Looking for
the Mind's Eye
By Joseph McLaughlin
This is what's happening right now.
Light
is bouncing off the page and entering your eyes, creating
inverted shapes
on your retinas. The shapes trigger chemical
reactions in rod and cone cells, which send electrical impulses
carried on optic nerves to the back of your brain. The impulses
pass through the optic chiasma, with half from each eye entering
each brain hemisphere. They collect in lateral geniculate
nuclei – relay
stations in each hemisphere - before shooting into your
visual cortex.
And then...consciousness. You “see” the printed
page.
If it seems like a step near the end of the process
is missing, you’re right. Scientists have yet to grasp
fully how neurons tripping inside the darkness of our brains
can create
the experience of vivid reds and brilliant blues, not to mention
light, depth and motion.
“The very fact that you can open your eyes and see
things is amazing,” says Gary Hatfield, the Adam Seybert
Professor in Moral and Intellectual Philosophy. “But
there’s
a gap between the brain process and the experience itself.
At present, we don’t have any real clue about how to
bridge it.”
Hatfield is one of the most comprehensive
thinkers regarding theories of vision and assorted philosophical
streams of
thought, such as philosophy of science and philosophy of
psychology.
He taught at Harvard and Johns Hopkins before arriving 18
years ago at Penn, where he co-founded the university’s
Visual Studies Program. He is affiliated in some way with
every program,
center, study group and institute on campus that wrestles
with the issues of human perception.
“In the philosophy department, he is the person to
study this with,” says former student Morgan Wallhagen,
Gr’04,
who earned his doctoral degree last May and now teaches philosophy
to Penn undergraduates. He says the opportunity to study
with
Hatfield was the deciding factor in his decision to come
to Penn.
Birth of a Question
The disconnect between biological processes and conscious
experience – known
as the mind-body problem – is the missing link for
cognitive scientists, perception researchers and philosophers
such as
Hatfield. “It’s a question for everyone who thinks
in a scientific manner about the origin of living things,” he
says from a couch in his Logan Hall office, surrounded by
books stacked near to the ceiling. It is also a question
that has occu-pied his thoughts from an early age.
Hatfield
first took an interest in sight as a young boy growing
up near Wichita, Kansas. His mother introduced
him to the
visual media through her painting and sculpting, while
his father,
a former biology teacher turned school principal, fostered
a love of science in his preschool-aged son.
By the time he
reached elementary school, Hatfield was hooked on the science
of seeing. “My father brought home The
Book of Knowledge, and I got completely absorbed in
the process, including the relation between the brain and
visual
experience,” he
recalls.
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When the time came for his second-grade class to
give presentations on one of the five senses, he learned
firsthand the inherent
problem of explaining visual perception. “One of the
members of the class asked me a question about that. After
I had finished the presentation, he asked, ‘But how
does it really work? How does the brain really make us see?’ And
there wasn’t
anything else I could say.”So he began learning as
much as possible about seeing and sense perception. Hatfield
filled his high school electives
with
art classes and majored in history of art and psychology
as an undergraduate. After receiving a doctoral degree from
the
University of Wisconsin, conferred jointly in philosophy,
psychology and history of science, he was ready to investigate
the mind-body
problem.
What he encountered, however, was a fractured scholarly
community that often shunned interdisciplinary collaboration.
Philosophers
approached the issue by exploring consciousness while brain
scientists examined the phenomenon by tracking neural pathways.
Communication between the two sides was virtually nonexistent.
For
much of the 20th century, natural scientists followed the
tenets of behaviorism, which seeks to explain humans without
paying attention to mental events such as seeing the color
red or psychological processes
like getting angry. Because mental events were thought to
be subjective, they were disregarded. “Most neuroscientists
were uncomfortable with using a mentalist vocabulary to describe
what the brain does,” Hatfield says. “That consciousness
wasn’t talked about for a period of years was a matter
of wishful thinking.” The mind-body problem
was, essentially, swept under the rug.
A New Terminology
By the 1990s, some neuroscientists were sensing that a strictly
behav-iorist approach was not sufficient to answer their
questions about the human mind. They could not reconcile
buzzing molecules
inside the brain with human awareness. They began to consider
philosoph-ical perspectives and gradually became interested
in how theories of consciousness relate to their ideas about
advanced brain processes.
“Consciousness is quite a difficult thing to analyze,
and philosophers have been working on the description of
consciousness for
quite a long time,” Hatfield explains. “Neuroscientists
realized that some of what philosophers had to say was useful.” For
this cross-disciplinary hand-holding to prosper, however,
it would need philosophers who understood the framework and
language of neuroscience. Hatfield’s
grasp of science and psychology facilitated this sharing
of ideas.
“Professor Hatfield believes that philosophy should
draw upon whatever body of knowledge that
it can, whatever areas of inquiry might be relevant,” Wallhagen
says. “He’s not dogmatic in the way that some
philosophers can be. He thinks that work in the philosophy
of the mind should
be sensitive to the latest results in the relevant sciences.”
Today, Hatfield continues to foster
the exchange of ideas between science and philosophy. He
and Edward Pugh, an ophthalmology
professor in the School of Medicine, recently finished a
paper
that seeks to create some common ground for scientists to
discuss issues of consciousness. The paper focuses on qualia – mental
states that are linked to sense and emotional perception.
Running fingers over sandpaper, smelling a skunk, feeling
a sharp pain
and seeing bright purple
are all examples of qualia.
The paper is an attempt to convince
philosophers and working scientists that qualia
have a place in nature and can be studied through the methods
of natural science, contrary to the doctrine of behaviorism.
Since scientists are often unsure about how to put consciousness
into the scheme of nature, he and Pugh try to debunk the
assumptions that have caused neuroscientists to fear qualitative
data.
“Now, I don’t think that psychologists or neuroscientists
have all the answers to my questions any more than I have
all the answers that might arise from some of their concepts,” he
says. “But I think we can both get a little further
insight into the things we’re
thinking about through this interchange.”
The
ability to encourage dialogue is an aspect that Hatfield
also brings to his teaching. “One of the things he
does in the classroom, which is very difficult, is to engage
the
students in conversation so they are doing some of the work
in class,” Wallhagen says. “Since he’s
open to different approaches, he encourages them to follow
their
instincts, even if it’s a little unpopular.”
Whether
people will ever develop a complete understanding of how
they experience the world around them remains a topic
of
scholarly debate. For his part, Hatfield maintains that communication
between philosophers and scientists will only further the
creation of new knowledge about the human brain, an aspiration
that
his second-grade self would surely appreciate.
“I know a lot more now about how the brain works,” Hatfield
says. “But the issue of how the brain really makes
us see, in the sense of how does it produce conscious experience,
remains a mystery. If you believe that life evolved from
the
primal ooze, then we must ask how consciousness came into
that mix. It’s a fundamental question.” |