This undated photo provided by the family's attorney shows Tamir Rice, 12. (AP Photo/Courtesy Richardson & Kucharski Co., L.P.A.)

On Monday, a grand jury in Cleveland declined to bring criminal charges against the two police officers involved  in the fatal shooting of 12-year-old Tamir Rice last November. Cuyahoga County District Attorney Tim McGinty has already drawn sharp criticism from Rice's family and on social media for his handling of the case.

Cuyahoga County Prosecutor Timothy McGinty announced that a grand jury will not bring charges against police officers involved in the killing of 12-year-old Tamir Rice, who was carrying a toy gun. (Reuters)

Prosecutors said "Tamir was big for his age — 5-foot-7 and 175 pounds, with a men's XL jacket and size-36 pants — and could have easily passed for someone much older," according to the Los Angeles Times. They cited "unnamed associates" of the 12-year-old who said Tamir was known to pull his toy gun out "like a robber." The language echoes statements given by the responding police officers, who said they believed the boy was much older than 12.

To some social science researchers, these characterizations would not come as a surprise. Rice is black. And research published last year by the American Psychological Association found "evidence that black boys are seen as older and less innocent and that they prompt a less essential conception of childhood than do their white same-age peers." In other words, people tend to think of black boys as bigger and older than they actually are.

In one experiment, a group of 60 police officers from a large urban police force were asked to assess the age of white, black and Latino children based on photographs. The officers were randomly assigned to be told that the children in the photographs were accused of either a misdemeanor or felony charge. The officers overestimate the age of black felony-suspected children by close to five years, but they actually underestimated the age of white felony-suspected children by nearly a year.

[Read more: Police are searching black drivers more often, but finding more illegal stuff with white drivers]

Particularly relevant to the Tamir Rice case: "Black 13-year-olds were miscategorized as adults by police officers (average age error 4.59 years)."

Similar experiments involving 169 mostly white students found that "participants began to think of black children as significantly less innocent than other children at every age group, beginning at the age of 10." These experiments also showed that respondents were more likely to see the black children as "culpable" of a hypothetical felony compared with white and Latino children.

This research comports with other research done in the mid-2000s, which confronted police officers and civilians with photos of black and white armed and unarmed people, and asked them to press a "shoot" or "don't shoot" button for each image. Cops and civilians were more likely to press "shoot" for black images overall, but they were slower to press "don't shoot" for unarmed black images, and quicker to press "shoot" when an image showed an armed black man.

The APA researchers sum up their findings this way: "Our findings suggest that, although most children are allowed to be innocent until adulthood, black children may be perceived as innocent only until deemed suspicious." The Tamir Rice case illustrates that for some black children, those biases can play out with deadly consequences in just a fraction of a second.

Correction: One police officer fatally shot Tamir Rice. An earlier version of this story misstated how many officers fired at the 12 year old. 

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