When Do People Label Attackers as Terrorists versus Mentally Ill?
Skip to content
Social Impact Policy Mar 1, 2018

When Do People Label Attackers as Terrorists versus Mentally Ill?

New research shows that people’s assumptions go beyond stereotypes.

Terrorism vs. mental illness as a reason for violence

Yevgenia Nayberg

Based on the research of

Masi Noor

Nour Kteily

Birte Siem

Agostino Mazziotta

It is a sadly familiar scenario: a lone attacker commits a horrendous act of violence. In the immediate aftermath, the motive is unclear. Yet many people are quick to conclude he must be mentally ill; others just as quickly assume he is a terrorist.

Kellogg’s Nour Kteily wanted to understand the psychological underpinnings of this stark divide.

In a series of three experiments—two of which involved surveying participants immediately following a violent attack—Kteily and coauthors conclude that the driving force for this divide goes beyond stereotypes about terrorists. Instead, people are driven by a desire to protect their own views of the world and of the groups with which they associate themselves.

If a person who shares, say, our partisan beliefs or religion commits a heinous act, our instinct is to explain that away, Kteily says. Attributing violence to mental illness is one way to do that when there is no obvious motive.

But, the research shows, even after a motive becomes clear, people are still inclined to find ways to distance themselves from an in-group perpetrator.

“There is a desire, conscious or unconscious, to distance your group from nasty behavior, a desire to protect your cherished identity,” says Kteily, an assistant professor of management and organizations.

The consequences of this phenomenon go beyond simply reinforcing one’s own beliefs. When participants assumed a perpetrator was mentally ill, they were more likely to endorse a lenient punishment. The opposite was true when participants deemed the perpetrator a terrorist.

Motivated Reasoning

The backdrop for these findings is our increasingly partisan and polarized world.

“We’re getting more ideologically divided,” Kteily says. “So understanding the processes that lead to or that influence how we process information is incredibly important.”

Kteily and coauthors, Masi Noor, of Keele University in the UK, and Birte Siem and Agostino Mazziotta, both of FernUniversität in Germany, began with an established psychological concept called motivated reasoning.

“People will fill in the blanks with things that confirm their existing beliefs.”

People engage in motivated reasoning to lessen discomfort with an idea. For example, parents generally believe their children are good people. So when faced with the uncomfortable fact that their child started a schoolyard fight, parents may be motivated to explain away that reality by insisting that the other kid started it.

This motivation extends beyond our family to larger groups—both demographic groups like race or religion, and partisan groups that we voluntarily join.

Mental Illness versus Terrorism

The researchers’ first two studies tested whether people’s partisan beliefs predicted whether they would label a violent attacker as mentally ill or a terrorist.

It is jarring when someone from your group commits a violent act, the researchers reasoned. An easy way to protect your positive beliefs about your group is to blame the violent behavior on mental illness. After all, if people are not in control of their faculties, they—and by extension the group you both belong to—bear less culpability for their actions. On the other hand, if someone from a different group commits the same action, you will be more willing to attribute the violence to terrorism.

The first study was conducted on the day of the Brexit vote in Britain in 2016. A week earlier, a British man named Thomas Mair murdered Jo Cox, a Member of Parliament who was a strong supporter of the “Remain” campaign that advocated staying in the European Union.

The researchers quickly put together their study. They surveyed roughly 200 British participants online about their partisan feelings on the Brexit vote and about Mair’s motivation in stabbing Cox.

Importantly, on the day of the Brexit vote, Mair’s motives remained unclear.

Participants who supported the “Leave” campaign, and thus could see themselves being grouped with Mair if his motivations ended up being political, were more likely to say that Mair was mentally ill than a terrorist. Conversely, those who identified as “Remain” supporters—and thus would be less likely to find themselves in the same partisan group as Mair—tended to label him a terrorist.

“Any time there’s ambiguity about someone’s motives, that allows room for people to bring their own perspectives to bear on it,” Kteily says. “People will fill in the blanks with things that confirm their existing beliefs.”

A second study showed a similar pattern. German participants were surveyed immediately after a Syrian refugee injured 15 people at a German festival in 2016. Participants who identified themselves as pro-immigration were more likely to say the perpetrator was mentally ill. Those who self-identified as anti-immigration were more likely to call the refugee a terrorist.

Distancing the Attacker

Next, the researchers tested what happens when a perpetrator’s motive is clear. If people cannot attribute violent behavior to mental illness, will they find other ways to protect their own beliefs and cherished social identities?

These findings indicate that stereotypes are not the only force at work when someone is labeled either mentally ill or a terrorist.

The researchers surveyed about 500 Americans online. First, they assessed how strongly participants identified themselves with America through questions such as, “Being American is an important part of how I see myself.”

Next participants read about “Mr. A,” a college student arrested after brandishing a rifle and yelling at passersby. Some participants read that Mr. A had a history of heavy involvement in political gatherings; others read that he was bipolar; a third group got no information about his background.

Participants were then asked questions about Mr. A, including whether his parents were likely born in the U.S. and whether he was likely Christian, Jewish, Muslim, or atheist. The researchers wondered whether participants would distance themselves from Mr. A by saying he had foreign-born parents or assuming he belonged to a minority religion, which would allow them to protect their own sense of American-ness.

“Yeah, maybe this person is American,” Kteily says of their motivated reasoning. “But he isn’t really American. He’s not really one of us.”

Indeed, those who read about Mr. A’s political activities were more likely to distance themselves from him compared to those who thought he was mentally ill.

But there was further nuance to this result: It occurred most clearly when participants highly identified as American and therefore presumably cared more about protecting the American identity. When participants had a low level of American identification, they did not distance themselves more from the politically motivated Mr. A than from the mentally ill one.

