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Media Contact: Kathi Baker 06 July 2005
  kobaker@emory.edu    
  (404) 727-0464   Print  | Email ]
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Emory Researchers Find a Neurobiological Basis for Social Conformity
Sometimes it's called peer pressure. Sometimes it's called mob mentality. Either way, people have a powerful influence on each other's decision-making -- right or wrong. Gregory Berns, MD, PhD, associate professor in the Department of Psychiatry and Behavioral Sciences at Emory University, recently published a study in Biological Psychiatry, looking at the neurobiological basis for this powerful tendency to conform.

"It had been demonstrated by the social psychologist Solomon Asch that normal individuals will capitulate to a group's judgment -- even when the group is wrong," says Dr. Berns. "The question is 'Why?'"

In order to answer that question, Dr. Berns and his team of researchers used functional magnetic resonance imaging (fMRI) to measure what happens inside the brain when people either conform to a group's judgment, or go against it. With fMRI, researchers can actually see which parts of the brain are activated by a group's influence and, depending on which regions are affected, can infer whether perception or decision-making is being altered.

A total of 32 volunteers participated in the study. The 13 women and 19 men were between ages 19-41. Unknown to the volunteers, four actors were hired to portray a group of volunteer "peers." The actors and the volunteers were introduced to each other as though they were all participants. To insure cohesiveness in the group, they practiced using the testing equipment, took pictures of one another, and talked while they waited for the individual scanning sessions to begin.

Each participant was then placed in an fMRI scanner and was asked to mentally rotate three-dimensional objects on a computer screen and judge whether the objects were the same or different. They were told that during this period the entire group would see the stimuli, and after all of the group members had made their decisions about sameness, their responses would be displayed. In order to induce conformity, pictures of the actors were displayed on the computer screen along with each of their "answers." In one-third of the trials, all of the actors' answers were wrong, in one-third the actors were correct, and in the remaining third the actors' responses were hidden from the participant. There were also a few split decisions thrown in to make it believable. After viewing the actors' answers, the participants gave their own answers. In order to make sure that social pressure was having an effect, participants then repeated the task with pictures of computers that were generating the answers instead of the volunteer "peers."

Following the scanning procedure, participants were asked to complete a questionnaire to assess their perceptions about the experiment. Similar sets of questions were asked about going along with the group verses going against the group, and going along with or against the computers.

The results of the study showed evidence that when people conform to a group's judgment and the group is wrong, changes in activity are noted in the visual and perceptual parts of the brain. The scans showed that the part of the brain that is normally activated during conscious decision-making was not activated. This suggests that groups have the capacity to influence our perceptions of the world, especially when perception and judgment are not clear-cut.

In addition, there was evidence that the parts of the brain associated with negative emotional processing -- the amygdala and caudate nucleus -- are activated when people stand up for what they believe and go against the group. Other contributors to the study were Jonathan Chappelow, Caroline F. Zink, Giuseppe Pagnoni, and Megan E. Martin-Skurski. Jim Richards, an Atlanta businessman and philanthropist, financed the study and was instrumental in the conception of the experiment.



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