Identifying Altruism's Source

April 1, 2007
Boy assisting eldery woman across street

H Armstrong Roberts

Altruism describes the tendency of people to act in ways that put the welfare of others ahead of their own. But why do they do this?

The answer is unclear, says Dharol Tankersley, a graduate student in the laboratory of associate professor of biological psychiatry Scott A. Huettel Ph.D. ’99 at the Brain Imaging and Analysis Center. Tankersley is lead investigator on a study that shows that activation of a particular brain region predicts whether people tend to be selfish or altruistic.

“Although understanding the function of this brain region may not necessarily identify what drives people like Mother Teresa, it may give clues to the origins of important social behaviors like altruism,” Huettel says. Results of the study were published in the journal Nature Neuroscience.

In the study, researchers scanned the brains of forty-five people while they either played a computer game or watched the computer play the game on its own. In both cases, successful playing of the game earned money for a charity of the study participant’s choice. Brain scans revealed that a region of the brain called the posterior superior temporal sulcus was activated to a greater degree when people perceived an action—that is, when they watched the computer play the game—than when they acted themselves, Tankersley says. This region, which lies in the top and back portion of the brain, is generally activated when the mind is trying to figure out social relationships.

The researchers then characterized the participants as more or less altruistic, based on their responses to questions about how often they engaged in different helping behaviors, and compared the participants’ brain scans with their estimated level of altruistic behavior. The scans showed that increased activity in the posterior superior temporal sulcus strongly predicted a person’s likelihood of engaging in altruistic behavior.

According to the researchers, the results suggest that altruistic behavior may originate from how people view the world rather than how they act in it. They suggest that studying the brain systems that allow people to see the world as a series of meaningful interactions may ultimately help further understanding of disorders, such as autism or antisocial behavior, that are characterized by deficits in interpersonal interactions.