As part of an experiment, a group of white New Yorkers were briefly shown a picture of a man in overalls holding a knife and mugging another man dressed in a suit. One of the men was white, the other was black.
Now in actual fact it was the black man who wore the suit and was being robbed by the white guy. But that didn’t square with the prejudices of the viewers. To them, white men were executives and black men were blue collar workers. Blacks were the robbers, whites the victims. And so they reported what their mind told them they saw– a black labourer assaulting a white businessman.
It was because of inherent prejudice like this that Jesus told the story of the Good Samaritan, teaching us to judge people by what they are as individuals, not by what we perceive them to be as races.