One evening during graduate school, Mina Cikara was chatting with her future husband and another friend, who was wearing a baseball cap backward. At first, she recalls, it was a very civil conversation. But then her friend turned around, revealing a New York Yankees logo. When her boyfriend noticed the icon, he scoffed. “All of a sudden,” she says, “there’s chest puffing and chin jutting going on.”
On the surface, this interaction seems completely normal—the routine jostling of two sports rivals. But to a keen observer like Cikara, professor of psychology, it raises some deeper questions. Why did her boyfriend suddenly change his behavior when the friend’s fandom was revealed? What made the interaction so negative?
Trivial as a baseball rivalry may be, it reflects an increasingly divided world, often organized by categories—race, ethnicity, or political party—from which conflict emerges. Cikara seeks to understand how and why groups fall into conflict. After studying intergroup relations for nearly two decades, she has formulated a radical hypothesis. Perhaps group identities are not solely formed by a shared set of distinct traits. Instead, there may be a more fundamental social force that sets groups of people against each other. Hard-wired to work in teams, humans assess whether other groups could pose a threat—and respond accordingly.
Cikara has understood the centrality of group membership from birth. The daughter of Yugoslav immigrants—a Bosnian mother and a Serbian father—she was 10 when war, drawn along her family’s ethnic lines, broke out in the region. From her Southern California home, young Cikara wondered how hatred could spread so quickly.
She considered the dynamics of grouping during her social psychology courses at Vassar College, where, as an undergraduate, she grew fascinated by the notion that someone need not be “sick” to harm others. Operating in consort with allies, she noticed, could make people abandon their morality. Her interest in group psychology led her to a Ph.D. at Princeton, a post-doctoral stint at MIT, an assistant professorship at Carnegie Mellon, and, finally, to Harvard, where she was appointed assistant professor in 2014.
People naturally work in groups and find alliances in any setting, Cikara says. The most prominent groups in any society are readily apparent through physical traits, dress, behavior, or association. She wondered just how little information someone needs to figure out who is on a team. A few years ago, Cikara conducted an experiment, which, like much of her work, is simple, yet gives the subjects a sense of social connection even in the isolating environment of an MRI tube or an empty office. The experimenters presented participants with the political beliefs of three imaginary individuals: two characters who agreed with the participant an equal amount and a third who agreed with the participant more often. The subjects were not told whether the three characters were affiliated with any group, nor instructed to look for such connections. Nonetheless, they overwhelmingly noticed that one of those two equally agreeable characters was aligned with the third, simply through the similarity of their opinions. And, when asked which of the first two characters they liked more, participants preferred the one that allied with the third character, whose positions were most like their own. On paper, subjects should not have held strong preferences between the first two characters—they agreed with the participants at the same rate. But, Cikara says, “people could infer social clusters, and preferred the person who clustered with them, even though they were no more similar than the alternative character.”
This narrow experiment points to something much broader. Everywhere humans look, they see groups: layered social structures that nod toward hidden hierarchies of power and association. Simply through the observation of political beliefs, superficially described, participants perceived that two people were part of an “in-group” and one represented an “out-group.” And quickly, their landscape changed from individual to collective: the groups became a matter of us versus them.
Behavior, Cikara argues, differs depending on whether people believe they are operating on an individual level or a group level. That’s why her boyfriend’s tone flipped so quickly. No longer was he just interacting with one person: he was speaking to a whole group—and representing his own alliance.
Having seen that the simple fact of group affiliation changes how humans act toward each other, Cikara wanted to understand what they do with that information. At the most extreme, could the mere fact of a group label inspire someone to harm others?
Simulating violence within a psychology experiment is difficult. Asking someone to throw a punch in an air-conditioned lab fails to recreate the feeling of a passionate bar fight. So Cikara settled for something much tamer. For experimental purposes, she sorted participants into two random groups, ostensibly based on personality traits, and asked them to select which photograph a member of their team and a member of the other should use. She found that the study subjects selected less flattering photos for members of the other group than their own: a minute act of harm. These two groups had no shared history or strife—their division was completely bogus—but people still treated the other group worse than their own. When people think tribally, will they naturally start to dislike members of the “opposing” faction?
