Washington: On Monday a grand jury in Cleveland declined to bring criminal charges against the two police officers who fatally shot 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.

Prosecutors said "Tamir was big for his age - 170cm and 79.3 kgs, 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 characterisations 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.