In a study to be published in the May issue of Psychological Science, Jennifer Richeson of Dartmouth College and Nicole Shelton of Princeton found that white people with a high degree of racial bias suffer a decrease in a key element of thought called "executive function" immediately following interactions with black people.
The study involved 59 white college students who were given a commonly used test to assess the degree of racial bias in their thinking. The students spent time in conversation with either a black or white person and then were given a test of their ability to concentrate on a challenging mental task. The results showed that the more biased people appeared to be in the first test, the worse they did on the second if they spoke with a black person in between. In contrast, highly biased people who spoke with a white person, even about racially sensitive issues, suffered no subsequent loss of mental function.
"When you have to control your behavior, it takes a lot of energy," said Shelton. "And if you expend energy in a social interaction, then you don't have so much left over to do something else."
The study builds on two previous lines of research, Richeson and Shelton said. First, studies have shown that interracial interactions can be a source of stress and may be particularly so for those who have negative stereotypes of racial minorities. Stress and anxiety, in turn, have been shown to have a negative effect on cognitive functioning. Second, research has suggested that people's ability to fix their attention on certain high-level mental tasks -- called executive function -- is a limited, though renewable, resource. Dieters, for example, have been shown to experience reduced executive control following episodes in which they suppressed a desire to eat, Shelton said.
In their article, titled "When Prejudice Does Not Pay: Effects of Interracial Contact on Executive Function," the researchers describe a detailed series of tests and crosschecks that led to their conclusion. They also urge that the results be "interpreted conservatively" because a number of other factors could alter or eliminate the impairment effect. The effect may not persist, for example, when a person has repeated contact with the same minority group member.
The opening test to assess subtle forms of racial bias consisted of asking the participants to classify a series of words, as fast as possible, into one of four categories: black names, white names, pleasant words and unpleasant words. For instance, the name Jamal would appear on a computer screen and participants had to press a button on the keyboard to indicate that it is a black name. For half of the test, the categories "black names" and "pleasant words" required participants to press the same button, and "white names" and "unpleasant words" required them to press another button. For the other half of the test, the pairings were reversed. The test measured how long it took the participants to press the buttons in each setup. People revealed a racial bias if they consistently exhibited a delayed response when "black names" and "pleasant words" were on the same button, compared to when "white names" and "pleasant words" were on the same button.
The participants then went to another room where half met with a black person and half met with a white person. The participants introduced themselves and then were asked to comment for a few minutes on two subjects, one racially sensitive and one neutral: their views on racial profiling in light of the Sept. 11 attacks; and their feelings regarding the college fraternity system.
Finally, the participants returned to the first room to complete a widely used measure of cognitive function called the Stroop test. Participants sat in front of a computer that flashed the words "yellow," "red," "green" or "blue" or a row of Xs, all in color. In some cases the color of the letters matched the meaning of the word and in others it did not. For example, the word "yellow" could appear in red letters. The participants were asked to press keys to record the actual color, not meaning, of the words or Xs that flashed on the screen. Their response times for the matching and not-matching words were compared with those for the Xs.
Participants who appeared on the first test to have a relatively high degree of racial bias consistently performed worse on the Stroop test when they had spoken with a black person in between, but not when they had spoken with a white person. Participants with average scores on the first test showed less variation in their subsequent mental performance. The findings were further supported by analysis of videotapes of the conversations with the black person, which revealed that people who showed more signs of controlling their behavior, even during the race-neutral fraternity question, fared poorer on the subsequent test of cognitive function.
"People aren't walking around every day taking the Stroop test," said Shelton. "But you could think of work environments where you have to have a meeting with minority group members then you have to go back and work on a paper or teach a class. If you are cognitively drained, it's going to be hard to do that."