Published in the online edition of Nature Neuroscience on Nov. 16, the study combines the use of functional magnetic resonance imaging (fMRI), which measures brain activity, with other behavioral tests common to research in social and cognitive psychology to determine how white individuals respond to black individuals.
"We were surprised to find that brain activity in response to faces of black individuals predicted how research participants performed on cognitive tasks after actual interracial interactions," says Jennifer Richeson, Assistant Professor of Psychological and Brain Sciences, the lead author on the paper. "To my knowledge, this is the first study to use brain imaging data in tandem with more standard behavioral data to test a social psychological theory."
Their findings suggest that harboring racial bias, however unintentional, makes negotiating interracial interactions more cognitively demanding. Similar to the depletion of a muscle after intensive exercise, the data suggest that the demands of the interracial interaction result in reduced capacity to engage in subsequent cognitive tasks, say the researchers.
For the study, thirty white individuals were measured for racial bias, which involved a computer test to record the ease with which individuals associate white American and black American racial groups with positive and negative concepts. Racial bias is measured by a pattern in which individuals take longer to associate the white Americans with negative concepts and black Americans with positive concepts. The study participants then interacted with either a black or a white individual, and afterward they were asked to complete an unrelated cognitive task in which they had to inhibit instinctual responses. In a separate fMRI session, these individuals were presented with photographs of unfamiliar black male and white male faces, and the activity of brain regions thought to be critical to cognitive control was assessed.
"We found that white people with higher scores on the racial bias measure experienced greater neural activity in response to the photographs of black males," says Richeson. "This heightened activity was in the right dorsolateral prefrontal cortex, an area in the front of the brain that has been linked to the control of thoughts and behaviors. Plus, these same individuals performed worse on the cognitive test after an actual interaction with a black male, suggesting that they may have been depleted of the necessary resources to complete the task."
According to Richeson, most people find it unacceptable to behave in prejudiced ways during interracial interactions and make an effort to avoid doing so, regardless of their level of racial bias. A different research project by Richeson and her colleagues suggested that these efforts could leave individuals temporarily depleted of the resources needed to perform optimally on certain cognitive tasks. This new study by Richeson provides striking evidence that supports the idea that interracial contact temporarily impairs cognitive task performance.
These results suggest, according to the researchers, that harboring racial bias in an increasingly diverse society may be bad for one's cognitive performance.
Other authors on the paper include Abigail A. Baird, Assistant Professor of Psychological and Brain Sciences; Heather Gordon, Ph.D. student in Psychological and Brain Sciences; Todd F. Heatherton, the Champion International Professor of Psychological and Brain Sciences and Director of the Center for Social Brain Sciences at Dartmouth; Carrie Wyland, Ph.D. student in Psychological and Brain Sciences; Sophie Trawalter, Ph.D. student in Psychological and Brain Sciences; and J. Nicole Shelton, Assistant Professor of Psychology at Princeton University.
This research was supported by the National Science Foundation and the Rockefeller Center at Dartmouth College.