Police thought 12-year-old Tamir Rice was 20 when they shot him. This isn’t uncommon.

New details from the November 22 police shooting of 12-year-old Tamir Rice at a Cleveland park show that police officers severely overestimated Rice’s age.

Rice had been playing with a toy gun that looked real, which prompted at least one 911 call from a concerned witness. When police arrived at the scene, they shot Rice within two seconds of getting out of the squad car.

“Shots fired. Male down. Black male, maybe 20,” said the officer who called in the shooting, according to BuzzFeed. The child died from his wounds the next day.

This might seem ridiculous. How can police officers mix up a 12-year-old with a 20-year-old? But it’s actually one of the many ways police commonly misperceive threats by young, black men.

As part of a study published in the American Psychological Association’s Journal of Personality and Social Psychology in March, researchers analyzed the records of 176 mostly white, male police officers, and tested them to see if they held an unconscious “dehumanization bias” against black people by having them match photos of people with photos of big cats or apes. Researchers found that officers who dehumanized black people in the test were also likely to be the ones who had a record of using force on black children in custody.

In the same study, researchers interviewed 264 mostly white, female college students and found that they tended to perceive black children age 10 and older as “significantly less innocent” than their white counterparts.

“Children in most societies are considered to be in a distinct group with characteristics such as innocence and the need for protection,” Phillip Atiba Goff, a UCLA researcher and author of the study, said in a statement. “Our research found that black boys can be seen as responsible for their actions at an age when white boys still benefit from the assumption that children are essentially innocent.”

And it’s not just dehumanization bias. Recent research suggests there can be superhumanization bias at work as well, with white people more likely to associate paranormal or magical powers with black people than other white people. And the more they associate magical powers with black people, the less likely they are to believe black people feel pain.

Ferguson, Missouri, police officer Darren Wilson on August 9 shot and killed unarmed black 18-year-old Michael Brown. In interviews with a grand jury and law enforcement investigating the shooting, Wilson characterized Brown as a demon-like, dead-eyed giant who charged at him through a hail of gunfire.

Vox’s Lauren Williams explained:

[I]t’s this sort of belief that also leads people to think that, say, a black man is impervious to bullets. That a black man has superhuman strength and can crush someone with a single blow. That the only way to deal with someone like this is to put him down. The law says that if a police officer — or, in some states, a civilian — is “reasonably” afraid, he’s within his rights to do just that. And what could be more reasonable than fearing a brute who can feel no pain?

Some experts and advocates are taking steps to address this type of unconscious bias through new, more stringent training. But, as experts told me, police departments have to actually acknowledge the problem exists before they can try to address it. In Cleveland, it’s possible that it could have saved a 12-year-old’s life.