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Decisions that we make every day, such
as whether to take a hot bath or use a seat belt, have an
emotional component. This may explain why it's difficult for
people with certain types of brain injury to make so-called
rational personal decisions.
The circuits are very intertwined. There
isn't just one separate part of the brain that drives us in
emotional decisions and another part that drives us in rational
thinking. In fact, when decisions are personal even if they
are not emotional, the emotional part of the brain is actively
involved.
The old concept of the brain and decision-making
divided the concept of thinking into very separate "rational"
and "emotional" components, while the current view
is these components are integrated
and overlapping.
Using functional magnetic resonance imaging
(fMRI) in volunteers to scan brain activity during the decision-making
process, the researchers found the part of the brain typically
involved in emotions, the ventromedial frontal lobe, was highly
active even when the volunteers were making what typically
would be considered rational decisions.
In the study, six men and five women
underwent two fMRI scans each. During each scan the participants
had to perform two tasks: choosing the better of two desirable
events, such as taking a warm bath or eating a good meal,
or choosing the worse of two undesirable events, such as being
in a car accident or getting robbed.
In the first scan, people were asked
to make their decision based on how it would affect them personally.
In the second, people were asked similar questions, but told
to base their choices purely on cost, not on how the decision
would affect their lives.
On average, the fMRI scans showed significantly
more activity in the ventromedial frontal lobe when the people
were making the simple personal decisions than
when they were making the choices based on cost.
It gives some insight I think into our
psychological process in everyday life that perhaps we are
not aware often of how we make decisions. Our rational decisions
are more biased than we may think.
If you eliminate the emotional guiding
factors, it's impossible to make decisions in daily life.
Even while making a decision, such as 'should I put on my
seatbelt?' you intuitively realize that, without the seatbelt,
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 seatbelt.
The researchers suggest that in the future
it may be possible to use fMRI during psychotherapy. This
could involve imaging the parts of the brain involved in decision-making.
87th
Scientific Assembly and Annual Meeting of the Radiological
Society of North America in Chicago, Illinois November 26,
2001
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