Published online 12 April 2010 | Nature | doi:10.1038/news.2010.176

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Brain disorder eradicates ethnic but not gender bias.

Children without Williams syndrome form stereotypes about ethnic groups. US Army

Prejudice may seem inescapable, but scientists now report the first group of people who seem not to form racial stereotypes.

Children with a neurodevelopmental disorder called Williams syndrome (WS) are overly friendly because they do not fear strangers. Now, a study shows that these children also do not develop negative attitudes about other ethnic groups, even though they show patterns of gender stereotyping found in other children. "This is the first evidence that different forms of stereotypes are biologically dissociable," says Andreas Meyer-Lindenberg, director of the Central Institute of Mental Health in Mannheim, Germany, who led the study published today in Current Biology1.

Adults with WS show abnormal activity in a brain structure called the amygdala, which is involved in responding to social threats and triggering unconscious negative emotional reactions to other races2,3. Racial bias has been tied to fear: adults are more likely to associate negative objects and events, such as electric shocks, with people of other ethnic groups compared with those of their own group4. But according to Meyer-Lindenberg, his latest study offers the strongest evidence so far that social fear leads to racial stereotyping.

Show no fear

The team showed 18 pictures to 20 children with and 20 without WS, all of whom were of white European origin. Then they asked the children, aged 5-16 years, to choose individuals in the drawings who might engage in sex-specific activities, such as playing with dolls. Both groups of children showed the same patterns of gender stereotyping.

Children in the study were asked to associate characters in stories to pictures of dark- and light-skinned people. Williams, J.E., Best, D.L., and Boswell, D.A. Child Dev. (1975)

The children also heard stories about individuals, represented in drawings, who had negative attributes, such as being naughty and dirty, or positive traits, such as being pretty and smart. They were then asked to choose whether the story was about a light-skinned or a dark-skinned individual in the drawings. One example story was this: "There are two little boys. One of them is a kind little boy. Once he saw a kitten fall into a lake and he picked the kitten up to save it from drowning. Which is the kind little boy?"

Children without WS favoured positive characteristics for the light-skinned children and negative features for dark-skinned individuals, consistent with previous studies on both white and black children5, but those with WS lacked any bias. The obvious conclusion, Meyer-Lindenberg says, is that social fear is not required for gender stereotyping, but it is important in forming racial stereotypes.

"This is a really novel finding, enough to make us rethink what we mean by stereotyping," says Uta Frith, a developmental psychologist at University College London.

Absence of evidence

The results suggest that social fear contributes to racial stereotyping. But WS is associated with other cognitive impairments, such as mental retardation, that may also have a role, Meyer-Lindenberg says.

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Although the authors controlled for many factors, such as IQ and socioeconomic background, children with and without WS may have had different experiences of members of other racial groups, says John Gabrieli, a cognitive neuroscientist at the Massachusetts Institute of Technology in Cambridge. "To a certain degree, all children are exposed to sex roles from their parents, but not all are forced to think about race," he says. Less exposure to racial stereotypes could possibly explain the lack of racial bias in children with WS, he says.

Meyer-Lindenberg believes his findings will replicate in larger samples and different age groups. In future neuroimaging studies, he would like to tease apart the neural circuits involved in different types of stereotypes.

The study does not answer whether stereotyping is genetically determined or based on experience, Meyer-Lindenberg says. So he'd also like to examine the role of experience, for instance, by finding children who have been raised by two members of the same sex.

"Until this study, I think people never imagined that these two stereotypes would be biologically separable," Gabrieli says. "Whether it turns out to be due to genes, the environment or a complicated interaction, it shifts the discussion."