The issue of racial profiling has again raised its ugly head after a federal judge knocked down New York City's "stop-and-frisk" policy stating it violated the 14th Amendment's promise of equal protection because black and Hispanic residents were subject to stops and searches at a higher rate than whites.

New York Mayor Michael Bloomberg said the judge didn't understand the benefit of the policy, noting that "nowhere in her 195-page decision does she mention the historic cuts in crime or the number of lives that have been saved."

But is stop-and-frisk just another form of racial profiling? And what's the difference between profiling and racial profiling? Psychologists say that all of us act on stereotypes for different reasons, but the benefits of fighting against making judgments made from stereotypes are worth the effort.

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Racial profiling by police can fit one of several categories, according to Jack Glaser, associate dean of the School of Public Policy at the University of California, Berkeley, and an expert in racial profiling and discrimination.

Police officers can decide to pull over pedestrians who are minorities because they think they are more likely engaged in crime, or they can decide to spend more time patrolling black or Latino neighborhoods rather than neighborhoods with lots of crime, crime that may be correlated with poverty rather than race.

"When we have incomplete information, stereotypes fill that void," Glaser said. "There are these prevailing stereotypes that blacks and Latinos are more prone to crime and that enables people to make an inference about an individual because of they belong to."

Glaser said police in New York and other cities often make judgments about whether to stop someone based on sketchy data.

The difference between profiling and racial profiling is that profiling uses cues about a suspect's current behavior and the officer's personal history of prior situations to predict dangerous outcome, rather than the suspect's race, according to David Rollock, professor of psychological sciences at Purdue University.

While racial profiling helps us to make decisions, they may be incorrect ones. Thinkstock

"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.

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"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.