These findings also indicate that stereotypes are not the only force at work when someone is labeled either mentally ill or a terrorist, Kteily explains.

One could imagine that participants labeled Mr. A a Muslim when they learned he was politically motivated not because they wanted to distance him from their group, but because they stereotypically associated Islam with political violence.

However, the findings suggest this was not the case. Participants who strongly identified as American would presumably not have been any more or less exposed to stereotypes of Muslims being terrorists than participants who weakly identified as Americans. Yet the results differed between these two groups in how likely they were to assume Mr. A was Muslim.

The results also highlight why ascribing political versus mental-health motives to violent attackers matters: participants who believed Mr. A was politically motivated advocated for harsher punishment than those who thought he was mentally ill.

Growing Partisanship

This desire to protect one’s own group may help explain how one person’s terrorist is another’s mentally troubled perpetrator. But it does not make the discussions around these events any easier, Kteily says—especially as we dig in deeper and deeper into our respective partisan camps.

Kteily, who discussed his research in the week after the Parkland, Florida school shooting, referenced the heated debates about gun control that followed.

“People are bringing to bear information that fits preexisting beliefs. That’s part of why the debate becomes so fraught,” he says. “Any given set of data can be chopped and served up differently, and people do that in systematic ways that align with their partisan identity. We’re not unbiased consumers of information. Rather, we go looking within information to find what we already believe.”

Featured Faculty

Professor of Management & Organizations

About the Writer
Emily Stone is the senior research editor at Kellogg Insight.
About the Research
Noor, Masi, Nour Kteily, Birte Siem, and Agostino Mazziotta. In press. “’Terrorist' or 'Mentally Ill': Motivated Biases Rooted in Partisanship Shape Attributions.” Social Psychological and Personality Science.
Most Popular This Week
  1. 3 Things to Keep in Mind When Delivering Negative Feedback
    First, understand the purpose of the conversation, which is trickier than it sounds.
  2. Podcast: Workers Are Stressed Out. Here’s How Leaders Can Help.
    On this episode of The Insightful Leader: You can’t always control what happens at work. But reframing setbacks, and instituting some serious calendar discipline, can go a long way toward reducing stress.
  3. What Went Wrong at Silicon Valley Bank?
    And how can it be avoided next time? A new analysis sheds light on vulnerabilities within the U.S. banking industry.
    People visit a bank
  4. How Are Black–White Biracial People Perceived in Terms of Race?
    Understanding the answer—and why black and white Americans may percieve biracial people differently—is increasingly important in a multiracial society.
    How are biracial people perceived in terms of race
  5. Will AI Eventually Replace Doctors?
    Maybe not entirely. But the doctor–patient relationship is likely to change dramatically.
    doctors offices in small nodules
  6. Leaders, Don’t Be Afraid to Admit Your Flaws
    We prefer to work for people who can make themselves vulnerable, a new study finds. But there are limits.
    person removes mask to show less happy face
  7. Which Form of Government Is Best?
    Democracies may not outlast dictatorships, but they adapt better.
    Is democracy the best form of government?
  8. What Went Wrong at AIG?
    Unpacking the insurance giant's collapse during the 2008 financial crisis.
    What went wrong during the AIG financial crisis?
  9. What Happens to Worker Productivity after a Minimum Wage Increase?
    A pay raise boosts productivity for some—but the impact on the bottom line is more complicated.
    employees unload pallets from a truck using hand carts
  10. At Their Best, Self-Learning Algorithms Can Be a “Win-Win-Win”
    Lyft is using ”reinforcement learning” to match customers to drivers—leading to higher profits for the company, more work for drivers, and happier customers.
    person waiting for rideshare on roads paved with computing code
  11. When You’re Hot, You’re Hot: Career Successes Come in Clusters
    Bursts of brilliance happen for almost everyone. Explore the “hot streaks” of thousands of directors, artists and scientists in our graphic.
    An artist has a hot streak in her career.
  12. Why Do Some People Succeed after Failing, While Others Continue to Flounder?
    A new study dispels some of the mystery behind success after failure.
    Scientists build a staircase from paper
  13. Immigrants to the U.S. Create More Jobs than They Take
    A new study finds that immigrants are far more likely to found companies—both large and small—than native-born Americans.
    Immigrant CEO welcomes new hires
  14. Take 5: Tips for Widening—and Improving—Your Candidate Pool
    Common biases can cause companies to overlook a wealth of top talent.
  15. Why Well-Meaning NGOs Sometimes Do More Harm than Good
    Studies of aid groups in Ghana and Uganda show why it’s so important to coordinate with local governments and institutions.
    To succeed, foreign aid and health programs need buy-in and coordination with local partners.
  16. How Has Marketing Changed over the Past Half-Century?
    Phil Kotler’s groundbreaking textbook came out 55 years ago. Sixteen editions later, he and coauthor Alexander Chernev discuss how big data, social media, and purpose-driven branding are moving the field forward.
    people in 1967 and 2022 react to advertising
  17. How Peer Pressure Can Lead Teens to Underachieve—Even in Schools Where It’s “Cool to Be Smart”
    New research offers lessons for administrators hoping to improve student performance.
    Eager student raises hand while other student hesitates.
  18. How Much Do Campaign Ads Matter?
    Tone is key, according to new research, which found that a change in TV ad strategy could have altered the results of the 2000 presidential election.
    Political advertisements on television next to polling place
  19. Take 5: How Fear Influences Our Decisions
    Our anxieties about the future can have surprising implications for our health, our family lives, and our careers.
    A CEO's risk aversion encourages underperformance.
More in Social Impact