"One of our first priorities is to determine what is dangerous and what's not," Rollock said. "The world is this big confusing world of signals, and we have to figure out what is most dangerous first. We freely rely on culture, society and the media to tell us what we should be afraid of."
While racial profiling helps us to make decisions, they may be incorrect ones. For example, the police officer who pulls over someone for racial reasons risks alienating the community, not to mention catching the wrong guy. The next time the officer needs help of information, he or she may not get it, Rollock said.
"For the profiler, there's a real significant danger that they are likely to be inaccurate," he said. "You are not going to be able to do your job effectively."
Rollock cited one study recently of law enforcement stops for drug trafficking at airports. The most likely to be stopped were African-American women. They were also least likely to carry drugs. For Rollock, racial profiling is a personal issue. As a black man growing up in New York City, he remembers many times where he wasn't able to hail a cab even though he was better dressed than white patrons.
"It breeds suspicion and makes it difficult to trust," he said.
He's also had to counsel his sons to be careful when dealing with police.
Both experts say the solution involve getting more information before making a decision about whether someone is a danger. For people walking on the street or on a subway car, perhaps its finding other ways to ensure security -- such as cameras or call buttons -- rather fearing passengers from other races.
Glaser said fighting against stereotypes is difficult, but worthwhile. It starts, he said, with realizing that you've got them in the first place.