Study suggests humans who are rejected feel physical pain
Research highlights the need to belong

By Carey Goldberg
Globe Staff
10/10/2003

New brain-scanning research confirms what the lonely already know from the aching inside: The hurt of social rejection seems to activate parts of the brain in much the same way as physical pain.

The report published today in the journal Science is the first such finding to link pain and social exclusion in humans, researchers said, although animal brain studies have shown a similar link between pain and the distress of mother-child separation.

"Social pain isn't just in the mind," said Matthew Lieberman, coauthor of the report and an assistant professor at the University of California at Los Angeles. The study findings show "our need for social connectedness exists at a much more basic level in humans than we typically realize."

The study fits into a growing body of work about the critical importance of human connections, a hot topic among research psychologists in recent years, said Susan Fiske, a psychology professor at Princeton University. It increasingly appears, she said, that the need to belong is so deep that it is fundamental to survival: "Middle school girls know this better than anybody. . . . Sit at a lunch table with somebody, then get up and move, and they're destroyed."

The researchers, two from UCLA and one from Macquarie University in Australia, asked their subjects to lie in a magnetic resonance imaging machine. Their brains were scanned as they participated in a computer simulation of a three-way game of catch. The subjects, 13 undergraduates, were deceived into thinking that they were playing with people under other scanning machines.

At first, the subject would receive a few passes. Then it would appear that the other players had stopped throwing to the subject, and passed the ball only between themselves for 45 more throws.

When the subjects were left out of the game, an area of the brain associated with physical pain, the anterior cingulate cortex, experienced more activity. The more distress the subject felt, the more active that area of the brain became, reaching moderate-to-large levels of activation similar to the activation reported in a study in which subjects' skin was exposed to about 117-degree heat, Lieberman said.

It might seem that being left out of a trivial game of catch would hardly be enough to elicit a significant feeling of exclusion. But in fact, the study found that subjects felt left out not only when they stopped getting passes, but also even in an introductory period when they were told there were technical problems and they should just watch the other two players for a while. One caution Fiske offered about the study is that the anterior cingulate cortex also is linked with functions other than the experience of physical pain, including the processing of conflicts and inconsistencies. So its activation cannot be seen as incontrovertible proof that an experience is processed like physical pain.Lieberman said he and other coauthors planned next to explore whether a feeling of human connection -- for example, the presence of a loved one near the scanner -- lessens the distress of exclusion from the game.A better understanding of the pain of social exclusion could lead to the development of psychiatric medication for loneliness, said Jaak Panksepp, a neuroscientist at Bowling Green State University in Ohio who pioneered animal studies on the distress of mother-baby separation. He and others cautioned that the study in Science would need much more confirmation and development. Carey Goldberg can be reached at goldberg@globe.com.