thinking isn’t just a curiosity for psychologists, however. In the hands of President Trump, it’s become a potent political tool. To fight back, we need to understand how he weaponizes a cognitive bug in our brains.

Trump uses his unfiltered rhetoric to hype up several categories of visceral but remote threats, including MS-13 gang members and Islamic State jihadis. His favorite go-to, by far, is illegal immigration. From his opening campaign speech in 2015 about “rapists” crossing the border to his White House broadsides against immigrants from poor countries, Trump has worked assiduously to magnify and distort the perceived threat from foreigners.


Social scientists have amassed evidence that when people experience threat — either from Mother Nature (think disasters) or human-made conflict (think invasions) — they begin to “tighten.” In physical terms, they tense their muscles, ready for action. In political terms, they begin to crave order and security, often rallying around autocratic leaders who promise to restore safety — which is precisely the psychology leaders like Trump want to produce.

Groups facing fewer threats have evolved to have looser norms. They celebrate creativity, permissiveness and inclusion. The interplay of this tight-loose pattern forms our social DNA; it’s found across history and around the globe. Japan, for example, which has experienced chronic natural disasters and conflict, tends to veer tighter than New Zealand, which has experienced fewer threats. This primal response makes good evolutionary sense — when a threat is real, strong rules and leaders can create cohesion in the face of chaos.

The problem is that even threats that aren’t real but are wildly exaggerated and biased produce the same psychological tightening and hunger for autocratic leaders. In a new study building on ongoing immigration research, we’ve found that misperceptions among Trump’s base about the number of immigrants living in the country illegally are an important driver of their support for him. The hyped-up threat generates political tail winds for him when he proudly flaunts extreme rhetoric about immigrant “rapists” and fires off xenophobic tweets.

For a base that feels unduly threatened, Trump’s bombast satiates a psychologically predictable zeal for social order.


In July, we surveyed more than a thousand U.S.-born citizens to see if there was a relationship between their estimates of the number of immigrants living in the U.S. illegally, their feelings of threat and desire for tight rules, and their voting intentions.

We found that people tend to overestimate the percentage of people in living in the U.S. who immigrated illegally, and these estimations vary across party lines. Republicans estimated that a whopping 18% of the U.S. population is made up of people who are here illegally, while the Democrats estimated that statistic to be less than 13% on average. (The actual figure, according to a 2017 Pew Research Center study, is closer to 3%.)

These misperceptions have important psychological consequences. People who overestimated the number of people illegally living in the U.S. were more likely to perceive immigrants as a threat, despite all the evidence showing that immigrants generally commit less crime than native-born Americans, are beneficial to the U.S. economy and boost innovation.

The perceptions, in turn, were related to the desire for tighter rules and criminal punishments — and plans to vote for Trump in 2020. The data help us understand why Trump’s anti-immigrant rhetoric is so appealing to his followers.


To counteract the pull of Trump’s rhetoric, the roots of the problem must be addressed. By purposely making statements meant to incite reaction, Trump continues to fuel the feeling of threat — and the primal desire for order — among his base.

What we sorely need are information campaigns to help voters grasp how many immigrants actually reside in the U.S. illegally and what impact they have on American society. The truth could go a long way toward nullifying Trump’s most potent campaign weapon: his ability to prey on our unfounded fears.

Michele Gelfand is a distinguished professor of psychology at the University of Maryland and Emmy Denison is the manager of the Culture Lab at the University of Maryland.