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 slew 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.
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