Shedding the fears that we acquire about people of other races is as difficult as shaking our fear of spiders and snakes, researchers say. But personal contact with someone of another race helps ease those fears.
Psychologists at Harvard and New York University conditioned more than 70 NYU students to associate images of black and white men with a mildly uncomfortable electric shock.
When the students were repeatedly shown the same images without the shocks, their fears of the other racial group remained as deep-seated as those of a group conditioned to fear spiders and snakes.
The fear of the other race registered whether the test subjects were white or black. But the fears disappeared more quickly among participants who had dated across racial lines, the researchers say.
"What it says is, there's no question that there's a benefit to having positive contact with people of different races," said Mahzarin Banaji, a Harvard psychology professor and co-author of the study, published in the journal Science.
Studies as far back as the 1970s show that people have an easier time recognizing faces from their own racial groups. Known as the same-race advantage, it occurs more consistently among whites than blacks, particularly among whites who have little contact with blacks.
"It could be that in this country at least, black people have more contact with whites than whites have with blacks," said Laura Thomas, a researcher at the Center for Cognitive Neuroscience at Duke University.
The authors of the Science study say their work shows that we're reluctant to change what we've learned about people who look different. "It's not about race, so much as about social groups that you tend to label as yours and not yours. We're less willing to incorporate new information about people from a different social group," said Elizabeth Phelps, a cognitive neuroscientist at NYU.
Phelps said the study goes a step further than previous work by documenting for the first time whether we can "unlearn" fear.
She said that by recognizing such fears, people may be more willing to address them and become more sensitive to the hostilities faced by various groups, such as Arab Muslims here after the Sept. 11 attacks.
She finds it encouraging that the fear disappeared more quickly among students who had dated across racial lines. Some 50 percent of the black NYU students had dated someone of the other race and about 25 percent of the white students had cross-dated, Phelps said.
"It's naive to say that we don't have these biases," she said. "But it's nice to know they can be changed by social contact."
The study consisted of two experiments. In the first, 17 NYU students were shown images of two creatures that traditionally inspire fear (spiders and snakes), along with images of two creatures usually thought of as harmless (birds and butterflies). Electrodes attached to the fingertips measured participants' emotional states by detecting changes in their sweat glands.
The 13 females and four males each saw the four images six times. Each was given an electrical shock when viewing one of the creatures in each of the two sets . The participants then repeatedly viewed the same images without shocks to see how quickly the fear response disappeared.
In the second experiment, 73 students were hooked up to the electrodes and repeatedly viewed images of two black and two white males, all wearing neutral expressions. Each of the 37 black and 36 white participants was shocked while viewing one white face and one black face. The participants then viewed the same images repeatedly without shocks.
The fear responses persisted, despite the absence of shocks, when participants viewed images of opposite racial groups - just as they persisted when participants viewed snakes and spiders in the first experiment.
But the fear responses quickly disappeared when participants viewed images of their own racial groups or of butterflies and birds.
Participants also completed surveys probing their racial attitudes to detect bias.
Some experts said the Science study goes beyond our fear of other races. They said the findings are the result of our evolutionary development as creatures who have learned to fear outsiders as a survival mechanism.
"It's in our nature to be more skeptical, more wary of a member of an outside group," said Arne Ohman, a researcher at the Karolinska Institute in Stockholm, Sweden.
In a perspective article accompanying the report in Science, Ohman argues that what we call race is a relatively recent notion in human society. But fear of outside groups has been common for thousands of years among tribes of hunter-gatherers.
But not everyone sees the results as evidence of our evolutionary past. "I don't know if you can draw that conclusion," said William Cunningham, a psychologist at the University of Toronto.
Cunningham recently recorded brain scans of 13 white participants as they viewed photos of white and black faces for two types of intervals: moments that were so brief the images barely registered or for a half second so they were clearly visible.
He found that when black faces were presented very quickly, the brain region associated with emotion - the amygdala - was more activated. But when the black faces were shown for a half-second, there was greater activation in the frontal cortex areas associated with control and regulation. He published his findings last year in Psychological Science.
"People have a response that is negative initially, but then that's tempered by reflection and the initial response is modified," he said.