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鈥檚 mental resources have been temporarily drained by their efforts to suppress their prejudices.
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Jennifer Richeson, who led the study, was surprised by the results. She believes it is now important to understand these neurological responses. 鈥淚f we can understand the mechanism underlying this effect, we may be able to do something to intervene,鈥� Richeson, at Dartmouth College in New Hampshire, told 快猫短视频.
William Gehring, at the University of Michigan, agrees that the study raises 鈥渃ritical issues鈥� that should be addressed by future research on how races interact. 鈥淚t is indisputable that prejudice exists, and the scientific study of its cognitive and neural underpinnings is exceedingly important,鈥� he writes in an article accompanying Richeson鈥檚 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.
鈥淪ome people find it easier to pair black with negative than black with positive,鈥� 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 鈥渙ne must be cautious鈥� 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 鈥渞obust鈥� 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鈥� brains lit up in the frontal lobe area 鈥� 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. 鈥淚t鈥檚 pretty amazing,鈥� she says.
Executive function
The frontal lobe is associated with 鈥渆xecutive function鈥�, 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. 鈥淭hey are either trying to inhibit or control something 鈥� but we don鈥檛 know what that something is,鈥� she says. 鈥淚t 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.鈥�
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, 鈥渂eing biased has negative consequences for us鈥�, 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: 鈥淭his prospect is remote.鈥�
Journal reference: Nature Neuroscience (DOI: 10.1038/nn1156)