Michael Brown - Science: Blacks seem threatening, often assumed to have gun

http://www.motherjones.com/mojo/2014/08/michael-brown-study-racial-bias-weapon

The scientists measured threat perception and response in the brains of 40 students to targets in a video game, some of whom were carrying pistols while others carried wallets or cellphones. The study authors predicted that because there is a cultural perception that African-Americans are "more threatening," participants' "shoot response" would come more naturally. Indeed that’s how it panned out. The study found that the students shot black targets with guns more quickly than white targets with guns, and took longer to decide not to shoot unarmed blacks than unarmed whites.