A mental shortcut becomes almost irresistible and maybe even rational by some lights. The two young black men on one side of the street look like so many others the officer has locked up. Two white men on the other side of the street-even in the same clothes-do not. The officer does not make the same association about the two white guys, whether that officer is white or black. And that drives different behavior. The officer turns toward one side of the street and not the other. We need to come to grips with the fact that this behavior complicates the relationship between police and the communities they serve.