Researchers in
Japan have uncovered two brain signals in the human prefrontal cortex involved
in how humans predict the decisions of others.
Researchers at the RIKEN Brain Science Institute (BSI) in
Japan have uncovered two brain signals in the human prefrontal cortex involved
in how humans predict the decisions of others.
Their results suggest that the two signals, each located
in distinct prefrontal circuits, strike a balance between expected and observed
rewards and choices, enabling humans to predict the actions of people with
different values than their own.
On a daily basis, humans must are faced with situations
in which they must predict what decisions other people will make. These
predictions are essential to the social interactions that make up our personal
and professional lives.
The neural mechanism governing how humans learn to
predict the decisions of another person using mental simulation of their mind,
however, has long remained a mystery.
Learning another person’s values and mental processes is
often assumed to require simulation of the other’s mind: using one’s own
familiar mental processes to simulate unfamiliar processes in the mind of the
other. While simple and intuitive, this explanation is hard to prove due to the
difficulty in disentangling one’s own brain signals from those of the simulated
other.
In a new paper published recently in Neuron,
researchers used functional Magnetic Resonance Imaging (fMRI) to study the
behavior of subjects as they played a game by making predictions about the
other’s behavior based on the knowledge of others and their decisions. They
then generated a computer model of the simulation process to examine the brain
signals underlying the prediction of the other’s behavior.
The authors found that humans simulate the decisions of
other people using two brain signals encoded in the prefrontal cortex, an area
responsible for higher cognition.
One signal involves the estimated value of the reward to
the other person, and is called the reward signal, referring to the difference
between the other’s values, simulated in one’s mind, and the reward benefit
that the other actually received.
The other signal is called the action signal, relating to
the other’s expected action predicted by the simulation process in one’s mind,
and what the other person actually did, which may or may not be different.
They found that the reward signal is processed in a part
of the brain called the ventromedial prefrontal cortex. The action signal, on
the other hand, was found in a separate brain area called the dorsomedial
prefrontal cortex.
“Every day, we interact with a variety of other
individuals,” said lead author Shinsuke Suzuki. “Some may share similar values
with us and for those interactions simulation using the reward signal alone may
suffice. However, other people with different values may be quite different and
then the action signal may become quite important.”
Senior author Hiroyuki Nakahara believes that their
approach, using mathematical models based on human behavior with brain imaging,
will be useful to answer a wide range of questions about the social functions
employed by the brain.
“Perhaps we may one day better understand how and why
humans have the ability to predict others’ behavior, even those with different
characteristics. Ultimately, this knowledge could help improving political,
educational, and social systems in human societies,” Nakahara said.
The article can be found at: Suzuki S et al. (2012) Learning to Simulate
Others’ Decisions.
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Source: RIKEN
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