A dyslexia research team at Yale University's Center
for Learning and Attention lead by Dr. Sally Shaywitz
has found awindow on the brain through a new imaging
technique called functional MRI. These medical
scientists have identified parts of the brain used in
reading. By observing the flow of oxygen-rich blood to
working brain cells, they have found that people who
know how to sound out words can rapidly process what
they see. This information has shed new light on
dyslexia and how to help dyslexics.
When readers are asked to imagine "cat" without the "kah"
sound, they readily summon "at." The MRI photographs
show their brains lighting up like pinball machines.
When the brain gets it, the light bulbs really do go on.
However, the brains of people who can't sound out words
often look different on MRI pictures. There is less
blood flow to the language centers of the brain and, in
some cases, not much activity evident at all.
Scientist's are not sure why this is or what it means.
But simply put, without the ability to sound out words,
the brain is stumped.
Basically this research seems to be saying that the
brain learns to read the same way it learns to talk, one
sound at a time. When babies first learn to talk they
may slowly say one sound at a time. Once they get the
hang of it, they speed up. Our brain becomes adept at
processing and our experience is that of hearing words
but actually our brain is processing sounds (phonemes)
and putting them together so we hear words. When we read
the same process is in operation. Our brain is
processing one sound at a time but we perceive it as a
whole word. In good readers, the process is so fast it
appears that they are reading whole words but in fact
they are converting the letters on the written page into
sounds. The brain then recognizes groups of sounds as
words.
Reading is not automatic but must be learned. The
reader must develop a conscious awareness thatthe letters on
the page represent the sounds of the spoken word. To
read the word "cat," the reader must parse, or segment,
the word into its underlying phonological elements. Once
the word is in its phonological form, it can be
identified and understood. In dyslexia, an inefficient
phonological module produces representations that are
less clear and hence more difficult to bring to
awareness. (Scientific American, November 1996, page
100)
In READING the word (for example, "cat") is first
decoded into its phonological form ("kuh, aah, tuh") and
identified. Once it is identified, higher-level
cognitive functions such as intelligence and vocabulary
are applied to understand the word's meaning ("small
furry mammal that purrs"). In people who have dyslexia,
a phonological deficit impairs decoding, thus preventing
the reader from using his or her intelligence and
vocabulary to get to the word's meaning. (Scientific
American, November 1996, page 101)
According to Dr. Shaywitz, "Over the past two decades, a
coherent model of dyslexia has emerged that is based on
phonological processing. The phonological model is
consistent both with the clinical symptoms of dyslexia
and with what neuroscientists know about brain
organization and function. Investigators from many
laboratories, including my colleagues and I at the Yale
Center, have had the opportunity through 10 years of
cognitive, and more recently, neurobiological studies."
Dyslexics (or poor readers) are very frustrated by the
fact that they can understand what they hear but not
what they read. Dyslexics have average or above average
intelligence. Once they can properly decode words they
can understand the concept. Decoding skills are the key
to learning from written material.
Years of educational research has shown that the use of
intensive phonics is the only way to teachdyslexics and
learning disabled individuals how to read. The new brain
research shows why intensive phonics is also the best
way for everyone to learn to read.
Unfortunately, 80% of our nation's schools do not teach
reading by intensive phonics. Most school use either the
whole word method or a mix of whole word and phonics.
The pictures above illustrate why the brain is confused
by this approach.
Shaywitz, Sally, Dyslexia, Scientific American, November
1996 pp98-104