California researchers have found a physiological basis for social pain by monitoring the brains of people who thought they had been maliciously excluded from a computer game by other players.

Naomi I. Eisenberger, a scientist at the University of California, Los Angeles and the first author of the study to be published Friday in the journal Science, said the study suggests that the need for social inclusiveness is a deep-seated part of what it means to be human.

"These findings show how deeply rooted our need is for social connection," said Eisenberger. "There's something about exclusion from others that is perceived as being as harmful to our survival as something that can physically hurt us, and our body automatically knows this."

Eisenberger and her co-authors created a computer game in which test subjects were led to believe they were playing ball with two other players. At some point, the other players seemed to exclude the test subject from the game — making it appear the test subject had been suddenly rejected and blocked from playing with the group.

The shock and distress of this rejection registered in the same part of the brain, called the anterior cingulate cortex, that also responds to physical pain, Eisenberger said.

"The ACC is the same part of the brain that has been found to be associated with the unpleasantness of physical pain, the part of pain that really bothers us," Eisenberger said.

Eisenberger said the study suggests that social exclusion of any sort —— divorce, not being invited to a party, being turned down for a date —— would cause distress in the ACC.

"You can imagine that this part of the brain is active any time we are separated from our close companions," she said. "It would definitely be active when we experience a loss," such as a death or the end of a love affair.

In a commentary in Science, Jaak Panksepp of the department of psychology at Bowling Green State University in Ohio, said earlier studies have shown that the anterior cingulate cortex is linked to physical pain.

He said the new study by Eisenberger and her co-authors demonstrates that the ACC is also activated by the distress of social exclusion.

"Throughout history poets have written about the pain of a broken heart," Panksepp said in his commentary. "It seems that such poetic insights into the human condition are now supported by neurophysiological findings."

The tendency to feel rejection as an acute pain may have developed in humans as a defensive mechanism for the species, said Eisenberger.

"Because we have such a long time as infants and need to be taken care of, it is really important that we stay close to the social group. If we don't we're not going to survive," said Eisenberger. "The hypothesis is that the social attachment system that makes sure we don't stray too far from the group piggybacked onto the pain system to help our species survive."

This suggests that the need to be accepted as part of a social group is as important to humans as avoiding other types of pain, she said.

Just as an infant may learn to avoid fire by first being burned, humans may learn to stick together because rejection causes distress in the pain center of the brain, said Eisenberger.

"If it hurts to be separated from other people, then it will prevent us from straying too far from the social group," she said.