Consider American politics. The nation is becoming more polarized. But separate political philosophies fail to explain the degree of hostility in contemporary rhetoric. When two groups argue about ideas—their merits, morals, and implementation—it’s generally good for democracy. But tribal conflict detracts from the operation of politics and governance: seeing political opponents as citizens who hold opposing views is much healthier than perceiving those with other perspectives as fundamentally different beings who deserve to be crushed.
Importantly, Cikara argues, such political factions are formed not by policy positions; rather, they’re solidified by hatred of the other. In 2020, alongside other social scientists, Cikara analyzed what Americans think about the opposing political party. The polled data show that Americans hate their political opponents more than they like their political allies—a new phenomenon in the last decade. Even more intriguing, the survey shows that Americans overestimate how much their political foes hate them. The researchers argue that such political factions are not solely formed by political opinions, but rather are solidified by the suspicion that the opponent harbors ill will. Rival partisans get locked in a spiral of assuming that opponents hate them and ramping up their own animosity in turn.
But not every group is so antagonistic. When she was a graduate student at Princeton, Cikara worked with Susan Fiske, a psychologist who studies how and why people categorize others. According to Fiske, stereotypes are easy ways for humans to assess whether someone could cause harm. When people judge another group, they first weigh whether its members are friends or foes. Next, they determine whether that group is capable of following through on that feeling. The way people react to other groups is based on how threatened they feel. Fiske organizes stereotypes based on “warmth” (friend or foe) and “competence” (capability). Within that framework, Cikara was specifically interested in one category: groups perceived as unfriendly but smart. People act in strange, unkind ways toward members of those groups (which the researchers have found include Asians, Jews, and rich people), especially when those groups experience misfortune.
In May 2007, young socialite Paris Hilton walked into a Los Angeles traffic court following a series of driving infractions. As Cikara made dinner, she flipped through television coverage. Outside the courthouse, protestors partied, celebrating that “justice has been served,” she remembered. The revelry confused her. “Yeah, you shouldn’t drive under the influence,” Cikara said, but do those partiers “celebrate everybody’s DWI?” It is difficult to imagine someone attending a local courthouse to celebrate the minor charges against an everyday civilian. But when someone like Hilton—whose group (rich people) is stereotyped as cold and competent—suffers, others often rejoice. Similarly, when they succeed, others lament.
This flipping of emotion struck Cikara as strange. Was there something about Hilton specifically that drew people’s ire—perhaps misogyny or another stereotype—or was it simply her status as a wealthy celebrity? To investigate the phenomenon, Cikara devised 27 scenarios, divided equally among positive, neutral, and negative events, and created characters representing each quadrant of Fiske’s stereotype model. Would people respond similarly to an old woman (warm but incompetent) and an investment banker (cold yet competent) walking into a glass door? Using sensors that detect facial muscle activity, Cikara measured how participants reacted when reading each scenario. Most subjects’ cheek muscles responded more (consistent with a smile) when reading about a positive situation than a negative one. But when looking at high-status, competent people—Hilton’s celebrity category—participants smiled more when something bad happened. Emotions toward her group were inverted.
After those earlier studies of intergroup negativity, her recent paper considers why certain groups may become targets of hatred. What if intergroup hatred is driven, at its core, by simple competition and primal protectionism?
When the social landscape shifts quickly, perceptions also change. Such was the case in the northeastern United States between 1915 and 1930, when 1.5 million African Americans moved from the South. Earlier, Catholic immigrants from Ireland and Italy were considered an inferior out-group by the white Protestant majority. But by the end of the Great Migration, Irish and Italians came to be seen as part of the white majority.
