People embrace in front of a memorial outside Tree of Life synagogue on Sunday after a shooting there left 11 people dead in the Squirrel Hill neighborhood of Pittsburgh. (Brendan Smialowski/AFP/Getty Images)

Should Robert Bowers, the man who allegedly killed 11 worshipers at a synagogue in Pittsburgh, be called a terrorist? News reports suggest that he expressed extreme anti-Semitic and anti-immigrant views on social media platforms, claiming that Jews were committing genocide against white people by encouraging a migrant “invasion” from Central America.

In other words, the shooting may have been motivated by an extreme ideology, one of the criteria often used in definitions of terrorism (see the FBI terrorism definition here).

Georgetown professor Daniel Byman argues that it is “probably right” to call Bowers a terrorist but notes that public officials and the media often do not know what to call acts of violence by domestic extremists. Many observers voiced similar ambivalence about what to call Dylann Roof, the self-declared white supremacist who killed nine African American worshipers at the historic Emanuel African Methodist Episcopal Church in downtown Charleston, S.C., in 2015.

But what if Bowers was an Islamist militant instead of an alleged white supremacist? Would the terrorism label be readily used? In a forthcoming article with my colleague Vito D’Orazio, we find that the answer is likely “yes.”

Here’s how we did our research

We recruited 1,198 U.S.-based participants in April 2016 through Amazon’s Mechanical Turk service and conducted an experiment in which we presented subjects with a (fictional) news story describing a foiled shooting attempt. Participants were asked to describe the details of the story and label the type of violence reported from options that included terrorism and mass shooting, along with other labels such as individual homicide, gang violence and “unknown.” (Amazon.com founder and CEO Jeffrey P. Bezos owns The Washington Post.)

We divided participants into six groups of roughly 200 participants, each of which received slightly different stories. In the control group, we do not mention the suspect’s name or ethnicity. In another group, we describe the failed shooter as being white, while a third group is told he’s Arab American. A fourth group was told that the white shooter belongs to a white-supremacist group; a fifth that the Arab American shooter belongs to an Islamist extremist group; and a sixth that a person of unidentified ethnicity belongs to an unspecified extremist organization.

The results are statistically significant and striking. Relative to the control, the Arab suspect was 18 percentage points more likely to be called a terrorist. Conversely, there was no statistical difference between how participants labeled the white suspect and the control group’s unidentified suspect.

While belonging to any militant organization raises the odds of labeling an act of violence as terrorism, the ideology of the group matters a lot. Only 9.5 percent of respondents called the white supremacist a terrorist, while 58 percent did so for the Islamist extremist. Indeed, compared with those told that the suspect “has ties to an [unspecified] extremist group,” participants who were told the suspect belonged to a white-supremacist organization actually reduced the odds that they called the incident terrorism.

Americans are quick to label Muslim shooters terrorists and white shooters mentally ill

What we found is consistent with what Connor Huff and Joshua Kertzer found in a similar study, strengthening the idea that Americans are more likely to call Muslim perpetrators terrorists than they are to use that label for white perpetrators. This adds confidence that our results are not an artifact of our research method.

We ran a second wave of our study, this time with 450 participants, shortly after the Orlando nightclub shooting in 2016, in which Omar Mateen, who was Muslim, killed 49 people, to see whether the results grew stronger in the aftermath of a high-profile incident. The nightclub shooting had no effect on our results; the link between religion/ethnicity and the terrorism label seems to be quite stable.

Participants in both rounds of our experiment also were more likely to tell us that the white shooter was mentally ill, while the Arab American shooter was thought to be motivated by political or religious ideology — even though the story did not mention motive.

Apparently, Americans view violent acts very differently depending on the ethnicity of the perpetrator. Whites and self-declared white supremacists are rarely called terrorists, while people of Middle East descent are quickly given that label.

What we label violence has important consequences 

Does it matter? Yes. Calling an act of violence “terrorism” has legal, political and psychological implications. Mass shootings provoke policy debates about gun control and appropriate mental-health screening, which we also address in our study. Most of the time, such incidents prompt little meaningful legislation. The term “terrorism” is arguably more pejorative and threatening than “mass shooting” or “hate crime.” Terrorist incidents have pushed the United States to fight wars, change airport screening regulations and restrict immigration, among other responses. But these labels are applied inconsistently, depending on who is responsible for the violence.

Over the past decade, self-identified white supremacists have killed more Americans than Islamist militants. Yet a recent paper reveals that these attacks receive far less media attention than attacks by Muslims, contributing to the notion that Islamist terrorism is an existential threat while racist violence is a rare aberration. Some political leaders have fueled this narrative as well, by focusing on threats from foreigners rather than domestic extremists.

Calling people who commit hate crimes, including self-declared white supremacists, terrorists would draw attention and, potentially, resources, to racist violence carried out in the name of an extremist ideology against groups such as Jews, African Americans, Sikhs, Muslims, immigrants, members of the LGBTQ+ community and others. Self-declared white supremacists want to turn the United States into a culturally exclusive society. In that way, they resemble groups like the Islamic State, which wants to construct a “pure” religious community, expelling or subjugating those who think or pray differently.

Terrorism can be considered not just an objective fact but also a socially constructed reality, defined by the language and connotations embedded in the words used. White supremacy has a long and ugly history in the United States. Its extremist worldview also has the potential to inspire more attacks on large numbers of unarmed people.

Idean Salehyan is a professor of political science at the University of North Texas.