http://online.wsj.com/article/SB121450609076407973.html
SCIENCE JOURNAL
By ROBERT LEE HOTZ
Get Out of Your Own Way
Studies Show the Value of Not Overthinking a Decision
June 27, 2008; Page A9
Fi****ng in the stream of consciousness, researchers now can detect our
intentions and predict our choices before we are aware of them
ourselves. The brain, they have found, appears to make up its mind 10
seconds before we become conscious of a decision -- an eternity at the
speed of thought.
Their findings challenge conventional notions of choice.
"We think our decisions are conscious," said neuroscientist John-Dylan
Haynes at the Bernstein Center for Computational Neuroscience in
Berlin, who is pioneering this research. "But these data show that
consciousness is just the tip of the iceberg. This doesn't rule out
free will, but it does make it implausible."
Through a series of intriguing experiments, scientists in Germany,
Norway and the U.S. have analyzed the distinctive cerebral activity
that foreshadows our choices. They have tracked telltale waves of
change through the cells that orchestrate our memory, language, reason
and self-awareness.
In ways we are only beginning to understand, the synapses and neurons
in the human nervous system work in concert to perceive the world
around them, to learn from their perceptions, to remember im****tant
experiences, to plan ahead, and to decide and act on incomplete
information. In a rudimentary way, they predetermine our choices.
To probe what happens in the brain during the moments before people
sense they've reached a decision, Dr. Haynes and his colleagues
devised a deceptively simple experiment, re****ted in April in Nature
Neuroscience. They monitored the swift neural currents coursing
through the brains of student volunteers as they decided, at their own
pace and at random, whether to push a button with their left or right
hands.
In all, they tested seven men and seven women from 21 to 30 years old.
They recorded neural changes associated with thoughts using a
functional magnetic resonance imaging machine and analyzed the results
with an experimental pattern-recognition computer program.
While inside the brain scanner, the students watched random letters
stream across a screen. Whenever they felt the urge, they pressed a
button with their right hand or a button with their left hand. Then
they marked down the letter that had been on the screen in the instant
they had decided to press the button.
Studying the brain behavior leading up to the moment of conscious
decision, the researchers identified signals that let them know when
the students had decided to move 10 seconds or so before the students
knew it themselves. About 70% of the time, the researchers could also
predict which button the students would push.
"It's quite eerie," said Dr. Haynes.
Other researchers have pursued the act of decision deeper into the
subcurrents of the brain.
In experiments with laboratory animals re****ted this spring, Caltech
neuroscientist Richard Anderson and his colleagues explored how the
effort to plan a movement forces cells throughout the brain to work
together, organizing a choice below the threshold of awareness. Tuning
in on the electrical dialogue between working neurons, they pinpointed
the cells of what they called a "free choice" brain circuit that in
milliseconds synchronized scattered synapses to settle on a course of
action.
"It suggests we are looking at this actual decision being made," Dr.
Anderson said. "It is pretty fast."
And when those networks momentarily malfunction, people do make
mistakes. Working independently, psychologist Tom Eichele at Norway's
University of Bergen monitored brain activity in people performing
routine tasks and discovered neural static -- waves of disruptive
signals -- preceded an error by up to 30 seconds. "Thirty seconds is a
long time," Dr. Eichele said.
Such experiments suggest that our best reasons for some choices we
make are understood only by our cells. The findings lend credence to
researchers who argue that many im****tant decisions may be best made
by going with our gut -- not by thinking about them too much.
Dutch researchers led by psychologist Ap Dijksterhuis at the
University of Amsterdam recently found that people struggling to make
relatively complicated consumer choices -- which car to buy, apartment
to rent or vacation to take -- appeared to make sounder decisions when
they were distracted and unable to focus consciously on the problem.
Moreover, the more factors to be considered in a decision, the more
likely the unconscious brain handled it all better, they re****ted in
the peer-reviewed journal Science in 2006. "The idea that conscious
deliberation before making a decision is always good is simply one of
those illusions consciousness creates for us," Dr. Dijksterhuis said.
Does this make our self-awareness just a second thought?
All this work to deconstruct the mental machinery of choice may be the
best evidence of conscious free will. By measuring the brain's
physical processes, the mind seeks to know itself through its
reflection in the mirror of science.
"We are trying to understand who we are," said Antonio Damasio,
director of the Brain and Creativity Institute at the University of
Southern California, "by studying the organ that allows you to
understand who you are."
|
