As anti-Muslim rhetoric increases, American officials are cautioning that it could validate extremists’ perceptions that Americans are waging a war on Islam. Secretary of State John Kerry, for example, said Donald Trump’s statements “endanger national security” by handing ISIS and other terrorists a recruitment tool.

New research from the Kellogg School lends credence to this fear.

The research shows that feeling dehumanized by another group can lead you to dehumanize that group in return, which can increase support for aggressive actions against them. Meaning, if Americans think that Muslims see them as savages, Americans will be more likely to return the “favor,” perceiving Muslims to be savages. And both groups will be more likely to support aggressive acts—like drone strikes or torture—against the other.

It can create, says Kellogg’s Nour Kteily, “this vicious cycle where people are confirming the other side’s expectations of how [others] view them.”

“When they see you as animals, you tend to reply by seeing them as animals. When they see you as human, you tend to reply by seeing them as human.”

But the research also gives reason for hope.

When a group of people believes another group humanizes them, that first group is more likely to humanize the others in return. So, for example, if non-Muslim Americans reach out to Muslim neighbors to denounce hate speech against them, or if foreign Muslims voice their admiration of American democracy, the cycle could be broken.

“When they see you as animals, you tend to reply by seeing them as animals,” says Kteily, an assistant professor of management and organizations. “When they see you as human, you tend to reply by seeing them as human.”

The Vicious Cycle of Dehumanization

Previous research has shown that when we feel disliked by another group, we tend to respond in a variety of ways, sometimes becoming more uncomfortable around that group, and sometimes reciprocating by expressing dislike towards that group. But Kteily, and coauthors Gordon Hodson of Canada’s Brock University and Emile Bruneau of the University of Pennsylvania, wanted to get at a different aspect of intergroup conflicts: What happens when one group feels dehumanized by another?

Kteily and coauthors had previously demonstrated that Americans are willing to blatantly dehumanize other groups—Arabs or Mexican immigrants, for example—rating them as less evolved when asked to show where they fall on an Ascent of Man graphic. [Read more about this research here.]

This newer research builds upon that work. In a series of ten studies, the researchers asked Americans recruited online about Arabs and Muslims. They also asked Israelis about Palestinians, and Hungarians about ethnic Roma. Some studies led participants to believe that other groups dehumanized them, and others just gauged the participants’ existing beliefs about whether other groups dehumanized them without receiving specific prompts.

The distinction between mere dislike and actual dehumanization was measured by looking at the difference in responses to statements like “Arabs do not have positive attitudes towards Americans,” versus “Arabs think Americans are beasts,” as well as by seeing where participants ranked other groups on the Ascent of Man scale. Thus, the researchers were able to statistically distinguish dehumanization from dislike, both in terms of individuals’ expectations about how the other group perceived them as well as in terms of their own attitudes towards those groups.

In each study, the researchers showed that the more participants believed the other group dehumanized them, the more likely they were to dehumanize in return, over and above the effects of feeling disliked by that group.

Aggressive Actions

This cycle of dehumanization is of particular concern because the more you dehumanize another group, the more likely you are to condone aggressive or even violent actions against them.

“If you think about the way that Trump is talking, [Muslims] might feel that they’re perceived like animals,” Kteily says. “They might respond by seeing Americans as animals”—creating a cycle where Muslims act aggressively toward Americans, confirming to Americans that Muslims think they are animals, causing Americans to act aggressively, confirming to Muslims that Americans think they are animals. And so on and so forth.

The researchers demonstrated a link between feeling dehumanized and support for aggressive actions in a number of their studies. In one, they asked Americans about their feelings toward ISIS in the days after the January 2015 Charlie Hebdo attacks in Paris.

The more dehumanized a participant felt by ISIS, the more likely they were to dehumanize ISIS, and the more likely they were to support statements like, “To put an end to terrorist acts by ISIS, I think it is OK to use enhanced interrogation techniques.”

The researchers also looked at dehumanization in the context of the Iranian nuclear deal negotiations. They found that the amount a participant felt dehumanized by Iranians directly influenced how likely they were to sign a petition urging Congress to “examine military options against Iran.”

These aggressive acts need not be on the scale of international military initiatives. They can be more everyday occurrences.

Kteily and Bruneau wrote an op-ed in the Washington Post in September after 14-year-old Ahmed Mohamed was arrested for bringing a homemade clock to school. Dehumanizing perceptions of Muslims among some Americans may have contributed to this overreaction, they write.

“By dehumanizing members of certain groups, we see them as more threatening and aggressive,” they write. “This might help explain how an innocuous experiment became a menacing threat.”

For his part, Ahmed said of the arrest, “It made me feel like I wasn’t human.”

Humanizing

The final two of the researchers’ ten studies shows that the trend can be flipped on its head. When a group feels humanized, they humanize in return.

In one of these studies, one group of participants read a purportedly real article that supposedly summarized findings from a U.N. report on Muslims’ perceptions of Americans. These perceptions described Americans in humanizing terms, referring to them as being “culturally advanced” and “enlightened.” The rest of the participants did not read this article.

The two groups of participants—those who read the humanizing article and those who did not—ranked similarly in terms of prejudice against Muslims. But they varied in their level of dehumanization of Muslims: Those who read about Muslims’ humanizing perceptions of Americans ranked Muslims as more evolved on the Ascent of Man scale.

On a particularly encouraging note, the positive perceptions that were included in this pretend article were based on real research into Muslims’ attitudes toward Americans.

“There is a feeling of frustration amongst Muslim communities around the world about how they feel like they’re portrayed by people like Trump,” Kteily says. “At the same time, there’s also a lot of recognition of American accomplishments, and a great respect for many American institutions, which are, in many ways, humanizing perceptions.”