LONDON: Photographs of black faces trigger the brain’s “alarm button” in almost two-thirds of both white and black people, according to the results of a study by American neuroscientists published on Monday. The findings could help explain the pervasive impact of racial stereotypes and the “are you thinking what I’m thinking?” effect.

They could also throw light on how people deal with their unconscious responses to ethnic minorities, outsiders or strangers, because when volunteers in the study were told to label the photographs with descriptions such as “African-American” the response changed.

The amygdala is a tiny bit of the brain which serves as an alarm bell: it sets off a cascade of biological changes that prepare the body to respond to danger long before the brain is consciously aware of any potential hazard.

Matthew Lieberman and colleagues, of the University of California, Los Angeles, report in the online edition of Nature Neuroscience that they asked eight African-American volunteers and 11 Caucasians to look at photographs of expressionless faces, black and white.

The scientists scanned their unconscious brain activity with functional magnetic resonance imaging. Five of the eight black volunteers showed a bigger amygdala response when they saw pictures of other black individuals than when they saw white faces. Seven of the 11 white volunteers produced the same result.—Dawn/The Guardian News Service