Although many areas
of the human brain are devoted to social tasks like detecting another person
nearby, a new study has found that one small region carries information only
for decisions during social interactions. Specifically, the area is active when
we encounter a worthy opponent and decide whether to deceive them.
A brain imaging study conducted by researchers at the
Duke Center for Interdisciplinary Decision Science (D-CIDES) put human subjects
through a functional MRI brain scan while
playing a simplified game of poker against a computer and human opponents.
Using computer
algorithms to sort out what amount of information each
area of the brain was processing, the team found only one brain region -- the
temporal-parietal junction, or TPJ --- carried information that was unique to
decisions against the human opponent.
Some of the time, the subjects were dealt an obviously
weak hand. The researchers wanted to see whether they could watch the player
calculate whether to bluff his opponent. The brain signals in
the TPJ told the researchers whether the subject would soon bluff against a
human opponent, especially if that opponent was judged to be skilled. But
against a computer, signals in the TPJ did not predict the subject's decisions.
The TPJ is in a boundary area of the brain, and may be an
intersection for two streams of information, said lead researcher McKell
Carter, a postdoctoral fellow at Duke. It brings together a flow of attentional
information and biological information, such as "is that another
person?"
Carter observed that in general, participants paid more
attention to their human opponent
than their computer opponent while playing poker, which is consistent with
humans' drive to be social.
Throughout the poker game experiment, regions of the
brain that are typically thought to be social in nature did not carry
information specific to a social context. "The fact that all of these brain regions that
should be specifically social are used in other circumstances is a testament to
the remarkable flexibility and efficiency of our brains," said Carter.
"There are fundamental neural differences between
decisions in social and non-social situations," said D-CIDES Director
Scott Huettel, the Hubbard professor of psychology & neuroscience at Duke
and senior author of the study. "Social information may cause our brain to
play by different rules than non-social information, and it will be important
for both scientists and policymakers to understand what causes us to approach a
decision in a social or a non-social manner.
"Understanding how the brain identifies important
competitors and collaborators -- those people who are most relevant for our
future behavior -- will lead to new insights into social phenomena like
dehumanization and empathy," Huettel added.
The study, supported by National Institutes of Health,
appears in the July 6Science.
More information: "A
Distinct Role of the Temporal-parietal Junction in Predicting Socially Guided
Decisions," R. McKell Carter, Daniel L. Bowling, Crystal Reeck, and Scott
A. Huettel, Science, July 6, 2012. DOI 10.1126/science.1219681
Provided by Duke University
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