Posted on: 11/27/2001
Rational Decisions Guided by Emotion - Study
CHICAGO (Reuters) - Seemingly rational decisions about
ourselves that we make every day, such as whether to fasten a
seat belt, are actually laden with emotion, a U.S. researcher
said on Monday.
Based on X-ray images of the brains of people making
decisions, a study concluded there was evidence that types of
thinking considered "rational" and "emotional" overlapped, in
contrast to older concepts that the mind is sharply divided,
the researcher said.
"If you eliminate the emotional guiding factors, it's
impossible to make decisions in daily life," radiologist Dean
Shibata of the University of Rochester School of Medicine in
New York said in the study.
In the report presented at the annual meeting of the
Radiological Society of North America, Shibata said X-rays of
the brains of people in the act of making decisions that
affected their own lives showed an increase in mental activity
in their prefrontal lobes, the area where emotions are
In addition, analysis of magnetic resonance images taken of
the brains of 11 subjects corroborated previous evidence from
brain-damaged subjects that the area of the brain associated
with emotions play an important role in decision-making.
In the study, Shibata took images of subjects' brains as
they were asked first to make decisions based on how it would
affect them personally.
When asked to make the choice purely on the basis of cost,
there was less activity in the prefrontal lobes where emotions
"People who have had strokes or brain tumors that caused
injury to the prefrontal lobes of their brains, where emotions
are processed, have a very difficult time making even routine
personal decisions, such as scheduling a doctor's appointment,"
When it comes to making apparently rational decisions --
such as what product to buy for themselves or whether to wear a
seat belt -- people with damage to the prefrontal lobes are
stymied, he said. But making the decisions for another person
poses no problem for them.
"Even while making a decision, such as 'Should I put on my
seat belt?' you intuitively realize that without the seat belt,
you might get hurt in a crash. That's an emotional image. If
you can't envision that, you can't make the decision to wear
the seat belt," Shibata said.
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