The Hill We Climb: Overcoming Ingroup Versus Outgroup Biases

And so we lift our gazes not to what stands between us but what stands before us

We close the divide because we know, to put our future first, we must first put our differences aside.

… victory won’t lie in the blade. But in all the bridges we’ve made, that is the promise to glade, the hill we climb… .

—Amanda Gorman

On January 6, 2021, the United States Congress met to certify the results of the presidential election. Over the preceding years, America had become increasingly polarized amidst divisive political rhetoric, a global pandemic, and the ongoing plague of racism. At the same time, two miles west, President Trump accused the “radical left” of “stealing the election” and stoked supporters into a frenzied rage. Shortly before 2:00 PM, a mob broke into the federal Capitol. They pillaged the building; over 140 people were injured, and 5 died. The event shook the nation to its core. How did it get to this?

Conflict within a species is evolutionarily old. One of the earliest scientifically documented examples came from the legendary primatologist, Jane Goodall, at Gombe National Park in Tanzania (1). Through the 1960s, Goodall observed a cohort of chimpanzees that included two best friends, Goliath and Jomeo, who frequently groomed and played with each other. As time went on, the group gradually split into Northern and Southern tribes that quietly coexisted for several years. Then, in January 1974, the Northern tribe attacked the Southern tribe. The conflict soon degenerated into all-out war. One year later, Jomeo and five other chimpanzees brutally beat Goliath and left him to die.

Around the time of Goliath’s death, Henri Tajfel was studying group conflict in humans for more personal reasons. Tajfel was born in 1919 to a Jewish family in Poland. He was serving in the French army when his entire immediate family was murdered in the Holocaust. After the war, he moved to the United Kingdom where he spent his career studying social dynamics. The prevailing idea at the time was that group conflict emerged from deep biological or sociocultural differences—but Tajfel wasn’t convinced. In a seminal study, he recruited a cohort of teenage boys from the same school and told them that they were being assigned to groups based on the results of a test (2). They then played a game in which they awarded or deducted points from each other. The boys consistently favored ingroup members and penalized outgroup members—even when doing so came at their own expense. Little did the boys know, the assignments had been random. Which is to say: the mere act of identifying with a group—even if it was completely meaningless—led to immediate biases and changes in behavior.

How do we make sense of this at a neurobiological level? How is it that group identity can so powerfully influence perception and behavior?

One early theory came from V.S. Ramachandran, a behavioral neurologist and neuroscientist known for his uncanny ability to integrate diverse disciplines. In the early 1990s, Ramachandran became intrigued by a study from Giacomo Rizzolatti’s lab in Parma, Italy. The team had implanted electrodes into the premotor cortex of macaque monkeys and identified a population of neurons that fired when the animals were planning movement. Then, over lunch one day, they noticed something peculiar. One of the monkeys watched a graduate student lift an ice cream cone to his mouth—despite not moving a muscle, the monkey’s neurons began firing! Rizzolatti’s team had discovered a population of cells that activated simply by observing movement—what came to be known as the mirror neuron system (3).

Though Rizzolatti’s paper focused on movement, Ramachandran had a more expansive vision—that this mirroring principle could also apply to emotions and could serve as a cellular basis for empathy. In 2000, he boldly proclaimed: “Mirror neurons will do for psychology what DNA did for biology.”

Not surprisingly, Ramachandran thought this same system might play a key role in group identification. To explore this idea, he and Lindsey Oberman recruited 20 college students and showed them a series of video clips while recording EEGs (4). Each clip showed individuals tossing balls with varying degrees of group interaction: first, to themselves; second, to each other; and third, toward the camera, as if the viewer was participating. As predicted (based on motor involvement), mirror neurons were activated in all three conditions. But the story wasn’t so simple. If mirror neurons were only involved in motor processing, their activation should be equivalent across tasks. Instead, activation was highest when subjects “participated” and lowest when there were no interpersonal interactions. In other words, engagement of the mirror neuron system was associated with the perception of group belonging. But this was only the tip of the iceberg.

Mina Cikara was a psychology graduate student at Princeton when a date gone wrong launched her interest in group dynamics. She and her husband, an avid Red Sox fan, had gone to a game at Yankee stadium. Her husband wore a Red Sox hat, which initially invited good-natured banter. But as the innings wore on, the Yankees fans became increasingly aggressive. Attempting to de-escalate the situation, Cikara took her husband’s hat and put it on herself—surely, the fans wouldn’t harass someone who didn’t even care about baseball. But within 10 minutes, the animosity not only continued but Cikara found herself screaming back. (Ironically, her husband ultimately had to intervene.) Reflecting on the episode, Cikara was disturbed by how a seemingly innocuous situation had generated such extreme hostility (in both others and herself). When she finally calmed down, she couldn’t help but wonder: how can civilized people regress so quickly to such primal behaviors?

So Cikara recruited 18 “hardcore” Red Sox and Yankee fans [as defined by knowledge of players and extreme Likert scale ratings of love and hate for the teams (5)]. She set up an ESPN Gamecast monitor and used fMRI to scan participants while they watched various permutations of success and failure by the Red Sox, Yankees, or a neutral team. When fans watched their own team succeed, they showed higher activation of the ventral striatum, a structure implicated in reward. They also showed the same activation when they watched their rival team fail—a biological illustration of schadenfreude.

But the study didn’t end there. Two weeks later, the research team asked participants to rate how likely they would be to heckle, threaten, insult, and even physically strike rival fans. Astonishingly, higher ventral striatum activation was correlated with self-reported likelihood to commit acts of violence.

Of course, it’s not just about baseball—the impact of these networks is insidious and far reaching (6). Group membership determines how people interpret a wide range of scenarios: whether sports officials made the “right” call; how easily individuals recognize ingroup vs. outgroup faces (with fMRI showing differential activation of the fusiform face area); and, more dramatically, how individuals interpret identical statements from ingroup vs. outgroup politicians (with differential activation of semantic processing areas). A contemporary example is vaccination refusal during the COVID-19 pandemic—millions have decided to forgo a life-saving intervention due to the power of group rhetoric.

While most research has explored random group assignments, real-world affiliations are far from arbitrary. Human civilization has deliberately constructed divisions based on ethnicity, gender, socioeconomic status, sexuality, and other factors. These have calcified across generations and become substrates for disparities, hate crimes, civil war, and genocide. In the United States, these distinctions play out in Black and White. The impact of this calculated construct permeates our society—from omnipresent microaggressions to every level of the judicial and carceral system. In a chilling example, naive research participants, in a simulated scenario, consistently shot armed Black men faster than armed White men (7), a finding that echoes epidemiological data that Black people are three times more likely to be the victim of a fatal police shooting than White people (8).

Fortunately, research also points to potential interventions (9). For example, facial processing studies have shown that higher amygdala activation to outgroup faces is attenuated if participants view the faces for longer periods of time. Children who are exposed to diversity earlier in life demonstrate decreased fear responses to outgroups. Cognitive reframing tasks (e.g., mental tasks that shift from categorization to individuation) also decrease activation of brain regions implicated in racial bias (10). If we change the stereotypes we are taught at a young age, increase exposure to diversity, and consciously view people as individuals, we can change the ways our brains perceive and respond to others.

At President Biden’s inauguration, just two weeks after the Capitol insurrection, Amanda Gorman eloquently described the forces that divide America. “What stands between us” is a complex phenomenon that is older than humanity, deeply embedded in core neurobiological circuits. And yet, with targeted education and training—with willful effort—these processes can be malleable. For there is always light, if only we’re brave enough to see it. If only we’re brave enough to be it.