Further reading:
The Mind's Past, by Michael Gazzaniga, a book about the evolution of consciousness and split-brain experiments by one of the people who is doing the actual research.
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The human brain is a funny machine. Imperfectly designed by
natural selection, it finds itself in an environment that has little resemblance
with the one it evolved in. Gone is the savannah in which our ancestors had to
guard themselves from fierce creatures. Instead, we live in a complex and ever
expanding social milieu, our neighborhood now encompassing the whole planet. Is
it any wonder that our poor brains are not doing so well in this brave new wired
world?
Our brains seem to fail to grasp reality, as demonstrated
by the fact that a majority of Americans don't "believe" in evolution
(whatever "believing" in a scientific theory means), while a sizable
percentage is ready to accept the existence of an imaginary all-powerful god, as
well as of the devil, hell, and a sleuth of angels. Why is it so difficult to be
a reasonably skeptical person? What is it that makes so many apparently
intelligent people so gullible about things that their brains clearly have the
power to master? And-perhaps most importantly for the skeptic-how do we get
people to change their minds in an informed way on so wide an array of
irrationalities?
Obviously, I am not going to present the reader with the
magic bullet that can answer these questions, but a starting point is being
provided by recent research in neurobiology. It turns out that lately we have
learned a lot about how the brain works and why it makes mistakes while
interpreting reality. Since our most powerful tool doesn't come with an owner's
manual, it may pay off to spend a little time thinking about how we think.
Perhaps one of the most dramatic ways we are learning about
the brain is by studying patients who literally have a split one. The brain is
made of two hemispheres, joined by a structure called the corpus callosum which
contains nerve fibers that continuously exchange signals between the right and
left hemisphere. Some individuals have suffered more or less complete damage to
the corpus callosum, either because of a stroke or because of a surgical
operation. These subjects are invaluable to neurobiologists because it is
possible to interrogate the right and left hemispheres separately, see how
differently they think, and then piece this information together to reconstruct
the thought patterns of normal individuals. The problem with attempting to
"talk" to both hemispheres is that language is controlled by the left
one, the only hemisphere that can articulate things. Fortunately, the right side
can still "respond" to interrogations by virtue of its control over
the motor functions of the left half of the body, including the arm and
hand.
Perhaps the most astonishing thing neurobiologists have
discovered from split-brain patients is that the left hemisphere, which normally
"dominates" the right one, is literally in charge of our view of the
world. And it fights hard to preserve it. In a wonderfully elegant experiment, a
group of researchers led by Michael Gazzaniga at Dartmouth College showed
pictures to the right and left hemispheres of a split-brain patient and then
asked each hemisphere to pick another picture to accompany the one originally
presented. The right side was shown (through the left half of the visual field)
a house with snow and, logically enough, it picked a shovel. The left hemisphere
was shown a chicken leg (through the right half of the visual field), and it
picked a chicken head-also quite logically. The experimenters then verbally
asked the patient to explain his choices. The left hemisphere was the only one
that could articulate an answer, but remember-it did not know why his right
counterpart had chosen a shovel, since the information about the house with the
snow did not cross the severed corpus callosum. The patient's answer was as
astounding as illuminating: "Oh, that's simple. The chicken claw goes with
the chicken [which was true], and you need a shovel to clean out the chicken
shed [which was coherent, but completely false]." In other words, the left
hemisphere acted as an interpreter of the worldview of the individual and
fabricated a just-so story to fit all the available data!
These sort of experiments have shown that the left
hemisphere is in charge of our worldview, of the paradigms we currently hold
about a variety of aspects of reality. In normal patients, these paradigms are
constantly evaluated against external evidence, gathered by both hemispheres
through a suite of sensorial inputs. The left interpreter has the all-important
function of making sense of the world, and it does a reasonably good job at it.
However, when the incoming data is insufficient, or when some piece of evidence
contradicts the currently held view, the left hemisphere either rejects the
unfit information or it distorts it so to make sense of it. This process of
"rationalizing" the world goes on up to a certain point. If the degree
of conflicting information is too high (i.e., there is too much dissonance
between what one believes and what one perceives) then that most stupendous
phenomenon suddenly occurs: we change our minds (literally)!
The problem that rational people face, then, is twofold. On
the one hand, the brain has evolved a powerful mechanism to avoid to change its
mind too often, which means that people will stubbornly continue to believe all
sorts of nonsense because it is less painful than to radically alter their
worldview. On the other hand, we know that the problem is all the more
insurmountable when the data fed to the subject is poor, and unfortunately most
of what modern human beings are exposed to by the media is pure garbage.
However, there is no need to despair just yet.
Understanding the problem is a necessary (though by all means not sufficient)
step to solve it. Realizing where people's stubbornness (and sometimes our own)
comes from will help not getting unduly irritated or downright nasty when facing
patent irrationality in our fellow human beings. And empathy is one important
step toward connecting with anybody. The second message of modern
neurobiological research is perhaps an old one, but which now comes with the
weight of evidence: education is our (slow) way out. What we need to do is to
keep educating people, to feed good information to the brain's interpreter. If
neurobiologists are correct, most brains will come to understand reality if
properly nurtured. It is ignorance which provides the necessity for just-so
stories, with all the tragic consequences that follow when people defend a
flawed worldview at all costs.
Next Month: "The greatest democracy in the world and
the unfairness of American elections"
© by Massimo Pigliucci, 2001
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Rationally Speaking
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