In 2022, assistant professor of business administration Marco Tabellini published research demonstrating that areas that received more black migrants assimilated European immigrants more quickly. The presence of an even more “out” group normalized the existing minority. He was curious to replicate the study in contemporary circumstances, testing whether the influx of Mexican immigrants during the past few decades has had the effect of improving American white-black relations. Tabellini figured that white Americans would have more in common with the established African American population than newly arrived Mexican immigrants. He indeed found that Mexican migration improved white-black race relations—but the effect did not hold in the South. Curious about the discrepancy, he contacted Cikara.
Analyzing Tabellini’s data, Cikara noticed an important detail about relative population sizes. Because the South receives a large number of Mexican immigrants, one might think that the region would be a prime area for race relations to improve. But Cikara saw that Mexican communities in the South had not yet grown large enough to eclipse the size of the black communities. Very few social psychologists have studied relative group size (the rank of different minority populations), instead usually focusing on absolute population (examining areas with large minority populations). The new data made Cikara wonder about the scale of her observation. Humans, after all, are adept at perceiving relative rank, but less proficient at guessing exact figures.
She, Tabellini, and Stanford political scientist Vasiliki Fouka examined whether racial animosity in America could depend on the relative size of local minority populations. Accordingly, they calculated the relative population rank of black, Hispanic, Asian, and Arab people in each U.S. county and analogous regions in the United Kingdom. Then they counted how many hate crimes white people committed against those groups in every locality. Indeed, they found that Cikara was right: the relatively more populous minority groups are more likely to experience hate crimes.
“Every single way we looked at it,” she said, “the higher the rank of the group...the more likely that group was to be targeted with hate crimes, irrespective of which particular race was in that rank.”
The correlation between minority group rank and number of hate crimes turned out to be very strong. The effect held true no matter how much (or how little) density and diversity a place had, or whether the minority population was large or small. “Every single way we looked at it,” she said, “the higher the rank of the group…the more likely that group was to be targeted with hate crimes, irrespective of which particular race was in that rank.” (Though not a part of this initial study, the researchers wanted to figure out why group size matters so much. “We conjecture,” they write, “that people begin from the premise that they have finite resources with which to defend their groups,” and that they consider “a rank ordering of threat from greatest to least urgency.”)
Hate crimes may, in a sense, stem from the same primal instinct that underlies stereotypes. An innate desire to protect one’s group might send someone on a path toward hatred. Feeling threatened or envious leads people to smile at others’ pain. Hate crimes, Cikara thinks, could follow a similar pattern. “History is still a part of the story,” she says. But rather than groups getting targeted with hate crimes due to their characteristics, are they attacked because others presently perceive them as the greatest threat?
This reimagining of social conflict could provide a new framework to help counteract hatred. Analyzing population data, for example, could help law enforcement officers identify the most vulnerable local groups. Education organizations could help bridge relations between white people and the most prominent minority. Urban planners could encourage building more integrated neighborhoods, as local desegregation is the only factor that manages to break the relationship between minority rank and hate crime: living alongside different people, Cikara says, allows plentiful “opportunities for positive contact.”
Even though the correlation is strong, the researchers recognize that group rank is not the sole determinant of hatred. “Antisemitism, transphobia, Islamophobia: these are [directed at] really, really small communities in the U.S.,” she says, which are nonetheless targeted by people who claim they “are the greatest threats to our country and democracy.”
To Cikara, the gravity of grouping is clear. She often thinks back to the summer of 1991, when her maternal aunt’s family realized they needed to flee Mostar, now part of Bosnia and Herzegovina. Her aunt’s neighbor had told her that she, as a Bosnian Muslim, was “no longer welcome here.” The pair had known each other their whole lives, but political tensions amplified intergroup conflict.
Three decades later, Cikara still wants to understand how neighbors turn on each other. In the future, she plans to examine what happens when people enter “conflict mode.” What language do they use to assert their “victimhood,” and does their posture of oppression imply that their group has done no evil? How do people justify collective violence, and do they argue that the victims deserve punishment? Is it possible to move past the zero-sum framework of group relations, that anything good happening to one group implies that it’s bad for another?
Cikara’s research demonstrates the degree to which humans are hardwired to form groups inherently hostile to outsiders. In learning more about how and why humans hate, she could help shape a better world.
