People with implicit racial prejudices are left mentally exhausted after interacting with someone from a different race, perhaps because they are trying to quell their feelings.
The new study, the first of its kind, shows that areas in the brain associated with self-control light up in white people with implicit racial biases when they are shown images of black people.
Furthermore, the study showed that the level of this brain activity correlated very closely with poor performance in a test of thinking ability given right after a face-to-face interview with a black person. The researchers believe this indicates that the subject’s mental resources have been temporarily drained by their efforts to suppress their prejudices.
Jennifer Richeson, who led the study, was surprised by the results. She believes it is now important to understand these neurological responses. “If we can understand the mechanism underlying this effect, we may be able to do something to intervene,” Richeson, at Dartmouth College in New Hampshire, told New Scientist.
William Gehring, at the University of Michigan, agrees that the study raises “critical issues” that should be addressed by future research on how races interact. “It is indisputable that prejudice exists, and the scientific study of its cognitive and neural underpinnings is exceedingly important,” he writes in an article accompanying Richeson’s paper in Nature Neuroscience.
Positive and negative
In the study, 30 white students were given computer test asking them to classify names as those of black or white people, and words as being positive and negative concepts.
“Some people find it easier to pair black with negative than black with positive,” says Richeson. Those taking longer to press the key for positive words after a black name were scored as having implicit biases. The Implicit Association Test (IAT) is controversial. Gehring says “one must be cautious” regarding any claims that a test is a direct measure of racist attitudes.
The second part of the study involved the students interacting with either a black or white interviewer on controversial topics and then immediately afterwards being given an unrelated cognitive test. Finally, two weeks later, the students were shown photographs of unfamiliar black and white men, while in an MRI brains scanner.
A “robust” link was seen between the IAT-measured racial bias, poor cognitive performance after interview and brain activity in the scanner.
When viewing photos of black individuals, all the students’ brains lit up in the frontal lobe area – known to be involved in cognitive control, says Richeson. In sharp contrast, this area did not light up in any of the students viewing pictures of white individuals. “It’s pretty amazing,” she says.
The frontal lobe is associated with “executive function”, which allows people to control their emotions and thoughts, says Richeson.
The team does not know exactly why this brain area should light up in people with biases. “They are either trying to inhibit or control something – but we don’t know what that something is,” she says. “It could be an emotional reaction, or thoughts that come to mind. Or it could be something as benign as simply trying not to make errors.”
Richeson notes that those with low implicit bias showed no drop in their cognitive performance in the post-interview test. In a modern multicultural world, “being biased has negative consequences for us”, she says.
An editorial in Nature Neuroscience calls the work both interesting and ambitious. But it stresses that while the study links certain brain activity with implicit bias, it says nothing about what causes that bias or how the bias affects behaviour towards people of other races. And on the possibility of a brain scan to detect racism, the editorial says: “This prospect is remote.”
Journal reference: Nature Neuroscience (DOI: 10.1038/nn1156)