fMRI permits us to witness brain activity, the barrier
between subjective and objective knowledge is beginning
are elements of human experience that we all know are
there, but we haven't been able to measure," says
Dr. John Gabrieli, a Stanford neuroscientist. "But
that doesn't mean they're not real. For every psychological
thing you can think of, I believe you can find a correlative
function in the brain if you measure it right."
one novel experiment carried out in Kanwisher's lab, graduate
student Frank Tong asked subjects to wear glasses that
showed a different image to each eye. One eye saw a picture
of a face, and the other a picture of a place. Because
of a widely studied phenomenon called "binocular
rivalry," the brain will only process one of these
pictures at a time, but it randomly switches back and
forth from one to another. Anyone who's looked at ambiguous
figures such as "Old Woman or Young Woman?"
may have experienced a similar phenomenon.
the MRI machine recorded brain activity, the subjects
in Tong's study pressed a button to indicate when the
image switched for them. The active regions of the brain
switched at the same time, physiologically verifying a
phenomenon only the subjects could experience.
benefits of viewing the brain this wayof translating
the subjective into the objectiveare potentially
enormous to many fields. In education, for example, most
decisions about methodology are based on behavioral outcomes.
Reading instruction is a case in point. According to standardized
tests, some children do better when they are taught phonics,
learning to sound out letters and letter groups. Other
students do better when they are taught to recognize individual
words, seeing "dog" as a word, instead of sounding
out "duh-aw-guh." This makes sense, because
one person's brain can be very different from another's,
stronger and weaker in different areas. Currently, the
only way to tell how a child learns best is to wait a
year or more to see if he or she falls behind at learning
something one way, and then try to teach it another way.
if we had a better way than standardized tests (which
are really just behavioral output) to measure learning?
Gabrieli and his colleagues have begun using fMRI technology
to study how we learn reading skills. During the experiment,
adult subjects are given mirror-reversed text to read.
They read it very slowly, laboriously, often confusing
"b" and "d," or "p" and
"q." At first, their right parietal cortex,
the brain region associated with spatial processing, is
very active. After they've had a couple of weeks to practice,
they return to the machine and can read better, though
still laboriously. But now, their left temporal cortex,
the classic language cortex, is active, just as it would
be if they were reading normally. With further experimentation,
researchers may get a good idea of what learning "looks"
like, enabling them to measure it in children far earlier
than standardized tests allow.