There’s some truth to the idea that the broken-hearted may eat entire cartons of Ben & Jerry’s, or that kids picked last for dodgeball may lash out at their classmates.
Experiments have shown that social rejection prompts people to make poor decisions, such as eating more than they know they should or drinking too much. Now, a study in the current issue of the journal Social Neuroscience uncovers the neural basis for such poor decision-making. Researchers report that the feeling of social exclusion changes activity in specific regions of the brain responsible for self-control.
The researchers, a group of neuroscientists and psychologists from the University of Georgia and San Diego State University, asked 30 female undergraduates to fill out a personality questionnaire. After pretending a computer analyzed their answers, the researchers told half of the participants that the results suggested they would “end up alone” later in life.
The subjects then completed a series of math problems, a task that required that they pay attention, an important factor in self-control. While participants solved the problems, researchers examined their brains using magnetoencephalography (MEG), a form of imaging that measures the magnetic fields produced by the brain’s electrical activity. The study was the first to use MEG to test the effects of social exclusion on the brain.
Those who had been told they would end up alone in life answered the math questions more slowly and were more likely to answer them incorrectly. This supported the hypothesis that these subjects would be less in control of their actions.
The discipline needed to concentrate on the math problems parallels the discipline needed to avoid drinking too much or to keep one’s emotions in check, said W. Keith Campbell, the study’s lead author and a psychologist at the University of Georgia. Because a series of math problems requires participants to pay attention and also yields a high quantity of results, it is a standard test of self-control, Campbell said.
The study also found decreased activity in the parietal cortex, a part of the brain associated with paying attention, and the prefrontal cortex, a part of the brain involved in executive control of behavior. The decreased activation of these parts of the brain helps explain the lack of self-control that follows rejection, researchers said.
“It’s a clear link between the neural processes and the social behavior,” Campbell said.
Because MEG measures brain activity millisecond by millisecond, it can help demonstrate causality, said University of Georgia cognitive neuroscientist Brett Clementz, who co-authored the study. Excluded subjects had decreased activity in the parietal cortex and prefrontal cortex just before answering questions incorrectly, demonstrating that the change in brain activity was directly responsible for their poor performance.
Earlier research had established a lack of self-control following social exclusion, “but it was hard to explain why,” said Natalie Ciarocco, a social psychologist at Florida Atlantic University who was not involved in the study.
By identifying the parts of the brain affected by the feelings of exclusion, she said, this research goes a long way to explaining why exclusion has the effect it does.
The study is limited, however, by the fact that it only examined the short-term effect of exclusion, without offering conclusive evidence about the impact of life-long rejection, Clementz said.
“We have to debrief people,” he said. “We can’t let them think forever that they’re going to end up alone.”
Originally published November 30, 2006