THURSDAY, Sept. 16 (HealthDay News) -- Why is it that some
people are much better at turning their thoughts inward and
reflecting on their decisions than others? The answer,
neuroscientists say, may come down partly to differences in brain
In a study published in the Sept. 17 issue of
Science, researchers report that people who are good at introspection, or "thinking about thinking," have a greater volume of gray matter in the area of the brain that lies directly behind the eyes.
"What this study does is allow us to have a better understanding of the biology of the brain that is linked to quite a high level of thinking, which is our ability to reflect on our thoughts and behaviors," said one of the study's lead authors, Steve Fleming, a doctoral candidate at University College London's Wellcome Trust Centre for Neuroimaging.
Fleming noted that introspection isn't the same as knowing the
correct answer. "For example, if you're a contestant on a game show
and you're uncertain about your answer, you might choose to ask the
audience for help. That kind of introspective knowledge is
different from your basic ability to make the right decision."
For the study, Fleming and his colleagues gave 32 healthy adults
a computer test that was designed to measure how well each
participant did at a task, as well as how confident that person was
about his or her decisions during the task.
Each person was shown two screens, both of which contained six
patterned patches. One of the screens, however, contained a single
patch that was brighter than all the rest. The researchers asked
the participants to identify which screen contained the brighter
patch, and then to rate how confident they felt about their final
answers. After the experiment, participants' brains were scanned
using magnetic resonance imaging (MRI).
The researchers' theory was that individuals who were good at
introspection would feel confident after choosing the right answer,
and less so if they were incorrect. By tracking how accurately the
participants were able to rate their own decision-making,
researchers were able to gauge the participants' capacity for
Reviewing the results, Fleming's team found the capacity for
introspection varied widely. They also discovered that a person's
meta-cognitive, or "higher-thinking" introspective abilities, were
significantly associated with the amount of gray matter in the
right anterior prefrontal cortex of the brain and the structure of
neighboring white matter.
To control for differences in the participants' ability to
choose the correct answer, the researchers programmed the computer
to give harder tests to the better observers and easier tests to
the poorer observers.
In an editorial accompanying the study, the authors said that
designing the test so that all of the participants were never
completely sure if their answer was correct was a key advance.
"Previously, there's been some debate as to whether rating perceptual confidence genuinely involved metacognition," or whether people just focused on sensory input, said editorial co-author Hakwan Lau, an assistant professor of psychology at Columbia University in New York City. "So in a sense, by finding out which brain structures may be important for [introspection], they have contributed to clarifying the mechanisms underlying this sort of behavior."
Another expert agreed that the study findings were novel and
intriguing. "What's interesting about this study is that such a
high level of thought behavior can be correlated to a specific part
of the brain," said Paul Sanberg, distinguished professor of
neurosurgery and director of the University of South Florida Center
of Excellence for Aging and Brain Repair in Tampa.
"The reason this study is important is that you need to get a baseline of how the brain functions before you can begin to think about treatments that can help people enhance these kinds of behaviors," Sanberg said.
The association the researchers found doesn't necessarily mean
that people with more gray matter in the prefrontal cortex will be
more introspective than others, according to a statement
accompanying the study release.
Fleming said that an unanswered question is whether people are
born with these brain differences that allow them to be more
introspective, or whether their specific thoughts and behaviors
cause them to become better at it. "What we need to do is assess
whether we can train people to be more introspective, and if so,
does that lead to changes in these structures of the brain," he
He added that future studies are needed to look at whether the
findings hold up for other kinds of introspective behavior.
The Canadian Institutes of Health Research has more about
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