The Boston Globe interviewed experts on the social psychology of the Henry Louis Gates case, concluding that “regardless of people's stated attitudes about race, unconscious racial biases can influence their behavior in surprisingly powerful ways.” People who are not racist may unknowingly behave in ways that reflect racial stereotypes, even when they may disagree with such ideas. One study found that when participants in a computer simulation were told to shoot criminals but not unarmed citizens or police who appeared on the screen, more black than white men were incorrectly shot.
It's impossible to know whether hidden bias caused Cambridge police Sgt. James Crowley, a white man who teaches courses on how to avoid racial profiling, to arrest the African-American Gates. Research indicates that a large majority of white people, and about half of black people, are quicker to make positive associations with white people and negative associations with black people.