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Identifying
Altruism’s Source
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.
www.nature.com/neuro/journal/v10/n2/
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