A black Yale student was taking a nap in a common room in her dorm earlier this week when a white student saw her sleeping and decided to call the police.

Lolade Siyonbola, who is a graduate student at Yale, was woken up by the classmate and interrogated by law enforcement for 15 minutes. According to Siyonbola, the white student told police that she appeared out of place in the building.

“I deserve to be here. I pay tuition like everybody else,” Siyonbola told police officers in a video posted to Facebook. “I’m not going to justify my existence here.”

The Yale incident is the latest in a number of recent, high-profile cases where people of color have been racially profiled, confronted by police, and, in some cases, arrested after white business owners, employees, or bystanders viewed them with suspicion. Many of the incidents have spread on social media, calling national attention to the issue.

In April, two black men, Rashon Nelson and Donte Robinson, were arrested for trespassing as they waited inside a Philadelphia Starbucks for a business partner. The men later said they had been inside the Starbucks for mere minutes before the store’s manager called 911 because they sat down without ordering anything.

Not long after this, a black woman was violently arrested inside a Saraland, Alabama, Waffle House and had the front of her shirt pulled down by police officers after a manager called 911 because of a dispute over an extra charge on the woman’s bill.

That same month, the owner of a golf club in Pennsylvania called police on a group of black women who he said were playing too slowly. On April 30, two Native American teenagers were pulled aside by police during a tour of Colorado State University after a white parent on the tour called them. And on May 8, the president of Nordstrom Rack issued an apology after employees at a Missouri location called the police on three black men who were shopping for prom, accusing them of shoplifting. A white customer in the store called the men “a bunch of bums” as they looked through items.

If “shopping while black” and “driving while black” have been long used to describe a tendency for people and police to treat black people with suspicion, recent incidents have provided an increasing number of scenarios to add to the list.

But while it’s tempting to think that this recent wave of incidents is proof that this is a new phenomenon, that’s definitely not the case.

As many black writers have pointed out recently, people of color have long been subject to racial profiling in public, or private, spaces. If anything has changed, it’s that social media and the ubiquity of cellphone cameras have made it easier for black and brown people to share footage of confrontations and arrests in real time.

But though they’re not new, these incidents are a reminder that decades after the collapse of legal segregation, spaces like clothing stores, coffee shops, and universities remain strongly controlled along racial lines.

They also highlight something more complicated. Many people of color already have a tense relationship with law enforcement, due to documented racial bias, disparities in police use of force, and the impacts of officer-involved shootings. When white Americans needlessly call law enforcement on people of color, it makes an existing problem worse.

Some white people are calling the police for really minor things

When looking at the incidents that have occurred over the past month, one thing that stands out is how minor some of the alleged offenses are — and that someone feeling suspicious or uncomfortable is enough to warrant calling law enforcement.

For example, when a woman recently called police on a trio of black filmmakers staying in an Airbnb in Rialto, California, she told authorities that she was suspicious because they didn’t wave to her.

The owner of the Airbnb agreed with the neighbor, saying at a police press conference that “If the kids had simply smiled at (my neighbor) and waved back and acknowledged her and said, ‘We’re just Airbnb guests checking out,’ none of this would have ever happened. But instead, they were rude, unkind, not polite.”

Some people on social media have attempted to justify Siyonbola’s ordeal at Yale by saying she was “rude” for sleeping in the common room of her dorm.

These examples show how people of color are subject to arbitrary social expectations and heightened scrutiny. And it’s a phenomenon that academics argue is more likely to happen in places where people of color, especially black people, are in the minority.

Yale sociologist Elijah Anderson notes that there is a difference between “white spaces,” where black people are often not present or exist in a limited number, and “black spaces,” communities and spaces occupied by larger numbers of black people.

And because so much of America remains divided along racial lines, black people who enter white spaces are often viewed with suspicion unless they are in a service position, like working as a store clerk or a waiter. And as gentrification increases the number of these spaces, this can create huge difficulties.

Anderson notes that part of this suspicion arises from commonly held stereotypes of black people as being criminal and black behavior as being deviant. As a result, black people in these “white spaces” are forced to justify their presence, and face consequences when that justification isn’t accepted by others.

“In the minds of many of their detractors, to scrutinize and stop black people is to prevent crime and protect the neighborhood,” he explained in a 2015 paper. “Thus, for the black person, particularly young males, virtually every public encounter results in a degree of scrutiny that a ‘normal,’ white person would certainly not need to endure.”

But according to academic and writer Tressie McMillan Cottom, the desire to protect space in these instances is not simply motivated by concerns about safety or the desire to “see something, say something” — but a need for control.

On Twitter, Cottom explained that recent incidents like the one at Yale are rooted in an effort to preserve racial hierarchy by showing that black people can be removed at any time. “At millions of places, in a billion different interactions across the country ... a white person is doing all the daily management of white spaces and places,” she wrote.

White and black people have very different perceptions of police

If the recent spate of incidents has sparked a conversation about why black people are met with so much suspicion in public, another important part of the conversation focuses on why the police are being asked to respond to situations where they aren’t really needed.

And when white people call law enforcement on people of color for unnecessary reasons, they are adding to an existing problem, since minority groups are more likely to face police violence or harsh punishment from the justice system.

You don’t need to look far for examples of how this can play out.

In 2015, white residents of a McKinney, Texas, neighborhood called police on a group of black high schoolers holding a pool party, complaining about noise. One adult allegedly told the teenagers to return to “Section 8 [public] housing.” When police arrived, a black girl was violently slammed to the ground and pinned by an officer. Residents later posted signs thanking the officers for “keeping us safe.”

In 2014, John Crawford was fatally shot by police inside an Ohio Walmart after a man called 911, telling the dispatcher that Crawford was pointing the gun at people. Crawford was holding a BB gun, and video footage later showed that he was not waving the weapon.

As the Atlantic’s Adam Harris notes, black and white people call law enforcement at different rates, with people of color calling the police less often. And that difference is driven by a crucial perception: While white people see police as a force that will protect them, communities of color see a force that is more likely to do the opposite.

There’s a real reason for that. In addition to studies that reveal racial disparities in police use of force, data collected by the Guardian shows that black Americans are more likely than whites to be shot by police, when controlling for population.

And as Vox’s German Lopez has noted, high-profile incidents of police violence erode trust in law enforcement, and that trust can be difficult to regain. A 2016 study from a group of sociologists at Yale, Harvard, and Oxford found that after the 2004 police beating of Frank Jude in Milwaukee, Wisconsin, residents made 17 percent fewer 911 calls the next year. And those numbers remained low even after the officers involved in the incident had been punished. Researchers found similar results after high-profile incidents of police brutality in other predominantly black communities.

“White people have not had the same difficult relationship with police and state-sanctioned violence, making them less likely to fear harm by police,” Harris writes. “For black people, an examination of that history can easily discourage someone from picking up the phone —even when they’re in need of help.”

Put together, the incidents like the one at the Philadelphia Starbucks, Yale, and countless other places serve as additional proof of persistent racial divisions in the US. And those divisions, which include assumptions of black guilt in the most minor of circumstances, lead to more policing — part of a much larger problem.