Brain Scans Reveal Racial Biases

Negative feelings about black people may be subconsciously learned by both white and black Americans, suggests a brain imaging study. The research is among the first to test the brain physiology of racial biases in both black and white subjects.

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So to tease apart the novelty factor, Lieberman and his colleagues conducted a similar experiment — using a functional MRI scanner — with 11 white and eight black Americans. Each participant completed three matching tasks; a visual task where they had to match the race of a target photo to one of two comparison photos; a verbal task where they had to match a target photo to either the words “African American” or “Caucasian American” and a control test where they matched geometrical shapes.

Both black and white people showed increased amygdala activity on the visual matching task with black target photos. The same task with a white target face produced no such activity. Because black faces are presumed not to be “novel” to black subjects, Lieberman concluded they must have learned, through pervasive cultural cues, to associate black people with fear.

The results mimic studies which measure hidden biases using tests called Implicit Association Tests (IAT), says William Cunningham at the University of Toronto, Canada. IATs use subtle tasks, such as the time it takes for subjects to associate ideas of race and positive or negative words, to uncover unconscious attitudes. Many studies have found that black Americans show preferentially positive associations for white people in IATs.

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